void Heap::collect(SweepToggle sweepToggle)
{
SamplingRegion samplingRegion("Garbage Collection");
GCPHASE(Collect);
ASSERT(globalData()->identifierTable == wtfThreadData().currentIdentifierTable());
ASSERT(m_isSafeToCollect);
JAVASCRIPTCORE_GC_BEGIN();
m_activityCallback->willCollect();
double lastGCStartTime = WTF::currentTime();
if (lastGCStartTime - m_lastCodeDiscardTime > minute) {
discardAllCompiledCode();
m_lastCodeDiscardTime = WTF::currentTime();
}
#if ENABLE(GGC)
bool fullGC = sweepToggle == DoSweep;
if (!fullGC)
fullGC = (capacity() > 4 * m_sizeAfterLastCollect);
#else
bool fullGC = true;
#endif
{
GCPHASE(Canonicalize);
canonicalizeCellLivenessData();
}
markRoots(fullGC);
{
GCPHASE(FinalizeUnconditionalFinalizers);
finalizeUnconditionalFinalizers();
}
{
GCPHASE(FinalizeWeakHandles);
m_weakSet.sweep();
m_globalData->smallStrings.finalizeSmallStrings();
}
JAVASCRIPTCORE_GC_MARKED();
{
GCPHASE(ResetAllocator);
resetAllocators();
}
{
GCPHASE(DeleteCodeBlocks);
m_dfgCodeBlocks.deleteUnmarkedJettisonedCodeBlocks();
}
if (sweepToggle == DoSweep) {
SamplingRegion samplingRegion("Garbage Collection: Sweeping");
GCPHASE(Sweeping);
sweep();
m_objectSpace.shrink();
m_weakSet.shrink();
}
// To avoid pathological GC churn in large heaps, we set the new allocation
// limit to be the current size of the heap. This heuristic
// is a bit arbitrary. Using the current size of the heap after this
// collection gives us a 2X multiplier, which is a 1:1 (heap size :
// new bytes allocated) proportion, and seems to work well in benchmarks.
size_t newSize = size();
if (fullGC) {
m_sizeAfterLastCollect = newSize;
m_bytesAllocatedLimit = max(newSize, m_minBytesPerCycle);
}
m_bytesAllocated = 0;
double lastGCEndTime = WTF::currentTime();
m_lastGCLength = lastGCEndTime - lastGCStartTime;
JAVASCRIPTCORE_GC_END();
}
NEVER_INLINE void Heap::collectImpl(HeapOperation collectionType, void* stackOrigin, void* stackTop, MachineThreads::RegisterState& calleeSavedRegisters)
{
#if ENABLE(ALLOCATION_LOGGING)
dataLogF("JSC GC starting collection.\n");
#endif
double before = 0;
if (Options::logGC()) {
dataLog("[GC: ");
before = currentTimeMS();
}
SamplingRegion samplingRegion("Garbage Collection");
if (vm()->typeProfiler()) {
DeferGCForAWhile awhile(*this);
vm()->typeProfilerLog()->processLogEntries(ASCIILiteral("GC"));
}
RELEASE_ASSERT(!m_deferralDepth);
ASSERT(vm()->currentThreadIsHoldingAPILock());
RELEASE_ASSERT(vm()->atomicStringTable() == wtfThreadData().atomicStringTable());
ASSERT(m_isSafeToCollect);
JAVASCRIPTCORE_GC_BEGIN();
RELEASE_ASSERT(m_operationInProgress == NoOperation);
suspendCompilerThreads();
willStartCollection(collectionType);
GCPHASE(Collect);
double gcStartTime = WTF::monotonicallyIncreasingTime();
if (m_verifier) {
// Verify that live objects from the last GC cycle haven't been corrupted by
// mutators before we begin this new GC cycle.
m_verifier->verify(HeapVerifier::Phase::BeforeGC);
m_verifier->initializeGCCycle();
m_verifier->gatherLiveObjects(HeapVerifier::Phase::BeforeMarking);
}
flushOldStructureIDTables();
stopAllocation();
flushWriteBarrierBuffer();
markRoots(gcStartTime, stackOrigin, stackTop, calleeSavedRegisters);
if (m_verifier) {
m_verifier->gatherLiveObjects(HeapVerifier::Phase::AfterMarking);
m_verifier->verify(HeapVerifier::Phase::AfterMarking);
}
JAVASCRIPTCORE_GC_MARKED();
if (vm()->typeProfiler())
vm()->typeProfiler()->invalidateTypeSetCache();
reapWeakHandles();
pruneStaleEntriesFromWeakGCMaps();
sweepArrayBuffers();
snapshotMarkedSpace();
copyBackingStores();
finalizeUnconditionalFinalizers();
removeDeadCompilerWorklistEntries();
deleteUnmarkedCompiledCode();
deleteSourceProviderCaches();
notifyIncrementalSweeper();
rememberCurrentlyExecutingCodeBlocks();
resetAllocators();
updateAllocationLimits();
didFinishCollection(gcStartTime);
resumeCompilerThreads();
if (m_verifier) {
m_verifier->trimDeadObjects();
m_verifier->verify(HeapVerifier::Phase::AfterGC);
}
if (Options::logGC()) {
double after = currentTimeMS();
dataLog(after - before, " ms]\n");
}
}
