void GenMarkSweep::mark_sweep_phase3() {
GenCollectedHeap* gch = GenCollectedHeap::heap();
// Adjust the pointers to reflect the new locations
GCTraceTime(Info, gc, phases) tm("Phase 3: Adjust pointers", gc_timer());
// Need new claim bits for the pointer adjustment tracing.
ClassLoaderDataGraph::clear_claimed_marks();
// Because the closure below is created statically, we cannot
// use OopsInGenClosure constructor which takes a generation,
// as the Universe has not been created when the static constructors
// are run.
adjust_pointer_closure.set_orig_generation(gch->old_gen());
{
StrongRootsScope srs(1);
gch->gen_process_roots(&srs,
GenCollectedHeap::OldGen,
false, // Younger gens are not roots.
GenCollectedHeap::SO_AllCodeCache,
GenCollectedHeap::StrongAndWeakRoots,
&adjust_pointer_closure,
&adjust_pointer_closure,
&adjust_cld_closure);
}
gch->gen_process_weak_roots(&adjust_pointer_closure);
adjust_marks();
GenAdjustPointersClosure blk;
gch->generation_iterate(&blk, true);
}
void GenMarkSweep::mark_sweep_phase3(int level) {
GenCollectedHeap* gch = GenCollectedHeap::heap();
// Adjust the pointers to reflect the new locations
GCTraceTime tm("phase 3", PrintGC && Verbose, true, _gc_timer, _gc_tracer->gc_id());
trace("3");
// Need new claim bits for the pointer adjustment tracing.
ClassLoaderDataGraph::clear_claimed_marks();
// Because the closure below is created statically, we cannot
// use OopsInGenClosure constructor which takes a generation,
// as the Universe has not been created when the static constructors
// are run.
adjust_pointer_closure.set_orig_generation(gch->get_gen(level));
gch->gen_process_roots(level,
false, // Younger gens are not roots.
true, // activate StrongRootsScope
SharedHeap::SO_AllCodeCache,
GenCollectedHeap::StrongAndWeakRoots,
&adjust_pointer_closure,
&adjust_pointer_closure,
&adjust_cld_closure);
gch->gen_process_weak_roots(&adjust_pointer_closure);
adjust_marks();
GenAdjustPointersClosure blk;
gch->generation_iterate(&blk, true);
}
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 DefNewGeneration::collect(bool full,
bool clear_all_soft_refs,
size_t size,
bool is_tlab) {
assert(full || size > 0, "otherwise we don't want to collect");
GenCollectedHeap* gch = GenCollectedHeap::heap();
_gc_timer->register_gc_start();
DefNewTracer gc_tracer;
gc_tracer.report_gc_start(gch->gc_cause(), _gc_timer->gc_start());
_old_gen = gch->old_gen();
// If the next generation is too full to accommodate promotion
// from this generation, pass on collection; let the next generation
// do it.
if (!collection_attempt_is_safe()) {
log_trace(gc)(":: Collection attempt not safe ::");
gch->set_incremental_collection_failed(); // Slight lie: we did not even attempt one
return;
}
assert(to()->is_empty(), "Else not collection_attempt_is_safe");
init_assuming_no_promotion_failure();
GCTraceTime(Trace, gc) tm("DefNew", NULL, gch->gc_cause());
gch->trace_heap_before_gc(&gc_tracer);
// These can be shared for all code paths
IsAliveClosure is_alive(this);
ScanWeakRefClosure scan_weak_ref(this);
age_table()->clear();
to()->clear(SpaceDecorator::Mangle);
gch->rem_set()->prepare_for_younger_refs_iterate(false);
assert(gch->no_allocs_since_save_marks(),
"save marks have not been newly set.");
// Not very pretty.
CollectorPolicy* cp = gch->collector_policy();
FastScanClosure fsc_with_no_gc_barrier(this, false);
FastScanClosure fsc_with_gc_barrier(this, true);
KlassScanClosure klass_scan_closure(&fsc_with_no_gc_barrier,
gch->rem_set()->klass_rem_set());
CLDToKlassAndOopClosure cld_scan_closure(&klass_scan_closure,
&fsc_with_no_gc_barrier,
false);
set_promo_failure_scan_stack_closure(&fsc_with_no_gc_barrier);
FastEvacuateFollowersClosure evacuate_followers(gch,
&fsc_with_no_gc_barrier,
&fsc_with_gc_barrier);
assert(gch->no_allocs_since_save_marks(),
"save marks have not been newly set.");
{
// DefNew needs to run with n_threads == 0, to make sure the serial
// version of the card table scanning code is used.
// See: CardTableModRefBSForCTRS::non_clean_card_iterate_possibly_parallel.
StrongRootsScope srs(0);
gch->gen_process_roots(&srs,
GenCollectedHeap::YoungGen,
true, // Process younger gens, if any,
// as strong roots.
GenCollectedHeap::SO_ScavengeCodeCache,
GenCollectedHeap::StrongAndWeakRoots,
&fsc_with_no_gc_barrier,
&fsc_with_gc_barrier,
&cld_scan_closure);
}
// "evacuate followers".
evacuate_followers.do_void();
FastKeepAliveClosure keep_alive(this, &scan_weak_ref);
ReferenceProcessor* rp = ref_processor();
rp->setup_policy(clear_all_soft_refs);
const ReferenceProcessorStats& stats =
rp->process_discovered_references(&is_alive, &keep_alive, &evacuate_followers,
NULL, _gc_timer);
gc_tracer.report_gc_reference_stats(stats);
gc_tracer.report_tenuring_threshold(tenuring_threshold());
if (!_promotion_failed) {
// Swap the survivor spaces.
eden()->clear(SpaceDecorator::Mangle);
from()->clear(SpaceDecorator::Mangle);
if (ZapUnusedHeapArea) {
// This is now done here because of the piece-meal mangling which
// can check for valid mangling at intermediate points in the
// collection(s). When a young collection fails to collect
// sufficient space resizing of the young generation can occur
// an redistribute the spaces in the young generation. Mangle
// here so that unzapped regions don't get distributed to
// other spaces.
to()->mangle_unused_area();
}
swap_spaces();
assert(to()->is_empty(), "to space should be empty now");
adjust_desired_tenuring_threshold();
// A successful scavenge should restart the GC time limit count which is
// for full GC's.
AdaptiveSizePolicy* size_policy = gch->gen_policy()->size_policy();
size_policy->reset_gc_overhead_limit_count();
assert(!gch->incremental_collection_failed(), "Should be clear");
} else {
assert(_promo_failure_scan_stack.is_empty(), "post condition");
_promo_failure_scan_stack.clear(true); // Clear cached segments.
remove_forwarding_pointers();
log_debug(gc)("Promotion failed");
// Add to-space to the list of space to compact
// when a promotion failure has occurred. In that
// case there can be live objects in to-space
// as a result of a partial evacuation of eden
// and from-space.
swap_spaces(); // For uniformity wrt ParNewGeneration.
from()->set_next_compaction_space(to());
gch->set_incremental_collection_failed();
// Inform the next generation that a promotion failure occurred.
_old_gen->promotion_failure_occurred();
gc_tracer.report_promotion_failed(_promotion_failed_info);
// Reset the PromotionFailureALot counters.
NOT_PRODUCT(gch->reset_promotion_should_fail();)
}
// set new iteration safe limit for the survivor spaces
from()->set_concurrent_iteration_safe_limit(from()->top());
to()->set_concurrent_iteration_safe_limit(to()->top());
// We need to use a monotonically non-decreasing time in ms
// or we will see time-warp warnings and os::javaTimeMillis()
// does not guarantee monotonicity.
jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
update_time_of_last_gc(now);
gch->trace_heap_after_gc(&gc_tracer);
_gc_timer->register_gc_end();
gc_tracer.report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
}