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heap.cc
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heap.cc
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// Copyright 2012 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "v8.h"
#include "accessors.h"
#include "api.h"
#include "bootstrapper.h"
#include "codegen.h"
#include "compilation-cache.h"
#include "debug.h"
#include "deoptimizer.h"
#include "global-handles.h"
#include "heap-profiler.h"
#include "incremental-marking.h"
#include "liveobjectlist-inl.h"
#include "mark-compact.h"
#include "natives.h"
#include "objects-visiting.h"
#include "objects-visiting-inl.h"
#include "once.h"
#include "runtime-profiler.h"
#include "scopeinfo.h"
#include "snapshot.h"
#include "store-buffer.h"
#include "v8threads.h"
#include "v8utils.h"
#include "vm-state-inl.h"
#if V8_TARGET_ARCH_ARM && !V8_INTERPRETED_REGEXP
#include "regexp-macro-assembler.h"
#include "arm/regexp-macro-assembler-arm.h"
#endif
#if V8_TARGET_ARCH_MIPS && !V8_INTERPRETED_REGEXP
#include "regexp-macro-assembler.h"
#include "mips/regexp-macro-assembler-mips.h"
#endif
namespace v8 {
namespace internal {
Heap::Heap()
: isolate_(NULL),
// semispace_size_ should be a power of 2 and old_generation_size_ should be
// a multiple of Page::kPageSize.
#if defined(V8_TARGET_ARCH_X64)
#define LUMP_OF_MEMORY (2 * MB)
code_range_size_(512*MB),
#else
#define LUMP_OF_MEMORY MB
code_range_size_(0),
#endif
#if defined(ANDROID)
reserved_semispace_size_(4 * Max(LUMP_OF_MEMORY, Page::kPageSize)),
max_semispace_size_(4 * Max(LUMP_OF_MEMORY, Page::kPageSize)),
initial_semispace_size_(Page::kPageSize),
max_old_generation_size_(192*MB),
max_executable_size_(max_old_generation_size_),
#else
reserved_semispace_size_(8 * Max(LUMP_OF_MEMORY, Page::kPageSize)),
max_semispace_size_(8 * Max(LUMP_OF_MEMORY, Page::kPageSize)),
initial_semispace_size_(Page::kPageSize),
max_old_generation_size_(700ul * LUMP_OF_MEMORY),
max_executable_size_(256l * LUMP_OF_MEMORY),
#endif
// Variables set based on semispace_size_ and old_generation_size_ in
// ConfigureHeap (survived_since_last_expansion_, external_allocation_limit_)
// Will be 4 * reserved_semispace_size_ to ensure that young
// generation can be aligned to its size.
survived_since_last_expansion_(0),
sweep_generation_(0),
always_allocate_scope_depth_(0),
linear_allocation_scope_depth_(0),
contexts_disposed_(0),
global_ic_age_(0),
flush_monomorphic_ics_(false),
scan_on_scavenge_pages_(0),
new_space_(this),
old_pointer_space_(NULL),
old_data_space_(NULL),
code_space_(NULL),
map_space_(NULL),
cell_space_(NULL),
lo_space_(NULL),
gc_state_(NOT_IN_GC),
gc_post_processing_depth_(0),
ms_count_(0),
gc_count_(0),
remembered_unmapped_pages_index_(0),
unflattened_strings_length_(0),
#ifdef DEBUG
allocation_allowed_(true),
allocation_timeout_(0),
disallow_allocation_failure_(false),
debug_utils_(NULL),
#endif // DEBUG
new_space_high_promotion_mode_active_(false),
old_gen_promotion_limit_(kMinimumPromotionLimit),
old_gen_allocation_limit_(kMinimumAllocationLimit),
old_gen_limit_factor_(1),
size_of_old_gen_at_last_old_space_gc_(0),
external_allocation_limit_(0),
amount_of_external_allocated_memory_(0),
amount_of_external_allocated_memory_at_last_global_gc_(0),
old_gen_exhausted_(false),
store_buffer_rebuilder_(store_buffer()),
hidden_symbol_(NULL),
global_gc_prologue_callback_(NULL),
global_gc_epilogue_callback_(NULL),
gc_safe_size_of_old_object_(NULL),
total_regexp_code_generated_(0),
tracer_(NULL),
young_survivors_after_last_gc_(0),
high_survival_rate_period_length_(0),
survival_rate_(0),
previous_survival_rate_trend_(Heap::STABLE),
survival_rate_trend_(Heap::STABLE),
max_gc_pause_(0),
total_gc_time_ms_(0),
max_alive_after_gc_(0),
min_in_mutator_(kMaxInt),
alive_after_last_gc_(0),
last_gc_end_timestamp_(0.0),
store_buffer_(this),
marking_(this),
incremental_marking_(this),
number_idle_notifications_(0),
last_idle_notification_gc_count_(0),
last_idle_notification_gc_count_init_(false),
mark_sweeps_since_idle_round_started_(0),
ms_count_at_last_idle_notification_(0),
gc_count_at_last_idle_gc_(0),
scavenges_since_last_idle_round_(kIdleScavengeThreshold),
promotion_queue_(this),
configured_(false),
chunks_queued_for_free_(NULL),
relocation_mutex_(NULL) {
// Allow build-time customization of the max semispace size. Building
// V8 with snapshots and a non-default max semispace size is much
// easier if you can define it as part of the build environment.
#if defined(V8_MAX_SEMISPACE_SIZE)
max_semispace_size_ = reserved_semispace_size_ = V8_MAX_SEMISPACE_SIZE;
#endif
intptr_t max_virtual = OS::MaxVirtualMemory();
if (max_virtual > 0) {
if (code_range_size_ > 0) {
// Reserve no more than 1/8 of the memory for the code range.
code_range_size_ = Min(code_range_size_, max_virtual >> 3);
}
}
memset(roots_, 0, sizeof(roots_[0]) * kRootListLength);
native_contexts_list_ = NULL;
mark_compact_collector_.heap_ = this;
external_string_table_.heap_ = this;
// Put a dummy entry in the remembered pages so we can find the list the
// minidump even if there are no real unmapped pages.
RememberUnmappedPage(NULL, false);
ClearObjectStats(true);
}
intptr_t Heap::Capacity() {
if (!HasBeenSetUp()) return 0;
return new_space_.Capacity() +
old_pointer_space_->Capacity() +
old_data_space_->Capacity() +
code_space_->Capacity() +
map_space_->Capacity() +
cell_space_->Capacity();
}
intptr_t Heap::CommittedMemory() {
if (!HasBeenSetUp()) return 0;
return new_space_.CommittedMemory() +
old_pointer_space_->CommittedMemory() +
old_data_space_->CommittedMemory() +
code_space_->CommittedMemory() +
map_space_->CommittedMemory() +
cell_space_->CommittedMemory() +
lo_space_->Size();
}
intptr_t Heap::CommittedMemoryExecutable() {
if (!HasBeenSetUp()) return 0;
return isolate()->memory_allocator()->SizeExecutable();
}
intptr_t Heap::Available() {
if (!HasBeenSetUp()) return 0;
return new_space_.Available() +
old_pointer_space_->Available() +
old_data_space_->Available() +
code_space_->Available() +
map_space_->Available() +
cell_space_->Available();
}
bool Heap::HasBeenSetUp() {
return old_pointer_space_ != NULL &&
old_data_space_ != NULL &&
code_space_ != NULL &&
map_space_ != NULL &&
cell_space_ != NULL &&
lo_space_ != NULL;
}
int Heap::GcSafeSizeOfOldObject(HeapObject* object) {
if (IntrusiveMarking::IsMarked(object)) {
return IntrusiveMarking::SizeOfMarkedObject(object);
}
return object->SizeFromMap(object->map());
}
GarbageCollector Heap::SelectGarbageCollector(AllocationSpace space,
const char** reason) {
// Is global GC requested?
if (space != NEW_SPACE) {
isolate_->counters()->gc_compactor_caused_by_request()->Increment();
*reason = "GC in old space requested";
return MARK_COMPACTOR;
}
if (FLAG_gc_global || (FLAG_stress_compaction && (gc_count_ & 1) != 0)) {
*reason = "GC in old space forced by flags";
return MARK_COMPACTOR;
}
// Is enough data promoted to justify a global GC?
if (OldGenerationPromotionLimitReached()) {
isolate_->counters()->gc_compactor_caused_by_promoted_data()->Increment();
*reason = "promotion limit reached";
return MARK_COMPACTOR;
}
// Have allocation in OLD and LO failed?
if (old_gen_exhausted_) {
isolate_->counters()->
gc_compactor_caused_by_oldspace_exhaustion()->Increment();
*reason = "old generations exhausted";
return MARK_COMPACTOR;
}
// Is there enough space left in OLD to guarantee that a scavenge can
// succeed?
//
// Note that MemoryAllocator->MaxAvailable() undercounts the memory available
// for object promotion. It counts only the bytes that the memory
// allocator has not yet allocated from the OS and assigned to any space,
// and does not count available bytes already in the old space or code
// space. Undercounting is safe---we may get an unrequested full GC when
// a scavenge would have succeeded.
if (isolate_->memory_allocator()->MaxAvailable() <= new_space_.Size()) {
isolate_->counters()->
gc_compactor_caused_by_oldspace_exhaustion()->Increment();
*reason = "scavenge might not succeed";
return MARK_COMPACTOR;
}
// Default
*reason = NULL;
return SCAVENGER;
}
// TODO(1238405): Combine the infrastructure for --heap-stats and
// --log-gc to avoid the complicated preprocessor and flag testing.
void Heap::ReportStatisticsBeforeGC() {
// Heap::ReportHeapStatistics will also log NewSpace statistics when
// compiled --log-gc is set. The following logic is used to avoid
// double logging.
#ifdef DEBUG
if (FLAG_heap_stats || FLAG_log_gc) new_space_.CollectStatistics();
if (FLAG_heap_stats) {
ReportHeapStatistics("Before GC");
} else if (FLAG_log_gc) {
new_space_.ReportStatistics();
}
if (FLAG_heap_stats || FLAG_log_gc) new_space_.ClearHistograms();
#else
if (FLAG_log_gc) {
new_space_.CollectStatistics();
new_space_.ReportStatistics();
new_space_.ClearHistograms();
}
#endif // DEBUG
}
void Heap::PrintShortHeapStatistics() {
if (!FLAG_trace_gc_verbose) return;
PrintPID("Memory allocator, used: %6" V8_PTR_PREFIX "d KB"
", available: %6" V8_PTR_PREFIX "d KB\n",
isolate_->memory_allocator()->Size() / KB,
isolate_->memory_allocator()->Available() / KB);
PrintPID("New space, used: %6" V8_PTR_PREFIX "d KB"
", available: %6" V8_PTR_PREFIX "d KB"
", committed: %6" V8_PTR_PREFIX "d KB\n",
new_space_.Size() / KB,
new_space_.Available() / KB,
new_space_.CommittedMemory() / KB);
PrintPID("Old pointers, used: %6" V8_PTR_PREFIX "d KB"
", available: %6" V8_PTR_PREFIX "d KB"
", committed: %6" V8_PTR_PREFIX "d KB\n",
old_pointer_space_->SizeOfObjects() / KB,
old_pointer_space_->Available() / KB,
old_pointer_space_->CommittedMemory() / KB);
PrintPID("Old data space, used: %6" V8_PTR_PREFIX "d KB"
", available: %6" V8_PTR_PREFIX "d KB"
", committed: %6" V8_PTR_PREFIX "d KB\n",
old_data_space_->SizeOfObjects() / KB,
old_data_space_->Available() / KB,
old_data_space_->CommittedMemory() / KB);
PrintPID("Code space, used: %6" V8_PTR_PREFIX "d KB"
", available: %6" V8_PTR_PREFIX "d KB"
", committed: %6" V8_PTR_PREFIX "d KB\n",
code_space_->SizeOfObjects() / KB,
code_space_->Available() / KB,
code_space_->CommittedMemory() / KB);
PrintPID("Map space, used: %6" V8_PTR_PREFIX "d KB"
", available: %6" V8_PTR_PREFIX "d KB"
", committed: %6" V8_PTR_PREFIX "d KB\n",
map_space_->SizeOfObjects() / KB,
map_space_->Available() / KB,
map_space_->CommittedMemory() / KB);
PrintPID("Cell space, used: %6" V8_PTR_PREFIX "d KB"
", available: %6" V8_PTR_PREFIX "d KB"
", committed: %6" V8_PTR_PREFIX "d KB\n",
cell_space_->SizeOfObjects() / KB,
cell_space_->Available() / KB,
cell_space_->CommittedMemory() / KB);
PrintPID("Large object space, used: %6" V8_PTR_PREFIX "d KB"
", available: %6" V8_PTR_PREFIX "d KB"
", committed: %6" V8_PTR_PREFIX "d KB\n",
lo_space_->SizeOfObjects() / KB,
lo_space_->Available() / KB,
lo_space_->CommittedMemory() / KB);
PrintPID("All spaces, used: %6" V8_PTR_PREFIX "d KB"
", available: %6" V8_PTR_PREFIX "d KB"
", committed: %6" V8_PTR_PREFIX "d KB\n",
this->SizeOfObjects() / KB,
this->Available() / KB,
this->CommittedMemory() / KB);
PrintPID("Total time spent in GC : %d ms\n", total_gc_time_ms_);
}
// TODO(1238405): Combine the infrastructure for --heap-stats and
// --log-gc to avoid the complicated preprocessor and flag testing.
void Heap::ReportStatisticsAfterGC() {
// Similar to the before GC, we use some complicated logic to ensure that
// NewSpace statistics are logged exactly once when --log-gc is turned on.
#if defined(DEBUG)
if (FLAG_heap_stats) {
new_space_.CollectStatistics();
ReportHeapStatistics("After GC");
} else if (FLAG_log_gc) {
new_space_.ReportStatistics();
}
#else
if (FLAG_log_gc) new_space_.ReportStatistics();
#endif // DEBUG
}
void Heap::GarbageCollectionPrologue() {
isolate_->transcendental_cache()->Clear();
ClearJSFunctionResultCaches();
gc_count_++;
unflattened_strings_length_ = 0;
#ifdef VERIFY_HEAP
if (FLAG_verify_heap) {
Verify();
}
#endif
#ifdef DEBUG
ASSERT(allocation_allowed_ && gc_state_ == NOT_IN_GC);
allow_allocation(false);
if (FLAG_gc_verbose) Print();
ReportStatisticsBeforeGC();
#endif // DEBUG
LiveObjectList::GCPrologue();
store_buffer()->GCPrologue();
}
intptr_t Heap::SizeOfObjects() {
intptr_t total = 0;
AllSpaces spaces;
for (Space* space = spaces.next(); space != NULL; space = spaces.next()) {
total += space->SizeOfObjects();
}
return total;
}
void Heap::RepairFreeListsAfterBoot() {
PagedSpaces spaces;
for (PagedSpace* space = spaces.next();
space != NULL;
space = spaces.next()) {
space->RepairFreeListsAfterBoot();
}
}
void Heap::GarbageCollectionEpilogue() {
store_buffer()->GCEpilogue();
LiveObjectList::GCEpilogue();
// In release mode, we only zap the from space under heap verification.
if (Heap::ShouldZapGarbage()) {
ZapFromSpace();
}
#ifdef VERIFY_HEAP
if (FLAG_verify_heap) {
Verify();
}
#endif
#ifdef DEBUG
allow_allocation(true);
if (FLAG_print_global_handles) isolate_->global_handles()->Print();
if (FLAG_print_handles) PrintHandles();
if (FLAG_gc_verbose) Print();
if (FLAG_code_stats) ReportCodeStatistics("After GC");
#endif
isolate_->counters()->alive_after_last_gc()->Set(
static_cast<int>(SizeOfObjects()));
isolate_->counters()->symbol_table_capacity()->Set(
symbol_table()->Capacity());
isolate_->counters()->number_of_symbols()->Set(
symbol_table()->NumberOfElements());
if (CommittedMemory() > 0) {
isolate_->counters()->external_fragmentation_total()->AddSample(
static_cast<int>(100 - (SizeOfObjects() * 100.0) / CommittedMemory()));
isolate_->counters()->heap_fraction_map_space()->AddSample(
static_cast<int>(
(map_space()->CommittedMemory() * 100.0) / CommittedMemory()));
isolate_->counters()->heap_fraction_cell_space()->AddSample(
static_cast<int>(
(cell_space()->CommittedMemory() * 100.0) / CommittedMemory()));
isolate_->counters()->heap_sample_total_committed()->AddSample(
static_cast<int>(CommittedMemory() / KB));
isolate_->counters()->heap_sample_total_used()->AddSample(
static_cast<int>(SizeOfObjects() / KB));
isolate_->counters()->heap_sample_map_space_committed()->AddSample(
static_cast<int>(map_space()->CommittedMemory() / KB));
isolate_->counters()->heap_sample_cell_space_committed()->AddSample(
static_cast<int>(cell_space()->CommittedMemory() / KB));
}
#define UPDATE_COUNTERS_FOR_SPACE(space) \
isolate_->counters()->space##_bytes_available()->Set( \
static_cast<int>(space()->Available())); \
isolate_->counters()->space##_bytes_committed()->Set( \
static_cast<int>(space()->CommittedMemory())); \
isolate_->counters()->space##_bytes_used()->Set( \
static_cast<int>(space()->SizeOfObjects()));
#define UPDATE_FRAGMENTATION_FOR_SPACE(space) \
if (space()->CommittedMemory() > 0) { \
isolate_->counters()->external_fragmentation_##space()->AddSample( \
static_cast<int>(100 - \
(space()->SizeOfObjects() * 100.0) / space()->CommittedMemory())); \
}
#define UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE(space) \
UPDATE_COUNTERS_FOR_SPACE(space) \
UPDATE_FRAGMENTATION_FOR_SPACE(space)
UPDATE_COUNTERS_FOR_SPACE(new_space)
UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE(old_pointer_space)
UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE(old_data_space)
UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE(code_space)
UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE(map_space)
UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE(cell_space)
UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE(lo_space)
#undef UPDATE_COUNTERS_FOR_SPACE
#undef UPDATE_FRAGMENTATION_FOR_SPACE
#undef UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE
#if defined(DEBUG)
ReportStatisticsAfterGC();
#endif // DEBUG
#ifdef ENABLE_DEBUGGER_SUPPORT
isolate_->debug()->AfterGarbageCollection();
#endif // ENABLE_DEBUGGER_SUPPORT
}
void Heap::CollectAllGarbage(int flags, const char* gc_reason) {
// Since we are ignoring the return value, the exact choice of space does
// not matter, so long as we do not specify NEW_SPACE, which would not
// cause a full GC.
mark_compact_collector_.SetFlags(flags);
CollectGarbage(OLD_POINTER_SPACE, gc_reason);
mark_compact_collector_.SetFlags(kNoGCFlags);
}
void Heap::CollectAllAvailableGarbage(const char* gc_reason) {
// Since we are ignoring the return value, the exact choice of space does
// not matter, so long as we do not specify NEW_SPACE, which would not
// cause a full GC.
// Major GC would invoke weak handle callbacks on weakly reachable
// handles, but won't collect weakly reachable objects until next
// major GC. Therefore if we collect aggressively and weak handle callback
// has been invoked, we rerun major GC to release objects which become
// garbage.
// Note: as weak callbacks can execute arbitrary code, we cannot
// hope that eventually there will be no weak callbacks invocations.
// Therefore stop recollecting after several attempts.
mark_compact_collector()->SetFlags(kMakeHeapIterableMask |
kReduceMemoryFootprintMask);
isolate_->compilation_cache()->Clear();
const int kMaxNumberOfAttempts = 7;
for (int attempt = 0; attempt < kMaxNumberOfAttempts; attempt++) {
if (!CollectGarbage(OLD_POINTER_SPACE, MARK_COMPACTOR, gc_reason, NULL)) {
break;
}
}
mark_compact_collector()->SetFlags(kNoGCFlags);
new_space_.Shrink();
UncommitFromSpace();
Shrink();
incremental_marking()->UncommitMarkingDeque();
}
bool Heap::CollectGarbage(AllocationSpace space,
GarbageCollector collector,
const char* gc_reason,
const char* collector_reason) {
// The VM is in the GC state until exiting this function.
VMState state(isolate_, GC);
#ifdef DEBUG
// Reset the allocation timeout to the GC interval, but make sure to
// allow at least a few allocations after a collection. The reason
// for this is that we have a lot of allocation sequences and we
// assume that a garbage collection will allow the subsequent
// allocation attempts to go through.
allocation_timeout_ = Max(6, FLAG_gc_interval);
#endif
if (collector == SCAVENGER && !incremental_marking()->IsStopped()) {
if (FLAG_trace_incremental_marking) {
PrintF("[IncrementalMarking] Scavenge during marking.\n");
}
}
if (collector == MARK_COMPACTOR &&
!mark_compact_collector()->abort_incremental_marking_ &&
!incremental_marking()->IsStopped() &&
!incremental_marking()->should_hurry() &&
FLAG_incremental_marking_steps) {
// Make progress in incremental marking.
const intptr_t kStepSizeWhenDelayedByScavenge = 1 * MB;
incremental_marking()->Step(kStepSizeWhenDelayedByScavenge,
IncrementalMarking::NO_GC_VIA_STACK_GUARD);
if (!incremental_marking()->IsComplete()) {
if (FLAG_trace_incremental_marking) {
PrintF("[IncrementalMarking] Delaying MarkSweep.\n");
}
collector = SCAVENGER;
collector_reason = "incremental marking delaying mark-sweep";
}
}
bool next_gc_likely_to_collect_more = false;
{ GCTracer tracer(this, gc_reason, collector_reason);
GarbageCollectionPrologue();
// The GC count was incremented in the prologue. Tell the tracer about
// it.
tracer.set_gc_count(gc_count_);
// Tell the tracer which collector we've selected.
tracer.set_collector(collector);
HistogramTimer* rate = (collector == SCAVENGER)
? isolate_->counters()->gc_scavenger()
: isolate_->counters()->gc_compactor();
rate->Start();
next_gc_likely_to_collect_more =
PerformGarbageCollection(collector, &tracer);
rate->Stop();
ASSERT(collector == SCAVENGER || incremental_marking()->IsStopped());
// This can do debug callbacks and restart incremental marking.
GarbageCollectionEpilogue();
}
if (incremental_marking()->IsStopped()) {
if (incremental_marking()->WorthActivating() && NextGCIsLikelyToBeFull()) {
incremental_marking()->Start();
}
}
return next_gc_likely_to_collect_more;
}
void Heap::PerformScavenge() {
GCTracer tracer(this, NULL, NULL);
if (incremental_marking()->IsStopped()) {
PerformGarbageCollection(SCAVENGER, &tracer);
} else {
PerformGarbageCollection(MARK_COMPACTOR, &tracer);
}
}
#ifdef VERIFY_HEAP
// Helper class for verifying the symbol table.
class SymbolTableVerifier : public ObjectVisitor {
public:
void VisitPointers(Object** start, Object** end) {
// Visit all HeapObject pointers in [start, end).
for (Object** p = start; p < end; p++) {
if ((*p)->IsHeapObject()) {
// Check that the symbol is actually a symbol.
CHECK((*p)->IsTheHole() || (*p)->IsUndefined() || (*p)->IsSymbol());
}
}
}
};
static void VerifySymbolTable() {
SymbolTableVerifier verifier;
HEAP->symbol_table()->IterateElements(&verifier);
}
#endif // VERIFY_HEAP
static bool AbortIncrementalMarkingAndCollectGarbage(
Heap* heap,
AllocationSpace space,
const char* gc_reason = NULL) {
heap->mark_compact_collector()->SetFlags(Heap::kAbortIncrementalMarkingMask);
bool result = heap->CollectGarbage(space, gc_reason);
heap->mark_compact_collector()->SetFlags(Heap::kNoGCFlags);
return result;
}
void Heap::ReserveSpace(
int *sizes,
Address *locations_out) {
bool gc_performed = true;
int counter = 0;
static const int kThreshold = 20;
while (gc_performed && counter++ < kThreshold) {
gc_performed = false;
ASSERT(NEW_SPACE == FIRST_PAGED_SPACE - 1);
for (int space = NEW_SPACE; space <= LAST_PAGED_SPACE; space++) {
if (sizes[space] != 0) {
MaybeObject* allocation;
if (space == NEW_SPACE) {
allocation = new_space()->AllocateRaw(sizes[space]);
} else {
allocation = paged_space(space)->AllocateRaw(sizes[space]);
}
FreeListNode* node;
if (!allocation->To<FreeListNode>(&node)) {
if (space == NEW_SPACE) {
Heap::CollectGarbage(NEW_SPACE,
"failed to reserve space in the new space");
} else {
AbortIncrementalMarkingAndCollectGarbage(
this,
static_cast<AllocationSpace>(space),
"failed to reserve space in paged space");
}
gc_performed = true;
break;
} else {
// Mark with a free list node, in case we have a GC before
// deserializing.
node->set_size(this, sizes[space]);
locations_out[space] = node->address();
}
}
}
}
if (gc_performed) {
// Failed to reserve the space after several attempts.
V8::FatalProcessOutOfMemory("Heap::ReserveSpace");
}
}
void Heap::EnsureFromSpaceIsCommitted() {
if (new_space_.CommitFromSpaceIfNeeded()) return;
// Committing memory to from space failed.
// Try shrinking and try again.
Shrink();
if (new_space_.CommitFromSpaceIfNeeded()) return;
// Committing memory to from space failed again.
// Memory is exhausted and we will die.
V8::FatalProcessOutOfMemory("Committing semi space failed.");
}
void Heap::ClearJSFunctionResultCaches() {
if (isolate_->bootstrapper()->IsActive()) return;
Object* context = native_contexts_list_;
while (!context->IsUndefined()) {
// Get the caches for this context. GC can happen when the context
// is not fully initialized, so the caches can be undefined.
Object* caches_or_undefined =
Context::cast(context)->get(Context::JSFUNCTION_RESULT_CACHES_INDEX);
if (!caches_or_undefined->IsUndefined()) {
FixedArray* caches = FixedArray::cast(caches_or_undefined);
// Clear the caches:
int length = caches->length();
for (int i = 0; i < length; i++) {
JSFunctionResultCache::cast(caches->get(i))->Clear();
}
}
// Get the next context:
context = Context::cast(context)->get(Context::NEXT_CONTEXT_LINK);
}
}
void Heap::ClearNormalizedMapCaches() {
if (isolate_->bootstrapper()->IsActive() &&
!incremental_marking()->IsMarking()) {
return;
}
Object* context = native_contexts_list_;
while (!context->IsUndefined()) {
// GC can happen when the context is not fully initialized,
// so the cache can be undefined.
Object* cache =
Context::cast(context)->get(Context::NORMALIZED_MAP_CACHE_INDEX);
if (!cache->IsUndefined()) {
NormalizedMapCache::cast(cache)->Clear();
}
context = Context::cast(context)->get(Context::NEXT_CONTEXT_LINK);
}
}
void Heap::UpdateSurvivalRateTrend(int start_new_space_size) {
double survival_rate =
(static_cast<double>(young_survivors_after_last_gc_) * 100) /
start_new_space_size;
if (survival_rate > kYoungSurvivalRateHighThreshold) {
high_survival_rate_period_length_++;
} else {
high_survival_rate_period_length_ = 0;
}
if (survival_rate < kYoungSurvivalRateLowThreshold) {
low_survival_rate_period_length_++;
} else {
low_survival_rate_period_length_ = 0;
}
double survival_rate_diff = survival_rate_ - survival_rate;
if (survival_rate_diff > kYoungSurvivalRateAllowedDeviation) {
set_survival_rate_trend(DECREASING);
} else if (survival_rate_diff < -kYoungSurvivalRateAllowedDeviation) {
set_survival_rate_trend(INCREASING);
} else {
set_survival_rate_trend(STABLE);
}
survival_rate_ = survival_rate;
}
bool Heap::PerformGarbageCollection(GarbageCollector collector,
GCTracer* tracer) {
bool next_gc_likely_to_collect_more = false;
if (collector != SCAVENGER) {
PROFILE(isolate_, CodeMovingGCEvent());
}
#ifdef VERIFY_HEAP
if (FLAG_verify_heap) {
VerifySymbolTable();
}
#endif
if (collector == MARK_COMPACTOR && global_gc_prologue_callback_) {
ASSERT(!allocation_allowed_);
GCTracer::Scope scope(tracer, GCTracer::Scope::EXTERNAL);
global_gc_prologue_callback_();
}
GCType gc_type =
collector == MARK_COMPACTOR ? kGCTypeMarkSweepCompact : kGCTypeScavenge;
for (int i = 0; i < gc_prologue_callbacks_.length(); ++i) {
if (gc_type & gc_prologue_callbacks_[i].gc_type) {
gc_prologue_callbacks_[i].callback(gc_type, kNoGCCallbackFlags);
}
}
EnsureFromSpaceIsCommitted();
int start_new_space_size = Heap::new_space()->SizeAsInt();
if (IsHighSurvivalRate()) {
// We speed up the incremental marker if it is running so that it
// does not fall behind the rate of promotion, which would cause a
// constantly growing old space.
incremental_marking()->NotifyOfHighPromotionRate();
}
if (collector == MARK_COMPACTOR) {
// Perform mark-sweep with optional compaction.
MarkCompact(tracer);
sweep_generation_++;
bool high_survival_rate_during_scavenges = IsHighSurvivalRate() &&
IsStableOrIncreasingSurvivalTrend();
UpdateSurvivalRateTrend(start_new_space_size);
size_of_old_gen_at_last_old_space_gc_ = PromotedSpaceSizeOfObjects();
if (high_survival_rate_during_scavenges &&
IsStableOrIncreasingSurvivalTrend()) {
// Stable high survival rates of young objects both during partial and
// full collection indicate that mutator is either building or modifying
// a structure with a long lifetime.
// In this case we aggressively raise old generation memory limits to
// postpone subsequent mark-sweep collection and thus trade memory
// space for the mutation speed.
old_gen_limit_factor_ = 2;
} else {
old_gen_limit_factor_ = 1;
}
old_gen_promotion_limit_ =
OldGenPromotionLimit(size_of_old_gen_at_last_old_space_gc_);
old_gen_allocation_limit_ =
OldGenAllocationLimit(size_of_old_gen_at_last_old_space_gc_);
old_gen_exhausted_ = false;
} else {
tracer_ = tracer;
Scavenge();
tracer_ = NULL;
UpdateSurvivalRateTrend(start_new_space_size);
}
if (!new_space_high_promotion_mode_active_ &&
new_space_.Capacity() == new_space_.MaximumCapacity() &&
IsStableOrIncreasingSurvivalTrend() &&
IsHighSurvivalRate()) {
// Stable high survival rates even though young generation is at
// maximum capacity indicates that most objects will be promoted.
// To decrease scavenger pauses and final mark-sweep pauses, we
// have to limit maximal capacity of the young generation.
new_space_high_promotion_mode_active_ = true;
if (FLAG_trace_gc) {
PrintPID("Limited new space size due to high promotion rate: %d MB\n",
new_space_.InitialCapacity() / MB);
}
} else if (new_space_high_promotion_mode_active_ &&
IsStableOrDecreasingSurvivalTrend() &&
IsLowSurvivalRate()) {
// Decreasing low survival rates might indicate that the above high
// promotion mode is over and we should allow the young generation
// to grow again.
new_space_high_promotion_mode_active_ = false;
if (FLAG_trace_gc) {
PrintPID("Unlimited new space size due to low promotion rate: %d MB\n",
new_space_.MaximumCapacity() / MB);
}
}
if (new_space_high_promotion_mode_active_ &&
new_space_.Capacity() > new_space_.InitialCapacity()) {
new_space_.Shrink();
}
isolate_->counters()->objs_since_last_young()->Set(0);
gc_post_processing_depth_++;
{ DisableAssertNoAllocation allow_allocation;
GCTracer::Scope scope(tracer, GCTracer::Scope::EXTERNAL);
next_gc_likely_to_collect_more =
isolate_->global_handles()->PostGarbageCollectionProcessing(collector);
}
gc_post_processing_depth_--;
// Update relocatables.
Relocatable::PostGarbageCollectionProcessing();
if (collector == MARK_COMPACTOR) {
// Register the amount of external allocated memory.
amount_of_external_allocated_memory_at_last_global_gc_ =
amount_of_external_allocated_memory_;
}
GCCallbackFlags callback_flags = kNoGCCallbackFlags;
for (int i = 0; i < gc_epilogue_callbacks_.length(); ++i) {
if (gc_type & gc_epilogue_callbacks_[i].gc_type) {
gc_epilogue_callbacks_[i].callback(gc_type, callback_flags);
}
}
if (collector == MARK_COMPACTOR && global_gc_epilogue_callback_) {
ASSERT(!allocation_allowed_);
GCTracer::Scope scope(tracer, GCTracer::Scope::EXTERNAL);
global_gc_epilogue_callback_();
}
#ifdef VERIFY_HEAP
if (FLAG_verify_heap) {
VerifySymbolTable();
}
#endif
return next_gc_likely_to_collect_more;
}
void Heap::MarkCompact(GCTracer* tracer) {
gc_state_ = MARK_COMPACT;
LOG(isolate_, ResourceEvent("markcompact", "begin"));
mark_compact_collector_.Prepare(tracer);
ms_count_++;
tracer->set_full_gc_count(ms_count_);
MarkCompactPrologue();
mark_compact_collector_.CollectGarbage();
LOG(isolate_, ResourceEvent("markcompact", "end"));
gc_state_ = NOT_IN_GC;
isolate_->counters()->objs_since_last_full()->Set(0);