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android / platform / libcore / 8153779ad32 / . / hotspot / src / share / vm / memory / genCollectedHeap.cpp
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/*
* Copyright 2000-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*
*/
# include "incls/_precompiled.incl"
# include "incls/_genCollectedHeap.cpp.incl"
GenCollectedHeap* GenCollectedHeap::_gch;
NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
// The set of potentially parallel tasks in strong root scanning.
enum GCH_process_strong_roots_tasks {
// We probably want to parallelize both of these internally, but for now...
GCH_PS_younger_gens,
// Leave this one last.
GCH_PS_NumElements
};
GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
SharedHeap(policy),
_gen_policy(policy),
_gen_process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
_full_collections_completed(0)
{
if (_gen_process_strong_tasks == NULL ||
!_gen_process_strong_tasks->valid()) {
vm_exit_during_initialization("Failed necessary allocation.");
}
assert(policy != NULL, "Sanity check");
_preloading_shared_classes = false;
}
jint GenCollectedHeap::initialize() {
int i;
_n_gens = gen_policy()->number_of_generations();
// While there are no constraints in the GC code that HeapWordSize
// be any particular value, there are multiple other areas in the
// system which believe this to be true (e.g. oop->object_size in some
// cases incorrectly returns the size in wordSize units rather than
// HeapWordSize).
guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
// The heap must be at least as aligned as generations.
size_t alignment = Generation::GenGrain;
_gen_specs = gen_policy()->generations();
PermanentGenerationSpec *perm_gen_spec =
collector_policy()->permanent_generation();
// Make sure the sizes are all aligned.
for (i = 0; i < _n_gens; i++) {
_gen_specs[i]->align(alignment);
}
perm_gen_spec->align(alignment);
// If we are dumping the heap, then allocate a wasted block of address
// space in order to push the heap to a lower address. This extra
// address range allows for other (or larger) libraries to be loaded
// without them occupying the space required for the shared spaces.
if (DumpSharedSpaces) {
uintx reserved = 0;
uintx block_size = 64*1024*1024;
while (reserved < SharedDummyBlockSize) {
char* dummy = os::reserve_memory(block_size);
reserved += block_size;
}
}
// Allocate space for the heap.
char* heap_address;
size_t total_reserved = 0;
int n_covered_regions = 0;
ReservedSpace heap_rs(0);
heap_address = allocate(alignment, perm_gen_spec, &total_reserved,
&n_covered_regions, &heap_rs);
if (UseSharedSpaces) {
if (!heap_rs.is_reserved() || heap_address != heap_rs.base()) {
if (heap_rs.is_reserved()) {
heap_rs.release();
}
FileMapInfo* mapinfo = FileMapInfo::current_info();
mapinfo->fail_continue("Unable to reserve shared region.");
allocate(alignment, perm_gen_spec, &total_reserved, &n_covered_regions,
&heap_rs);
}
}
if (!heap_rs.is_reserved()) {
vm_shutdown_during_initialization(
"Could not reserve enough space for object heap");
return JNI_ENOMEM;
}
_reserved = MemRegion((HeapWord*)heap_rs.base(),
(HeapWord*)(heap_rs.base() + heap_rs.size()));
// It is important to do this in a way such that concurrent readers can't
// temporarily think somethings in the heap. (Seen this happen in asserts.)
_reserved.set_word_size(0);
_reserved.set_start((HeapWord*)heap_rs.base());
size_t actual_heap_size = heap_rs.size() - perm_gen_spec->misc_data_size()
- perm_gen_spec->misc_code_size();
_reserved.set_end((HeapWord*)(heap_rs.base() + actual_heap_size));
_rem_set = collector_policy()->create_rem_set(_reserved, n_covered_regions);
set_barrier_set(rem_set()->bs());
_gch = this;
for (i = 0; i < _n_gens; i++) {
ReservedSpace this_rs = heap_rs.first_part(_gen_specs[i]->max_size(),
UseSharedSpaces, UseSharedSpaces);
_gens[i] = _gen_specs[i]->init(this_rs, i, rem_set());
heap_rs = heap_rs.last_part(_gen_specs[i]->max_size());
}
_perm_gen = perm_gen_spec->init(heap_rs, PermSize, rem_set());
clear_incremental_collection_will_fail();
clear_last_incremental_collection_failed();
#ifndef SERIALGC
// If we are running CMS, create the collector responsible
// for collecting the CMS generations.
if (collector_policy()->is_concurrent_mark_sweep_policy()) {
bool success = create_cms_collector();
if (!success) return JNI_ENOMEM;
}
#endif // SERIALGC
return JNI_OK;
}
char* GenCollectedHeap::allocate(size_t alignment,
PermanentGenerationSpec* perm_gen_spec,
size_t* _total_reserved,
int* _n_covered_regions,
ReservedSpace* heap_rs){
const char overflow_msg[] = "The size of the object heap + VM data exceeds "
"the maximum representable size";
// Now figure out the total size.
size_t total_reserved = 0;
int n_covered_regions = 0;
const size_t pageSize = UseLargePages ?
os::large_page_size() : os::vm_page_size();
for (int i = 0; i < _n_gens; i++) {
total_reserved += _gen_specs[i]->max_size();
if (total_reserved < _gen_specs[i]->max_size()) {
vm_exit_during_initialization(overflow_msg);
}
n_covered_regions += _gen_specs[i]->n_covered_regions();
}
assert(total_reserved % pageSize == 0, "Gen size");
total_reserved += perm_gen_spec->max_size();
assert(total_reserved % pageSize == 0, "Perm Gen size");
if (total_reserved < perm_gen_spec->max_size()) {
vm_exit_during_initialization(overflow_msg);
}
n_covered_regions += perm_gen_spec->n_covered_regions();
// Add the size of the data area which shares the same reserved area
// as the heap, but which is not actually part of the heap.
size_t s = perm_gen_spec->misc_data_size() + perm_gen_spec->misc_code_size();
total_reserved += s;
if (total_reserved < s) {
vm_exit_during_initialization(overflow_msg);
}
if (UseLargePages) {
assert(total_reserved != 0, "total_reserved cannot be 0");
total_reserved = round_to(total_reserved, os::large_page_size());
if (total_reserved < os::large_page_size()) {
vm_exit_during_initialization(overflow_msg);
}
}
// Calculate the address at which the heap must reside in order for
// the shared data to be at the required address.
char* heap_address;
if (UseSharedSpaces) {
// Calculate the address of the first word beyond the heap.
FileMapInfo* mapinfo = FileMapInfo::current_info();
int lr = CompactingPermGenGen::n_regions - 1;
size_t capacity = align_size_up(mapinfo->space_capacity(lr), alignment);
heap_address = mapinfo->region_base(lr) + capacity;
// Calculate the address of the first word of the heap.
heap_address -= total_reserved;
} else {
heap_address = NULL; // any address will do.
}
*_total_reserved = total_reserved;
*_n_covered_regions = n_covered_regions;
*heap_rs = ReservedSpace(total_reserved, alignment,
UseLargePages, heap_address);
return heap_address;
}
void GenCollectedHeap::post_initialize() {
SharedHeap::post_initialize();
TwoGenerationCollectorPolicy *policy =
(TwoGenerationCollectorPolicy *)collector_policy();
guarantee(policy->is_two_generation_policy(), "Illegal policy type");
DefNewGeneration* def_new_gen = (DefNewGeneration*) get_gen(0);
assert(def_new_gen->kind() == Generation::DefNew ||
def_new_gen->kind() == Generation::ParNew ||
def_new_gen->kind() == Generation::ASParNew,
"Wrong generation kind");
Generation* old_gen = get_gen(1);
assert(old_gen->kind() == Generation::ConcurrentMarkSweep ||
old_gen->kind() == Generation::ASConcurrentMarkSweep ||
old_gen->kind() == Generation::MarkSweepCompact,
"Wrong generation kind");
policy->initialize_size_policy(def_new_gen->eden()->capacity(),
old_gen->capacity(),
def_new_gen->from()->capacity());
policy->initialize_gc_policy_counters();
}
void GenCollectedHeap::ref_processing_init() {
SharedHeap::ref_processing_init();
for (int i = 0; i < _n_gens; i++) {
_gens[i]->ref_processor_init();
}
}
size_t GenCollectedHeap::capacity() const {
size_t res = 0;
for (int i = 0; i < _n_gens; i++) {
res += _gens[i]->capacity();
}
return res;
}
size_t GenCollectedHeap::used() const {
size_t res = 0;
for (int i = 0; i < _n_gens; i++) {
res += _gens[i]->used();
}
return res;
}
// Save the "used_region" for generations level and lower,
// and, if perm is true, for perm gen.
void GenCollectedHeap::save_used_regions(int level, bool perm) {
assert(level < _n_gens, "Illegal level parameter");
for (int i = level; i >= 0; i--) {
_gens[i]->save_used_region();
}
if (perm) {
perm_gen()->save_used_region();
}
}
size_t GenCollectedHeap::max_capacity() const {
size_t res = 0;
for (int i = 0; i < _n_gens; i++) {
res += _gens[i]->max_capacity();
}
return res;
}
// Update the _full_collections_completed counter
// at the end of a stop-world full GC.
unsigned int GenCollectedHeap::update_full_collections_completed() {
MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
assert(_full_collections_completed <= _total_full_collections,
"Can't complete more collections than were started");
_full_collections_completed = _total_full_collections;
ml.notify_all();
return _full_collections_completed;
}
// Update the _full_collections_completed counter, as appropriate,
// at the end of a concurrent GC cycle. Note the conditional update
// below to allow this method to be called by a concurrent collector
// without synchronizing in any manner with the VM thread (which
// may already have initiated a STW full collection "concurrently").
unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
assert((_full_collections_completed <= _total_full_collections) &&
(count <= _total_full_collections),
"Can't complete more collections than were started");
if (count > _full_collections_completed) {
_full_collections_completed = count;
ml.notify_all();
}
return _full_collections_completed;
}
#ifndef PRODUCT
// Override of memory state checking method in CollectedHeap:
// Some collectors (CMS for example) can't have badHeapWordVal written
// in the first two words of an object. (For instance , in the case of
// CMS these words hold state used to synchronize between certain
// (concurrent) GC steps and direct allocating mutators.)
// The skip_header_HeapWords() method below, allows us to skip
// over the requisite number of HeapWord's. Note that (for
// generational collectors) this means that those many words are
// skipped in each object, irrespective of the generation in which
// that object lives. The resultant loss of precision seems to be
// harmless and the pain of avoiding that imprecision appears somewhat
// higher than we are prepared to pay for such rudimentary debugging
// support.
void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
size_t size) {
if (CheckMemoryInitialization && ZapUnusedHeapArea) {
// We are asked to check a size in HeapWords,
// but the memory is mangled in juint words.
juint* start = (juint*) (addr + skip_header_HeapWords());
juint* end = (juint*) (addr + size);
for (juint* slot = start; slot < end; slot += 1) {
assert(*slot == badHeapWordVal,
"Found non badHeapWordValue in pre-allocation check");
}
}
}
#endif
HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
bool is_tlab,
bool first_only) {
HeapWord* res;
for (int i = 0; i < _n_gens; i++) {
if (_gens[i]->should_allocate(size, is_tlab)) {
res = _gens[i]->allocate(size, is_tlab);
if (res != NULL) return res;
else if (first_only) break;
}
}
// Otherwise...
return NULL;
}
HeapWord* GenCollectedHeap::mem_allocate(size_t size,
bool is_large_noref,
bool is_tlab,
bool* gc_overhead_limit_was_exceeded) {
return collector_policy()->mem_allocate_work(size,
is_tlab,
gc_overhead_limit_was_exceeded);
}
bool GenCollectedHeap::must_clear_all_soft_refs() {
return _gc_cause == GCCause::_last_ditch_collection;
}
bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
return (cause == GCCause::_java_lang_system_gc ||
cause == GCCause::_gc_locker) &&
UseConcMarkSweepGC && ExplicitGCInvokesConcurrent;
}
void GenCollectedHeap::do_collection(bool full,
bool clear_all_soft_refs,
size_t size,
bool is_tlab,
int max_level) {
bool prepared_for_verification = false;
ResourceMark rm;
DEBUG_ONLY(Thread* my_thread = Thread::current();)
assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
assert(my_thread->is_VM_thread() ||
my_thread->is_ConcurrentGC_thread(),
"incorrect thread type capability");
assert(Heap_lock->is_locked(), "the requesting thread should have the Heap_lock");
guarantee(!is_gc_active(), "collection is not reentrant");
assert(max_level < n_gens(), "sanity check");
if (GC_locker::check_active_before_gc()) {
return; // GC is disabled (e.g. JNI GetXXXCritical operation)
}
const size_t perm_prev_used = perm_gen()->used();
if (PrintHeapAtGC) {
Universe::print_heap_before_gc();
if (Verbose) {
gclog_or_tty->print_cr("GC Cause: %s", GCCause::to_string(gc_cause()));
}
}
{
FlagSetting fl(_is_gc_active, true);
bool complete = full && (max_level == (n_gens()-1));
const char* gc_cause_str = "GC ";
if (complete) {
GCCause::Cause cause = gc_cause();
if (cause == GCCause::_java_lang_system_gc) {
gc_cause_str = "Full GC (System) ";
} else {
gc_cause_str = "Full GC ";
}
}
gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
TraceTime t(gc_cause_str, PrintGCDetails, false, gclog_or_tty);
gc_prologue(complete);
increment_total_collections(complete);
size_t gch_prev_used = used();
int starting_level = 0;
if (full) {
// Search for the oldest generation which will collect all younger
// generations, and start collection loop there.
for (int i = max_level; i >= 0; i--) {
if (_gens[i]->full_collects_younger_generations()) {
starting_level = i;
break;
}
}
}
bool must_restore_marks_for_biased_locking = false;
int max_level_collected = starting_level;
for (int i = starting_level; i <= max_level; i++) {
if (_gens[i]->should_collect(full, size, is_tlab)) {
// Timer for individual generations. Last argument is false: no CR
TraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, gclog_or_tty);
TraceCollectorStats tcs(_gens[i]->counters());
TraceMemoryManagerStats tmms(_gens[i]->kind());
size_t prev_used = _gens[i]->used();
_gens[i]->stat_record()->invocations++;
_gens[i]->stat_record()->accumulated_time.start();
if (PrintGC && Verbose) {
gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
i,
_gens[i]->stat_record()->invocations,
size*HeapWordSize);
}
if (VerifyBeforeGC && i >= VerifyGCLevel &&
total_collections() >= VerifyGCStartAt) {
HandleMark hm; // Discard invalid handles created during verification
if (!prepared_for_verification) {
prepare_for_verify();
prepared_for_verification = true;
}
gclog_or_tty->print(" VerifyBeforeGC:");
Universe::verify(true);
}
COMPILER2_PRESENT(DerivedPointerTable::clear());
if (!must_restore_marks_for_biased_locking &&
_gens[i]->performs_in_place_marking()) {
// We perform this mark word preservation work lazily
// because it's only at this point that we know whether we
// absolutely have to do it; we want to avoid doing it for
// scavenge-only collections where it's unnecessary
must_restore_marks_for_biased_locking = true;
BiasedLocking::preserve_marks();
}
// Do collection work
{
// Note on ref discovery: For what appear to be historical reasons,
// GCH enables and disabled (by enqueing) refs discovery.
// In the future this should be moved into the generation's
// collect method so that ref discovery and enqueueing concerns
// are local to a generation. The collect method could return
// an appropriate indication in the case that notification on
// the ref lock was needed. This will make the treatment of
// weak refs more uniform (and indeed remove such concerns
// from GCH). XXX
HandleMark hm; // Discard invalid handles created during gc
save_marks(); // save marks for all gens
// We want to discover references, but not process them yet.
// This mode is disabled in process_discovered_references if the
// generation does some collection work, or in
// enqueue_discovered_references if the generation returns
// without doing any work.
ReferenceProcessor* rp = _gens[i]->ref_processor();
// If the discovery of ("weak") refs in this generation is
// atomic wrt other collectors in this configuration, we
// are guaranteed to have empty discovered ref lists.
if (rp->discovery_is_atomic()) {
rp->verify_no_references_recorded();
rp->enable_discovery();
} else {
// collect() will enable discovery as appropriate
}
_gens[i]->collect(full, clear_all_soft_refs, size, is_tlab);
if (!rp->enqueuing_is_done()) {
rp->enqueue_discovered_references();
} else {
rp->set_enqueuing_is_done(false);
}
rp->verify_no_references_recorded();
}
max_level_collected = i;
// Determine if allocation request was met.
if (size > 0) {
if (!is_tlab || _gens[i]->supports_tlab_allocation()) {
if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) {
size = 0;
}
}
}
COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
_gens[i]->stat_record()->accumulated_time.stop();
update_gc_stats(i, full);
if (VerifyAfterGC && i >= VerifyGCLevel &&
total_collections() >= VerifyGCStartAt) {
HandleMark hm; // Discard invalid handles created during verification
gclog_or_tty->print(" VerifyAfterGC:");
Universe::verify(false);
}
if (PrintGCDetails) {
gclog_or_tty->print(":");
_gens[i]->print_heap_change(prev_used);
}
}
}
// Update "complete" boolean wrt what actually transpired --
// for instance, a promotion failure could have led to
// a whole heap collection.
complete = complete || (max_level_collected == n_gens() - 1);
if (PrintGCDetails) {
print_heap_change(gch_prev_used);
// Print perm gen info for full GC with PrintGCDetails flag.
if (complete) {
print_perm_heap_change(perm_prev_used);
}
}
for (int j = max_level_collected; j >= 0; j -= 1) {
// Adjust generation sizes.
_gens[j]->compute_new_size();
}
if (complete) {
// Ask the permanent generation to adjust size for full collections
perm()->compute_new_size();
update_full_collections_completed();
}
// Track memory usage and detect low memory after GC finishes
MemoryService::track_memory_usage();
gc_epilogue(complete);
if (must_restore_marks_for_biased_locking) {
BiasedLocking::restore_marks();
}
}
AdaptiveSizePolicy* sp = gen_policy()->size_policy();
AdaptiveSizePolicyOutput(sp, total_collections());
if (PrintHeapAtGC) {
Universe::print_heap_after_gc();
}
if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
vm_exit(-1);
}
}
HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
return collector_policy()->satisfy_failed_allocation(size, is_tlab);
}
void GenCollectedHeap::set_par_threads(int t) {
SharedHeap::set_par_threads(t);
_gen_process_strong_tasks->set_par_threads(t);
}
class AssertIsPermClosure: public OopClosure {
public:
void do_oop(oop* p) {
assert((*p) == NULL || (*p)->is_perm(), "Referent should be perm.");
}
};
static AssertIsPermClosure assert_is_perm_closure;
void GenCollectedHeap::
gen_process_strong_roots(int level,
bool younger_gens_as_roots,
bool collecting_perm_gen,
SharedHeap::ScanningOption so,
OopsInGenClosure* older_gens,
OopsInGenClosure* not_older_gens) {
// General strong roots.
SharedHeap::process_strong_roots(collecting_perm_gen, so,
not_older_gens, older_gens);
if (younger_gens_as_roots) {
if (!_gen_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
for (int i = 0; i < level; i++) {
not_older_gens->set_generation(_gens[i]);
_gens[i]->oop_iterate(not_older_gens);
}
not_older_gens->reset_generation();
}
}
// When collection is parallel, all threads get to cooperate to do
// older-gen scanning.
for (int i = level+1; i < _n_gens; i++) {
older_gens->set_generation(_gens[i]);
rem_set()->younger_refs_iterate(_gens[i], older_gens);
older_gens->reset_generation();
}
_gen_process_strong_tasks->all_tasks_completed();
}
void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure,
OopClosure* non_root_closure) {
SharedHeap::process_weak_roots(root_closure, non_root_closure);
// "Local" "weak" refs
for (int i = 0; i < _n_gens; i++) {
_gens[i]->ref_processor()->weak_oops_do(root_closure);
}
}
#define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
void GenCollectedHeap:: \
oop_since_save_marks_iterate(int level, \
OopClosureType* cur, \
OopClosureType* older) { \
_gens[level]->oop_since_save_marks_iterate##nv_suffix(cur); \
for (int i = level+1; i < n_gens(); i++) { \
_gens[i]->oop_since_save_marks_iterate##nv_suffix(older); \
} \
perm_gen()->oop_since_save_marks_iterate##nv_suffix(older); \
}
ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
#undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
for (int i = level; i < _n_gens; i++) {
if (!_gens[i]->no_allocs_since_save_marks()) return false;
}
return perm_gen()->no_allocs_since_save_marks();
}
bool GenCollectedHeap::supports_inline_contig_alloc() const {
return _gens[0]->supports_inline_contig_alloc();
}
HeapWord** GenCollectedHeap::top_addr() const {
return _gens[0]->top_addr();
}
HeapWord** GenCollectedHeap::end_addr() const {
return _gens[0]->end_addr();
}
size_t GenCollectedHeap::unsafe_max_alloc() {
return _gens[0]->unsafe_max_alloc_nogc();
}
// public collection interfaces
void GenCollectedHeap::collect(GCCause::Cause cause) {
if (should_do_concurrent_full_gc(cause)) {
#ifndef SERIALGC
// mostly concurrent full collection
collect_mostly_concurrent(cause);
#else // SERIALGC
ShouldNotReachHere();
#endif // SERIALGC
} else {
#ifdef ASSERT
if (cause == GCCause::_scavenge_alot) {
// minor collection only
collect(cause, 0);
} else {
// Stop-the-world full collection
collect(cause, n_gens() - 1);
}
#else
// Stop-the-world full collection
collect(cause, n_gens() - 1);
#endif
}
}
void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
// The caller doesn't have the Heap_lock
assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
MutexLocker ml(Heap_lock);
collect_locked(cause, max_level);
}
// This interface assumes that it's being called by the
// vm thread. It collects the heap assuming that the
// heap lock is already held and that we are executing in
// the context of the vm thread.
void GenCollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
assert(Thread::current()->is_VM_thread(), "Precondition#1");
assert(Heap_lock->is_locked(), "Precondition#2");
GCCauseSetter gcs(this, cause);
switch (cause) {
case GCCause::_heap_inspection:
case GCCause::_heap_dump: {
HandleMark hm;
do_full_collection(false, // don't clear all soft refs
n_gens() - 1);
break;
}
default: // XXX FIX ME
ShouldNotReachHere(); // Unexpected use of this function
}
}
void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
// The caller has the Heap_lock
assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
collect_locked(cause, n_gens() - 1);
}
// this is the private collection interface
// The Heap_lock is expected to be held on entry.
void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
if (_preloading_shared_classes) {
warning("\nThe permanent generation is not large enough to preload "
"requested classes.\nUse -XX:PermSize= to increase the initial "
"size of the permanent generation.\n");
vm_exit(2);
}
// Read the GC count while holding the Heap_lock
unsigned int gc_count_before = total_collections();
unsigned int full_gc_count_before = total_full_collections();
{
MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
VM_GenCollectFull op(gc_count_before, full_gc_count_before,
cause, max_level);
VMThread::execute(&op);
}
}
#ifndef SERIALGC
bool GenCollectedHeap::create_cms_collector() {
assert(((_gens[1]->kind() == Generation::ConcurrentMarkSweep) ||
(_gens[1]->kind() == Generation::ASConcurrentMarkSweep)) &&
_perm_gen->as_gen()->kind() == Generation::ConcurrentMarkSweep,
"Unexpected generation kinds");
// Skip two header words in the block content verification
NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
CMSCollector* collector = new CMSCollector(
(ConcurrentMarkSweepGeneration*)_gens[1],
(ConcurrentMarkSweepGeneration*)_perm_gen->as_gen(),
_rem_set->as_CardTableRS(),
(ConcurrentMarkSweepPolicy*) collector_policy());
if (collector == NULL || !collector->completed_initialization()) {
if (collector) {
delete collector; // Be nice in embedded situation
}
vm_shutdown_during_initialization("Could not create CMS collector");
return false;
}
return true; // success
}
void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
MutexLocker ml(Heap_lock);
// Read the GC counts while holding the Heap_lock
unsigned int full_gc_count_before = total_full_collections();
unsigned int gc_count_before = total_collections();
{
MutexUnlocker mu(Heap_lock);
VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
VMThread::execute(&op);
}
}
#endif // SERIALGC
void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
int max_level) {
int local_max_level;
if (!incremental_collection_will_fail() &&
gc_cause() == GCCause::_gc_locker) {
local_max_level = 0;
} else {
local_max_level = max_level;
}
do_collection(true /* full */,
clear_all_soft_refs /* clear_all_soft_refs */,
0 /* size */,
false /* is_tlab */,
local_max_level /* max_level */);
// Hack XXX FIX ME !!!
// A scavenge may not have been attempted, or may have
// been attempted and failed, because the old gen was too full
if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
incremental_collection_will_fail()) {
if (PrintGCDetails) {
gclog_or_tty->print_cr("GC locker: Trying a full collection "
"because scavenge failed");
}
// This time allow the old gen to be collected as well
do_collection(true /* full */,
clear_all_soft_refs /* clear_all_soft_refs */,
0 /* size */,
false /* is_tlab */,
n_gens() - 1 /* max_level */);
}
}
// Returns "TRUE" iff "p" points into the allocated area of the heap.
bool GenCollectedHeap::is_in(const void* p) const {
#ifndef ASSERT
guarantee(VerifyBeforeGC ||
VerifyDuringGC ||
VerifyBeforeExit ||
VerifyAfterGC, "too expensive");
#endif
// This might be sped up with a cache of the last generation that
// answered yes.
for (int i = 0; i < _n_gens; i++) {
if (_gens[i]->is_in(p)) return true;
}
if (_perm_gen->as_gen()->is_in(p)) return true;
// Otherwise...
return false;
}
// Returns "TRUE" iff "p" points into the allocated area of the heap.
bool GenCollectedHeap::is_in_youngest(void* p) {
return _gens[0]->is_in(p);
}
void GenCollectedHeap::oop_iterate(OopClosure* cl) {
for (int i = 0; i < _n_gens; i++) {
_gens[i]->oop_iterate(cl);
}
}
void GenCollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl) {
for (int i = 0; i < _n_gens; i++) {
_gens[i]->oop_iterate(mr, cl);
}
}
void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
for (int i = 0; i < _n_gens; i++) {
_gens[i]->object_iterate(cl);
}
perm_gen()->object_iterate(cl);
}
void GenCollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
for (int i = 0; i < _n_gens; i++) {
_gens[i]->object_iterate_since_last_GC(cl);
}
}
Space* GenCollectedHeap::space_containing(const void* addr) const {
for (int i = 0; i < _n_gens; i++) {
Space* res = _gens[i]->space_containing(addr);
if (res != NULL) return res;
}
Space* res = perm_gen()->space_containing(addr);
if (res != NULL) return res;
// Otherwise...
assert(false, "Could not find containing space");
return NULL;
}
HeapWord* GenCollectedHeap::block_start(const void* addr) const {
assert(is_in_reserved(addr), "block_start of address outside of heap");
for (int i = 0; i < _n_gens; i++) {
if (_gens[i]->is_in_reserved(addr)) {
assert(_gens[i]->is_in(addr),
"addr should be in allocated part of generation");
return _gens[i]->block_start(addr);
}
}
if (perm_gen()->is_in_reserved(addr)) {
assert(perm_gen()->is_in(addr),
"addr should be in allocated part of perm gen");
return perm_gen()->block_start(addr);
}
assert(false, "Some generation should contain the address");
return NULL;
}
size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
assert(is_in_reserved(addr), "block_size of address outside of heap");
for (int i = 0; i < _n_gens; i++) {
if (_gens[i]->is_in_reserved(addr)) {
assert(_gens[i]->is_in(addr),
"addr should be in allocated part of generation");
return _gens[i]->block_size(addr);
}
}
if (perm_gen()->is_in_reserved(addr)) {
assert(perm_gen()->is_in(addr),
"addr should be in allocated part of perm gen");
return perm_gen()->block_size(addr);
}
assert(false, "Some generation should contain the address");
return 0;
}
bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
assert(block_start(addr) == addr, "addr must be a block start");
for (int i = 0; i < _n_gens; i++) {
if (_gens[i]->is_in_reserved(addr)) {
return _gens[i]->block_is_obj(addr);
}
}
if (perm_gen()->is_in_reserved(addr)) {
return perm_gen()->block_is_obj(addr);
}
assert(false, "Some generation should contain the address");
return false;
}
bool GenCollectedHeap::supports_tlab_allocation() const {
for (int i = 0; i < _n_gens; i += 1) {
if (_gens[i]->supports_tlab_allocation()) {
return true;
}
}
return false;
}
size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
size_t result = 0;
for (int i = 0; i < _n_gens; i += 1) {
if (_gens[i]->supports_tlab_allocation()) {
result += _gens[i]->tlab_capacity();
}
}
return result;
}
size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
size_t result = 0;
for (int i = 0; i < _n_gens; i += 1) {
if (_gens[i]->supports_tlab_allocation()) {
result += _gens[i]->unsafe_max_tlab_alloc();
}
}
return result;
}
HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
bool gc_overhead_limit_was_exceeded;
HeapWord* result = mem_allocate(size /* size */,
false /* is_large_noref */,
true /* is_tlab */,
&gc_overhead_limit_was_exceeded);
return result;
}
// Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
// from the list headed by "*prev_ptr".
static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
bool first = true;
size_t min_size = 0; // "first" makes this conceptually infinite.
ScratchBlock **smallest_ptr, *smallest;
ScratchBlock *cur = *prev_ptr;
while (cur) {
assert(*prev_ptr == cur, "just checking");
if (first || cur->num_words < min_size) {
smallest_ptr = prev_ptr;
smallest = cur;
min_size = smallest->num_words;
first = false;
}
prev_ptr = &cur->next;
cur = cur->next;
}
smallest = *smallest_ptr;
*smallest_ptr = smallest->next;
return smallest;
}
// Sort the scratch block list headed by res into decreasing size order,
// and set "res" to the result.
static void sort_scratch_list(ScratchBlock*& list) {
ScratchBlock* sorted = NULL;
ScratchBlock* unsorted = list;
while (unsorted) {
ScratchBlock *smallest = removeSmallestScratch(&unsorted);
smallest->next = sorted;
sorted = smallest;
}
list = sorted;
}
ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
size_t max_alloc_words) {
ScratchBlock* res = NULL;
for (int i = 0; i < _n_gens; i++) {
_gens[i]->contribute_scratch(res, requestor, max_alloc_words);
}
sort_scratch_list(res);
return res;
}
size_t GenCollectedHeap::large_typearray_limit() {
return gen_policy()->large_typearray_limit();
}
class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
void do_generation(Generation* gen) {
gen->prepare_for_verify();
}
};
void GenCollectedHeap::prepare_for_verify() {
ensure_parsability(false); // no need to retire TLABs
GenPrepareForVerifyClosure blk;
generation_iterate(&blk, false);
perm_gen()->prepare_for_verify();
}
void GenCollectedHeap::generation_iterate(GenClosure* cl,
bool old_to_young) {
if (old_to_young) {
for (int i = _n_gens-1; i >= 0; i--) {
cl->do_generation(_gens[i]);
}
} else {
for (int i = 0; i < _n_gens; i++) {
cl->do_generation(_gens[i]);
}
}
}
void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
for (int i = 0; i < _n_gens; i++) {
_gens[i]->space_iterate(cl, true);
}
perm_gen()->space_iterate(cl, true);
}
bool GenCollectedHeap::is_maximal_no_gc() const {
for (int i = 0; i < _n_gens; i++) { // skip perm gen
if (!_gens[i]->is_maximal_no_gc()) {
return false;
}
}
return true;
}
void GenCollectedHeap::save_marks() {
for (int i = 0; i < _n_gens; i++) {
_gens[i]->save_marks();
}
perm_gen()->save_marks();
}
void GenCollectedHeap::compute_new_generation_sizes(int collectedGen) {
for (int i = 0; i <= collectedGen; i++) {
_gens[i]->compute_new_size();
}
}
GenCollectedHeap* GenCollectedHeap::heap() {
assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
return _gch;
}
void GenCollectedHeap::prepare_for_compaction() {
Generation* scanning_gen = _gens[_n_gens-1];
// Start by compacting into same gen.
CompactPoint cp(scanning_gen, NULL, NULL);
while (scanning_gen != NULL) {
scanning_gen->prepare_for_compaction(&cp);
scanning_gen = prev_gen(scanning_gen);
}
}
GCStats* GenCollectedHeap::gc_stats(int level) const {
return _gens[level]->gc_stats();
}
void GenCollectedHeap::verify(bool allow_dirty, bool silent) {
if (!silent) {
gclog_or_tty->print("permgen ");
}
perm_gen()->verify(allow_dirty);
for (int i = _n_gens-1; i >= 0; i--) {
Generation* g = _gens[i];
if (!silent) {
gclog_or_tty->print(g->name());
gclog_or_tty->print(" ");
}
g->verify(allow_dirty);
}
if (!silent) {
gclog_or_tty->print("remset ");
}
rem_set()->verify();
if (!silent) {
gclog_or_tty->print("ref_proc ");
}
ReferenceProcessor::verify();
}
void GenCollectedHeap::print() const { print_on(tty); }
void GenCollectedHeap::print_on(outputStream* st) const {
for (int i = 0; i < _n_gens; i++) {
_gens[i]->print_on(st);
}
perm_gen()->print_on(st);
}
void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
if (workers() != NULL) {
workers()->threads_do(tc);
}
#ifndef SERIALGC
if (UseConcMarkSweepGC) {
ConcurrentMarkSweepThread::threads_do(tc);
}
#endif // SERIALGC
}
void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
#ifndef SERIALGC
if (UseParNewGC) {
workers()->print_worker_threads_on(st);
}
if (UseConcMarkSweepGC) {
ConcurrentMarkSweepThread::print_all_on(st);
}
#endif // SERIALGC
}
void GenCollectedHeap::print_tracing_info() const {
if (TraceGen0Time) {
get_gen(0)->print_summary_info();
}
if (TraceGen1Time) {
get_gen(1)->print_summary_info();
}
}
void GenCollectedHeap::print_heap_change(size_t prev_used) const {
if (PrintGCDetails && Verbose) {
gclog_or_tty->print(" " SIZE_FORMAT
"->" SIZE_FORMAT
"(" SIZE_FORMAT ")",
prev_used, used(), capacity());
} else {
gclog_or_tty->print(" " SIZE_FORMAT "K"
"->" SIZE_FORMAT "K"
"(" SIZE_FORMAT "K)",
prev_used / K, used() / K, capacity() / K);
}
}
//New method to print perm gen info with PrintGCDetails flag
void GenCollectedHeap::print_perm_heap_change(size_t perm_prev_used) const {
gclog_or_tty->print(", [%s :", perm_gen()->short_name());
perm_gen()->print_heap_change(perm_prev_used);
gclog_or_tty->print("]");
}
class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
private:
bool _full;
public:
void do_generation(Generation* gen) {
gen->gc_prologue(_full);
}
GenGCPrologueClosure(bool full) : _full(full) {};
};
void GenCollectedHeap::gc_prologue(bool full) {
assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
always_do_update_barrier = false;
// Fill TLAB's and such
CollectedHeap::accumulate_statistics_all_tlabs();
ensure_parsability(true); // retire TLABs
// Call allocation profiler
AllocationProfiler::iterate_since_last_gc();
// Walk generations
GenGCPrologueClosure blk(full);
generation_iterate(&blk, false); // not old-to-young.
perm_gen()->gc_prologue(full);
};
class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
private:
bool _full;
public:
void do_generation(Generation* gen) {
gen->gc_epilogue(_full);
}
GenGCEpilogueClosure(bool full) : _full(full) {};
};
void GenCollectedHeap::gc_epilogue(bool full) {
// Remember if a partial collection of the heap failed, and
// we did a complete collection.
if (full && incremental_collection_will_fail()) {
set_last_incremental_collection_failed();
} else {
clear_last_incremental_collection_failed();
}
// Clear the flag, if set; the generation gc_epilogues will set the
// flag again if the condition persists despite the collection.
clear_incremental_collection_will_fail();
#ifdef COMPILER2
assert(DerivedPointerTable::is_empty(), "derived pointer present");
size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
#endif /* COMPILER2 */
resize_all_tlabs();
GenGCEpilogueClosure blk(full);
generation_iterate(&blk, false); // not old-to-young.
perm_gen()->gc_epilogue(full);
always_do_update_barrier = UseConcMarkSweepGC;
};
class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
public:
void do_generation(Generation* gen) {
gen->ensure_parsability();
}
};
void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
CollectedHeap::ensure_parsability(retire_tlabs);
GenEnsureParsabilityClosure ep_cl;
generation_iterate(&ep_cl, false);
perm_gen()->ensure_parsability();
}
oop GenCollectedHeap::handle_failed_promotion(Generation* gen,
oop obj,
size_t obj_size,
oop* ref) {
assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
HeapWord* result = NULL;
// First give each higher generation a chance to allocate the promoted object.
Generation* allocator = next_gen(gen);
if (allocator != NULL) {
do {
result = allocator->allocate(obj_size, false);
} while (result == NULL && (allocator = next_gen(allocator)) != NULL);
}
if (result == NULL) {
// Then give gen and higher generations a chance to expand and allocate the
// object.
do {
result = gen->expand_and_allocate(obj_size, false);
} while (result == NULL && (gen = next_gen(gen)) != NULL);
}
if (result != NULL) {
Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
}
return oop(result);
}
class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
jlong _time; // in ms
jlong _now; // in ms
public:
GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
jlong time() { return _time; }
void do_generation(Generation* gen) {
_time = MIN2(_time, gen->time_of_last_gc(_now));
}
};
jlong GenCollectedHeap::millis_since_last_gc() {
jlong now = os::javaTimeMillis();
GenTimeOfLastGCClosure tolgc_cl(now);
// iterate over generations getting the oldest
// time that a generation was collected
generation_iterate(&tolgc_cl, false);
tolgc_cl.do_generation(perm_gen());
// XXX Despite the assert above, since javaTimeMillis()
// doesnot guarantee monotonically increasing return
// values (note, i didn't say "strictly monotonic"),
// we need to guard against getting back a time
// later than now. This should be fixed by basing
// on someting like gethrtime() which guarantees
// monotonicity. Note that cond_wait() is susceptible
// to a similar problem, because its interface is
// based on absolute time in the form of the
// system time's notion of UCT. See also 4506635
// for yet another problem of similar nature. XXX
jlong retVal = now - tolgc_cl.time();
if (retVal < 0) {
NOT_PRODUCT(warning("time warp: %d", retVal);)
return 0;
}
return retVal;
}