void GenMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
// Recursively traverse all live objects and mark them
GCTraceTime(Trace, gc) tm("Phase 1: Mark live objects", _gc_timer);
GenCollectedHeap* gch = GenCollectedHeap::heap();
// Because follow_root_closure is created statically, cannot
// use OopsInGenClosure constructor which takes a generation,
// as the Universe has not been created when the static constructors
// are run.
follow_root_closure.set_orig_generation(gch->old_gen());
// Need new claim bits before marking starts.
ClassLoaderDataGraph::clear_claimed_marks();
{
StrongRootsScope srs(1);
gch->gen_process_roots(&srs,
GenCollectedHeap::OldGen,
false, // Younger gens are not roots.
GenCollectedHeap::SO_None,
ClassUnloading,
&follow_root_closure,
&follow_root_closure,
&follow_cld_closure);
}
// Process reference objects found during marking
{
ref_processor()->setup_policy(clear_all_softrefs);
const ReferenceProcessorStats& stats =
ref_processor()->process_discovered_references(
&is_alive, &keep_alive, &follow_stack_closure, NULL, _gc_timer);
gc_tracer()->report_gc_reference_stats(stats);
}
// This is the point where the entire marking should have completed.
assert(_marking_stack.is_empty(), "Marking should have completed");
// Unload classes and purge the SystemDictionary.
bool purged_class = SystemDictionary::do_unloading(&is_alive);
// Unload nmethods.
CodeCache::do_unloading(&is_alive, purged_class);
// Prune dead klasses from subklass/sibling/implementor lists.
Klass::clean_weak_klass_links(&is_alive);
// Delete entries for dead interned strings.
StringTable::unlink(&is_alive);
// Clean up unreferenced symbols in symbol table.
SymbolTable::unlink();
gc_tracer()->report_object_count_after_gc(&is_alive);
}
void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
// Recursively traverse all live objects and mark them
GCTraceTime tm("phase 1", PrintGCDetails && Verbose, true, _gc_timer);
trace(" 1");
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
// General strong roots.
{
ParallelScavengeHeap::ParStrongRootsScope psrs;
Universe::oops_do(mark_and_push_closure());
JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
CodeBlobToOopClosure each_active_code_blob(mark_and_push_closure(), /*do_marking=*/ true);
Threads::oops_do(mark_and_push_closure(), &each_active_code_blob);
ObjectSynchronizer::oops_do(mark_and_push_closure());
FlatProfiler::oops_do(mark_and_push_closure());
Management::oops_do(mark_and_push_closure());
JvmtiExport::oops_do(mark_and_push_closure());
SystemDictionary::always_strong_oops_do(mark_and_push_closure());
// Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
//CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
}
// Flush marking stack.
follow_stack();
// Process reference objects found during marking
{
ref_processor()->setup_policy(clear_all_softrefs);
const ReferenceProcessorStats& stats =
ref_processor()->process_discovered_references(
is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer);
gc_tracer()->report_gc_reference_stats(stats);
}
// Follow system dictionary roots and unload classes
bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
// Follow code cache roots
CodeCache::do_unloading(is_alive_closure(), mark_and_push_closure(),
purged_class);
follow_stack(); // Flush marking stack
// Update subklass/sibling/implementor links of live klasses
follow_weak_klass_links();
assert(_marking_stack.is_empty(), "just drained");
// Visit memoized mdo's and clear unmarked weak refs
follow_mdo_weak_refs();
assert(_marking_stack.is_empty(), "just drained");
// Visit interned string tables and delete unmarked oops
StringTable::unlink(is_alive_closure());
// Clean up unreferenced symbols in symbol table.
SymbolTable::unlink();
assert(_marking_stack.is_empty(), "stack should be empty by now");
_gc_tracer->report_object_count_after_gc(is_alive_closure());
}
void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
// Recursively traverse all live objects and mark them
GCTraceTime tm("phase 1", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
trace(" 1");
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
// Need to clear claim bits before the tracing starts.
ClassLoaderDataGraph::clear_claimed_marks();
// General strong roots.
{
ParallelScavengeHeap::ParStrongRootsScope psrs;
Universe::oops_do(mark_and_push_closure());
JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
CLDToOopClosure mark_and_push_from_cld(mark_and_push_closure());
MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations);
Threads::oops_do(mark_and_push_closure(), &mark_and_push_from_cld, &each_active_code_blob);
ObjectSynchronizer::oops_do(mark_and_push_closure());
FlatProfiler::oops_do(mark_and_push_closure());
Management::oops_do(mark_and_push_closure());
JvmtiExport::oops_do(mark_and_push_closure());
SystemDictionary::always_strong_oops_do(mark_and_push_closure());
ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure());
// Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
//CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
}
// Flush marking stack.
follow_stack();
// Process reference objects found during marking
{
ref_processor()->setup_policy(clear_all_softrefs);
const ReferenceProcessorStats& stats =
ref_processor()->process_discovered_references(
is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer, _gc_tracer->gc_id());
gc_tracer()->report_gc_reference_stats(stats);
}
// This is the point where the entire marking should have completed.
assert(_marking_stack.is_empty(), "Marking should have completed");
// Unload classes and purge the SystemDictionary.
bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
// Unload nmethods.
CodeCache::do_unloading(is_alive_closure(), purged_class);
// Prune dead klasses from subklass/sibling/implementor lists.
Klass::clean_weak_klass_links(is_alive_closure());
// Delete entries for dead interned strings.
StringTable::unlink(is_alive_closure());
// Clean up unreferenced symbols in symbol table.
SymbolTable::unlink();
_gc_tracer->report_object_count_after_gc(is_alive_closure());
}
void G1MarkSweep::mark_sweep_phase3() {
G1CollectedHeap* g1h = G1CollectedHeap::heap();
// Adjust the pointers to reflect the new locations
GCTraceTime tm("phase 3", G1Log::fine() && Verbose, true, gc_timer(), gc_tracer()->gc_id());
// Need cleared claim bits for the roots processing
ClassLoaderDataGraph::clear_claimed_marks();
CodeBlobToOopClosure adjust_code_closure(&GenMarkSweep::adjust_pointer_closure, CodeBlobToOopClosure::FixRelocations);
{
G1RootProcessor root_processor(g1h, 1);
root_processor.process_all_roots(&GenMarkSweep::adjust_pointer_closure,
&GenMarkSweep::adjust_cld_closure,
&adjust_code_closure);
}
assert(GenMarkSweep::ref_processor() == g1h->ref_processor_stw(), "Sanity");
g1h->ref_processor_stw()->weak_oops_do(&GenMarkSweep::adjust_pointer_closure);
// Now adjust pointers in remaining weak roots. (All of which should
// have been cleared if they pointed to non-surviving objects.)
JNIHandles::weak_oops_do(&always_true, &GenMarkSweep::adjust_pointer_closure);
if (G1StringDedup::is_enabled()) {
G1StringDedup::oops_do(&GenMarkSweep::adjust_pointer_closure);
}
GenMarkSweep::adjust_marks();
G1AdjustPointersClosure blk;
g1h->heap_region_iterate(&blk);
}
void G1MarkSweep::mark_sweep_phase2() {
// Now all live objects are marked, compute the new object addresses.
// It is not required that we traverse spaces in the same order in
// phase2, phase3 and phase4, but the ValidateMarkSweep live oops
// tracking expects us to do so. See comment under phase4.
GCTraceTime tm("phase 2", G1Log::fine() && Verbose, true, gc_timer(), gc_tracer()->gc_id());
prepare_compaction();
}
void G1MarkSweep::mark_sweep_phase4() {
// All pointers are now adjusted, move objects accordingly
// The ValidateMarkSweep live oops tracking expects us to traverse spaces
// in the same order in phase2, phase3 and phase4. We don't quite do that
// here (code and comment not fixed for perm removal), so we tell the validate code
// to use a higher index (saved from phase2) when verifying perm_gen.
G1CollectedHeap* g1h = G1CollectedHeap::heap();
GCTraceTime tm("phase 4", G1Log::fine() && Verbose, true, gc_timer(), gc_tracer()->gc_id());
G1SpaceCompactClosure blk;
g1h->heap_region_iterate(&blk);
}
void G1MarkSweep::mark_sweep_phase1(bool& marked_for_unloading,
bool clear_all_softrefs) {
// Recursively traverse all live objects and mark them
GCTraceTime(Info, gc, phases) tm("Phase 1: Mark live objects", gc_timer());
G1CollectedHeap* g1h = G1CollectedHeap::heap();
// Need cleared claim bits for the roots processing
ClassLoaderDataGraph::clear_claimed_marks();
MarkingCodeBlobClosure follow_code_closure(&GenMarkSweep::follow_root_closure, !CodeBlobToOopClosure::FixRelocations);
{
G1RootProcessor root_processor(g1h, 1);
if (ClassUnloading) {
root_processor.process_strong_roots(&GenMarkSweep::follow_root_closure,
&GenMarkSweep::follow_cld_closure,
&follow_code_closure);
} else {
root_processor.process_all_roots_no_string_table(
&GenMarkSweep::follow_root_closure,
&GenMarkSweep::follow_cld_closure,
&follow_code_closure);
}
}
{
GCTraceTime(Debug, gc, phases) trace("Reference Processing", gc_timer());
// Process reference objects found during marking
ReferenceProcessor* rp = GenMarkSweep::ref_processor();
assert(rp == g1h->ref_processor_stw(), "Sanity");
rp->setup_policy(clear_all_softrefs);
const ReferenceProcessorStats& stats =
rp->process_discovered_references(&GenMarkSweep::is_alive,
&GenMarkSweep::keep_alive,
&GenMarkSweep::follow_stack_closure,
NULL,
gc_timer());
gc_tracer()->report_gc_reference_stats(stats);
}
// This is the point where the entire marking should have completed.
assert(GenMarkSweep::_marking_stack.is_empty(), "Marking should have completed");
if (ClassUnloading) {
GCTraceTime(Debug, gc, phases) trace("Class Unloading", gc_timer());
// Unload classes and purge the SystemDictionary.
bool purged_class = SystemDictionary::do_unloading(&GenMarkSweep::is_alive);
// Unload nmethods.
CodeCache::do_unloading(&GenMarkSweep::is_alive, purged_class);
// Prune dead klasses from subklass/sibling/implementor lists.
Klass::clean_weak_klass_links(&GenMarkSweep::is_alive);
}
{
GCTraceTime(Debug, gc, phases) trace("Scrub String and Symbol Tables", gc_timer());
// Delete entries for dead interned string and clean up unreferenced symbols in symbol table.
g1h->unlink_string_and_symbol_table(&GenMarkSweep::is_alive);
}
if (G1StringDedup::is_enabled()) {
GCTraceTime(Debug, gc, phases) trace("String Deduplication Unlink", gc_timer());
G1StringDedup::unlink(&GenMarkSweep::is_alive);
}
if (VerifyDuringGC) {
HandleMark hm; // handle scope
#if defined(COMPILER2) || INCLUDE_JVMCI
DerivedPointerTableDeactivate dpt_deact;
#endif
g1h->prepare_for_verify();
// Note: we can verify only the heap here. When an object is
// marked, the previous value of the mark word (including
// identity hash values, ages, etc) is preserved, and the mark
// word is set to markOop::marked_value - effectively removing
// any hash values from the mark word. These hash values are
// used when verifying the dictionaries and so removing them
// from the mark word can make verification of the dictionaries
// fail. At the end of the GC, the original mark word values
// (including hash values) are restored to the appropriate
// objects.
GCTraceTime(Info, gc, verify)("During GC (full)");
g1h->verify(VerifyOption_G1UseMarkWord);
}
gc_tracer()->report_object_count_after_gc(&GenMarkSweep::is_alive);
}
void G1MarkSweep::mark_sweep_phase1(bool& marked_for_unloading,
bool clear_all_softrefs) {
// Recursively traverse all live objects and mark them
GCTraceTime tm("phase 1", G1Log::fine() && Verbose, true, gc_timer());
GenMarkSweep::trace(" 1");
SharedHeap* sh = SharedHeap::heap();
// Need cleared claim bits for the strong roots processing
ClassLoaderDataGraph::clear_claimed_marks();
sh->process_strong_roots(true, // activate StrongRootsScope
false, // not scavenging.
SharedHeap::SO_SystemClasses,
&GenMarkSweep::follow_root_closure,
&GenMarkSweep::follow_code_root_closure,
&GenMarkSweep::follow_klass_closure);
// Process reference objects found during marking
ReferenceProcessor* rp = GenMarkSweep::ref_processor();
assert(rp == G1CollectedHeap::heap()->ref_processor_stw(), "Sanity");
rp->setup_policy(clear_all_softrefs);
const ReferenceProcessorStats& stats =
rp->process_discovered_references(&GenMarkSweep::is_alive,
&GenMarkSweep::keep_alive,
&GenMarkSweep::follow_stack_closure,
NULL,
gc_timer());
gc_tracer()->report_gc_reference_stats(stats);
// This is the point where the entire marking should have completed.
assert(GenMarkSweep::_marking_stack.is_empty(), "Marking should have completed");
// Unload classes and purge the SystemDictionary.
bool purged_class = SystemDictionary::do_unloading(&GenMarkSweep::is_alive);
// Unload nmethods.
CodeCache::do_unloading(&GenMarkSweep::is_alive, purged_class);
// Prune dead klasses from subklass/sibling/implementor lists.
Klass::clean_weak_klass_links(&GenMarkSweep::is_alive);
// Delete entries for dead interned strings.
StringTable::unlink(&GenMarkSweep::is_alive);
// Clean up unreferenced symbols in symbol table.
SymbolTable::unlink();
if (VerifyDuringGC) {
HandleMark hm; // handle scope
COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact);
Universe::heap()->prepare_for_verify();
// Note: we can verify only the heap here. When an object is
// marked, the previous value of the mark word (including
// identity hash values, ages, etc) is preserved, and the mark
// word is set to markOop::marked_value - effectively removing
// any hash values from the mark word. These hash values are
// used when verifying the dictionaries and so removing them
// from the mark word can make verification of the dictionaries
// fail. At the end of the GC, the orginal mark word values
// (including hash values) are restored to the appropriate
// objects.
if (!VerifySilently) {
gclog_or_tty->print(" VerifyDuringGC:(full)[Verifying ");
}
Universe::heap()->verify(VerifySilently, VerifyOption_G1UseMarkWord);
if (!VerifySilently) {
gclog_or_tty->print_cr("]");
}
}
gc_tracer()->report_object_count_after_gc(&GenMarkSweep::is_alive);
}