| /* |
| * Copyright (c) 1997, 2021, 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/classLoaderDataGraph.hpp" |
| #include "classfile/dictionary.hpp" |
| #include "classfile/stringTable.hpp" |
| #include "classfile/symbolTable.hpp" |
| #include "code/codeCache.hpp" |
| #include "code/icBuffer.hpp" |
| #include "code/nmethod.hpp" |
| #include "code/pcDesc.hpp" |
| #include "code/scopeDesc.hpp" |
| #include "compiler/compilationPolicy.hpp" |
| #include "gc/shared/collectedHeap.hpp" |
| #include "gc/shared/gcLocker.hpp" |
| #include "gc/shared/oopStorage.hpp" |
| #include "gc/shared/strongRootsScope.hpp" |
| #include "gc/shared/workgroup.hpp" |
| #include "interpreter/interpreter.hpp" |
| #include "jfr/jfrEvents.hpp" |
| #include "logging/log.hpp" |
| #include "logging/logStream.hpp" |
| #include "memory/resourceArea.hpp" |
| #include "memory/universe.hpp" |
| #include "oops/oop.inline.hpp" |
| #include "oops/symbol.hpp" |
| #include "runtime/atomic.hpp" |
| #include "runtime/deoptimization.hpp" |
| #include "runtime/frame.inline.hpp" |
| #include "runtime/handles.inline.hpp" |
| #include "runtime/interfaceSupport.inline.hpp" |
| #include "runtime/mutexLocker.hpp" |
| #include "runtime/orderAccess.hpp" |
| #include "runtime/osThread.hpp" |
| #include "runtime/safepoint.hpp" |
| #include "runtime/safepointMechanism.inline.hpp" |
| #include "runtime/signature.hpp" |
| #include "runtime/stackWatermarkSet.inline.hpp" |
| #include "runtime/stubCodeGenerator.hpp" |
| #include "runtime/stubRoutines.hpp" |
| #include "runtime/sweeper.hpp" |
| #include "runtime/synchronizer.hpp" |
| #include "runtime/thread.inline.hpp" |
| #include "runtime/threadSMR.hpp" |
| #include "runtime/threadWXSetters.inline.hpp" |
| #include "runtime/timerTrace.hpp" |
| #include "services/runtimeService.hpp" |
| #include "utilities/events.hpp" |
| #include "utilities/macros.hpp" |
| |
| static void post_safepoint_begin_event(EventSafepointBegin& event, |
| uint64_t safepoint_id, |
| int thread_count, |
| int critical_thread_count) { |
| if (event.should_commit()) { |
| event.set_safepointId(safepoint_id); |
| event.set_totalThreadCount(thread_count); |
| event.set_jniCriticalThreadCount(critical_thread_count); |
| event.commit(); |
| } |
| } |
| |
| static void post_safepoint_cleanup_event(EventSafepointCleanup& event, uint64_t safepoint_id) { |
| if (event.should_commit()) { |
| event.set_safepointId(safepoint_id); |
| event.commit(); |
| } |
| } |
| |
| static void post_safepoint_synchronize_event(EventSafepointStateSynchronization& event, |
| uint64_t safepoint_id, |
| int initial_number_of_threads, |
| int threads_waiting_to_block, |
| uint64_t iterations) { |
| if (event.should_commit()) { |
| event.set_safepointId(safepoint_id); |
| event.set_initialThreadCount(initial_number_of_threads); |
| event.set_runningThreadCount(threads_waiting_to_block); |
| event.set_iterations(iterations); |
| event.commit(); |
| } |
| } |
| |
| static void post_safepoint_cleanup_task_event(EventSafepointCleanupTask& event, |
| uint64_t safepoint_id, |
| const char* name) { |
| if (event.should_commit()) { |
| event.set_safepointId(safepoint_id); |
| event.set_name(name); |
| event.commit(); |
| } |
| } |
| |
| static void post_safepoint_end_event(EventSafepointEnd& event, uint64_t safepoint_id) { |
| if (event.should_commit()) { |
| event.set_safepointId(safepoint_id); |
| event.commit(); |
| } |
| } |
| |
| // SafepointCheck |
| SafepointStateTracker::SafepointStateTracker(uint64_t safepoint_id, bool at_safepoint) |
| : _safepoint_id(safepoint_id), _at_safepoint(at_safepoint) {} |
| |
| bool SafepointStateTracker::safepoint_state_changed() { |
| return _safepoint_id != SafepointSynchronize::safepoint_id() || |
| _at_safepoint != SafepointSynchronize::is_at_safepoint(); |
| } |
| |
| // -------------------------------------------------------------------------------------------------- |
| // Implementation of Safepoint begin/end |
| |
| SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized; |
| int SafepointSynchronize::_waiting_to_block = 0; |
| volatile uint64_t SafepointSynchronize::_safepoint_counter = 0; |
| uint64_t SafepointSynchronize::_safepoint_id = 0; |
| const uint64_t SafepointSynchronize::InactiveSafepointCounter = 0; |
| int SafepointSynchronize::_current_jni_active_count = 0; |
| |
| WaitBarrier* SafepointSynchronize::_wait_barrier; |
| |
| static bool timeout_error_printed = false; |
| |
| // Statistic related |
| static jlong _safepoint_begin_time = 0; |
| static volatile int _nof_threads_hit_polling_page = 0; |
| |
| void SafepointSynchronize::init(Thread* vmthread) { |
| // WaitBarrier should never be destroyed since we will have |
| // threads waiting on it while exiting. |
| _wait_barrier = new WaitBarrier(vmthread); |
| SafepointTracing::init(); |
| } |
| |
| void SafepointSynchronize::increment_jni_active_count() { |
| assert(Thread::current()->is_VM_thread(), "Only VM thread may increment"); |
| ++_current_jni_active_count; |
| } |
| |
| void SafepointSynchronize::decrement_waiting_to_block() { |
| assert(_waiting_to_block > 0, "sanity check"); |
| assert(Thread::current()->is_VM_thread(), "Only VM thread may decrement"); |
| --_waiting_to_block; |
| } |
| |
| bool SafepointSynchronize::thread_not_running(ThreadSafepointState *cur_state) { |
| if (!cur_state->is_running()) { |
| return true; |
| } |
| cur_state->examine_state_of_thread(SafepointSynchronize::safepoint_counter()); |
| if (!cur_state->is_running()) { |
| return true; |
| } |
| LogTarget(Trace, safepoint) lt; |
| if (lt.is_enabled()) { |
| ResourceMark rm; |
| LogStream ls(lt); |
| cur_state->print_on(&ls); |
| } |
| return false; |
| } |
| |
| #ifdef ASSERT |
| static void assert_list_is_valid(const ThreadSafepointState* tss_head, int still_running) { |
| int a = 0; |
| const ThreadSafepointState *tmp_tss = tss_head; |
| while (tmp_tss != NULL) { |
| ++a; |
| assert(tmp_tss->is_running(), "Illegal initial state"); |
| tmp_tss = tmp_tss->get_next(); |
| } |
| assert(a == still_running, "Must be the same"); |
| } |
| #endif // ASSERT |
| |
| static void back_off(int64_t start_time) { |
| // We start with fine-grained nanosleeping until a millisecond has |
| // passed, at which point we resort to plain naked_short_sleep. |
| if (os::javaTimeNanos() - start_time < NANOSECS_PER_MILLISEC) { |
| os::naked_short_nanosleep(10 * (NANOUNITS / MICROUNITS)); |
| } else { |
| os::naked_short_sleep(1); |
| } |
| } |
| |
| int SafepointSynchronize::synchronize_threads(jlong safepoint_limit_time, int nof_threads, int* initial_running) |
| { |
| JavaThreadIteratorWithHandle jtiwh; |
| |
| #ifdef ASSERT |
| for (; JavaThread *cur = jtiwh.next(); ) { |
| assert(cur->safepoint_state()->is_running(), "Illegal initial state"); |
| } |
| jtiwh.rewind(); |
| #endif // ASSERT |
| |
| // Iterate through all threads until it has been determined how to stop them all at a safepoint. |
| int still_running = nof_threads; |
| ThreadSafepointState *tss_head = NULL; |
| ThreadSafepointState **p_prev = &tss_head; |
| for (; JavaThread *cur = jtiwh.next(); ) { |
| ThreadSafepointState *cur_tss = cur->safepoint_state(); |
| assert(cur_tss->get_next() == NULL, "Must be NULL"); |
| if (thread_not_running(cur_tss)) { |
| --still_running; |
| } else { |
| *p_prev = cur_tss; |
| p_prev = cur_tss->next_ptr(); |
| } |
| } |
| *p_prev = NULL; |
| |
| DEBUG_ONLY(assert_list_is_valid(tss_head, still_running);) |
| |
| *initial_running = still_running; |
| |
| // If there is no thread still running, we are already done. |
| if (still_running <= 0) { |
| assert(tss_head == NULL, "Must be empty"); |
| return 1; |
| } |
| |
| int iterations = 1; // The first iteration is above. |
| int64_t start_time = os::javaTimeNanos(); |
| |
| do { |
| // Check if this has taken too long: |
| if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) { |
| print_safepoint_timeout(); |
| } |
| |
| p_prev = &tss_head; |
| ThreadSafepointState *cur_tss = tss_head; |
| while (cur_tss != NULL) { |
| assert(cur_tss->is_running(), "Illegal initial state"); |
| if (thread_not_running(cur_tss)) { |
| --still_running; |
| *p_prev = NULL; |
| ThreadSafepointState *tmp = cur_tss; |
| cur_tss = cur_tss->get_next(); |
| tmp->set_next(NULL); |
| } else { |
| *p_prev = cur_tss; |
| p_prev = cur_tss->next_ptr(); |
| cur_tss = cur_tss->get_next(); |
| } |
| } |
| |
| DEBUG_ONLY(assert_list_is_valid(tss_head, still_running);) |
| |
| if (still_running > 0) { |
| back_off(start_time); |
| } |
| |
| iterations++; |
| } while (still_running > 0); |
| |
| assert(tss_head == NULL, "Must be empty"); |
| |
| return iterations; |
| } |
| |
| void SafepointSynchronize::arm_safepoint() { |
| // Begin the process of bringing the system to a safepoint. |
| // Java threads can be in several different states and are |
| // stopped by different mechanisms: |
| // |
| // 1. Running interpreted |
| // When executing branching/returning byte codes interpreter |
| // checks if the poll is armed, if so blocks in SS::block(). |
| // 2. Running in native code |
| // When returning from the native code, a Java thread must check |
| // the safepoint _state to see if we must block. If the |
| // VM thread sees a Java thread in native, it does |
| // not wait for this thread to block. The order of the memory |
| // writes and reads of both the safepoint state and the Java |
| // threads state is critical. In order to guarantee that the |
| // memory writes are serialized with respect to each other, |
| // the VM thread issues a memory barrier instruction. |
| // 3. Running compiled Code |
| // Compiled code reads the local polling page that |
| // is set to fault if we are trying to get to a safepoint. |
| // 4. Blocked |
| // A thread which is blocked will not be allowed to return from the |
| // block condition until the safepoint operation is complete. |
| // 5. In VM or Transitioning between states |
| // If a Java thread is currently running in the VM or transitioning |
| // between states, the safepointing code will poll the thread state |
| // until the thread blocks itself when it attempts transitions to a |
| // new state or locking a safepoint checked monitor. |
| |
| // We must never miss a thread with correct safepoint id, so we must make sure we arm |
| // the wait barrier for the next safepoint id/counter. |
| // Arming must be done after resetting _current_jni_active_count, _waiting_to_block. |
| _wait_barrier->arm(static_cast<int>(_safepoint_counter + 1)); |
| |
| assert((_safepoint_counter & 0x1) == 0, "must be even"); |
| // The store to _safepoint_counter must happen after any stores in arming. |
| Atomic::release_store(&_safepoint_counter, _safepoint_counter + 1); |
| |
| // We are synchronizing |
| OrderAccess::storestore(); // Ordered with _safepoint_counter |
| _state = _synchronizing; |
| |
| // Arming the per thread poll while having _state != _not_synchronized means safepointing |
| log_trace(safepoint)("Setting thread local yield flag for threads"); |
| OrderAccess::storestore(); // storestore, global state -> local state |
| for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur = jtiwh.next(); ) { |
| // Make sure the threads start polling, it is time to yield. |
| SafepointMechanism::arm_local_poll(cur); |
| } |
| |
| OrderAccess::fence(); // storestore|storeload, global state -> local state |
| } |
| |
| // Roll all threads forward to a safepoint and suspend them all |
| void SafepointSynchronize::begin() { |
| assert(Thread::current()->is_VM_thread(), "Only VM thread may execute a safepoint"); |
| |
| EventSafepointBegin begin_event; |
| SafepointTracing::begin(VMThread::vm_op_type()); |
| |
| Universe::heap()->safepoint_synchronize_begin(); |
| |
| // By getting the Threads_lock, we assure that no threads are about to start or |
| // exit. It is released again in SafepointSynchronize::end(). |
| Threads_lock->lock(); |
| |
| assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state"); |
| |
| int nof_threads = Threads::number_of_threads(); |
| |
| _nof_threads_hit_polling_page = 0; |
| |
| log_debug(safepoint)("Safepoint synchronization initiated using %s wait barrier. (%d threads)", _wait_barrier->description(), nof_threads); |
| |
| // Reset the count of active JNI critical threads |
| _current_jni_active_count = 0; |
| |
| // Set number of threads to wait for |
| _waiting_to_block = nof_threads; |
| |
| jlong safepoint_limit_time = 0; |
| if (SafepointTimeout) { |
| // Set the limit time, so that it can be compared to see if this has taken |
| // too long to complete. |
| safepoint_limit_time = SafepointTracing::start_of_safepoint() + (jlong)SafepointTimeoutDelay * (NANOUNITS / MILLIUNITS); |
| timeout_error_printed = false; |
| } |
| |
| EventSafepointStateSynchronization sync_event; |
| int initial_running = 0; |
| |
| // Arms the safepoint, _current_jni_active_count and _waiting_to_block must be set before. |
| arm_safepoint(); |
| |
| // Will spin until all threads are safe. |
| int iterations = synchronize_threads(safepoint_limit_time, nof_threads, &initial_running); |
| assert(_waiting_to_block == 0, "No thread should be running"); |
| |
| #ifndef PRODUCT |
| // Mark all threads |
| if (VerifyCrossModifyFence) { |
| JavaThreadIteratorWithHandle jtiwh; |
| for (; JavaThread *cur = jtiwh.next(); ) { |
| cur->set_requires_cross_modify_fence(true); |
| } |
| } |
| |
| if (safepoint_limit_time != 0) { |
| jlong current_time = os::javaTimeNanos(); |
| if (safepoint_limit_time < current_time) { |
| log_warning(safepoint)("# SafepointSynchronize: Finished after " |
| INT64_FORMAT_W(6) " ms", |
| (int64_t)(current_time - SafepointTracing::start_of_safepoint()) / (NANOUNITS / MILLIUNITS)); |
| } |
| } |
| #endif |
| |
| assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); |
| |
| // Record state |
| _state = _synchronized; |
| |
| OrderAccess::fence(); |
| |
| // Set the new id |
| ++_safepoint_id; |
| |
| #ifdef ASSERT |
| // Make sure all the threads were visited. |
| for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur = jtiwh.next(); ) { |
| assert(cur->was_visited_for_critical_count(_safepoint_counter), "missed a thread"); |
| } |
| #endif // ASSERT |
| |
| // Update the count of active JNI critical regions |
| GCLocker::set_jni_lock_count(_current_jni_active_count); |
| |
| post_safepoint_synchronize_event(sync_event, |
| _safepoint_id, |
| initial_running, |
| _waiting_to_block, iterations); |
| |
| SafepointTracing::synchronized(nof_threads, initial_running, _nof_threads_hit_polling_page); |
| |
| // We do the safepoint cleanup first since a GC related safepoint |
| // needs cleanup to be completed before running the GC op. |
| EventSafepointCleanup cleanup_event; |
| do_cleanup_tasks(); |
| post_safepoint_cleanup_event(cleanup_event, _safepoint_id); |
| |
| post_safepoint_begin_event(begin_event, _safepoint_id, nof_threads, _current_jni_active_count); |
| SafepointTracing::cleanup(); |
| } |
| |
| void SafepointSynchronize::disarm_safepoint() { |
| uint64_t active_safepoint_counter = _safepoint_counter; |
| { |
| JavaThreadIteratorWithHandle jtiwh; |
| #ifdef ASSERT |
| // A pending_exception cannot be installed during a safepoint. The threads |
| // may install an async exception after they come back from a safepoint into |
| // pending_exception after they unblock. But that should happen later. |
| for (; JavaThread *cur = jtiwh.next(); ) { |
| assert (!(cur->has_pending_exception() && |
| cur->safepoint_state()->is_at_poll_safepoint()), |
| "safepoint installed a pending exception"); |
| } |
| #endif // ASSERT |
| |
| OrderAccess::fence(); // keep read and write of _state from floating up |
| assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization"); |
| |
| // Change state first to _not_synchronized. |
| // No threads should see _synchronized when running. |
| _state = _not_synchronized; |
| |
| // Set the next dormant (even) safepoint id. |
| assert((_safepoint_counter & 0x1) == 1, "must be odd"); |
| Atomic::release_store(&_safepoint_counter, _safepoint_counter + 1); |
| |
| OrderAccess::fence(); // Keep the local state from floating up. |
| |
| jtiwh.rewind(); |
| for (; JavaThread *current = jtiwh.next(); ) { |
| // Clear the visited flag to ensure that the critical counts are collected properly. |
| DEBUG_ONLY(current->reset_visited_for_critical_count(active_safepoint_counter);) |
| ThreadSafepointState* cur_state = current->safepoint_state(); |
| assert(!cur_state->is_running(), "Thread not suspended at safepoint"); |
| cur_state->restart(); // TSS _running |
| assert(cur_state->is_running(), "safepoint state has not been reset"); |
| } |
| } // ~JavaThreadIteratorWithHandle |
| |
| // Release threads lock, so threads can be created/destroyed again. |
| Threads_lock->unlock(); |
| |
| // Wake threads after local state is correctly set. |
| _wait_barrier->disarm(); |
| } |
| |
| // Wake up all threads, so they are ready to resume execution after the safepoint |
| // operation has been carried out |
| void SafepointSynchronize::end() { |
| assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); |
| EventSafepointEnd event; |
| assert(Thread::current()->is_VM_thread(), "Only VM thread can execute a safepoint"); |
| |
| disarm_safepoint(); |
| |
| Universe::heap()->safepoint_synchronize_end(); |
| |
| SafepointTracing::end(); |
| |
| post_safepoint_end_event(event, safepoint_id()); |
| } |
| |
| bool SafepointSynchronize::is_cleanup_needed() { |
| // Need a safepoint if some inline cache buffers is non-empty |
| if (!InlineCacheBuffer::is_empty()) return true; |
| if (StringTable::needs_rehashing()) return true; |
| if (SymbolTable::needs_rehashing()) return true; |
| return false; |
| } |
| |
| class ParallelSPCleanupThreadClosure : public ThreadClosure { |
| public: |
| void do_thread(Thread* thread) { |
| if (thread->is_Java_thread()) { |
| StackWatermarkSet::start_processing(thread->as_Java_thread(), StackWatermarkKind::gc); |
| } |
| } |
| }; |
| |
| class ParallelSPCleanupTask : public AbstractGangTask { |
| private: |
| SubTasksDone _subtasks; |
| uint _num_workers; |
| bool _do_lazy_roots; |
| |
| class Tracer { |
| private: |
| const char* _name; |
| EventSafepointCleanupTask _event; |
| TraceTime _timer; |
| |
| public: |
| Tracer(const char* name) : |
| _name(name), |
| _event(), |
| _timer(name, TRACETIME_LOG(Info, safepoint, cleanup)) {} |
| ~Tracer() { |
| post_safepoint_cleanup_task_event(_event, SafepointSynchronize::safepoint_id(), _name); |
| } |
| }; |
| |
| public: |
| ParallelSPCleanupTask(uint num_workers) : |
| AbstractGangTask("Parallel Safepoint Cleanup"), |
| _subtasks(SafepointSynchronize::SAFEPOINT_CLEANUP_NUM_TASKS), |
| _num_workers(num_workers), |
| _do_lazy_roots(!VMThread::vm_operation()->skip_thread_oop_barriers() && |
| Universe::heap()->uses_stack_watermark_barrier()) {} |
| |
| void work(uint worker_id) { |
| if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_LAZY_ROOT_PROCESSING)) { |
| if (_do_lazy_roots) { |
| Tracer t("lazy partial thread root processing"); |
| ParallelSPCleanupThreadClosure cl; |
| Threads::threads_do(&cl); |
| } |
| } |
| |
| if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_UPDATE_INLINE_CACHES)) { |
| Tracer t("updating inline caches"); |
| InlineCacheBuffer::update_inline_caches(); |
| } |
| |
| if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_COMPILATION_POLICY)) { |
| Tracer t("compilation policy safepoint handler"); |
| CompilationPolicy::do_safepoint_work(); |
| } |
| |
| if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_SYMBOL_TABLE_REHASH)) { |
| if (SymbolTable::needs_rehashing()) { |
| Tracer t("rehashing symbol table"); |
| SymbolTable::rehash_table(); |
| } |
| } |
| |
| if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_STRING_TABLE_REHASH)) { |
| if (StringTable::needs_rehashing()) { |
| Tracer t("rehashing string table"); |
| StringTable::rehash_table(); |
| } |
| } |
| |
| if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_SYSTEM_DICTIONARY_RESIZE)) { |
| if (Dictionary::does_any_dictionary_needs_resizing()) { |
| Tracer t("resizing system dictionaries"); |
| ClassLoaderDataGraph::resize_dictionaries(); |
| } |
| } |
| |
| if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_REQUEST_OOPSTORAGE_CLEANUP)) { |
| // Don't bother reporting event or time for this very short operation. |
| // To have any utility we'd also want to report whether needed. |
| OopStorage::trigger_cleanup_if_needed(); |
| } |
| |
| _subtasks.all_tasks_claimed(); |
| } |
| }; |
| |
| // Various cleaning tasks that should be done periodically at safepoints. |
| void SafepointSynchronize::do_cleanup_tasks() { |
| |
| TraceTime timer("safepoint cleanup tasks", TRACETIME_LOG(Info, safepoint, cleanup)); |
| |
| CollectedHeap* heap = Universe::heap(); |
| assert(heap != NULL, "heap not initialized yet?"); |
| WorkGang* cleanup_workers = heap->safepoint_workers(); |
| if (cleanup_workers != NULL) { |
| // Parallel cleanup using GC provided thread pool. |
| uint num_cleanup_workers = cleanup_workers->active_workers(); |
| ParallelSPCleanupTask cleanup(num_cleanup_workers); |
| cleanup_workers->run_task(&cleanup); |
| } else { |
| // Serial cleanup using VMThread. |
| ParallelSPCleanupTask cleanup(1); |
| cleanup.work(0); |
| } |
| |
| assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); |
| |
| if (log_is_enabled(Debug, monitorinflation)) { |
| // The VMThread calls do_final_audit_and_print_stats() which calls |
| // audit_and_print_stats() at the Info level at VM exit time. |
| ObjectSynchronizer::audit_and_print_stats(false /* on_exit */); |
| } |
| } |
| |
| // Methods for determining if a JavaThread is safepoint safe. |
| |
| // False means unsafe with undetermined state. |
| // True means a determined state, but it may be an unsafe state. |
| // If called from a non-safepoint context safepoint_count MUST be InactiveSafepointCounter. |
| bool SafepointSynchronize::try_stable_load_state(JavaThreadState *state, JavaThread *thread, uint64_t safepoint_count) { |
| assert((safepoint_count != InactiveSafepointCounter && |
| Thread::current() == (Thread*)VMThread::vm_thread() && |
| SafepointSynchronize::_state != _not_synchronized) |
| || safepoint_count == InactiveSafepointCounter, "Invalid check"); |
| |
| // To handle the thread_blocked state on the backedge of the WaitBarrier from |
| // previous safepoint and reading the reset value (0/InactiveSafepointCounter) we |
| // re-read state after we read thread safepoint id. The JavaThread changes its |
| // thread state from thread_blocked before resetting safepoint id to 0. |
| // This guarantees the second read will be from an updated thread state. It can |
| // either be different state making this an unsafe state or it can see blocked |
| // again. When we see blocked twice with a 0 safepoint id, either: |
| // - It is normally blocked, e.g. on Mutex, TBIVM. |
| // - It was in SS:block(), looped around to SS:block() and is blocked on the WaitBarrier. |
| // - It was in SS:block() but now on a Mutex. |
| // All of these cases are safe. |
| |
| *state = thread->thread_state(); |
| OrderAccess::loadload(); |
| uint64_t sid = thread->safepoint_state()->get_safepoint_id(); // Load acquire |
| if (sid != InactiveSafepointCounter && sid != safepoint_count) { |
| // In an old safepoint, state not relevant. |
| return false; |
| } |
| return *state == thread->thread_state(); |
| } |
| |
| static bool safepoint_safe_with(JavaThread *thread, JavaThreadState state) { |
| switch(state) { |
| case _thread_in_native: |
| // native threads are safe if they have no java stack or have walkable stack |
| return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable(); |
| |
| case _thread_blocked: |
| // On wait_barrier or blocked. |
| // Blocked threads should already have walkable stack. |
| assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable"); |
| return true; |
| |
| default: |
| return false; |
| } |
| } |
| |
| bool SafepointSynchronize::handshake_safe(JavaThread *thread) { |
| if (thread->is_terminated()) { |
| return true; |
| } |
| JavaThreadState stable_state; |
| if (try_stable_load_state(&stable_state, thread, InactiveSafepointCounter)) { |
| return safepoint_safe_with(thread, stable_state); |
| } |
| return false; |
| } |
| |
| |
| // ------------------------------------------------------------------------------------------------------- |
| // Implementation of Safepoint blocking point |
| |
| void SafepointSynchronize::block(JavaThread *thread) { |
| assert(thread != NULL, "thread must be set"); |
| |
| // Threads shouldn't block if they are in the middle of printing, but... |
| ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id()); |
| |
| // Only bail from the block() call if the thread is gone from the |
| // thread list; starting to exit should still block. |
| if (thread->is_terminated()) { |
| // block current thread if we come here from native code when VM is gone |
| thread->block_if_vm_exited(); |
| |
| // otherwise do nothing |
| return; |
| } |
| |
| JavaThreadState state = thread->thread_state(); |
| thread->frame_anchor()->make_walkable(thread); |
| |
| uint64_t safepoint_id = SafepointSynchronize::safepoint_counter(); |
| // Check that we have a valid thread_state at this point |
| switch(state) { |
| case _thread_in_vm_trans: |
| case _thread_in_Java: // From compiled code |
| case _thread_in_native_trans: |
| case _thread_blocked_trans: |
| case _thread_new_trans: |
| |
| // We have no idea where the VMThread is, it might even be at next safepoint. |
| // So we can miss this poll, but stop at next. |
| |
| // Load dependent store, it must not pass loading of safepoint_id. |
| thread->safepoint_state()->set_safepoint_id(safepoint_id); // Release store |
| |
| // This part we can skip if we notice we miss or are in a future safepoint. |
| OrderAccess::storestore(); |
| // Load in wait barrier should not float up |
| thread->set_thread_state_fence(_thread_blocked); |
| |
| _wait_barrier->wait(static_cast<int>(safepoint_id)); |
| assert(_state != _synchronized, "Can't be"); |
| |
| // If barrier is disarmed stop store from floating above loads in barrier. |
| OrderAccess::loadstore(); |
| thread->set_thread_state(state); |
| |
| // Then we reset the safepoint id to inactive. |
| thread->safepoint_state()->reset_safepoint_id(); // Release store |
| |
| OrderAccess::fence(); |
| |
| break; |
| |
| default: |
| fatal("Illegal threadstate encountered: %d", state); |
| } |
| guarantee(thread->safepoint_state()->get_safepoint_id() == InactiveSafepointCounter, |
| "The safepoint id should be set only in block path"); |
| |
| // cross_modify_fence is done by SafepointMechanism::process_if_requested |
| // which is the only caller here. |
| } |
| |
| // ------------------------------------------------------------------------------------------------------ |
| // Exception handlers |
| |
| |
| void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) { |
| assert(thread->thread_state() == _thread_in_Java, "should come from Java code"); |
| |
| // Enable WXWrite: the function is called implicitly from java code. |
| MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXWrite, thread)); |
| |
| if (log_is_enabled(Info, safepoint, stats)) { |
| Atomic::inc(&_nof_threads_hit_polling_page); |
| } |
| |
| ThreadSafepointState* state = thread->safepoint_state(); |
| |
| state->handle_polling_page_exception(); |
| } |
| |
| |
| void SafepointSynchronize::print_safepoint_timeout() { |
| if (!timeout_error_printed) { |
| timeout_error_printed = true; |
| // Print out the thread info which didn't reach the safepoint for debugging |
| // purposes (useful when there are lots of threads in the debugger). |
| LogTarget(Warning, safepoint) lt; |
| if (lt.is_enabled()) { |
| ResourceMark rm; |
| LogStream ls(lt); |
| |
| ls.cr(); |
| ls.print_cr("# SafepointSynchronize::begin: Timeout detected:"); |
| ls.print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint."); |
| ls.print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:"); |
| for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur_thread = jtiwh.next(); ) { |
| if (cur_thread->safepoint_state()->is_running()) { |
| ls.print("# "); |
| cur_thread->print_on(&ls); |
| ls.cr(); |
| } |
| } |
| ls.print_cr("# SafepointSynchronize::begin: (End of list)"); |
| } |
| } |
| |
| // To debug the long safepoint, specify both AbortVMOnSafepointTimeout & |
| // ShowMessageBoxOnError. |
| if (AbortVMOnSafepointTimeout) { |
| // Send the blocking thread a signal to terminate and write an error file. |
| for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur_thread = jtiwh.next(); ) { |
| if (cur_thread->safepoint_state()->is_running()) { |
| if (!os::signal_thread(cur_thread, SIGILL, "blocking a safepoint")) { |
| break; // Could not send signal. Report fatal error. |
| } |
| // Give cur_thread a chance to report the error and terminate the VM. |
| os::naked_sleep(3000); |
| } |
| } |
| fatal("Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.", |
| SafepointTimeoutDelay, VMThread::vm_operation()->name()); |
| } |
| } |
| |
| // ------------------------------------------------------------------------------------------------------- |
| // Implementation of ThreadSafepointState |
| |
| ThreadSafepointState::ThreadSafepointState(JavaThread *thread) |
| : _at_poll_safepoint(false), _thread(thread), _safepoint_safe(false), |
| _safepoint_id(SafepointSynchronize::InactiveSafepointCounter), _next(NULL) { |
| } |
| |
| void ThreadSafepointState::create(JavaThread *thread) { |
| ThreadSafepointState *state = new ThreadSafepointState(thread); |
| thread->set_safepoint_state(state); |
| } |
| |
| void ThreadSafepointState::destroy(JavaThread *thread) { |
| if (thread->safepoint_state()) { |
| delete(thread->safepoint_state()); |
| thread->set_safepoint_state(NULL); |
| } |
| } |
| |
| uint64_t ThreadSafepointState::get_safepoint_id() const { |
| return Atomic::load_acquire(&_safepoint_id); |
| } |
| |
| void ThreadSafepointState::reset_safepoint_id() { |
| Atomic::release_store(&_safepoint_id, SafepointSynchronize::InactiveSafepointCounter); |
| } |
| |
| void ThreadSafepointState::set_safepoint_id(uint64_t safepoint_id) { |
| Atomic::release_store(&_safepoint_id, safepoint_id); |
| } |
| |
| void ThreadSafepointState::examine_state_of_thread(uint64_t safepoint_count) { |
| assert(is_running(), "better be running or just have hit safepoint poll"); |
| |
| JavaThreadState stable_state; |
| if (!SafepointSynchronize::try_stable_load_state(&stable_state, _thread, safepoint_count)) { |
| // We could not get stable state of the JavaThread. |
| // Consider it running and just return. |
| return; |
| } |
| |
| if (safepoint_safe_with(_thread, stable_state)) { |
| account_safe_thread(); |
| return; |
| } |
| |
| // All other thread states will continue to run until they |
| // transition and self-block in state _blocked |
| // Safepoint polling in compiled code causes the Java threads to do the same. |
| // Note: new threads may require a malloc so they must be allowed to finish |
| |
| assert(is_running(), "examine_state_of_thread on non-running thread"); |
| return; |
| } |
| |
| void ThreadSafepointState::account_safe_thread() { |
| SafepointSynchronize::decrement_waiting_to_block(); |
| if (_thread->in_critical()) { |
| // Notice that this thread is in a critical section |
| SafepointSynchronize::increment_jni_active_count(); |
| } |
| DEBUG_ONLY(_thread->set_visited_for_critical_count(SafepointSynchronize::safepoint_counter());) |
| assert(!_safepoint_safe, "Must be unsafe before safe"); |
| _safepoint_safe = true; |
| } |
| |
| void ThreadSafepointState::restart() { |
| assert(_safepoint_safe, "Must be safe before unsafe"); |
| _safepoint_safe = false; |
| } |
| |
| void ThreadSafepointState::print_on(outputStream *st) const { |
| const char *s = _safepoint_safe ? "_at_safepoint" : "_running"; |
| |
| st->print_cr("Thread: " INTPTR_FORMAT |
| " [0x%2x] State: %s _at_poll_safepoint %d", |
| p2i(_thread), _thread->osthread()->thread_id(), s, _at_poll_safepoint); |
| |
| _thread->print_thread_state_on(st); |
| } |
| |
| // --------------------------------------------------------------------------------------------------------------------- |
| |
| // Process pending operation. |
| void ThreadSafepointState::handle_polling_page_exception() { |
| JavaThread* self = thread(); |
| assert(self == Thread::current()->as_Java_thread(), "must be self"); |
| |
| // Step 1: Find the nmethod from the return address |
| address real_return_addr = self->saved_exception_pc(); |
| |
| CodeBlob *cb = CodeCache::find_blob(real_return_addr); |
| assert(cb != NULL && cb->is_compiled(), "return address should be in nmethod"); |
| CompiledMethod* nm = (CompiledMethod*)cb; |
| |
| // Find frame of caller |
| frame stub_fr = self->last_frame(); |
| CodeBlob* stub_cb = stub_fr.cb(); |
| assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub"); |
| RegisterMap map(self, true, false); |
| frame caller_fr = stub_fr.sender(&map); |
| |
| // Should only be poll_return or poll |
| assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" ); |
| |
| // This is a poll immediately before a return. The exception handling code |
| // has already had the effect of causing the return to occur, so the execution |
| // will continue immediately after the call. In addition, the oopmap at the |
| // return point does not mark the return value as an oop (if it is), so |
| // it needs a handle here to be updated. |
| if( nm->is_at_poll_return(real_return_addr) ) { |
| // See if return type is an oop. |
| bool return_oop = nm->method()->is_returning_oop(); |
| Handle return_value; |
| if (return_oop) { |
| // The oop result has been saved on the stack together with all |
| // the other registers. In order to preserve it over GCs we need |
| // to keep it in a handle. |
| oop result = caller_fr.saved_oop_result(&map); |
| assert(oopDesc::is_oop_or_null(result), "must be oop"); |
| return_value = Handle(self, result); |
| assert(Universe::heap()->is_in_or_null(result), "must be heap pointer"); |
| } |
| |
| // We get here if compiled return polls found a reason to call into the VM. |
| // One condition for that is that the top frame is not yet safe to use. |
| // The following stack watermark barrier poll will catch such situations. |
| StackWatermarkSet::after_unwind(self); |
| |
| // Process pending operation |
| SafepointMechanism::process_if_requested_with_exit_check(self, true /* check asyncs */); |
| |
| // restore oop result, if any |
| if (return_oop) { |
| caller_fr.set_saved_oop_result(&map, return_value()); |
| } |
| } |
| |
| // This is a safepoint poll. Verify the return address and block. |
| else { |
| |
| // verify the blob built the "return address" correctly |
| assert(real_return_addr == caller_fr.pc(), "must match"); |
| |
| set_at_poll_safepoint(true); |
| // Process pending operation |
| // We never deliver an async exception at a polling point as the |
| // compiler may not have an exception handler for it. The polling |
| // code will notice the pending async exception, deoptimize and |
| // the exception will be delivered. (Polling at a return point |
| // is ok though). Sure is a lot of bother for a deprecated feature... |
| SafepointMechanism::process_if_requested_with_exit_check(self, false /* check asyncs */); |
| set_at_poll_safepoint(false); |
| |
| // If we have a pending async exception deoptimize the frame |
| // as otherwise we may never deliver it. |
| if (self->has_async_exception_condition()) { |
| ThreadInVMfromJava __tiv(self, false /* check asyncs */); |
| Deoptimization::deoptimize_frame(self, caller_fr.id()); |
| } |
| |
| // If an exception has been installed we must check for a pending deoptimization |
| // Deoptimize frame if exception has been thrown. |
| |
| if (self->has_pending_exception() ) { |
| RegisterMap map(self, true, false); |
| frame caller_fr = stub_fr.sender(&map); |
| if (caller_fr.is_deoptimized_frame()) { |
| // The exception patch will destroy registers that are still |
| // live and will be needed during deoptimization. Defer the |
| // Async exception should have deferred the exception until the |
| // next safepoint which will be detected when we get into |
| // the interpreter so if we have an exception now things |
| // are messed up. |
| |
| fatal("Exception installed and deoptimization is pending"); |
| } |
| } |
| } |
| } |
| |
| |
| // ------------------------------------------------------------------------------------------------------- |
| // Implementation of SafepointTracing |
| |
| jlong SafepointTracing::_last_safepoint_begin_time_ns = 0; |
| jlong SafepointTracing::_last_safepoint_sync_time_ns = 0; |
| jlong SafepointTracing::_last_safepoint_cleanup_time_ns = 0; |
| jlong SafepointTracing::_last_safepoint_end_time_ns = 0; |
| jlong SafepointTracing::_last_app_time_ns = 0; |
| int SafepointTracing::_nof_threads = 0; |
| int SafepointTracing::_nof_running = 0; |
| int SafepointTracing::_page_trap = 0; |
| VM_Operation::VMOp_Type SafepointTracing::_current_type; |
| jlong SafepointTracing::_max_sync_time = 0; |
| jlong SafepointTracing::_max_vmop_time = 0; |
| uint64_t SafepointTracing::_op_count[VM_Operation::VMOp_Terminating] = {0}; |
| |
| void SafepointTracing::init() { |
| // Application start |
| _last_safepoint_end_time_ns = os::javaTimeNanos(); |
| } |
| |
| // Helper method to print the header. |
| static void print_header(outputStream* st) { |
| // The number of spaces is significant here, and should match the format |
| // specifiers in print_statistics(). |
| |
| st->print("VM Operation " |
| "[ threads: total initial_running ]" |
| "[ time: sync cleanup vmop total ]"); |
| |
| st->print_cr(" page_trap_count"); |
| } |
| |
| // This prints a nice table. To get the statistics to not shift due to the logging uptime |
| // decorator, use the option as: -Xlog:safepoint+stats:[outputfile]:none |
| void SafepointTracing::statistics_log() { |
| LogTarget(Info, safepoint, stats) lt; |
| assert (lt.is_enabled(), "should only be called when printing statistics is enabled"); |
| LogStream ls(lt); |
| |
| static int _cur_stat_index = 0; |
| |
| // Print header every 30 entries |
| if ((_cur_stat_index % 30) == 0) { |
| print_header(&ls); |
| _cur_stat_index = 1; // wrap |
| } else { |
| _cur_stat_index++; |
| } |
| |
| ls.print("%-28s [ " |
| INT32_FORMAT_W(8) " " INT32_FORMAT_W(8) " " |
| "]", |
| VM_Operation::name(_current_type), |
| _nof_threads, |
| _nof_running); |
| ls.print("[ " |
| INT64_FORMAT_W(10) " " INT64_FORMAT_W(10) " " |
| INT64_FORMAT_W(10) " " INT64_FORMAT_W(10) " ]", |
| (int64_t)(_last_safepoint_sync_time_ns - _last_safepoint_begin_time_ns), |
| (int64_t)(_last_safepoint_cleanup_time_ns - _last_safepoint_sync_time_ns), |
| (int64_t)(_last_safepoint_end_time_ns - _last_safepoint_cleanup_time_ns), |
| (int64_t)(_last_safepoint_end_time_ns - _last_safepoint_begin_time_ns)); |
| |
| ls.print_cr(INT32_FORMAT_W(16), _page_trap); |
| } |
| |
| // This method will be called when VM exits. This tries to summarize the sampling. |
| // Current thread may already be deleted, so don't use ResourceMark. |
| void SafepointTracing::statistics_exit_log() { |
| if (!log_is_enabled(Info, safepoint, stats)) { |
| return; |
| } |
| for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) { |
| if (_op_count[index] != 0) { |
| log_info(safepoint, stats)("%-28s" UINT64_FORMAT_W(10), VM_Operation::name(index), |
| _op_count[index]); |
| } |
| } |
| |
| log_info(safepoint, stats)("Maximum sync time " INT64_FORMAT" ns", |
| (int64_t)(_max_sync_time)); |
| log_info(safepoint, stats)("Maximum vm operation time (except for Exit VM operation) " |
| INT64_FORMAT " ns", |
| (int64_t)(_max_vmop_time)); |
| } |
| |
| void SafepointTracing::begin(VM_Operation::VMOp_Type type) { |
| _op_count[type]++; |
| _current_type = type; |
| |
| // update the time stamp to begin recording safepoint time |
| _last_safepoint_begin_time_ns = os::javaTimeNanos(); |
| _last_safepoint_sync_time_ns = 0; |
| _last_safepoint_cleanup_time_ns = 0; |
| |
| _last_app_time_ns = _last_safepoint_begin_time_ns - _last_safepoint_end_time_ns; |
| _last_safepoint_end_time_ns = 0; |
| |
| RuntimeService::record_safepoint_begin(_last_app_time_ns); |
| } |
| |
| void SafepointTracing::synchronized(int nof_threads, int nof_running, int traps) { |
| _last_safepoint_sync_time_ns = os::javaTimeNanos(); |
| _nof_threads = nof_threads; |
| _nof_running = nof_running; |
| _page_trap = traps; |
| RuntimeService::record_safepoint_synchronized(_last_safepoint_sync_time_ns - _last_safepoint_begin_time_ns); |
| } |
| |
| void SafepointTracing::cleanup() { |
| _last_safepoint_cleanup_time_ns = os::javaTimeNanos(); |
| } |
| |
| void SafepointTracing::end() { |
| _last_safepoint_end_time_ns = os::javaTimeNanos(); |
| |
| if (_max_sync_time < (_last_safepoint_sync_time_ns - _last_safepoint_begin_time_ns)) { |
| _max_sync_time = _last_safepoint_sync_time_ns - _last_safepoint_begin_time_ns; |
| } |
| if (_max_vmop_time < (_last_safepoint_end_time_ns - _last_safepoint_sync_time_ns)) { |
| _max_vmop_time = _last_safepoint_end_time_ns - _last_safepoint_sync_time_ns; |
| } |
| if (log_is_enabled(Info, safepoint, stats)) { |
| statistics_log(); |
| } |
| |
| log_info(safepoint)( |
| "Safepoint \"%s\", " |
| "Time since last: " JLONG_FORMAT " ns, " |
| "Reaching safepoint: " JLONG_FORMAT " ns, " |
| "At safepoint: " JLONG_FORMAT " ns, " |
| "Total: " JLONG_FORMAT " ns", |
| VM_Operation::name(_current_type), |
| _last_app_time_ns, |
| _last_safepoint_cleanup_time_ns - _last_safepoint_begin_time_ns, |
| _last_safepoint_end_time_ns - _last_safepoint_cleanup_time_ns, |
| _last_safepoint_end_time_ns - _last_safepoint_begin_time_ns |
| ); |
| |
| RuntimeService::record_safepoint_end(_last_safepoint_end_time_ns - _last_safepoint_cleanup_time_ns); |
| } |