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android / platform / external / jetbrains / jdk8u_hotspot / a482fc01a461b60a024295f544eaa063285fee2d / . / src / share / vm / runtime / thread.cpp
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/*
* Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "classfile/classLoader.hpp"
#include "classfile/javaClasses.hpp"
#include "classfile/systemDictionary.hpp"
#include "classfile/vmSymbols.hpp"
#include "code/scopeDesc.hpp"
#include "compiler/compileBroker.hpp"
#include "interpreter/interpreter.hpp"
#include "interpreter/linkResolver.hpp"
#include "interpreter/oopMapCache.hpp"
#include "jvmtifiles/jvmtiEnv.hpp"
#include "memory/gcLocker.inline.hpp"
#include "memory/metaspaceShared.hpp"
#include "memory/oopFactory.hpp"
#include "memory/universe.inline.hpp"
#include "oops/instanceKlass.hpp"
#include "oops/objArrayOop.hpp"
#include "oops/oop.inline.hpp"
#include "oops/symbol.hpp"
#include "prims/jvm_misc.hpp"
#include "prims/jvmtiExport.hpp"
#include "prims/jvmtiThreadState.hpp"
#include "prims/privilegedStack.hpp"
#include "runtime/arguments.hpp"
#include "runtime/biasedLocking.hpp"
#include "runtime/deoptimization.hpp"
#include "runtime/fprofiler.hpp"
#include "runtime/frame.inline.hpp"
#include "runtime/init.hpp"
#include "runtime/interfaceSupport.hpp"
#include "runtime/java.hpp"
#include "runtime/javaCalls.hpp"
#include "runtime/jniPeriodicChecker.hpp"
#include "runtime/memprofiler.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/objectMonitor.hpp"
#include "runtime/orderAccess.inline.hpp"
#include "runtime/osThread.hpp"
#include "runtime/safepoint.hpp"
#include "runtime/sharedRuntime.hpp"
#include "runtime/statSampler.hpp"
#include "runtime/stubRoutines.hpp"
#include "runtime/task.hpp"
#include "runtime/thread.inline.hpp"
#include "runtime/threadCritical.hpp"
#include "runtime/threadLocalStorage.hpp"
#include "runtime/vframe.hpp"
#include "runtime/vframeArray.hpp"
#include "runtime/vframe_hp.hpp"
#include "runtime/vmThread.hpp"
#include "runtime/vm_operations.hpp"
#include "services/attachListener.hpp"
#include "services/management.hpp"
#include "services/memTracker.hpp"
#include "services/threadService.hpp"
#include "trace/tracing.hpp"
#include "trace/traceMacros.hpp"
#include "utilities/defaultStream.hpp"
#include "utilities/dtrace.hpp"
#include "utilities/events.hpp"
#include "utilities/preserveException.hpp"
#include "utilities/macros.hpp"
#ifdef TARGET_OS_FAMILY_linux
# include "os_linux.inline.hpp"
#endif
#ifdef TARGET_OS_FAMILY_solaris
# include "os_solaris.inline.hpp"
#endif
#ifdef TARGET_OS_FAMILY_windows
# include "os_windows.inline.hpp"
#endif
#ifdef TARGET_OS_FAMILY_bsd
# include "os_bsd.inline.hpp"
#endif
#if INCLUDE_ALL_GCS
#include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
#include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
#include "gc_implementation/parallelScavenge/pcTasks.hpp"
#endif // INCLUDE_ALL_GCS
#ifdef COMPILER1
#include "c1/c1_Compiler.hpp"
#endif
#ifdef COMPILER2
#include "opto/c2compiler.hpp"
#include "opto/idealGraphPrinter.hpp"
#endif
#if INCLUDE_RTM_OPT
#include "runtime/rtmLocking.hpp"
#endif
PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
#ifdef DTRACE_ENABLED
// Only bother with this argument setup if dtrace is available
#ifndef USDT2
HS_DTRACE_PROBE_DECL(hotspot, vm__init__begin);
HS_DTRACE_PROBE_DECL(hotspot, vm__init__end);
HS_DTRACE_PROBE_DECL5(hotspot, thread__start, char*, intptr_t,
intptr_t, intptr_t, bool);
HS_DTRACE_PROBE_DECL5(hotspot, thread__stop, char*, intptr_t,
intptr_t, intptr_t, bool);
#define DTRACE_THREAD_PROBE(probe, javathread) \
{ \
ResourceMark rm(this); \
int len = 0; \
const char* name = (javathread)->get_thread_name(); \
len = strlen(name); \
HS_DTRACE_PROBE5(hotspot, thread__##probe, \
name, len, \
java_lang_Thread::thread_id((javathread)->threadObj()), \
(javathread)->osthread()->thread_id(), \
java_lang_Thread::is_daemon((javathread)->threadObj())); \
}
#else /* USDT2 */
#define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
#define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
#define DTRACE_THREAD_PROBE(probe, javathread) \
{ \
ResourceMark rm(this); \
int len = 0; \
const char* name = (javathread)->get_thread_name(); \
len = strlen(name); \
HOTSPOT_THREAD_PROBE_##probe( /* probe = start, stop */ \
(char *) name, len, \
java_lang_Thread::thread_id((javathread)->threadObj()), \
(uintptr_t) (javathread)->osthread()->thread_id(), \
java_lang_Thread::is_daemon((javathread)->threadObj())); \
}
#endif /* USDT2 */
#else // ndef DTRACE_ENABLED
#define DTRACE_THREAD_PROBE(probe, javathread)
#endif // ndef DTRACE_ENABLED
// Class hierarchy
// - Thread
// - VMThread
// - WatcherThread
// - ConcurrentMarkSweepThread
// - JavaThread
// - CompilerThread
// ======= Thread ========
// Support for forcing alignment of thread objects for biased locking
void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
if (UseBiasedLocking) {
const int alignment = markOopDesc::biased_lock_alignment;
size_t aligned_size = size + (alignment - sizeof(intptr_t));
void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
: AllocateHeap(aligned_size, flags, CURRENT_PC,
AllocFailStrategy::RETURN_NULL);
void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
"JavaThread alignment code overflowed allocated storage");
if (TraceBiasedLocking) {
if (aligned_addr != real_malloc_addr)
tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
real_malloc_addr, aligned_addr);
}
((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
return aligned_addr;
} else {
return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
: AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
}
}
void Thread::operator delete(void* p) {
if (UseBiasedLocking) {
void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
FreeHeap(real_malloc_addr, mtThread);
} else {
FreeHeap(p, mtThread);
}
}
// Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
// JavaThread
Thread::Thread() {
// stack and get_thread
set_stack_base(NULL);
set_stack_size(0);
set_self_raw_id(0);
set_lgrp_id(-1);
// allocated data structures
set_osthread(NULL);
set_resource_area(new (mtThread)ResourceArea());
DEBUG_ONLY(_current_resource_mark = NULL;)
set_handle_area(new (mtThread) HandleArea(NULL));
set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
set_active_handles(NULL);
set_free_handle_block(NULL);
set_last_handle_mark(NULL);
// This initial value ==> never claimed.
_oops_do_parity = 0;
_metadata_on_stack_buffer = NULL;
// the handle mark links itself to last_handle_mark
new HandleMark(this);
// plain initialization
debug_only(_owned_locks = NULL;)
debug_only(_allow_allocation_count = 0;)
NOT_PRODUCT(_allow_safepoint_count = 0;)
NOT_PRODUCT(_skip_gcalot = false;)
_jvmti_env_iteration_count = 0;
set_allocated_bytes(0);
_vm_operation_started_count = 0;
_vm_operation_completed_count = 0;
_current_pending_monitor = NULL;
_current_pending_monitor_is_from_java = true;
_current_waiting_monitor = NULL;
_num_nested_signal = 0;
omFreeList = NULL ;
omFreeCount = 0 ;
omFreeProvision = 32 ;
omInUseList = NULL ;
omInUseCount = 0 ;
#ifdef ASSERT
_visited_for_critical_count = false;
#endif
_SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);
_suspend_flags = 0;
// thread-specific hashCode stream generator state - Marsaglia shift-xor form
_hashStateX = os::random() ;
_hashStateY = 842502087 ;
_hashStateZ = 0x8767 ; // (int)(3579807591LL & 0xffff) ;
_hashStateW = 273326509 ;
_OnTrap = 0 ;
_schedctl = NULL ;
_Stalled = 0 ;
_TypeTag = 0x2BAD ;
// Many of the following fields are effectively final - immutable
// Note that nascent threads can't use the Native Monitor-Mutex
// construct until the _MutexEvent is initialized ...
// CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
// we might instead use a stack of ParkEvents that we could provision on-demand.
// The stack would act as a cache to avoid calls to ParkEvent::Allocate()
// and ::Release()
_ParkEvent = ParkEvent::Allocate (this) ;
_SleepEvent = ParkEvent::Allocate (this) ;
_MutexEvent = ParkEvent::Allocate (this) ;
_MuxEvent = ParkEvent::Allocate (this) ;
#ifdef CHECK_UNHANDLED_OOPS
if (CheckUnhandledOops) {
_unhandled_oops = new UnhandledOops(this);
}
#endif // CHECK_UNHANDLED_OOPS
#ifdef ASSERT
if (UseBiasedLocking) {
assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
assert(this == _real_malloc_address ||
this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
"bug in forced alignment of thread objects");
}
#endif /* ASSERT */
}
void Thread::initialize_thread_local_storage() {
// Note: Make sure this method only calls
// non-blocking operations. Otherwise, it might not work
// with the thread-startup/safepoint interaction.
// During Java thread startup, safepoint code should allow this
// method to complete because it may need to allocate memory to
// store information for the new thread.
// initialize structure dependent on thread local storage
ThreadLocalStorage::set_thread(this);
}
void Thread::record_stack_base_and_size() {
set_stack_base(os::current_stack_base());
set_stack_size(os::current_stack_size());
if (is_Java_thread()) {
((JavaThread*) this)->set_stack_overflow_limit();
}
// CR 7190089: on Solaris, primordial thread's stack is adjusted
// in initialize_thread(). Without the adjustment, stack size is
// incorrect if stack is set to unlimited (ulimit -s unlimited).
// So far, only Solaris has real implementation of initialize_thread().
//
// set up any platform-specific state.
os::initialize_thread(this);
#if INCLUDE_NMT
// record thread's native stack, stack grows downward
address stack_low_addr = stack_base() - stack_size();
MemTracker::record_thread_stack(stack_low_addr, stack_size());
#endif // INCLUDE_NMT
}
Thread::~Thread() {
// Reclaim the objectmonitors from the omFreeList of the moribund thread.
ObjectSynchronizer::omFlush (this) ;
EVENT_THREAD_DESTRUCT(this);
// stack_base can be NULL if the thread is never started or exited before
// record_stack_base_and_size called. Although, we would like to ensure
// that all started threads do call record_stack_base_and_size(), there is
// not proper way to enforce that.
#if INCLUDE_NMT
if (_stack_base != NULL) {
address low_stack_addr = stack_base() - stack_size();
MemTracker::release_thread_stack(low_stack_addr, stack_size());
#ifdef ASSERT
set_stack_base(NULL);
#endif
}
#endif // INCLUDE_NMT
// deallocate data structures
delete resource_area();
// since the handle marks are using the handle area, we have to deallocated the root
// handle mark before deallocating the thread's handle area,
assert(last_handle_mark() != NULL, "check we have an element");
delete last_handle_mark();
assert(last_handle_mark() == NULL, "check we have reached the end");
// It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
// We NULL out the fields for good hygiene.
ParkEvent::Release (_ParkEvent) ; _ParkEvent = NULL ;
ParkEvent::Release (_SleepEvent) ; _SleepEvent = NULL ;
ParkEvent::Release (_MutexEvent) ; _MutexEvent = NULL ;
ParkEvent::Release (_MuxEvent) ; _MuxEvent = NULL ;
delete handle_area();
delete metadata_handles();
// osthread() can be NULL, if creation of thread failed.
if (osthread() != NULL) os::free_thread(osthread());
delete _SR_lock;
// clear thread local storage if the Thread is deleting itself
if (this == Thread::current()) {
ThreadLocalStorage::set_thread(NULL);
} else {
// In the case where we're not the current thread, invalidate all the
// caches in case some code tries to get the current thread or the
// thread that was destroyed, and gets stale information.
ThreadLocalStorage::invalidate_all();
}
CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
}
// NOTE: dummy function for assertion purpose.
void Thread::run() {
ShouldNotReachHere();
}
#ifdef ASSERT
// Private method to check for dangling thread pointer
void check_for_dangling_thread_pointer(Thread *thread) {
assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
"possibility of dangling Thread pointer");
}
#endif
#ifndef PRODUCT
// Tracing method for basic thread operations
void Thread::trace(const char* msg, const Thread* const thread) {
if (!TraceThreadEvents) return;
ResourceMark rm;
ThreadCritical tc;
const char *name = "non-Java thread";
int prio = -1;
if (thread->is_Java_thread()
&& !thread->is_Compiler_thread()) {
// The Threads_lock must be held to get information about
// this thread but may not be in some situations when
// tracing thread events.
bool release_Threads_lock = false;
if (!Threads_lock->owned_by_self()) {
Threads_lock->lock();
release_Threads_lock = true;
}
JavaThread* jt = (JavaThread *)thread;
name = (char *)jt->get_thread_name();
oop thread_oop = jt->threadObj();
if (thread_oop != NULL) {
prio = java_lang_Thread::priority(thread_oop);
}
if (release_Threads_lock) {
Threads_lock->unlock();
}
}
tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);
}
#endif
ThreadPriority Thread::get_priority(const Thread* const thread) {
trace("get priority", thread);
ThreadPriority priority;
// Can return an error!
(void)os::get_priority(thread, priority);
assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
return priority;
}
void Thread::set_priority(Thread* thread, ThreadPriority priority) {
trace("set priority", thread);
debug_only(check_for_dangling_thread_pointer(thread);)
// Can return an error!
(void)os::set_priority(thread, priority);
}
void Thread::start(Thread* thread) {
trace("start", thread);
// Start is different from resume in that its safety is guaranteed by context or
// being called from a Java method synchronized on the Thread object.
if (!DisableStartThread) {
if (thread->is_Java_thread()) {
// Initialize the thread state to RUNNABLE before starting this thread.
// Can not set it after the thread started because we do not know the
// exact thread state at that time. It could be in MONITOR_WAIT or
// in SLEEPING or some other state.
java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
java_lang_Thread::RUNNABLE);
}
os::start_thread(thread);
}
}
// Enqueue a VM_Operation to do the job for us - sometime later
void Thread::send_async_exception(oop java_thread, oop java_throwable) {
VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
VMThread::execute(vm_stop);
}
//
// Check if an external suspend request has completed (or has been
// cancelled). Returns true if the thread is externally suspended and
// false otherwise.
//
// The bits parameter returns information about the code path through
// the routine. Useful for debugging:
//
// set in is_ext_suspend_completed():
// 0x00000001 - routine was entered
// 0x00000010 - routine return false at end
// 0x00000100 - thread exited (return false)
// 0x00000200 - suspend request cancelled (return false)
// 0x00000400 - thread suspended (return true)
// 0x00001000 - thread is in a suspend equivalent state (return true)
// 0x00002000 - thread is native and walkable (return true)
// 0x00004000 - thread is native_trans and walkable (needed retry)
//
// set in wait_for_ext_suspend_completion():
// 0x00010000 - routine was entered
// 0x00020000 - suspend request cancelled before loop (return false)
// 0x00040000 - thread suspended before loop (return true)
// 0x00080000 - suspend request cancelled in loop (return false)
// 0x00100000 - thread suspended in loop (return true)
// 0x00200000 - suspend not completed during retry loop (return false)
//
// Helper class for tracing suspend wait debug bits.
//
// 0x00000100 indicates that the target thread exited before it could
// self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
// 0x00080000 each indicate a cancelled suspend request so they don't
// count as wait failures either.
#define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
class TraceSuspendDebugBits : public StackObj {
private:
JavaThread * jt;
bool is_wait;
bool called_by_wait; // meaningful when !is_wait
uint32_t * bits;
public:
TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
uint32_t *_bits) {
jt = _jt;
is_wait = _is_wait;
called_by_wait = _called_by_wait;
bits = _bits;
}
~TraceSuspendDebugBits() {
if (!is_wait) {
#if 1
// By default, don't trace bits for is_ext_suspend_completed() calls.
// That trace is very chatty.
return;
#else
if (!called_by_wait) {
// If tracing for is_ext_suspend_completed() is enabled, then only
// trace calls to it from wait_for_ext_suspend_completion()
return;
}
#endif
}
if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
MutexLocker ml(Threads_lock); // needed for get_thread_name()
ResourceMark rm;
tty->print_cr(
"Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
jt->get_thread_name(), *bits);
guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
}
}
}
};
#undef DEBUG_FALSE_BITS
bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) {
TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
bool did_trans_retry = false; // only do thread_in_native_trans retry once
bool do_trans_retry; // flag to force the retry
*bits |= 0x00000001;
do {
do_trans_retry = false;
if (is_exiting()) {
// Thread is in the process of exiting. This is always checked
// first to reduce the risk of dereferencing a freed JavaThread.
*bits |= 0x00000100;
return false;
}
if (!is_external_suspend()) {
// Suspend request is cancelled. This is always checked before
// is_ext_suspended() to reduce the risk of a rogue resume
// confusing the thread that made the suspend request.
*bits |= 0x00000200;
return false;
}
if (is_ext_suspended()) {
// thread is suspended
*bits |= 0x00000400;
return true;
}
// Now that we no longer do hard suspends of threads running
// native code, the target thread can be changing thread state
// while we are in this routine:
//
// _thread_in_native -> _thread_in_native_trans -> _thread_blocked
//
// We save a copy of the thread state as observed at this moment
// and make our decision about suspend completeness based on the
// copy. This closes the race where the thread state is seen as
// _thread_in_native_trans in the if-thread_blocked check, but is
// seen as _thread_blocked in if-thread_in_native_trans check.
JavaThreadState save_state = thread_state();
if (save_state == _thread_blocked && is_suspend_equivalent()) {
// If the thread's state is _thread_blocked and this blocking
// condition is known to be equivalent to a suspend, then we can
// consider the thread to be externally suspended. This means that
// the code that sets _thread_blocked has been modified to do
// self-suspension if the blocking condition releases. We also
// used to check for CONDVAR_WAIT here, but that is now covered by
// the _thread_blocked with self-suspension check.
//
// Return true since we wouldn't be here unless there was still an
// external suspend request.
*bits |= 0x00001000;
return true;
} else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
// Threads running native code will self-suspend on native==>VM/Java
// transitions. If its stack is walkable (should always be the case
// unless this function is called before the actual java_suspend()
// call), then the wait is done.
*bits |= 0x00002000;
return true;
} else if (!called_by_wait && !did_trans_retry &&
save_state == _thread_in_native_trans &&
frame_anchor()->walkable()) {
// The thread is transitioning from thread_in_native to another
// thread state. check_safepoint_and_suspend_for_native_trans()
// will force the thread to self-suspend. If it hasn't gotten
// there yet we may have caught the thread in-between the native
// code check above and the self-suspend. Lucky us. If we were
// called by wait_for_ext_suspend_completion(), then it
// will be doing the retries so we don't have to.
//
// Since we use the saved thread state in the if-statement above,
// there is a chance that the thread has already transitioned to
// _thread_blocked by the time we get here. In that case, we will
// make a single unnecessary pass through the logic below. This
// doesn't hurt anything since we still do the trans retry.
*bits |= 0x00004000;
// Once the thread leaves thread_in_native_trans for another
// thread state, we break out of this retry loop. We shouldn't
// need this flag to prevent us from getting back here, but
// sometimes paranoia is good.
did_trans_retry = true;
// We wait for the thread to transition to a more usable state.
for (int i = 1; i <= SuspendRetryCount; i++) {
// We used to do an "os::yield_all(i)" call here with the intention
// that yielding would increase on each retry. However, the parameter
// is ignored on Linux which means the yield didn't scale up. Waiting
// on the SR_lock below provides a much more predictable scale up for
// the delay. It also provides a simple/direct point to check for any
// safepoint requests from the VMThread
// temporarily drops SR_lock while doing wait with safepoint check
// (if we're a JavaThread - the WatcherThread can also call this)
// and increase delay with each retry
SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
// check the actual thread state instead of what we saved above
if (thread_state() != _thread_in_native_trans) {
// the thread has transitioned to another thread state so
// try all the checks (except this one) one more time.
do_trans_retry = true;
break;
}
} // end retry loop
}
} while (do_trans_retry);
*bits |= 0x00000010;
return false;
}
//
// Wait for an external suspend request to complete (or be cancelled).
// Returns true if the thread is externally suspended and false otherwise.
//
bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
uint32_t *bits) {
TraceSuspendDebugBits tsdb(this, true /* is_wait */,
false /* !called_by_wait */, bits);
// local flag copies to minimize SR_lock hold time
bool is_suspended;
bool pending;
uint32_t reset_bits;
// set a marker so is_ext_suspend_completed() knows we are the caller
*bits |= 0x00010000;
// We use reset_bits to reinitialize the bits value at the top of
// each retry loop. This allows the caller to make use of any
// unused bits for their own marking purposes.
reset_bits = *bits;
{
MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
delay, bits);
pending = is_external_suspend();
}
// must release SR_lock to allow suspension to complete
if (!pending) {
// A cancelled suspend request is the only false return from
// is_ext_suspend_completed() that keeps us from entering the
// retry loop.
*bits |= 0x00020000;
return false;
}
if (is_suspended) {
*bits |= 0x00040000;
return true;
}
for (int i = 1; i <= retries; i++) {
*bits = reset_bits; // reinit to only track last retry
// We used to do an "os::yield_all(i)" call here with the intention
// that yielding would increase on each retry. However, the parameter
// is ignored on Linux which means the yield didn't scale up. Waiting
// on the SR_lock below provides a much more predictable scale up for
// the delay. It also provides a simple/direct point to check for any
// safepoint requests from the VMThread
{
MutexLocker ml(SR_lock());
// wait with safepoint check (if we're a JavaThread - the WatcherThread
// can also call this) and increase delay with each retry
SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
delay, bits);
// It is possible for the external suspend request to be cancelled
// (by a resume) before the actual suspend operation is completed.
// Refresh our local copy to see if we still need to wait.
pending = is_external_suspend();
}
if (!pending) {
// A cancelled suspend request is the only false return from
// is_ext_suspend_completed() that keeps us from staying in the
// retry loop.
*bits |= 0x00080000;
return false;
}
if (is_suspended) {
*bits |= 0x00100000;
return true;
}
} // end retry loop
// thread did not suspend after all our retries
*bits |= 0x00200000;
return false;
}
#ifndef PRODUCT
void JavaThread::record_jump(address target, address instr, const char* file, int line) {
// This should not need to be atomic as the only way for simultaneous
// updates is via interrupts. Even then this should be rare or non-existant
// and we don't care that much anyway.
int index = _jmp_ring_index;
_jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1);
_jmp_ring[index]._target = (intptr_t) target;
_jmp_ring[index]._instruction = (intptr_t) instr;
_jmp_ring[index]._file = file;
_jmp_ring[index]._line = line;
}
#endif /* PRODUCT */
// Called by flat profiler
// Callers have already called wait_for_ext_suspend_completion
// The assertion for that is currently too complex to put here:
bool JavaThread::profile_last_Java_frame(frame* _fr) {
bool gotframe = false;
// self suspension saves needed state.
if (has_last_Java_frame() && _anchor.walkable()) {
*_fr = pd_last_frame();
gotframe = true;
}
return gotframe;
}
void Thread::interrupt(Thread* thread) {
trace("interrupt", thread);
debug_only(check_for_dangling_thread_pointer(thread);)
os::interrupt(thread);
}
bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
trace("is_interrupted", thread);
debug_only(check_for_dangling_thread_pointer(thread);)
// Note: If clear_interrupted==false, this simply fetches and
// returns the value of the field osthread()->interrupted().
return os::is_interrupted(thread, clear_interrupted);
}
// GC Support
bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
jint thread_parity = _oops_do_parity;
if (thread_parity != strong_roots_parity) {
jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
if (res == thread_parity) {
return true;
} else {
guarantee(res == strong_roots_parity, "Or else what?");
assert(SharedHeap::heap()->workers()->active_workers() > 0,
"Should only fail when parallel.");
return false;
}
}
assert(SharedHeap::heap()->workers()->active_workers() > 0,
"Should only fail when parallel.");
return false;
}
void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
active_handles()->oops_do(f);
// Do oop for ThreadShadow
f->do_oop((oop*)&_pending_exception);
handle_area()->oops_do(f);
}
void Thread::nmethods_do(CodeBlobClosure* cf) {
// no nmethods in a generic thread...
}
void Thread::metadata_do(void f(Metadata*)) {
if (metadata_handles() != NULL) {
for (int i = 0; i< metadata_handles()->length(); i++) {
f(metadata_handles()->at(i));
}
}
}
void Thread::print_on(outputStream* st) const {
// get_priority assumes osthread initialized
if (osthread() != NULL) {
int os_prio;
if (os::get_native_priority(this, &os_prio) == OS_OK) {
st->print("os_prio=%d ", os_prio);
}
st->print("tid=" INTPTR_FORMAT " ", this);
ext().print_on(st);
osthread()->print_on(st);
}
debug_only(if (WizardMode) print_owned_locks_on(st);)
}
// Thread::print_on_error() is called by fatal error handler. Don't use
// any lock or allocate memory.
void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
if (is_VM_thread()) st->print("VMThread");
else if (is_Compiler_thread()) st->print("CompilerThread");
else if (is_Java_thread()) st->print("JavaThread");
else if (is_GC_task_thread()) st->print("GCTaskThread");
else if (is_Watcher_thread()) st->print("WatcherThread");
else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread");
else st->print("Thread");
st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
_stack_base - _stack_size, _stack_base);
if (osthread()) {
st->print(" [id=%d]", osthread()->thread_id());
}
}
#ifdef ASSERT
void Thread::print_owned_locks_on(outputStream* st) const {
Monitor *cur = _owned_locks;
if (cur == NULL) {
st->print(" (no locks) ");
} else {
st->print_cr(" Locks owned:");
while(cur) {
cur->print_on(st);
cur = cur->next();
}
}
}
static int ref_use_count = 0;
bool Thread::owns_locks_but_compiled_lock() const {
for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
if (cur != Compile_lock) return true;
}
return false;
}
#endif
#ifndef PRODUCT
// The flag: potential_vm_operation notifies if this particular safepoint state could potential
// invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
// no threads which allow_vm_block's are held
void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
// Check if current thread is allowed to block at a safepoint
if (!(_allow_safepoint_count == 0))
fatal("Possible safepoint reached by thread that does not allow it");
if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
fatal("LEAF method calling lock?");
}
#ifdef ASSERT
if (potential_vm_operation && is_Java_thread()
&& !Universe::is_bootstrapping()) {
// Make sure we do not hold any locks that the VM thread also uses.
// This could potentially lead to deadlocks
for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
// Threads_lock is special, since the safepoint synchronization will not start before this is
// acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
// since it is used to transfer control between JavaThreads and the VMThread
// Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first!
if ( (cur->allow_vm_block() &&
cur != Threads_lock &&
cur != Compile_lock && // Temporary: should not be necessary when we get spearate compilation
cur != VMOperationRequest_lock &&
cur != VMOperationQueue_lock) ||
cur->rank() == Mutex::special) {
fatal(err_msg("Thread holding lock at safepoint that vm can block on: %s", cur->name()));
}
}
}
if (GCALotAtAllSafepoints) {
// We could enter a safepoint here and thus have a gc
InterfaceSupport::check_gc_alot();
}
#endif
}
#endif
bool Thread::is_in_stack(address adr) const {
assert(Thread::current() == this, "is_in_stack can only be called from current thread");
address end = os::current_stack_pointer();
// Allow non Java threads to call this without stack_base
if (_stack_base == NULL) return true;
if (stack_base() >= adr && adr >= end) return true;
return false;
}
bool Thread::is_in_usable_stack(address adr) const {
size_t stack_guard_size = os::uses_stack_guard_pages() ? (StackYellowPages + StackRedPages) * os::vm_page_size() : 0;
size_t usable_stack_size = _stack_size - stack_guard_size;
return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
}
// We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
// However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
// used for compilation in the future. If that change is made, the need for these methods
// should be revisited, and they should be removed if possible.
bool Thread::is_lock_owned(address adr) const {
return on_local_stack(adr);
}
bool Thread::set_as_starting_thread() {
// NOTE: this must be called inside the main thread.
return os::create_main_thread((JavaThread*)this);
}
static void initialize_class(Symbol* class_name, TRAPS) {
Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
InstanceKlass::cast(klass)->initialize(CHECK);
}
// Creates the initial ThreadGroup
static Handle create_initial_thread_group(TRAPS) {
Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
instanceKlassHandle klass (THREAD, k);
Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
{
JavaValue result(T_VOID);
JavaCalls::call_special(&result,
system_instance,
klass,
vmSymbols::object_initializer_name(),
vmSymbols::void_method_signature(),
CHECK_NH);
}
Universe::set_system_thread_group(system_instance());
Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
{
JavaValue result(T_VOID);
Handle string = java_lang_String::create_from_str("main", CHECK_NH);
JavaCalls::call_special(&result,
main_instance,
klass,
vmSymbols::object_initializer_name(),
vmSymbols::threadgroup_string_void_signature(),
system_instance,
string,
CHECK_NH);
}
return main_instance;
}
// Creates the initial Thread
static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) {
Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
instanceKlassHandle klass (THREAD, k);
instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
java_lang_Thread::set_thread(thread_oop(), thread);
java_lang_Thread::set_priority(thread_oop(), NormPriority);
thread->set_threadObj(thread_oop());
Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
JavaValue result(T_VOID);
JavaCalls::call_special(&result, thread_oop,
klass,
vmSymbols::object_initializer_name(),
vmSymbols::threadgroup_string_void_signature(),
thread_group,
string,
CHECK_NULL);
return thread_oop();
}
static void call_initializeSystemClass(TRAPS) {
Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
instanceKlassHandle klass (THREAD, k);
JavaValue result(T_VOID);
JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
vmSymbols::void_method_signature(), CHECK);
}
char java_runtime_name[128] = "";
char java_runtime_version[128] = "";
// extract the JRE name from sun.misc.Version.java_runtime_name
static const char* get_java_runtime_name(TRAPS) {
Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
Handle(), Handle(), CHECK_AND_CLEAR_NULL);
fieldDescriptor fd;
bool found = k != NULL &&
InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
vmSymbols::string_signature(), &fd);
if (found) {
oop name_oop = k->java_mirror()->obj_field(fd.offset());
if (name_oop == NULL)
return NULL;
const char* name = java_lang_String::as_utf8_string(name_oop,
java_runtime_name,
sizeof(java_runtime_name));
return name;
} else {
return NULL;
}
}
// extract the JRE version from sun.misc.Version.java_runtime_version
static const char* get_java_runtime_version(TRAPS) {
Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
Handle(), Handle(), CHECK_AND_CLEAR_NULL);
fieldDescriptor fd;
bool found = k != NULL &&
InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
vmSymbols::string_signature(), &fd);
if (found) {
oop name_oop = k->java_mirror()->obj_field(fd.offset());
if (name_oop == NULL)
return NULL;
const char* name = java_lang_String::as_utf8_string(name_oop,
java_runtime_version,
sizeof(java_runtime_version));
return name;
} else {
return NULL;
}
}
// General purpose hook into Java code, run once when the VM is initialized.
// The Java library method itself may be changed independently from the VM.
static void call_postVMInitHook(TRAPS) {
Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD);
instanceKlassHandle klass (THREAD, k);
if (klass.not_null()) {
JavaValue result(T_VOID);
JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
vmSymbols::void_method_signature(),
CHECK);
}
}
static void reset_vm_info_property(TRAPS) {
// the vm info string
ResourceMark rm(THREAD);
const char *vm_info = VM_Version::vm_info_string();
// java.lang.System class
Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
instanceKlassHandle klass (THREAD, k);
// setProperty arguments
Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
// return value
JavaValue r(T_OBJECT);
// public static String setProperty(String key, String value);
JavaCalls::call_static(&r,
klass,
vmSymbols::setProperty_name(),
vmSymbols::string_string_string_signature(),
key_str,
value_str,
CHECK);
}
void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) {
assert(thread_group.not_null(), "thread group should be specified");
assert(threadObj() == NULL, "should only create Java thread object once");
Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
instanceKlassHandle klass (THREAD, k);
instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
java_lang_Thread::set_thread(thread_oop(), this);
java_lang_Thread::set_priority(thread_oop(), NormPriority);
set_threadObj(thread_oop());
JavaValue result(T_VOID);
if (thread_name != NULL) {
Handle name = java_lang_String::create_from_str(thread_name, CHECK);
// Thread gets assigned specified name and null target
JavaCalls::call_special(&result,
thread_oop,
klass,
vmSymbols::object_initializer_name(),
vmSymbols::threadgroup_string_void_signature(),
thread_group, // Argument 1
name, // Argument 2
THREAD);
} else {
// Thread gets assigned name "Thread-nnn" and null target
// (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
JavaCalls::call_special(&result,
thread_oop,
klass,
vmSymbols::object_initializer_name(),
vmSymbols::threadgroup_runnable_void_signature(),
thread_group, // Argument 1
Handle(), // Argument 2
THREAD);
}
if (daemon) {
java_lang_Thread::set_daemon(thread_oop());
}
if (HAS_PENDING_EXCEPTION) {
return;
}
KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
Handle threadObj(this, this->threadObj());
JavaCalls::call_special(&result,
thread_group,
group,
vmSymbols::add_method_name(),
vmSymbols::thread_void_signature(),
threadObj, // Arg 1
THREAD);
}
// NamedThread -- non-JavaThread subclasses with multiple
// uniquely named instances should derive from this.
NamedThread::NamedThread() : Thread() {
_name = NULL;
_processed_thread = NULL;
}
NamedThread::~NamedThread() {
if (_name != NULL) {
FREE_C_HEAP_ARRAY(char, _name, mtThread);
_name = NULL;
}
}
void NamedThread::set_name(const char* format, ...) {
guarantee(_name == NULL, "Only get to set name once.");
_name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
guarantee(_name != NULL, "alloc failure");
va_list ap;
va_start(ap, format);
jio_vsnprintf(_name, max_name_len, format, ap);
va_end(ap);
}
// ======= WatcherThread ========
// The watcher thread exists to simulate timer interrupts. It should
// be replaced by an abstraction over whatever native support for
// timer interrupts exists on the platform.
WatcherThread* WatcherThread::_watcher_thread = NULL;
bool WatcherThread::_startable = false;
volatile bool WatcherThread::_should_terminate = false;
WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
if (os::create_thread(this, os::watcher_thread)) {
_watcher_thread = this;
// Set the watcher thread to the highest OS priority which should not be
// used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
// is created. The only normal thread using this priority is the reference
// handler thread, which runs for very short intervals only.
// If the VMThread's priority is not lower than the WatcherThread profiling
// will be inaccurate.
os::set_priority(this, MaxPriority);
if (!DisableStartThread) {
os::start_thread(this);
}
}
}
int WatcherThread::sleep() const {
MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
// remaining will be zero if there are no tasks,
// causing the WatcherThread to sleep until a task is
// enrolled
int remaining = PeriodicTask::time_to_wait();
int time_slept = 0;
// we expect this to timeout - we only ever get unparked when
// we should terminate or when a new task has been enrolled
OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
jlong time_before_loop = os::javaTimeNanos();
for (;;) {
bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, remaining);
jlong now = os::javaTimeNanos();
if (remaining == 0) {
// if we didn't have any tasks we could have waited for a long time
// consider the time_slept zero and reset time_before_loop
time_slept = 0;
time_before_loop = now;
} else {
// need to recalulate since we might have new tasks in _tasks
time_slept = (int) ((now - time_before_loop) / 1000000);
}
// Change to task list or spurious wakeup of some kind
if (timedout || _should_terminate) {
break;
}
remaining = PeriodicTask::time_to_wait();
if (remaining == 0) {
// Last task was just disenrolled so loop around and wait until
// another task gets enrolled
continue;
}
remaining -= time_slept;
if (remaining <= 0)
break;
}
return time_slept;
}
void WatcherThread::run() {
assert(this == watcher_thread(), "just checking");
this->record_stack_base_and_size();
this->initialize_thread_local_storage();
this->set_active_handles(JNIHandleBlock::allocate_block());
while(!_should_terminate) {
assert(watcher_thread() == Thread::current(), "thread consistency check");
assert(watcher_thread() == this, "thread consistency check");
// Calculate how long it'll be until the next PeriodicTask work
// should be done, and sleep that amount of time.
int time_waited = sleep();
if (is_error_reported()) {
// A fatal error has happened, the error handler(VMError::report_and_die)
// should abort JVM after creating an error log file. However in some
// rare cases, the error handler itself might deadlock. Here we try to
// kill JVM if the fatal error handler fails to abort in 2 minutes.
//
// This code is in WatcherThread because WatcherThread wakes up
// periodically so the fatal error handler doesn't need to do anything;
// also because the WatcherThread is less likely to crash than other
// threads.
for (;;) {
if (!ShowMessageBoxOnError
&& (OnError == NULL || OnError[0] == '\0')
&& Arguments::abort_hook() == NULL) {
os::sleep(this, 2 * 60 * 1000, false);
fdStream err(defaultStream::output_fd());
err.print_raw_cr("# [ timer expired, abort... ]");
// skip atexit/vm_exit/vm_abort hooks
os::die();
}
// Wake up 5 seconds later, the fatal handler may reset OnError or
// ShowMessageBoxOnError when it is ready to abort.
os::sleep(this, 5 * 1000, false);
}
}
PeriodicTask::real_time_tick(time_waited);
}
// Signal that it is terminated
{
MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
_watcher_thread = NULL;
Terminator_lock->notify();
}
// Thread destructor usually does this..
ThreadLocalStorage::set_thread(NULL);
}
void WatcherThread::start() {
assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
if (watcher_thread() == NULL && _startable) {
_should_terminate = false;
// Create the single instance of WatcherThread
new WatcherThread();
}
}
void WatcherThread::make_startable() {
assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
_startable = true;
}
void WatcherThread::stop() {
{
MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
_should_terminate = true;
OrderAccess::fence(); // ensure WatcherThread sees update in main loop
WatcherThread* watcher = watcher_thread();
if (watcher != NULL)
watcher->unpark();
}
// it is ok to take late safepoints here, if needed
MutexLocker mu(Terminator_lock);
while(watcher_thread() != NULL) {
// This wait should make safepoint checks, wait without a timeout,
// and wait as a suspend-equivalent condition.
//
// Note: If the FlatProfiler is running, then this thread is waiting
// for the WatcherThread to terminate and the WatcherThread, via the
// FlatProfiler task, is waiting for the external suspend request on
// this thread to complete. wait_for_ext_suspend_completion() will
// eventually timeout, but that takes time. Making this wait a
// suspend-equivalent condition solves that timeout problem.
//
Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
Mutex::_as_suspend_equivalent_flag);
}
}
void WatcherThread::unpark() {
MutexLockerEx ml(PeriodicTask_lock->owned_by_self() ? NULL : PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
PeriodicTask_lock->notify();
}
void WatcherThread::print_on(outputStream* st) const {
st->print("\"%s\" ", name());
Thread::print_on(st);
st->cr();
}
// ======= JavaThread ========
// A JavaThread is a normal Java thread
void JavaThread::initialize() {
// Initialize fields
// Set the claimed par_id to UINT_MAX (ie not claiming any par_ids)
set_claimed_par_id(UINT_MAX);
set_saved_exception_pc(NULL);
set_threadObj(NULL);
_anchor.clear();
set_entry_point(NULL);
set_jni_functions(jni_functions());
set_callee_target(NULL);
set_vm_result(NULL);
set_vm_result_2(NULL);
set_vframe_array_head(NULL);
set_vframe_array_last(NULL);
set_deferred_locals(NULL);
set_deopt_mark(NULL);
set_deopt_nmethod(NULL);
clear_must_deopt_id();
set_monitor_chunks(NULL);
set_next(NULL);
set_thread_state(_thread_new);
_terminated = _not_terminated;
_privileged_stack_top = NULL;
_array_for_gc = NULL;
_suspend_equivalent = false;
_in_deopt_handler = 0;
_doing_unsafe_access = false;
_stack_guard_state = stack_guard_unused;
(void)const_cast<oop&>(_exception_oop = NULL);
_exception_pc = 0;
_exception_handler_pc = 0;
_is_method_handle_return = 0;
_jvmti_thread_state= NULL;
_should_post_on_exceptions_flag = JNI_FALSE;
_jvmti_get_loaded_classes_closure = NULL;
_interp_only_mode = 0;
_special_runtime_exit_condition = _no_async_condition;
_pending_async_exception = NULL;
_thread_stat = NULL;
_thread_stat = new ThreadStatistics();
_blocked_on_compilation = false;
_jni_active_critical = 0;
_pending_jni_exception_check_fn = NULL;
_do_not_unlock_if_synchronized = false;
_cached_monitor_info = NULL;
_parker = Parker::Allocate(this) ;
#ifndef PRODUCT
_jmp_ring_index = 0;
for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) {
record_jump(NULL, NULL, NULL, 0);
}
#endif /* PRODUCT */
set_thread_profiler(NULL);
if (FlatProfiler::is_active()) {
// This is where we would decide to either give each thread it's own profiler
// or use one global one from FlatProfiler,
// or up to some count of the number of profiled threads, etc.
ThreadProfiler* pp = new ThreadProfiler();
pp->engage();
set_thread_profiler(pp);
}
// Setup safepoint state info for this thread
ThreadSafepointState::create(this);
debug_only(_java_call_counter = 0);
// JVMTI PopFrame support
_popframe_condition = popframe_inactive;
_popframe_preserved_args = NULL;
_popframe_preserved_args_size = 0;
_frames_to_pop_failed_realloc = 0;
pd_initialize();
}
#if INCLUDE_ALL_GCS
SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
#endif // INCLUDE_ALL_GCS
JavaThread::JavaThread(bool is_attaching_via_jni) :
Thread()
#if INCLUDE_ALL_GCS
, _satb_mark_queue(&_satb_mark_queue_set),
_dirty_card_queue(&_dirty_card_queue_set)
#endif // INCLUDE_ALL_GCS
{
initialize();
if (is_attaching_via_jni) {
_jni_attach_state = _attaching_via_jni;
} else {
_jni_attach_state = _not_attaching_via_jni;
}
assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
}
bool JavaThread::reguard_stack(address cur_sp) {
if (_stack_guard_state != stack_guard_yellow_disabled) {
return true; // Stack already guarded or guard pages not needed.
}
if (register_stack_overflow()) {
// For those architectures which have separate register and
// memory stacks, we must check the register stack to see if
// it has overflowed.
return false;
}
// Java code never executes within the yellow zone: the latter is only
// there to provoke an exception during stack banging. If java code
// is executing there, either StackShadowPages should be larger, or
// some exception code in c1, c2 or the interpreter isn't unwinding
// when it should.
guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
enable_stack_yellow_zone();
return true;
}
bool JavaThread::reguard_stack(void) {
return reguard_stack(os::current_stack_pointer());
}
void JavaThread::block_if_vm_exited() {
if (_terminated == _vm_exited) {
// _vm_exited is set at safepoint, and Threads_lock is never released
// we will block here forever
Threads_lock->lock_without_safepoint_check();
ShouldNotReachHere();
}
}
// Remove this ifdef when C1 is ported to the compiler interface.
static void compiler_thread_entry(JavaThread* thread, TRAPS);
JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
Thread()
#if INCLUDE_ALL_GCS
, _satb_mark_queue(&_satb_mark_queue_set),
_dirty_card_queue(&_dirty_card_queue_set)
#endif // INCLUDE_ALL_GCS
{
if (TraceThreadEvents) {
tty->print_cr("creating thread %p", this);
}
initialize();
_jni_attach_state = _not_attaching_via_jni;
set_entry_point(entry_point);
// Create the native thread itself.
// %note runtime_23
os::ThreadType thr_type = os::java_thread;
thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
os::java_thread;
os::create_thread(this, thr_type, stack_sz);
// The _osthread may be NULL here because we ran out of memory (too many threads active).
// We need to throw and OutOfMemoryError - however we cannot do this here because the caller
// may hold a lock and all locks must be unlocked before throwing the exception (throwing
// the exception consists of creating the exception object & initializing it, initialization
// will leave the VM via a JavaCall and then all locks must be unlocked).
//
// The thread is still suspended when we reach here. Thread must be explicit started
// by creator! Furthermore, the thread must also explicitly be added to the Threads list
// by calling Threads:add. The reason why this is not done here, is because the thread
// object must be fully initialized (take a look at JVM_Start)
}
JavaThread::~JavaThread() {
if (TraceThreadEvents) {
tty->print_cr("terminate thread %p", this);
}
// JSR166 -- return the parker to the free list
Parker::Release(_parker);
_parker = NULL ;
// Free any remaining previous UnrollBlock
vframeArray* old_array = vframe_array_last();
if (old_array != NULL) {
Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
old_array->set_unroll_block(NULL);
delete old_info;
delete old_array;
}
GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
if (deferred != NULL) {
// This can only happen if thread is destroyed before deoptimization occurs.
assert(deferred->length() != 0, "empty array!");
do {
jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
deferred->remove_at(0);
// individual jvmtiDeferredLocalVariableSet are CHeapObj's
delete dlv;
} while (deferred->length() != 0);
delete deferred;
}
// All Java related clean up happens in exit
ThreadSafepointState::destroy(this);
if (_thread_profiler != NULL) delete _thread_profiler;
if (_thread_stat != NULL) delete _thread_stat;
}
// The first routine called by a new Java thread
void JavaThread::run() {
// initialize thread-local alloc buffer related fields
this->initialize_tlab();
// used to test validitity of stack trace backs
this->record_base_of_stack_pointer();
// Record real stack base and size.
this->record_stack_base_and_size();
// Initialize thread local storage; set before calling MutexLocker
this->initialize_thread_local_storage();
this->create_stack_guard_pages();
this->cache_global_variables();
// Thread is now sufficient initialized to be handled by the safepoint code as being
// in the VM. Change thread state from _thread_new to _thread_in_vm
ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
assert(JavaThread::current() == this, "sanity check");
assert(!Thread::current()->owns_locks(), "sanity check");
DTRACE_THREAD_PROBE(start, this);
// This operation might block. We call that after all safepoint checks for a new thread has
// been completed.
this->set_active_handles(JNIHandleBlock::allocate_block());
if (JvmtiExport::should_post_thread_life()) {
JvmtiExport::post_thread_start(this);
}
EventThreadStart event;
if (event.should_commit()) {
event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
event.commit();
}
// We call another function to do the rest so we are sure that the stack addresses used
// from there will be lower than the stack base just computed
thread_main_inner();
// Note, thread is no longer valid at this point!
}
void JavaThread::thread_main_inner() {
assert(JavaThread::current() == this, "sanity check");
assert(this->threadObj() != NULL, "just checking");
// Execute thread entry point unless this thread has a pending exception
// or has been stopped before starting.
// Note: Due to JVM_StopThread we can have pending exceptions already!
if (!this->has_pending_exception() &&
!java_lang_Thread::is_stillborn(this->threadObj())) {
{
ResourceMark rm(this);
this->set_native_thread_name(this->get_thread_name());
}
HandleMark hm(this);
this->entry_point()(this, this);
}
DTRACE_THREAD_PROBE(stop, this);
this->exit(false);
delete this;
}
static void ensure_join(JavaThread* thread) {
// We do not need to grap the Threads_lock, since we are operating on ourself.
Handle threadObj(thread, thread->threadObj());
assert(threadObj.not_null(), "java thread object must exist");
ObjectLocker lock(threadObj, thread);
// Ignore pending exception (ThreadDeath), since we are exiting anyway
thread->clear_pending_exception();
// Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
// Clear the native thread instance - this makes isAlive return false and allows the join()
// to complete once we've done the notify_all below
java_lang_Thread::set_thread(threadObj(), NULL);
lock.notify_all(thread);
// Ignore pending exception (ThreadDeath), since we are exiting anyway
thread->clear_pending_exception();
}
// For any new cleanup additions, please check to see if they need to be applied to
// cleanup_failed_attach_current_thread as well.
void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
assert(this == JavaThread::current(), "thread consistency check");
HandleMark hm(this);
Handle uncaught_exception(this, this->pending_exception());
this->clear_pending_exception();
Handle threadObj(this, this->threadObj());
assert(threadObj.not_null(), "Java thread object should be created");
if (get_thread_profiler() != NULL) {
get_thread_profiler()->disengage();
ResourceMark rm;
get_thread_profiler()->print(get_thread_name());
}
// FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
{
EXCEPTION_MARK;
CLEAR_PENDING_EXCEPTION;
}
// FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This
// has to be fixed by a runtime query method
if (!destroy_vm || JDK_Version::is_jdk12x_version()) {
// JSR-166: change call from from ThreadGroup.uncaughtException to
// java.lang.Thread.dispatchUncaughtException
if (uncaught_exception.not_null()) {
Handle group(this, java_lang_Thread::threadGroup(threadObj()));
{
EXCEPTION_MARK;
// Check if the method Thread.dispatchUncaughtException() exists. If so
// call it. Otherwise we have an older library without the JSR-166 changes,
// so call ThreadGroup.uncaughtException()
KlassHandle recvrKlass(THREAD, threadObj->klass());
CallInfo callinfo;
KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass,
vmSymbols::dispatchUncaughtException_name(),
vmSymbols::throwable_void_signature(),
KlassHandle(), false, false, THREAD);
CLEAR_PENDING_EXCEPTION;
methodHandle method = callinfo.selected_method();
if (method.not_null()) {
JavaValue result(T_VOID);
JavaCalls::call_virtual(&result,
threadObj, thread_klass,
vmSymbols::dispatchUncaughtException_name(),
vmSymbols::throwable_void_signature(),
uncaught_exception,
THREAD);
} else {
KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass());
JavaValue result(T_VOID);
JavaCalls::call_virtual(&result,
group, thread_group,
vmSymbols::uncaughtException_name(),
vmSymbols::thread_throwable_void_signature(),
threadObj, // Arg 1
uncaught_exception, // Arg 2
THREAD);
}
if (HAS_PENDING_EXCEPTION) {
ResourceMark rm(this);
jio_fprintf(defaultStream::error_stream(),
"\nException: %s thrown from the UncaughtExceptionHandler"
" in thread \"%s\"\n",
pending_exception()->klass()->external_name(),
get_thread_name());
CLEAR_PENDING_EXCEPTION;
}
}
}
// Called before the java thread exit since we want to read info
// from java_lang_Thread object
EventThreadEnd event;
if (event.should_commit()) {
event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
event.commit();
}
// Call after last event on thread
EVENT_THREAD_EXIT(this);
// Call Thread.exit(). We try 3 times in case we got another Thread.stop during
// the execution of the method. If that is not enough, then we don't really care. Thread.stop
// is deprecated anyhow.
if (!is_Compiler_thread()) {
int count = 3;
while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
EXCEPTION_MARK;
JavaValue result(T_VOID);
KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
JavaCalls::call_virtual(&result,
threadObj, thread_klass,
vmSymbols::exit_method_name(),
vmSymbols::void_method_signature(),
THREAD);
CLEAR_PENDING_EXCEPTION;
}
}
// notify JVMTI
if (JvmtiExport::should_post_thread_life()) {
JvmtiExport::post_thread_end(this);
}
// We have notified the agents that we are exiting, before we go on,
// we must check for a pending external suspend request and honor it
// in order to not surprise the thread that made the suspend request.
while (true) {
{
MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
if (!is_external_suspend()) {
set_terminated(_thread_exiting);
ThreadService::current_thread_exiting(this);
break;
}
// Implied else:
// Things get a little tricky here. We have a pending external
// suspend request, but we are holding the SR_lock so we
// can't just self-suspend. So we temporarily drop the lock
// and then self-suspend.
}
ThreadBlockInVM tbivm(this);
java_suspend_self();
// We're done with this suspend request, but we have to loop around
// and check again. Eventually we will get SR_lock without a pending
// external suspend request and will be able to mark ourselves as
// exiting.
}
// no more external suspends are allowed at this point
} else {
// before_exit() has already posted JVMTI THREAD_END events
}
// Notify waiters on thread object. This has to be done after exit() is called
// on the thread (if the thread is the last thread in a daemon ThreadGroup the
// group should have the destroyed bit set before waiters are notified).
ensure_join(this);
assert(!this->has_pending_exception(), "ensure_join should have cleared");
// 6282335 JNI DetachCurrentThread spec states that all Java monitors
// held by this thread must be released. A detach operation must only
// get here if there are no Java frames on the stack. Therefore, any
// owned monitors at this point MUST be JNI-acquired monitors which are
// pre-inflated and in the monitor cache.
//
// ensure_join() ignores IllegalThreadStateExceptions, and so does this.
if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
assert(!this->has_last_Java_frame(), "detaching with Java frames?");
ObjectSynchronizer::release_monitors_owned_by_thread(this);
assert(!this->has_pending_exception(), "release_monitors should have cleared");
}
// These things needs to be done while we are still a Java Thread. Make sure that thread
// is in a consistent state, in case GC happens
assert(_privileged_stack_top == NULL, "must be NULL when we get here");
if (active_handles() != NULL) {
JNIHandleBlock* block = active_handles();
set_active_handles(NULL);
JNIHandleBlock::release_block(block);
}
if (free_handle_block() != NULL) {
JNIHandleBlock* block = free_handle_block();
set_free_handle_block(NULL);
JNIHandleBlock::release_block(block);
}
// These have to be removed while this is still a valid thread.
remove_stack_guard_pages();
if (UseTLAB) {
tlab().make_parsable(true); // retire TLAB
}
if (JvmtiEnv::environments_might_exist()) {
JvmtiExport::cleanup_thread(this);
}
// We must flush any deferred card marks before removing a thread from
// the list of active threads.
Universe::heap()->flush_deferred_store_barrier(this);
assert(deferred_card_mark().is_empty(), "Should have been flushed");
#if INCLUDE_ALL_GCS
// We must flush the G1-related buffers before removing a thread
// from the list of active threads. We must do this after any deferred
// card marks have been flushed (above) so that any entries that are
// added to the thread's dirty card queue as a result are not lost.
if (UseG1GC) {
flush_barrier_queues();
}
#endif // INCLUDE_ALL_GCS
// Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
Threads::remove(this);
}
#if INCLUDE_ALL_GCS
// Flush G1-related queues.
void JavaThread::flush_barrier_queues() {
satb_mark_queue().flush();
dirty_card_queue().flush();
}
void JavaThread::initialize_queues() {
assert(!SafepointSynchronize::is_at_safepoint(),
"we should not be at a safepoint");
ObjPtrQueue& satb_queue = satb_mark_queue();
SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
// The SATB queue should have been constructed with its active
// field set to false.
assert(!satb_queue.is_active(), "SATB queue should not be active");
assert(satb_queue.is_empty(), "SATB queue should be empty");
// If we are creating the thread during a marking cycle, we should
// set the active field of the SATB queue to true.
if (satb_queue_set.is_active()) {
satb_queue.set_active(true);
}
DirtyCardQueue& dirty_queue = dirty_card_queue();
// The dirty card queue should have been constructed with its
// active field set to true.
assert(dirty_queue.is_active(), "dirty card queue should be active");
}
#endif // INCLUDE_ALL_GCS
void JavaThread::cleanup_failed_attach_current_thread() {
if (get_thread_profiler() != NULL) {
get_thread_profiler()->disengage();
ResourceMark rm;
get_thread_profiler()->print(get_thread_name());
}
if (active_handles() != NULL) {
JNIHandleBlock* block = active_handles();
set_active_handles(NULL);
JNIHandleBlock::release_block(block);
}
if (free_handle_block() != NULL) {
JNIHandleBlock* block = free_handle_block();
set_free_handle_block(NULL);
JNIHandleBlock::release_block(block);
}
// These have to be removed while this is still a valid thread.
remove_stack_guard_pages();
if (UseTLAB) {
tlab().make_parsable(true); // retire TLAB, if any
}
#if INCLUDE_ALL_GCS
if (UseG1GC) {
flush_barrier_queues();
}
#endif // INCLUDE_ALL_GCS
Threads::remove(this);
delete this;
}
JavaThread* JavaThread::active() {
Thread* thread = ThreadLocalStorage::thread();
assert(thread != NULL, "just checking");
if (thread->is_Java_thread()) {
return (JavaThread*) thread;
} else {
assert(thread->is_VM_thread(), "this must be a vm thread");
VM_Operation* op = ((VMThread*) thread)->vm_operation();
JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
assert(ret->is_Java_thread(), "must be a Java thread");
return ret;
}
}
bool JavaThread::is_lock_owned(address adr) const {
if (Thread::is_lock_owned(adr)) return true;
for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
if (chunk->contains(adr)) return true;
}
return false;
}
void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
chunk->set_next(monitor_chunks());
set_monitor_chunks(chunk);
}
void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
guarantee(monitor_chunks() != NULL, "must be non empty");
if (monitor_chunks() == chunk) {
set_monitor_chunks(chunk->next());
} else {
MonitorChunk* prev = monitor_chunks();
while (prev->next() != chunk) prev = prev->next();
prev->set_next(chunk->next());
}
}
// JVM support.
// Note: this function shouldn't block if it's called in
// _thread_in_native_trans state (such as from
// check_special_condition_for_native_trans()).
void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
if (has_last_Java_frame() && has_async_condition()) {
// If we are at a polling page safepoint (not a poll return)
// then we must defer async exception because live registers
// will be clobbered by the exception path. Poll return is
// ok because the call we a returning from already collides
// with exception handling registers and so there is no issue.
// (The exception handling path kills call result registers but
// this is ok since the exception kills the result anyway).
if (is_at_poll_safepoint()) {
// if the code we are returning to has deoptimized we must defer
// the exception otherwise live registers get clobbered on the
// exception path before deoptimization is able to retrieve them.
//
RegisterMap map(this, false);
frame caller_fr = last_frame().sender(&map);
assert(caller_fr.is_compiled_frame(), "what?");
if (caller_fr.is_deoptimized_frame()) {
if (TraceExceptions) {
ResourceMark rm;
tty->print_cr("deferred async exception at compiled safepoint");
}
return;
}
}
}
JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
if (condition == _no_async_condition) {
// Conditions have changed since has_special_runtime_exit_condition()
// was called:
// - if we were here only because of an external suspend request,
// then that was taken care of above (or cancelled) so we are done
// - if we were here because of another async request, then it has
// been cleared between the has_special_runtime_exit_condition()
// and now so again we are done
return;
}
// Check for pending async. exception
if (_pending_async_exception != NULL) {
// Only overwrite an already pending exception, if it is not a threadDeath.
if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
// We cannot call Exceptions::_throw(...) here because we cannot block
set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
if (TraceExceptions) {
ResourceMark rm;
tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
if (has_last_Java_frame() ) {
frame f = last_frame();
tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
}
tty->print_cr(" of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
}
_pending_async_exception = NULL;
clear_has_async_exception();
}
}
if (check_unsafe_error &&
condition == _async_unsafe_access_error && !has_pending_exception()) {
condition = _no_async_condition; // done
switch (thread_state()) {
case _thread_in_vm:
{
JavaThread* THREAD = this;
THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
}
case _thread_in_native:
{
ThreadInVMfromNative tiv(this);
JavaThread* THREAD = this;
THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
}
case _thread_in_Java:
{
ThreadInVMfromJava tiv(this);
JavaThread* THREAD = this;
THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
}
default:
ShouldNotReachHere();
}
}
assert(condition == _no_async_condition || has_pending_exception() ||
(!check_unsafe_error && condition == _async_unsafe_access_error),
"must have handled the async condition, if no exception");
}
void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
//
// Check for pending external suspend. Internal suspend requests do
// not use handle_special_runtime_exit_condition().
// If JNIEnv proxies are allowed, don't self-suspend if the target
// thread is not the current thread. In older versions of jdbx, jdbx
// threads could call into the VM with another thread's JNIEnv so we
// can be here operating on behalf of a suspended thread (4432884).
bool do_self_suspend = is_external_suspend_with_lock();
if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
//
// Because thread is external suspended the safepoint code will count
// thread as at a safepoint. This can be odd because we can be here
// as _thread_in_Java which would normally transition to _thread_blocked
// at a safepoint. We would like to mark the thread as _thread_blocked
// before calling java_suspend_self like all other callers of it but
// we must then observe proper safepoint protocol. (We can't leave
// _thread_blocked with a safepoint in progress). However we can be
// here as _thread_in_native_trans so we can't use a normal transition
// constructor/destructor pair because they assert on that type of
// transition. We could do something like:
//
// JavaThreadState state = thread_state();
// set_thread_state(_thread_in_vm);
// {
// ThreadBlockInVM tbivm(this);
// java_suspend_self()
// }
// set_thread_state(_thread_in_vm_trans);
// if (safepoint) block;
// set_thread_state(state);
//
// but that is pretty messy. Instead we just go with the way the
// code has worked before and note that this is the only path to
// java_suspend_self that doesn't put the thread in _thread_blocked
// mode.
frame_anchor()->make_walkable(this);
java_suspend_self();
// We might be here for reasons in addition to the self-suspend request
// so check for other async requests.
}
if (check_asyncs) {
check_and_handle_async_exceptions();
}
}
void JavaThread::send_thread_stop(oop java_throwable) {
assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
// Do not throw asynchronous exceptions against the compiler thread
// (the compiler thread should not be a Java thread -- fix in 1.4.2)
if (is_Compiler_thread()) return;
{
// Actually throw the Throwable against the target Thread - however
// only if there is no thread death exception installed already.
if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
// If the topmost frame is a runtime stub, then we are calling into
// OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
// must deoptimize the caller before continuing, as the compiled exception handler table
// may not be valid
if (has_last_Java_frame()) {
frame f = last_frame();
if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
// BiasedLocking needs an updated RegisterMap for the revoke monitors pass
RegisterMap reg_map(this, UseBiasedLocking);
frame compiled_frame = f.sender(&reg_map);
if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
Deoptimization::deoptimize(this, compiled_frame, &reg_map);
}
}
}
// Set async. pending exception in thread.
set_pending_async_exception(java_throwable);
if (TraceExceptions) {
ResourceMark rm;
tty->print_cr("Pending Async. exception installed of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
}
// for AbortVMOnException flag
NOT_PRODUCT(Exceptions::debug_check_abort(InstanceKlass::cast(_pending_async_exception->klass())->external_name()));
}
}
// Interrupt thread so it will wake up from a potential wait()
Thread::interrupt(this);
}
// External suspension mechanism.
//
// Tell the VM to suspend a thread when ever it knows that it does not hold on
// to any VM_locks and it is at a transition
// Self-suspension will happen on the transition out of the vm.
// Catch "this" coming in from JNIEnv pointers when the thread has been freed
//
// Guarantees on return:
// + Target thread will not execute any new bytecode (that's why we need to
// force a safepoint)
// + Target thread will not enter any new monitors
//
void JavaThread::java_suspend() {
{ MutexLocker mu(Threads_lock);
if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
return;
}
}
{ MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
if (!is_external_suspend()) {
// a racing resume has cancelled us; bail out now
return;
}
// suspend is done
uint32_t debug_bits = 0;
// Warning: is_ext_suspend_completed() may temporarily drop the
// SR_lock to allow the thread to reach a stable thread state if
// it is currently in a transient thread state.
if (is_ext_suspend_completed(false /* !called_by_wait */,
SuspendRetryDelay, &debug_bits) ) {
return;
}
}
VM_ForceSafepoint vm_suspend;
VMThread::execute(&vm_suspend);
}
// Part II of external suspension.
// A JavaThread self suspends when it detects a pending external suspend
// request. This is usually on transitions. It is also done in places
// where continuing to the next transition would surprise the caller,
// e.g., monitor entry.
//
// Returns the number of times that the thread self-suspended.
//
// Note: DO NOT call java_suspend_self() when you just want to block current
// thread. java_suspend_self() is the second stage of cooperative
// suspension for external suspend requests and should only be used
// to complete an external suspend request.
//
int JavaThread::java_suspend_self() {
int ret = 0;
// we are in the process of exiting so don't suspend
if (is_exiting()) {
clear_external_suspend();
return ret;
}
assert(_anchor.walkable() ||
(is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
"must have walkable stack");
MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
assert(!this->is_ext_suspended(),
"a thread trying to self-suspend should not already be suspended");
if (this->is_suspend_equivalent()) {
// If we are self-suspending as a result of the lifting of a
// suspend equivalent condition, then the suspend_equivalent
// flag is not cleared until we set the ext_suspended flag so
// that wait_for_ext_suspend_completion() returns consistent
// results.
this->clear_suspend_equivalent();
}
// A racing resume may have cancelled us before we grabbed SR_lock
// above. Or another external suspend request could be waiting for us
// by the time we return from SR_lock()->wait(). The thread
// that requested the suspension may already be trying to walk our
// stack and if we return now, we can change the stack out from under
// it. This would be a "bad thing (TM)" and cause the stack walker
// to crash. We stay self-suspended until there are no more pending
// external suspend requests.
while (is_external_suspend()) {
ret++;
this->set_ext_suspended();
// _ext_suspended flag is cleared by java_resume()
while (is_ext_suspended()) {
this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
}
}
return ret;
}
#ifdef ASSERT
// verify the JavaThread has not yet been published in the Threads::list, and
// hence doesn't need protection from concurrent access at this stage
void JavaThread::verify_not_published() {
if (!Threads_lock->owned_by_self()) {
MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
assert( !Threads::includes(this),
"java thread shouldn't have been published yet!");
}
else {
assert( !Threads::includes(this),
"java thread shouldn't have been published yet!");
}
}
#endif
// Slow path when the native==>VM/Java barriers detect a safepoint is in
// progress or when _suspend_flags is non-zero.
// Current thread needs to self-suspend if there is a suspend request and/or
// block if a safepoint is in progress.
// Async exception ISN'T checked.
// Note only the ThreadInVMfromNative transition can call this function
// directly and when thread state is _thread_in_native_trans
void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
JavaThread *curJT = JavaThread::current();
bool do_self_suspend = thread->is_external_suspend();
assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
// If JNIEnv proxies are allowed, don't self-suspend if the target
// thread is not the current thread. In older versions of jdbx, jdbx
// threads could call into the VM with another thread's JNIEnv so we
// can be here operating on behalf of a suspended thread (4432884).
if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
JavaThreadState state = thread->thread_state();
// We mark this thread_blocked state as a suspend-equivalent so
// that a caller to is_ext_suspend_completed() won't be confused.
// The suspend-equivalent state is cleared by java_suspend_self().
thread->set_suspend_equivalent();
// If the safepoint code sees the _thread_in_native_trans state, it will
// wait until the thread changes to other thread state. There is no
// guarantee on how soon we can obtain the SR_lock and complete the
// self-suspend request. It would be a bad idea to let safepoint wait for
// too long. Temporarily change the state to _thread_blocked to
// let the VM thread know that this thread is ready for GC. The problem
// of changing thread state is that safepoint could happen just after
// java_suspend_self() returns after being resumed, and VM thread will
// see the _thread_blocked state. We must check for safepoint
// after restoring the state and make sure we won't leave while a safepoint
// is in progress.
thread->set_thread_state(_thread_blocked);
thread->java_suspend_self();
thread->set_thread_state(state);
// Make sure new state is seen by VM thread
if (os::is_MP()) {
if (UseMembar) {
// Force a fence between the write above and read below
OrderAccess::fence();
} else {
// Must use this rather than serialization page in particular on Windows
InterfaceSupport::serialize_memory(thread);
}
}
}
if (SafepointSynchronize::do_call_back()) {
// If we are safepointing, then block the caller which may not be
// the same as the target thread (see above).
SafepointSynchronize::block(curJT);
}
if (thread->is_deopt_suspend()) {
thread->clear_deopt_suspend();
RegisterMap map(thread, false);
frame f = thread->last_frame();
while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
f = f.sender(&map);
}
if (f.id() == thread->must_deopt_id()) {
thread->clear_must_deopt_id();
f.deoptimize(thread);
} else {
fatal("missed deoptimization!");
}
}
}
// Slow path when the native==>VM/Java barriers detect a safepoint is in
// progress or when _suspend_flags is non-zero.
// Current thread needs to self-suspend if there is a suspend request and/or
// block if a safepoint is in progress.
// Also check for pending async exception (not including unsafe access error).
// Note only the native==>VM/Java barriers can call this function and when
// thread state is _thread_in_native_trans.
void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
check_safepoint_and_suspend_for_native_trans(thread);
if (thread->has_async_exception()) {
// We are in _thread_in_native_trans state, don't handle unsafe
// access error since that may block.
thread->check_and_handle_async_exceptions(false);
}
}
// This is a variant of the normal
// check_special_condition_for_native_trans with slightly different
// semantics for use by critical native wrappers. It does all the
// normal checks but also performs the transition back into
// thread_in_Java state. This is required so that critical natives
// can potentially block and perform a GC if they are the last thread
// exiting the GC_locker.
void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
check_special_condition_for_native_trans(thread);
// Finish the transition
thread->set_thread_state(_thread_in_Java);
if (thread->do_critical_native_unlock()) {
ThreadInVMfromJavaNoAsyncException tiv(thread);
GC_locker::unlock_critical(thread);
thread->clear_critical_native_unlock();
}
}
// We need to guarantee the Threads_lock here, since resumes are not
// allowed during safepoint synchronization
// Can only resume from an external suspension
void JavaThread::java_resume() {
assert_locked_or_safepoint(Threads_lock);
// Sanity check: thread is gone, has started exiting or the thread
// was not externally suspended.
if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
return;
}
MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
clear_external_suspend();
if (is_ext_suspended()) {
clear_ext_suspended();
SR_lock()->notify_all();
}
}
void JavaThread::create_stack_guard_pages() {
if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
address low_addr = stack_base() - stack_size();
size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
int allocate = os::allocate_stack_guard_pages();
// warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
warning("Attempt to allocate stack guard pages failed.");
return;
}
if (os::guard_memory((char *) low_addr, len)) {
_stack_guard_state = stack_guard_enabled;
} else {
warning("Attempt to protect stack guard pages failed.");
if (os::uncommit_memory((char *) low_addr, len)) {
warning("Attempt to deallocate stack guard pages failed.");
}
}
}
void JavaThread::remove_stack_guard_pages() {
assert(Thread::current() == this, "from different thread");
if (_stack_guard_state == stack_guard_unused) return;
address low_addr = stack_base() - stack_size();
size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
if (os::allocate_stack_guard_pages()) {
if (os::remove_stack_guard_pages((char *) low_addr, len)) {
_stack_guard_state = stack_guard_unused;
} else {
warning("Attempt to deallocate stack guard pages failed.");
}
} else {
if (_stack_guard_state == stack_guard_unused) return;
if (os::unguard_memory((char *) low_addr, len)) {
_stack_guard_state = stack_guard_unused;
} else {
warning("Attempt to unprotect stack guard pages failed.");
}
}
}
void JavaThread::enable_stack_yellow_zone() {
assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
assert(_stack_guard_state != stack_guard_enabled, "already enabled");
// The base notation is from the stacks point of view, growing downward.
// We need to adjust it to work correctly with guard_memory()
address base = stack_yellow_zone_base() - stack_yellow_zone_size();
guarantee(base < stack_base(),"Error calculating stack yellow zone");
guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone");
if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
_stack_guard_state = stack_guard_enabled;
} else {
warning("Attempt to guard stack yellow zone failed.");
}
enable_register_stack_guard();
}
void JavaThread::disable_stack_yellow_zone() {
assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
// Simply return if called for a thread that does not use guard pages.
if (_stack_guard_state == stack_guard_unused) return;
// The base notation is from the stacks point of view, growing downward.
// We need to adjust it to work correctly with guard_memory()
address base = stack_yellow_zone_base() - stack_yellow_zone_size();
if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
_stack_guard_state = stack_guard_yellow_disabled;
} else {
warning("Attempt to unguard stack yellow zone failed.");
}
disable_register_stack_guard();
}
void JavaThread::enable_stack_red_zone() {
// The base notation is from the stacks point of view, growing downward.
// We need to adjust it to work correctly with guard_memory()
assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
address base = stack_red_zone_base() - stack_red_zone_size();
guarantee(base < stack_base(),"Error calculating stack red zone");
guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone");
if(!os::guard_memory((char *) base, stack_red_zone_size())) {
warning("Attempt to guard stack red zone failed.");
}
}
void JavaThread::disable_stack_red_zone() {
// The base notation is from the stacks point of view, growing downward.
// We need to adjust it to work correctly with guard_memory()
assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
address base = stack_red_zone_base() - stack_red_zone_size();
if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
warning("Attempt to unguard stack red zone failed.");
}
}
void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
// ignore is there is no stack
if (!has_last_Java_frame()) return;
// traverse the stack frames. Starts from top frame.
for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
frame* fr = fst.current();
f(fr, fst.register_map());
}
}
#ifndef PRODUCT
// Deoptimization
// Function for testing deoptimization
void JavaThread::deoptimize() {
// BiasedLocking needs an updated RegisterMap for the revoke monitors pass
StackFrameStream fst(this, UseBiasedLocking);
bool deopt = false; // Dump stack only if a deopt actually happens.
bool only_at = strlen(DeoptimizeOnlyAt) > 0;
// Iterate over all frames in the thread and deoptimize
for(; !fst.is_done(); fst.next()) {
if(fst.current()->can_be_deoptimized()) {
if (only_at) {
// Deoptimize only at particular bcis. DeoptimizeOnlyAt
// consists of comma or carriage return separated numbers so
// search for the current bci in that string.
address pc = fst.current()->pc();
nmethod* nm = (nmethod*) fst.current()->cb();
ScopeDesc* sd = nm->scope_desc_at( pc);
char buffer[8];
jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
size_t len = strlen(buffer);
const char * found = strstr(DeoptimizeOnlyAt, buffer);
while (found != NULL) {
if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
(found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
// Check that the bci found is bracketed by terminators.
break;
}
found = strstr(found + 1, buffer);
}
if (!found) {
continue;
}
}
if (DebugDeoptimization && !deopt) {
deopt = true; // One-time only print before deopt
tty->print_cr("[BEFORE Deoptimization]");
trace_frames();
trace_stack();
}
Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
}
}
if (DebugDeoptimization && deopt) {
tty->print_cr("[AFTER Deoptimization]");
trace_frames();
}
}
// Make zombies
void JavaThread::make_zombies() {
for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
if (fst.current()->can_be_deoptimized()) {
// it is a Java nmethod
nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
nm->make_not_entrant();
}
}
}
#endif // PRODUCT
void JavaThread::deoptimized_wrt_marked_nmethods() {
if (!has_last_Java_frame()) return;
// BiasedLocking needs an updated RegisterMap for the revoke monitors pass
StackFrameStream fst(this, UseBiasedLocking);
for(; !fst.is_done(); fst.next()) {
if (fst.current()->should_be_deoptimized()) {
if (LogCompilation && xtty != NULL) {
nmethod* nm = fst.current()->cb()->as_nmethod_or_null();
xtty->elem("deoptimized thread='" UINTX_FORMAT "' compile_id='%d'",
this->name(), nm != NULL ? nm->compile_id() : -1);
}
Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
}
}
}
// GC support
static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); }
void JavaThread::gc_epilogue() {
frames_do(frame_gc_epilogue);
}
static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); }
void JavaThread::gc_prologue() {
frames_do(frame_gc_prologue);
}
// If the caller is a NamedThread, then remember, in the current scope,
// the given JavaThread in its _processed_thread field.
class RememberProcessedThread: public StackObj {
NamedThread* _cur_thr;
public:
RememberProcessedThread(JavaThread* jthr) {
Thread* thread = Thread::current();
if (thread->is_Named_thread()) {
_cur_thr = (NamedThread *)thread;
_cur_thr->set_processed_thread(jthr);
} else {
_cur_thr = NULL;
}
}
~RememberProcessedThread() {
if (_cur_thr) {
_cur_thr->set_processed_thread(NULL);
}
}
};
void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
// Verify that the deferred card marks have been flushed.
assert(deferred_card_mark().is_empty(), "Should be empty during GC");
// The ThreadProfiler oops_do is done from FlatProfiler::oops_do
// since there may be more than one thread using each ThreadProfiler.
// Traverse the GCHandles
Thread::oops_do(f, cld_f, cf);
assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
(has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
if (has_last_Java_frame()) {
// Record JavaThread to GC thread
RememberProcessedThread rpt(this);
// Traverse the privileged stack
if (_privileged_stack_top != NULL) {
_privileged_stack_top->oops_do(f);
}
// traverse the registered growable array
if (_array_for_gc != NULL) {
for (int index = 0; index < _array_for_gc->length(); index++) {
f->do_oop(_array_for_gc->adr_at(index));
}
}
// Traverse the monitor chunks
for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
chunk->oops_do(f);
}
// Traverse the execution stack
for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
fst.current()->oops_do(f, cld_f, cf, fst.register_map());
}
}
// callee_target is never live across a gc point so NULL it here should
// it still contain a methdOop.
set_callee_target(NULL);
assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
// If we have deferred set_locals there might be oops waiting to be
// written
GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
if (list != NULL) {
for (int i = 0; i < list->length(); i++) {
list->at(i)->oops_do(f);
}
}
// Traverse instance variables at the end since the GC may be moving things
// around using this function
f->do_oop((oop*) &_threadObj);
f->do_oop((oop*) &_vm_result);
f->do_oop((oop*) &_exception_oop);
f->do_oop((oop*) &_pending_async_exception);
if (jvmti_thread_state() != NULL) {
jvmti_thread_state()->oops_do(f);
}
}
void JavaThread::nmethods_do(CodeBlobClosure* cf) {
Thread::nmethods_do(cf); // (super method is a no-op)
assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
(has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
if (has_last_Java_frame()) {
// Traverse the execution stack
for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
fst.current()->nmethods_do(cf);
}
}
}
void JavaThread::metadata_do(void f(Metadata*)) {
Thread::metadata_do(f);
if (has_last_Java_frame()) {
// Traverse the execution stack to call f() on the methods in the stack
for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
fst.current()->metadata_do(f);
}
} else if (is_Compiler_thread()) {
// need to walk ciMetadata in current compile tasks to keep alive.
CompilerThread* ct = (CompilerThread*)this;
if (ct->env() != NULL) {
ct->env()->metadata_do(f);
}
}
}
// Printing
const char* _get_thread_state_name(JavaThreadState _thread_state) {
switch (_thread_state) {
case _thread_uninitialized: return "_thread_uninitialized";
case _thread_new: return "_thread_new";
case _thread_new_trans: return "_thread_new_trans";
case _thread_in_native: return "_thread_in_native";
case _thread_in_native_trans: return "_thread_in_native_trans";
case _thread_in_vm: return "_thread_in_vm";
case _thread_in_vm_trans: return "_thread_in_vm_trans";
case _thread_in_Java: return "_thread_in_Java";
case _thread_in_Java_trans: return "_thread_in_Java_trans";
case _thread_blocked: return "_thread_blocked";
case _thread_blocked_trans: return "_thread_blocked_trans";
default: return "unknown thread state";
}
}
#ifndef PRODUCT
void JavaThread::print_thread_state_on(outputStream *st) const {
st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
};
void JavaThread::print_thread_state() const {
print_thread_state_on(tty);
};
#endif // PRODUCT
// Called by Threads::print() for VM_PrintThreads operation
void JavaThread::print_on(outputStream *st) const {
st->print("\"%s\" ", get_thread_name());
oop thread_oop = threadObj();
if (thread_oop != NULL) {
st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
}
Thread::print_on(st);
// print guess for valid stack memory region (assume 4K pages); helps lock debugging
st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) {
st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
}
#ifndef PRODUCT
print_thread_state_on(st);
_safepoint_state->print_on(st);
#endif // PRODUCT
}
// Called by fatal error handler. The difference between this and
// JavaThread::print() is that we can't grab lock or allocate memory.
void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
oop thread_obj = threadObj();
if (thread_obj != NULL) {
if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
}
st->print(" [");
st->print("%s", _get_thread_state_name(_thread_state));
if (osthread()) {
st->print(", id=%d", osthread()->thread_id());
}
st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
_stack_base - _stack_size, _stack_base);
st->print("]");
return;
}
// Verification
static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
void JavaThread::verify() {
// Verify oops in the thread.
oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
// Verify the stack frames.
frames_do(frame_verify);
}
// CR 6300358 (sub-CR 2137150)
// Most callers of this method assume that it can't return NULL but a
// thread may not have a name whilst it is in the process of attaching to
// the VM - see CR 6412693, and there are places where a JavaThread can be
// seen prior to having it's threadObj set (eg JNI attaching threads and
// if vm exit occurs during initialization). These cases can all be accounted
// for such that this method never returns NULL.
const char* JavaThread::get_thread_name() const {
#ifdef ASSERT
// early safepoints can hit while current thread does not yet have TLS
if (!SafepointSynchronize::is_at_safepoint()) {
Thread *cur = Thread::current();
if (!(cur->is_Java_thread() && cur == this)) {
// Current JavaThreads are allowed to get their own name without
// the Threads_lock.
assert_locked_or_safepoint(Threads_lock);
}
}
#endif // ASSERT
return get_thread_name_string();
}
// Returns a non-NULL representation of this thread's name, or a suitable
// descriptive string if there is no set name
const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
const char* name_str;
oop thread_obj = threadObj();
if (thread_obj != NULL) {
oop name = java_lang_Thread::name(thread_obj);
if (name != NULL) {
if (buf == NULL) {
name_str = java_lang_String::as_utf8_string(name);
}
else {
name_str = java_lang_String::as_utf8_string(name, buf, buflen);
}
}
else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
name_str = "<no-name - thread is attaching>";
}
else {
name_str = Thread::name();
}
}
else {
name_str = Thread::name();
}
assert(name_str != NULL, "unexpected NULL thread name");
return name_str;
}
const char* JavaThread::get_threadgroup_name() const {
debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
oop thread_obj = threadObj();
if (thread_obj != NULL) {
oop thread_group = java_lang_Thread::threadGroup(thread_obj);
if (thread_group != NULL) {
typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
// ThreadGroup.name can be null
if (name != NULL) {
const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
return str;
}
}
}
return NULL;
}
const char* JavaThread::get_parent_name() const {
debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
oop thread_obj = threadObj();
if (thread_obj != NULL) {
oop thread_group = java_lang_Thread::threadGroup(thread_obj);
if (thread_group != NULL) {
oop parent = java_lang_ThreadGroup::parent(thread_group);
if (parent != NULL) {
typeArrayOop name = java_lang_ThreadGroup::name(parent);
// ThreadGroup.name can be null
if (name != NULL) {
const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
return str;
}
}
}
}
return NULL;
}
ThreadPriority JavaThread::java_priority() const {
oop thr_oop = threadObj();
if (thr_oop == NULL) return NormPriority; // Bootstrapping
ThreadPriority priority = java_lang_Thread::priority(thr_oop);
assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
return priority;
}
void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
// Link Java Thread object <-> C++ Thread
// Get the C++ thread object (an oop) from the JNI handle (a jthread)
// and put it into a new Handle. The Handle "thread_oop" can then
// be used to pass the C++ thread object to other methods.
// Set the Java level thread object (jthread) field of the
// new thread (a JavaThread *) to C++ thread object using the
// "thread_oop" handle.
// Set the thread field (a JavaThread *) of the
// oop representing the java_lang_Thread to the new thread (a JavaThread *).
Handle thread_oop(Thread::current(),
JNIHandles::resolve_non_null(jni_thread));
assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
"must be initialized");
set_threadObj(thread_oop());
java_lang_Thread::set_thread(thread_oop(), this);
if (prio == NoPriority) {
prio = java_lang_Thread::priority(thread_oop());
assert(prio != NoPriority, "A valid priority should be present");
}
// Push the Java priority down to the native thread; needs Threads_lock
Thread::set_priority(this, prio);
prepare_ext();
// Add the new thread to the Threads list and set it in motion.
// We must have threads lock in order to call Threads::add.
// It is crucial that we do not block before the thread is
// added to the Threads list for if a GC happens, then the java_thread oop
// will not be visited by GC.
Threads::add(this);
}
oop JavaThread::current_park_blocker() {
// Support for JSR-166 locks
oop thread_oop = threadObj();
if (thread_oop != NULL &&
JDK_Version::current().supports_thread_park_blocker()) {
return java_lang_Thread::park_blocker(thread_oop);
}
return NULL;
}
void JavaThread::print_stack_on(outputStream* st) {
if (!has_last_Java_frame()) return;
ResourceMark rm;
HandleMark hm;
RegisterMap reg_map(this);
vframe* start_vf = last_java_vframe(&reg_map);
int count = 0;
for (vframe* f = start_vf; f; f = f->sender() ) {
if (f->is_java_frame()) {
javaVFrame* jvf = javaVFrame::cast(f);
java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
// Print out lock information
if (JavaMonitorsInStackTrace) {
jvf->print_lock_info_on(st, count);
}
} else {
// Ignore non-Java frames
}
// Bail-out case for too deep stacks
count++;
if (MaxJavaStackTraceDepth == count) return;
}
}
// JVMTI PopFrame support
void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
if (in_bytes(size_in_bytes) != 0) {
_popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
_popframe_preserved_args_size = in_bytes(size_in_bytes);
Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
}
}
void* JavaThread::popframe_preserved_args() {
return _popframe_preserved_args;
}
ByteSize JavaThread::popframe_preserved_args_size() {
return in_ByteSize(_popframe_preserved_args_size);
}
WordSize JavaThread::popframe_preserved_args_size_in_words() {
int sz = in_bytes(popframe_preserved_args_size());
assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
return in_WordSize(sz / wordSize);
}
void JavaThread::popframe_free_preserved_args() {
assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args, mtThread);
_popframe_preserved_args = NULL;
_popframe_preserved_args_size = 0;
}
#ifndef PRODUCT
void JavaThread::trace_frames() {
tty->print_cr("[Describe stack]");
int frame_no = 1;
for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
tty->print(" %d. ", frame_no++);
fst.current()->print_value_on(tty,this);
tty->cr();
}
}
class PrintAndVerifyOopClosure: public OopClosure {
protected:
template <class T> inline void do_oop_work(T* p) {
oop obj = oopDesc::load_decode_heap_oop(p);
if (obj == NULL) return;
tty->print(INTPTR_FORMAT ": ", p);
if (obj->is_oop_or_null()) {
if (obj->is_objArray()) {
tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj);
} else {
obj->print();
}
} else {
tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj);
}
tty->cr();
}
public:
virtual void do_oop(oop* p) { do_oop_work(p); }
virtual void do_oop(narrowOop* p) { do_oop_work(p); }
};
static void oops_print(frame* f, const RegisterMap *map) {
PrintAndVerifyOopClosure print;
f->print_value();
f->oops_do(&print, NULL, NULL, (RegisterMap*)map);
}
// Print our all the locations that contain oops and whether they are
// valid or not. This useful when trying to find the oldest frame
// where an oop has gone bad since the frame walk is from youngest to
// oldest.
void JavaThread::trace_oops() {
tty->print_cr("[Trace oops]");
frames_do(oops_print);
}
#ifdef ASSERT
// Print or validate the layout of stack frames
void JavaThread::print_frame_layout(int depth, bool validate_only) {
ResourceMark rm;
PRESERVE_EXCEPTION_MARK;
FrameValues values;
int frame_no = 0;
for(StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
fst.current()->describe(values, ++frame_no);
if (depth == frame_no) break;
}
if (validate_only) {
values.validate();
} else {
tty->print_cr("[Describe stack layout]");
values.print(this);
}
}
#endif
void JavaThread::trace_stack_from(vframe* start_vf) {
ResourceMark rm;
int vframe_no = 1;
for (vframe* f = start_vf; f; f = f->sender() ) {
if (f->is_java_frame()) {
javaVFrame::cast(f)->print_activation(vframe_no++);
} else {
f->print();
}
if (vframe_no > StackPrintLimit) {
tty->print_cr("...<more frames>...");
return;
}
}
}
void JavaThread::trace_stack() {
if (!has_last_Java_frame()) return;
ResourceMark rm;
HandleMark hm;
RegisterMap reg_map(this);
trace_stack_from(last_java_vframe(&reg_map));
}
#endif // PRODUCT
javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
assert(reg_map != NULL, "a map must be given");
frame f = last_frame();
for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) {
if (vf->is_java_frame()) return javaVFrame::cast(vf);
}
return NULL;
}
Klass* JavaThread::security_get_caller_class(int depth) {
vframeStream vfst(this);
vfst.security_get_caller_frame(depth);
if (!vfst.at_end()) {
return vfst.method()->method_holder();
}
return NULL;
}
static void compiler_thread_entry(JavaThread* thread, TRAPS) {
assert(thread->is_Compiler_thread(), "must be compiler thread");
CompileBroker::compiler_thread_loop();
}
// Create a CompilerThread
CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
: JavaThread(&compiler_thread_entry) {
_env = NULL;
_log = NULL;
_task = NULL;
_queue = queue;
_counters = counters;
_buffer_blob = NULL;
_scanned_nmethod = NULL;
_compiler = NULL;
#ifndef PRODUCT
_ideal_graph_printer = NULL;
#endif
}
void CompilerThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
JavaThread::oops_do(f, cld_f, cf);
if (_scanned_nmethod != NULL && cf != NULL) {
// Safepoints can occur when the sweeper is scanning an nmethod so
// process it here to make sure it isn't unloaded in the middle of
// a scan.
cf->do_code_blob(_scanned_nmethod);
}
}
// ======= Threads ========
// The Threads class links together all active threads, and provides
// operations over all threads. It is protected by its own Mutex
// lock, which is also used in other contexts to protect thread
// operations from having the thread being operated on from exiting
// and going away unexpectedly (e.g., safepoint synchronization)
JavaThread* Threads::_thread_list = NULL;
int Threads::_number_of_threads = 0;
int Threads::_number_of_non_daemon_threads = 0;
int Threads::_return_code = 0;
size_t JavaThread::_stack_size_at_create = 0;
#ifdef ASSERT
bool Threads::_vm_complete = false;
#endif
// All JavaThreads
#define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
// All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
void Threads::threads_do(ThreadClosure* tc) {
assert_locked_or_safepoint(Threads_lock);
// ALL_JAVA_THREADS iterates through all JavaThreads
ALL_JAVA_THREADS(p) {
tc->do_thread(p);
}
// Someday we could have a table or list of all non-JavaThreads.
// For now, just manually iterate through them.
tc->do_thread(VMThread::vm_thread());
Universe::heap()->gc_threads_do(tc);
WatcherThread *wt = WatcherThread::watcher_thread();
// Strictly speaking, the following NULL check isn't sufficient to make sure
// the data for WatcherThread is still valid upon being examined. However,
// considering that WatchThread terminates when the VM is on the way to
// exit at safepoint, the chance of the above is extremely small. The right
// way to prevent termination of WatcherThread would be to acquire
// Terminator_lock, but we can't do that without violating the lock rank
// checking in some cases.
if (wt != NULL)
tc->do_thread(wt);
// If CompilerThreads ever become non-JavaThreads, add them here
}
jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
extern void JDK_Version_init();
// Preinitialize version info.
VM_Version::early_initialize();
// Check version
if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
// Initialize the output stream module
ostream_init();
// Process java launcher properties.
Arguments::process_sun_java_launcher_properties(args);
// Initialize the os module before using TLS
os::init();
// Initialize system properties.
Arguments::init_system_properties();
// So that JDK version can be used as a discrimintor when parsing arguments
JDK_Version_init();
// Update/Initialize System properties after JDK version number is known
Arguments::init_version_specific_system_properties();
// Parse arguments
jint parse_result = Arguments::parse(args);
if (parse_result != JNI_OK) return parse_result;
os::init_before_ergo();
jint ergo_result = Arguments::apply_ergo();
if (ergo_result != JNI_OK) return ergo_result;
if (PauseAtStartup) {
os::pause();
}
#ifndef USDT2
HS_DTRACE_PROBE(hotspot, vm__init__begin);
#else /* USDT2 */
HOTSPOT_VM_INIT_BEGIN();
#endif /* USDT2 */
// Record VM creation timing statistics
TraceVmCreationTime create_vm_timer;
create_vm_timer.start();
// Timing (must come after argument parsing)
TraceTime timer("Create VM", TraceStartupTime);
// Initialize the os module after parsing the args
jint os_init_2_result = os::init_2();
if (os_init_2_result != JNI_OK) return os_init_2_result;
jint adjust_after_os_result = Arguments::adjust_after_os();
if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
// intialize TLS
ThreadLocalStorage::init();
// Initialize output stream logging
ostream_init_log();
// Convert -Xrun to -agentlib: if there is no JVM_OnLoad
// Must be before create_vm_init_agents()
if (Arguments::init_libraries_at_startup()) {
convert_vm_init_libraries_to_agents();
}
// Launch -agentlib/-agentpath and converted -Xrun agents
if (Arguments::init_agents_at_startup()) {
create_vm_init_agents();
}
// Initialize Threads state
_thread_list = NULL;
_number_of_threads = 0;
_number_of_non_daemon_threads = 0;
// Initialize global data structures and create system classes in heap
vm_init_globals();
// Attach the main thread to this os thread
JavaThread* main_thread = new JavaThread();
main_thread->set_thread_state(_thread_in_vm);
// must do this before set_active_handles and initialize_thread_local_storage
// Note: on solaris initialize_thread_local_storage() will (indirectly)
// change the stack size recorded here to one based on the java thread
// stacksize. This adjusted size is what is used to figure the placement
// of the guard pages.
main_thread->record_stack_base_and_size();
main_thread->initialize_thread_local_storage();
main_thread->set_active_handles(JNIHandleBlock::allocate_block());
if (!main_thread->set_as_starting_thread()) {
vm_shutdown_during_initialization(
"Failed necessary internal allocation. Out of swap space");
delete main_thread;
*canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
return JNI_ENOMEM;
}
// Enable guard page *after* os::create_main_thread(), otherwise it would
// crash Linux VM, see notes in os_linux.cpp.
main_thread->create_stack_guard_pages();
// Initialize Java-Level synchronization subsystem
ObjectMonitor::Initialize() ;
// Initialize global modules
jint status = init_globals();
if (status != JNI_OK) {
delete main_thread;
*canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
return status;
}
// Should be done after the heap is fully created
main_thread->cache_global_variables();
HandleMark hm;
{ MutexLocker mu(Threads_lock);
Threads::add(main_thread);
}
// Any JVMTI raw monitors entered in onload will transition into
// real raw monitor. VM is setup enough here for raw monitor enter.
JvmtiExport::transition_pending_onload_raw_monitors();
// Create the VMThread
{ TraceTime timer("Start VMThread", TraceStartupTime);
VMThread::create();
Thread* vmthread = VMThread::vm_thread();
if (!os::create_thread(vmthread, os::vm_thread))
vm_exit_during_initialization("Cannot create VM thread. Out of system resources.");
// Wait for the VM thread to become ready, and VMThread::run to initialize
// Monitors can have spurious returns, must always check another state flag
{
MutexLocker ml(Notify_lock);
os::start_thread(vmthread);
while (vmthread->active_handles() == NULL) {
Notify_lock->wait();
}
}
}
assert (Universe::is_fully_initialized(), "not initialized");
if (VerifyDuringStartup) {
// Make sure we're starting with a clean slate.
VM_Verify verify_op;
VMThread::execute(&verify_op);
}
EXCEPTION_MARK;
// At this point, the Universe is initialized, but we have not executed
// any byte code. Now is a good time (the only time) to dump out the
// internal state of the JVM for sharing.
if (DumpSharedSpaces) {
MetaspaceShared::preload_and_dump(CHECK_0);
ShouldNotReachHere();
}
// Always call even when there are not JVMTI environments yet, since environments
// may be attached late and JVMTI must track phases of VM execution
JvmtiExport::enter_start_phase();
// Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
JvmtiExport::post_vm_start();
{
TraceTime timer("Initialize java.lang classes", TraceStartupTime);
if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
create_vm_init_libraries();
}
initialize_class(vmSymbols::java_lang_String(), CHECK_0);
// Initialize java_lang.System (needed before creating the thread)
initialize_class(vmSymbols::java_lang_System(), CHECK_0);
initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK_0);
Handle thread_group = create_initial_thread_group(CHECK_0);
Universe::set_main_thread_group(thread_group());
initialize_class(vmSymbols::java_lang_Thread(), CHECK_0);
oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0);
main_thread->set_threadObj(thread_object);
// Set thread status to running since main thread has
// been started and running.
java_lang_Thread::set_thread_status(thread_object,
java_lang_Thread::RUNNABLE);
// The VM creates & returns objects of this class. Make sure it's initialized.
initialize_class(vmSymbols::java_lang_Class(), CHECK_0);
// The VM preresolves methods to these classes. Make sure that they get initialized
initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK_0);
initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK_0);
call_initializeSystemClass(CHECK_0);
// get the Java runtime name after java.lang.System is initialized
JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
// an instance of OutOfMemory exception has been allocated earlier
initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK_0);
initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK_0);
initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK_0);
initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK_0);
initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK_0);
initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK_0);
initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK_0);
initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK_0);
}
// See : bugid 4211085.
// Background : the static initializer of java.lang.Compiler tries to read
// property"java.compiler" and read & write property "java.vm.info".
// When a security manager is installed through the command line
// option "-Djava.security.manager", the above properties are not
// readable and the static initializer for java.lang.Compiler fails
// resulting in a NoClassDefFoundError. This can happen in any
// user code which calls methods in java.lang.Compiler.
// Hack : the hack is to pre-load and initialize this class, so that only
// system domains are on the stack when the properties are read.
// Currently even the AWT code has calls to methods in java.lang.Compiler.
// On the classic VM, java.lang.Compiler is loaded very early to load the JIT.
// Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and
// read and write"java.vm.info" in the default policy file. See bugid 4211383
// Once that is done, we should remove this hack.
initialize_class(vmSymbols::java_lang_Compiler(), CHECK_0);
// More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to
// the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot
// compiler does not get loaded through java.lang.Compiler). "java -version" with the
// hotspot vm says "nojit" all the time which is confusing. So, we reset it here.
// This should also be taken out as soon as 4211383 gets fixed.
reset_vm_info_property(CHECK_0);
quicken_jni_functions();
// Must be run after init_ft which initializes ft_enabled
if (TRACE_INITIALIZE() != JNI_OK) {
vm_exit_during_initialization("Failed to initialize tracing backend");
}
// Set flag that basic initialization has completed. Used by exceptions and various
// debug stuff, that does not work until all basic classes have been initialized.
set_init_completed();
Metaspace::post_initialize();
#ifndef USDT2
HS_DTRACE_PROBE(hotspot, vm__init__end);
#else /* USDT2 */
HOTSPOT_VM_INIT_END();
#endif /* USDT2 */
// record VM initialization completion time
#if INCLUDE_MANAGEMENT
Management::record_vm_init_completed();
#endif // INCLUDE_MANAGEMENT
// Compute system loader. Note that this has to occur after set_init_completed, since
// valid exceptions may be thrown in the process.
// Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
// set_init_completed has just been called, causing exceptions not to be shortcut
// anymore. We call vm_exit_during_initialization directly instead.
SystemDictionary::compute_java_system_loader(THREAD);
if (HAS_PENDING_EXCEPTION) {
vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
}
#if INCLUDE_ALL_GCS
// Support for ConcurrentMarkSweep. This should be cleaned up
// and better encapsulated. The ugly nested if test would go away
// once things are properly refactored. XXX YSR
if (UseConcMarkSweepGC || UseG1GC) {
if (UseConcMarkSweepGC) {
ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD);
} else {
ConcurrentMarkThread::makeSurrogateLockerThread(THREAD);
}
if (HAS_PENDING_EXCEPTION) {
vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
}
}
#endif // INCLUDE_ALL_GCS
// Always call even when there are not JVMTI environments yet, since environments
// may be attached late and JVMTI must track phases of VM execution
JvmtiExport::enter_live_phase();
// Signal Dispatcher needs to be started before VMInit event is posted
os::signal_init();
// Start Attach Listener if +StartAttachListener or it can't be started lazily
if (!DisableAttachMechanism) {
AttachListener::vm_start();
if (StartAttachListener || AttachListener::init_at_startup()) {
AttachListener::init();
}
}
// Launch -Xrun agents
// Must be done in the JVMTI live phase so that for backward compatibility the JDWP
// back-end can launch with -Xdebug -Xrunjdwp.
if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
create_vm_init_libraries();
}
// Notify JVMTI agents that VM initialization is complete - nop if no agents.
JvmtiExport::post_vm_initialized();
if (TRACE_START() != JNI_OK) {
vm_exit_during_initialization("Failed to start tracing backend.");
}
if (CleanChunkPoolAsync) {
Chunk::start_chunk_pool_cleaner_task();
}
// initialize compiler(s)
#if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK)
CompileBroker::compilation_init();
#endif
if (EnableInvokeDynamic) {
// Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
// It is done after compilers are initialized, because otherwise compilations of
// signature polymorphic MH intrinsics can be missed
// (see SystemDictionary::find_method_handle_intrinsic).
initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK_0);
initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK_0);
initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK_0);
}
#if INCLUDE_MANAGEMENT
Management::initialize(THREAD);
#endif // INCLUDE_MANAGEMENT
if (HAS_PENDING_EXCEPTION) {
// management agent fails to start possibly due to
// configuration problem and is responsible for printing
// stack trace if appropriate. Simply exit VM.
vm_exit(1);
}
if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
if (MemProfiling) MemProfiler::engage();
StatSampler::engage();
if (CheckJNICalls) JniPeriodicChecker::engage();
BiasedLocking::init();
#if INCLUDE_RTM_OPT
RTMLockingCounters::init();
#endif
if (JDK_Version::current().post_vm_init_hook_enabled()) {
call_postVMInitHook(THREAD);
// The Java side of PostVMInitHook.run must deal with all
// exceptions and provide means of diagnosis.
if (HAS_PENDING_EXCEPTION) {
CLEAR_PENDING_EXCEPTION;
}
}
{
MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
// Make sure the watcher thread can be started by WatcherThread::start()
// or by dynamic enrollment.
WatcherThread::make_startable();
// Start up the WatcherThread if there are any periodic tasks
// NOTE: All PeriodicTasks should be registered by now. If they
// aren't, late joiners might appear to start slowly (we might
// take a while to process their first tick).
if (PeriodicTask::num_tasks() > 0) {
WatcherThread::start();
}
}
create_vm_timer.end();
#ifdef ASSERT
_vm_complete = true;
#endif
return JNI_OK;
}
// type for the Agent_OnLoad and JVM_OnLoad entry points
extern "C" {
typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
}
// Find a command line agent library and return its entry point for
// -agentlib: -agentpath: -Xrun
// num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) {
OnLoadEntry_t on_load_entry = NULL;
void *library = NULL;
if (!agent->valid()) {
char buffer[JVM_MAXPATHLEN];
char ebuf[1024];
const char *name = agent->name();
const char *msg = "Could not find agent library ";
// First check to see if agent is statically linked into executable
if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
library = agent->os_lib();
} else if (agent->is_absolute_path()) {
library = os::dll_load(name, ebuf, sizeof ebuf);
if (library == NULL) {
const char *sub_msg = " in absolute path, with error: ";
size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
// If we can't find the agent, exit.
vm_exit_during_initialization(buf, NULL);
FREE_C_HEAP_ARRAY(char, buf, mtThread);
}
} else {
// Try to load the agent from the standard dll directory
if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
name)) {
library = os::dll_load(buffer, ebuf, sizeof ebuf);
}
if (library == NULL) { // Try the local directory
char ns[1] = {0};
if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
library = os::dll_load(buffer, ebuf, sizeof ebuf);
}
if (library == NULL) {
const char *sub_msg = " on the library path, with error: ";
size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
// If we can't find the agent, exit.
vm_exit_during_initialization(buf, NULL);
FREE_C_HEAP_ARRAY(char, buf, mtThread);
}
}
}
agent->set_os_lib(library);
agent->set_valid();
}
// Find the OnLoad function.
on_load_entry =
CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
false,
on_load_symbols,
num_symbol_entries));
return on_load_entry;
}
// Find the JVM_OnLoad entry point
static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
}
// Find the Agent_OnLoad entry point
static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
}
// For backwards compatibility with -Xrun
// Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
// treated like -agentpath:
// Must be called before agent libraries are created
void Threads::convert_vm_init_libraries_to_agents() {
AgentLibrary* agent;
AgentLibrary* next;
for (agent = Arguments::libraries(); agent != NULL; agent = next) {
next = agent->next(); // cache the next agent now as this agent may get moved off this list
OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
// If there is an JVM_OnLoad function it will get called later,
// otherwise see if there is an Agent_OnLoad
if (on_load_entry == NULL) {
on_load_entry = lookup_agent_on_load(agent);
if (on_load_entry != NULL) {
// switch it to the agent list -- so that Agent_OnLoad will be called,
// JVM_OnLoad won't be attempted and Agent_OnUnload will
Arguments::convert_library_to_agent(agent);
} else {
vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
}
}
}
}
// Create agents for -agentlib: -agentpath: and converted -Xrun
// Invokes Agent_OnLoad
// Called very early -- before JavaThreads exist
void Threads::create_vm_init_agents() {
extern struct JavaVM_ main_vm;
AgentLibrary* agent;
JvmtiExport::enter_onload_phase();
for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
if (on_load_entry != NULL) {
// Invoke the Agent_OnLoad function
jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
if (err != JNI_OK) {
vm_exit_during_initialization("agent library failed to init", agent->name());
}
} else {
vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
}
}
JvmtiExport::enter_primordial_phase();
}
extern "C" {
typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
}
void Threads::shutdown_vm_agents() {
// Send any Agent_OnUnload notifications
const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
extern struct JavaVM_ main_vm;
for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
// Find the Agent_OnUnload function.
Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
os::find_agent_function(agent,
false,
on_unload_symbols,
num_symbol_entries));
// Invoke the Agent_OnUnload function
if (unload_entry != NULL) {
JavaThread* thread = JavaThread::current();
ThreadToNativeFromVM ttn(thread);
HandleMark hm(thread);
(*unload_entry)(&main_vm);
}
}
}
// Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
// Invokes JVM_OnLoad
void Threads::create_vm_init_libraries() {
extern struct JavaVM_ main_vm;
AgentLibrary* agent;
for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
if (on_load_entry != NULL) {
// Invoke the JVM_OnLoad function
JavaThread* thread = JavaThread::current();
ThreadToNativeFromVM ttn(thread);
HandleMark hm(thread);
jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
if (err != JNI_OK) {
vm_exit_during_initialization("-Xrun library failed to init", agent->name());
}
} else {
vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
}
}
}
JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
JavaThread* java_thread = NULL;
// Sequential search for now. Need to do better optimization later.
for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
oop tobj = thread->threadObj();
if (!thread->is_exiting() &&
tobj != NULL &&
java_tid == java_lang_Thread::thread_id(tobj)) {
java_thread = thread;
break;
}
}
return java_thread;
}
// Last thread running calls java.lang.Shutdown.shutdown()
void JavaThread::invoke_shutdown_hooks() {
HandleMark hm(this);
// We could get here with a pending exception, if so clear it now.
if (this->has_pending_exception()) {
this->clear_pending_exception();
}
EXCEPTION_MARK;
Klass* k =
SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
THREAD);
if (k != NULL) {
// SystemDictionary::resolve_or_null will return null if there was
// an exception. If we cannot load the Shutdown class, just don't
// call Shutdown.shutdown() at all. This will mean the shutdown hooks
// and finalizers (if runFinalizersOnExit is set) won't be run.
// Note that if a shutdown hook was registered or runFinalizersOnExit
// was called, the Shutdown class would have already been loaded
// (Runtime.addShutdownHook and runFinalizersOnExit will load it).
instanceKlassHandle shutdown_klass (THREAD, k);
JavaValue result(T_VOID);
JavaCalls::call_static(&result,
shutdown_klass,
vmSymbols::shutdown_method_name(),
vmSymbols::void_method_signature(),
THREAD);
}
CLEAR_PENDING_EXCEPTION;
}
// Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
// the program falls off the end of main(). Another VM exit path is through
// vm_exit() when the program calls System.exit() to return a value or when
// there is a serious error in VM. The two shutdown paths are not exactly
// the same, but they share Shutdown.shutdown() at Java level and before_exit()
// and VM_Exit op at VM level.
//
// Shutdown sequence:
// + Shutdown native memory tracking if it is on
// + Wait until we are the last non-daemon thread to execute
// <-- every thing is still working at this moment -->
// + Call java.lang.Shutdown.shutdown(), which will invoke Java level
// shutdown hooks, run finalizers if finalization-on-exit
// + Call before_exit(), prepare for VM exit
// > run VM level shutdown hooks (they are registered through JVM_OnExit(),
// currently the only user of this mechanism is File.deleteOnExit())
// > stop flat profiler, StatSampler, watcher thread, CMS threads,
// post thread end and vm death events to JVMTI,
// stop signal thread
// + Call JavaThread::exit(), it will:
// > release JNI handle blocks, remove stack guard pages
// > remove this thread from Threads list
// <-- no more Java code from this thread after this point -->
// + Stop VM thread, it will bring the remaining VM to a safepoint and stop
// the compiler threads at safepoint
// <-- do not use anything that could get blocked by Safepoint -->
// + Disable tracing at JNI/JVM barriers
// + Set _vm_exited flag for threads that are still running native code
// + Delete this thread
// + Call exit_globals()
// > deletes tty
// > deletes PerfMemory resources
// + Return to caller
bool Threads::destroy_vm() {
JavaThread* thread = JavaThread::current();
#ifdef ASSERT
_vm_complete = false;
#endif
// Wait until we are the last non-daemon thread to execute
{ MutexLocker nu(Threads_lock);
while (Threads::number_of_non_daemon_threads() > 1 )
// This wait should make safepoint checks, wait without a timeout,
// and wait as a suspend-equivalent condition.
//
// Note: If the FlatProfiler is running and this thread is waiting
// for another non-daemon thread to finish, then the FlatProfiler
// is waiting for the external suspend request on this thread to
// complete. wait_for_ext_suspend_completion() will eventually
// timeout, but that takes time. Making this wait a suspend-
// equivalent condition solves that timeout problem.
//
Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
Mutex::_as_suspend_equivalent_flag);
}
// Hang forever on exit if we are reporting an error.
if (ShowMessageBoxOnError && is_error_reported()) {
os::infinite_sleep();
}
os::wait_for_keypress_at_exit();
if (JDK_Version::is_jdk12x_version()) {
// We are the last thread running, so check if finalizers should be run.
// For 1.3 or later this is done in thread->invoke_shutdown_hooks()
HandleMark rm(thread);
Universe::run_finalizers_on_exit();
} else {
// run Java level shutdown hooks
thread->invoke_shutdown_hooks();
}
before_exit(thread);
thread->exit(true);
// Stop VM thread.
{
// 4945125 The vm thread comes to a safepoint during exit.
// GC vm_operations can get caught at the safepoint, and the
// heap is unparseable if they are caught. Grab the Heap_lock
// to prevent this. The GC vm_operations will not be able to
// queue until after the vm thread is dead. After this point,
// we'll never emerge out of the safepoint before the VM exits.
MutexLocker ml(Heap_lock);
VMThread::wait_for_vm_thread_exit();
assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
VMThread::destroy();
}
// clean up ideal graph printers
#if defined(COMPILER2) && !defined(PRODUCT)
IdealGraphPrinter::clean_up();
#endif
// Now, all Java threads are gone except daemon threads. Daemon threads
// running Java code or in VM are stopped by the Safepoint. However,
// daemon threads executing native code are still running. But they
// will be stopped at native=>Java/VM barriers. Note that we can't
// simply kill or suspend them, as it is inherently deadlock-prone.
#ifndef PRODUCT
// disable function tracing at JNI/JVM barriers
TraceJNICalls = false;
TraceJVMCalls = false;
TraceRuntimeCalls = false;
#endif
VM_Exit::set_vm_exited();
notify_vm_shutdown();
delete thread;
// exit_globals() will delete tty
exit_globals();
return true;
}
jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
if (version == JNI_VERSION_1_1) return JNI_TRUE;
return is_supported_jni_version(version);
}
jboolean Threads::is_supported_jni_version(jint version) {
if (version == JNI_VERSION_1_2) return JNI_TRUE;
if (version == JNI_VERSION_1_4) return JNI_TRUE;
if (version == JNI_VERSION_1_6) return JNI_TRUE;
if (version == JNI_VERSION_1_8) return JNI_TRUE;
return JNI_FALSE;
}
void Threads::add(JavaThread* p, bool force_daemon) {
// The threads lock must be owned at this point
assert_locked_or_safepoint(Threads_lock);
// See the comment for this method in thread.hpp for its purpose and
// why it is called here.
p->initialize_queues();
p->set_next(_thread_list);
_thread_list = p;
_number_of_threads++;
oop threadObj = p->threadObj();
bool daemon = true;
// Bootstrapping problem: threadObj can be null for initial
// JavaThread (or for threads attached via JNI)
if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
_number_of_non_daemon_threads++;
daemon = false;
}
ThreadService::add_thread(p, daemon);
// Possible GC point.
Events::log(p, "Thread added: " INTPTR_FORMAT, p);
}
void Threads::remove(JavaThread* p) {
// Extra scope needed for Thread_lock, so we can check
// that we do not remove thread without safepoint code notice
{ MutexLocker ml(Threads_lock);
assert(includes(p), "p must be present");
JavaThread* current = _thread_list;
JavaThread* prev = NULL;
while (current != p) {
prev = current;
current = current->next();
}
if (prev) {
prev->set_next(current->next());
} else {
_thread_list = p->next();
}
_number_of_threads--;
oop threadObj = p->threadObj();
bool daemon = true;
if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
_number_of_non_daemon_threads--;
daemon = false;
// Only one thread left, do a notify on the Threads_lock so a thread waiting
// on destroy_vm will wake up.
if (number_of_non_daemon_threads() == 1)
Threads_lock->notify_all();
}
ThreadService::remove_thread(p, daemon);
// Make sure that safepoint code disregard this thread. This is needed since
// the thread might mess around with locks after this point. This can cause it
// to do callbacks into the safepoint code. However, the safepoint code is not aware
// of this thread since it is removed from the queue.
p->set_terminated_value();
} // unlock Threads_lock
// Since Events::log uses a lock, we grab it outside the Threads_lock
Events::log(p, "Thread exited: " INTPTR_FORMAT, p);
}
// Threads_lock must be held when this is called (or must be called during a safepoint)
bool Threads::includes(JavaThread* p) {
assert(Threads_lock->is_locked(), "sanity check");
ALL_JAVA_THREADS(q) {
if (q == p ) {
return true;
}
}
return false;
}
// Operations on the Threads list for GC. These are not explicitly locked,
// but the garbage collector must provide a safe context for them to run.
// In particular, these things should never be called when the Threads_lock
// is held by some other thread. (Note: the Safepoint abstraction also
// uses the Threads_lock to gurantee this property. It also makes sure that
// all threads gets blocked when exiting or starting).
void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
ALL_JAVA_THREADS(p) {
p->oops_do(f, cld_f, cf);
}
VMThread::vm_thread()->oops_do(f, cld_f, cf);
}
void Threads::possibly_parallel_oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
// Introduce a mechanism allowing parallel threads to claim threads as
// root groups. Overhead should be small enough to use all the time,
// even in sequential code.
SharedHeap* sh = SharedHeap::heap();
// Cannot yet substitute active_workers for n_par_threads
// because of G1CollectedHeap::verify() use of
// SharedHeap::process_roots(). n_par_threads == 0 will
// turn off parallelism in process_roots while active_workers
// is being used for parallelism elsewhere.
bool is_par = sh->n_par_threads() > 0;
assert(!is_par ||
(SharedHeap::heap()->n_par_threads() ==
SharedHeap::heap()->workers()->active_workers()), "Mismatch");
int cp = SharedHeap::heap()->strong_roots_parity();
ALL_JAVA_THREADS(p) {
if (p->claim_oops_do(is_par, cp)) {
p->oops_do(f, cld_f, cf);
}
}
VMThread* vmt = VMThread::vm_thread();
if (vmt->claim_oops_do(is_par, cp)) {
vmt->oops_do(f, cld_f, cf);
}
}
#if INCLUDE_ALL_GCS
// Used by ParallelScavenge
void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
ALL_JAVA_THREADS(p) {
q->enqueue(new ThreadRootsTask(p));
}
q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
}
// Used by Parallel Old
void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
ALL_JAVA_THREADS(p) {
q->enqueue(new ThreadRootsMarkingTask(p));
}
q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
}
#endif // INCLUDE_ALL_GCS
void Threads::nmethods_do(CodeBlobClosure* cf) {
ALL_JAVA_THREADS(p) {
p->nmethods_do(cf);
}
VMThread::vm_thread()->nmethods_do(cf);
}
void Threads::metadata_do(void f(Metadata*)) {
ALL_JAVA_THREADS(p) {
p->metadata_do(f);
}
}
void Threads::gc_epilogue() {
ALL_JAVA_THREADS(p) {
p->gc_epilogue();
}
}
void Threads::gc_prologue() {
ALL_JAVA_THREADS(p) {
p->gc_prologue();
}
}
void Threads::deoptimized_wrt_marked_nmethods() {
ALL_JAVA_THREADS(p) {
p->deoptimized_wrt_marked_nmethods();
}
}
// Get count Java threads that are waiting to enter the specified monitor.
GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
address monitor, bool doLock) {
assert(doLock || SafepointSynchronize::is_at_safepoint(),
"must grab Threads_lock or be at safepoint");
GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
int i = 0;
{
MutexLockerEx ml(doLock ? Threads_lock : NULL);
ALL_JAVA_THREADS(p) {
if (p->is_Compiler_thread()) continue;
address pending = (address)p->current_pending_monitor();
if (pending == monitor) { // found a match
if (i < count) result->append(p); // save the first count matches
i++;
}
}
}
return result;
}
JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) {
assert(doLock ||
Threads_lock->owned_by_self() ||
SafepointSynchronize::is_at_safepoint(),
"must grab Threads_lock or be at safepoint");
// NULL owner means not locked so we can skip the search
if (owner == NULL) return NULL;
{
MutexLockerEx ml(doLock ? Threads_lock : NULL);
ALL_JAVA_THREADS(p) {
// first, see if owner is the address of a Java thread
if (owner == (address)p) return p;
}
}
// Cannot assert on lack of success here since this function may be
// used by code that is trying to report useful problem information
// like deadlock detection.
if (UseHeavyMonitors) return NULL;
//
// If we didn't find a matching Java thread and we didn't force use of
// heavyweight monitors, then the owner is the stack address of the
// Lock Word in the owning Java thread's stack.
//
JavaThread* the_owner = NULL;
{
MutexLockerEx ml(doLock ? Threads_lock : NULL);
ALL_JAVA_THREADS(q) {
if (q->is_lock_owned(owner)) {
the_owner = q;
break;
}
}
}
// cannot assert on lack of success here; see above comment
return the_owner;
}
// Threads::print_on() is called at safepoint by VM_PrintThreads operation.
void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) {
char buf[32];
st->print_cr("%s", os::local_time_string(buf, sizeof(buf)));
st->print_cr("Full thread dump %s (%s %s):",
Abstract_VM_Version::vm_name(),
Abstract_VM_Version::vm_release(),
Abstract_VM_Version::vm_info_string()
);
st->cr();
#if INCLUDE_ALL_GCS
// Dump concurrent locks
ConcurrentLocksDump concurrent_locks;
if (print_concurrent_locks) {
concurrent_locks.dump_at_safepoint();
}
#endif // INCLUDE_ALL_GCS
ALL_JAVA_THREADS(p) {
ResourceMark rm;
p->print_on(st);
if (print_stacks) {
if (internal_format) {
p->trace_stack();
} else {
p->print_stack_on(st);
}
}
st->cr();
#if INCLUDE_ALL_GCS
if (print_concurrent_locks) {
concurrent_locks.print_locks_on(p, st);
}
#endif // INCLUDE_ALL_GCS
}
VMThread::vm_thread()->print_on(st);
st->cr();
Universe::heap()->print_gc_threads_on(st);
WatcherThread* wt = WatcherThread::watcher_thread();
if (wt != NULL) {
wt->print_on(st);
st->cr();
}
CompileBroker::print_compiler_threads_on(st);
st->flush();
}
// Threads::print_on_error() is called by fatal error handler. It's possible
// that VM is not at safepoint and/or current thread is inside signal handler.
// Don't print stack trace, as the stack may not be walkable. Don't allocate
// memory (even in resource area), it might deadlock the error handler.
void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) {
bool found_current = false;
st->print_cr("Java Threads: ( => current thread )");
ALL_JAVA_THREADS(thread) {
bool is_current = (current == thread);
found_current = found_current || is_current;
st->print("%s", is_current ? "=>" : " ");
st->print(PTR_FORMAT, thread);
st->print(" ");
thread->print_on_error(st, buf, buflen);
st->cr();
}
st->cr();
st->print_cr("Other Threads:");
if (VMThread::vm_thread()) {
bool is_current = (current == VMThread::vm_thread());
found_current = found_current || is_current;
st->print("%s", current == VMThread::vm_thread() ? "=>" : " ");
st->print(PTR_FORMAT, VMThread::vm_thread());
st->print(" ");
VMThread::vm_thread()->print_on_error(st, buf, buflen);
st->cr();
}
WatcherThread* wt = WatcherThread::watcher_thread();
if (wt != NULL) {
bool is_current = (current == wt);
found_current = found_current || is_current;
st->print("%s", is_current ? "=>" : " ");
st->print(PTR_FORMAT, wt);
st->print(" ");
wt->print_on_error(st, buf, buflen);
st->cr();
}
if (!found_current) {
st->cr();
st->print("=>" PTR_FORMAT " (exited) ", current);
current->print_on_error(st, buf, buflen);
st->cr();
}
}
// Internal SpinLock and Mutex
// Based on ParkEvent
// Ad-hoc mutual exclusion primitives: SpinLock and Mux
//
// We employ SpinLocks _only for low-contention, fixed-length
// short-duration critical sections where we're concerned
// about native mutex_t or HotSpot Mutex:: latency.
// The mux construct provides a spin-then-block mutual exclusion
// mechanism.
//
// Testing has shown that contention on the ListLock guarding gFreeList
// is common. If we implement ListLock as a simple SpinLock it's common
// for the JVM to devolve to yielding with little progress. This is true
// despite the fact that the critical sections protected by ListLock are
// extremely short.
//
// TODO-FIXME: ListLock should be of type SpinLock.
// We should make this a 1st-class type, integrated into the lock
// hierarchy as leaf-locks. Critically, the SpinLock structure
// should have sufficient padding to avoid false-sharing and excessive
// cache-coherency traffic.
typedef volatile int SpinLockT ;
void Thread::SpinAcquire (volatile int * adr, const char * LockName) {
if (Atomic::cmpxchg (1, adr, 0) == 0) {
return ; // normal fast-path return
}
// Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
TEVENT (SpinAcquire - ctx) ;
int ctr = 0 ;
int Yields = 0 ;
for (;;) {
while (*adr != 0) {
++ctr ;
if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
if (Yields > 5) {
os::naked_short_sleep(1);
} else {
os::NakedYield() ;
++Yields ;
}
} else {
SpinPause() ;
}
}
if (Atomic::cmpxchg (1, adr, 0) == 0) return ;
}
}
void Thread::SpinRelease (volatile int * adr) {
assert (*adr != 0, "invariant") ;
OrderAccess::fence() ; // guarantee at least release consistency.
// Roach-motel semantics.
// It's safe if subsequent LDs and STs float "up" into the critical section,
// but prior LDs and STs within the critical section can't be allowed
// to reorder or float past the ST that releases the lock.
*adr = 0 ;
}
// muxAcquire and muxRelease:
//
// * muxAcquire and muxRelease support a single-word lock-word construct.
// The LSB of the word is set IFF the lock is held.
// The remainder of the word points to the head of a singly-linked list
// of threads blocked on the lock.
//
// * The current implementation of muxAcquire-muxRelease uses its own
// dedicated Thread._MuxEvent instance. If we're interested in
// minimizing the peak number of extant ParkEvent instances then
// we could eliminate _MuxEvent and "borrow" _ParkEvent as long
// as certain invariants were satisfied. Specifically, care would need
// to be taken with regards to consuming unpark() "permits".
// A safe rule of thumb is that a thread would never call muxAcquire()
// if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
// park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
// consume an unpark() permit intended for monitorenter, for instance.
// One way around this would be to widen the restricted-range semaphore
// implemented in park(). Another alternative would be to provide
// multiple instances of the PlatformEvent() for each thread. One
// instance would be dedicated to muxAcquire-muxRelease, for instance.
//
// * Usage:
// -- Only as leaf locks
// -- for short-term locking only as muxAcquire does not perform
// thread state transitions.
//
// Alternatives:
// * We could implement muxAcquire and muxRelease with MCS or CLH locks
// but with parking or spin-then-park instead of pure spinning.
// * Use Taura-Oyama-Yonenzawa locks.
// * It's possible to construct a 1-0 lock if we encode the lockword as
// (List,LockByte). Acquire will CAS the full lockword while Release
// will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
// acquiring threads use timers (ParkTimed) to detect and recover from
// the stranding window. Thread/Node structures must be aligned on 256-byte
// boundaries by using placement-new.
// * Augment MCS with advisory back-link fields maintained with CAS().
// Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
// The validity of the backlinks must be ratified before we trust the value.
// If the backlinks are invalid the exiting thread must back-track through the
// the forward links, which are always trustworthy.
// * Add a successor indication. The LockWord is currently encoded as
// (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
// to provide the usual futile-wakeup optimization.
// See RTStt for details.
// * Consider schedctl.sc_nopreempt to cover the critical section.
//
typedef volatile intptr_t MutexT ; // Mux Lock-word
enum MuxBits { LOCKBIT = 1 } ;
void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) {
intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
if (w == 0) return ;
if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
return ;
}
TEVENT (muxAcquire - Contention) ;
ParkEvent * const Self = Thread::current()->_MuxEvent ;
assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ;
for (;;) {
int its = (os::is_MP() ? 100 : 0) + 1 ;
// Optional spin phase: spin-then-park strategy
while (--its >= 0) {
w = *Lock ;
if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
return ;
}
}
Self->reset() ;
Self->OnList = intptr_t(Lock) ;
// The following fence() isn't _strictly necessary as the subsequent
// CAS() both serializes execution and ratifies the fetched *Lock value.
OrderAccess::fence();
for (;;) {
w = *Lock ;
if ((w & LOCKBIT) == 0) {
if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
Self->OnList = 0 ; // hygiene - allows stronger asserts
return ;
}
continue ; // Interference -- *Lock changed -- Just retry
}
assert (w & LOCKBIT, "invariant") ;
Self->ListNext = (ParkEvent *) (w & ~LOCKBIT );
if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ;
}
while (Self->OnList != 0) {
Self->park() ;
}
}
}
void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) {
intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
if (w == 0) return ;
if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
return ;
}
TEVENT (muxAcquire - Contention) ;
ParkEvent * ReleaseAfter = NULL ;
if (ev == NULL) {
ev = ReleaseAfter = ParkEvent::Allocate (NULL) ;
}
assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ;
for (;;) {
guarantee (ev->OnList == 0, "invariant") ;
int its = (os::is_MP() ? 100 : 0) + 1 ;
// Optional spin phase: spin-then-park strategy
while (--its >= 0) {
w = *Lock ;
if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
if (ReleaseAfter != NULL) {
ParkEvent::Release (ReleaseAfter) ;
}
return ;
}
}
ev->reset() ;
ev->OnList = intptr_t(Lock) ;
// The following fence() isn't _strictly necessary as the subsequent
// CAS() both serializes execution and ratifies the fetched *Lock value.
OrderAccess::fence();
for (;;) {
w = *Lock ;
if ((w & LOCKBIT) == 0) {
if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
ev->OnList = 0 ;
// We call ::Release while holding the outer lock, thus
// artificially lengthening the critical section.
// Consider deferring the ::Release() until the subsequent unlock(),
// after we've dropped the outer lock.
if (ReleaseAfter != NULL) {
ParkEvent::Release (ReleaseAfter) ;
}
return ;
}
continue ; // Interference -- *Lock changed -- Just retry
}
assert (w & LOCKBIT, "invariant") ;
ev->ListNext = (ParkEvent *) (w & ~LOCKBIT );
if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ;
}
while (ev->OnList != 0) {
ev->park() ;
}
}
}
// Release() must extract a successor from the list and then wake that thread.
// It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
// similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
// Release() would :
// (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
// (B) Extract a successor from the private list "in-hand"
// (C) attempt to CAS() the residual back into *Lock over null.
// If there were any newly arrived threads and the CAS() would fail.
// In that case Release() would detach the RATs, re-merge the list in-hand
// with the RATs and repeat as needed. Alternately, Release() might
// detach and extract a successor, but then pass the residual list to the wakee.
// The wakee would be responsible for reattaching and remerging before it
// competed for the lock.
//
// Both "pop" and DMR are immune from ABA corruption -- there can be
// multiple concurrent pushers, but only one popper or detacher.
// This implementation pops from the head of the list. This is unfair,
// but tends to provide excellent throughput as hot threads remain hot.
// (We wake recently run threads first).
void Thread::muxRelease (volatile intptr_t * Lock) {
for (;;) {
const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ;
assert (w & LOCKBIT, "invariant") ;
if (w == LOCKBIT) return ;
ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ;
assert (List != NULL, "invariant") ;
assert (List->OnList == intptr_t(Lock), "invariant") ;
ParkEvent * nxt = List->ListNext ;
// The following CAS() releases the lock and pops the head element.
if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
continue ;
}
List->OnList = 0 ;
OrderAccess::fence() ;
List->unpark () ;
return ;
}
}
void Threads::verify() {
ALL_JAVA_THREADS(p) {
p->verify();
}
VMThread* thread = VMThread::vm_thread();
if (thread != NULL) thread->verify();
}