/* * Copyright (c) 2001, 2018, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "precompiled.hpp" #include "gc/serial/defNewGeneration.inline.hpp" #include "gc/serial/serialHeap.inline.hpp" #include "gc/serial/tenuredGeneration.hpp" #include "gc/shared/adaptiveSizePolicy.hpp" #include "gc/shared/ageTable.inline.hpp" #include "gc/shared/cardTableRS.hpp" #include "gc/shared/collectorCounters.hpp" #include "gc/shared/gcHeapSummary.hpp" #include "gc/shared/gcLocker.hpp" #include "gc/shared/gcPolicyCounters.hpp" #include "gc/shared/gcTimer.hpp" #include "gc/shared/gcTrace.hpp" #include "gc/shared/gcTraceTime.inline.hpp" #include "gc/shared/genOopClosures.inline.hpp" #include "gc/shared/generationSpec.hpp" #include "gc/shared/preservedMarks.inline.hpp" #include "gc/shared/referencePolicy.hpp" #include "gc/shared/referenceProcessorPhaseTimes.hpp" #include "gc/shared/space.inline.hpp" #include "gc/shared/spaceDecorator.hpp" #include "gc/shared/strongRootsScope.hpp" #include "gc/shared/weakProcessor.hpp" #include "logging/log.hpp" #include "memory/iterator.inline.hpp" #include "memory/resourceArea.hpp" #include "oops/instanceRefKlass.hpp" #include "oops/oop.inline.hpp" #include "runtime/atomic.hpp" #include "runtime/java.hpp" #include "runtime/prefetch.inline.hpp" #include "runtime/thread.inline.hpp" #include "utilities/align.hpp" #include "utilities/copy.hpp" #include "utilities/globalDefinitions.hpp" #include "utilities/stack.inline.hpp" // // DefNewGeneration functions. // Methods of protected closure types. DefNewGeneration::IsAliveClosure::IsAliveClosure(Generation* young_gen) : _young_gen(young_gen) { assert(_young_gen->kind() == Generation::ParNew || _young_gen->kind() == Generation::DefNew, "Expected the young generation here"); } bool DefNewGeneration::IsAliveClosure::do_object_b(oop p) { return (HeapWord*)p >= _young_gen->reserved().end() || p->is_forwarded(); } DefNewGeneration::KeepAliveClosure:: KeepAliveClosure(ScanWeakRefClosure* cl) : _cl(cl) { _rs = GenCollectedHeap::heap()->rem_set(); } void DefNewGeneration::KeepAliveClosure::do_oop(oop* p) { DefNewGeneration::KeepAliveClosure::do_oop_work(p); } void DefNewGeneration::KeepAliveClosure::do_oop(narrowOop* p) { DefNewGeneration::KeepAliveClosure::do_oop_work(p); } DefNewGeneration::FastKeepAliveClosure:: FastKeepAliveClosure(DefNewGeneration* g, ScanWeakRefClosure* cl) : DefNewGeneration::KeepAliveClosure(cl) { _boundary = g->reserved().end(); } void DefNewGeneration::FastKeepAliveClosure::do_oop(oop* p) { DefNewGeneration::FastKeepAliveClosure::do_oop_work(p); } void DefNewGeneration::FastKeepAliveClosure::do_oop(narrowOop* p) { DefNewGeneration::FastKeepAliveClosure::do_oop_work(p); } DefNewGeneration::FastEvacuateFollowersClosure:: FastEvacuateFollowersClosure(SerialHeap* heap, FastScanClosure* cur, FastScanClosure* older) : _heap(heap), _scan_cur_or_nonheap(cur), _scan_older(older) { } void DefNewGeneration::FastEvacuateFollowersClosure::do_void() { do { _heap->oop_since_save_marks_iterate(_scan_cur_or_nonheap, _scan_older); } while (!_heap->no_allocs_since_save_marks()); guarantee(_heap->young_gen()->promo_failure_scan_is_complete(), "Failed to finish scan"); } ScanClosure::ScanClosure(DefNewGeneration* g, bool gc_barrier) : OopsInClassLoaderDataOrGenClosure(g), _g(g), _gc_barrier(gc_barrier) { _boundary = _g->reserved().end(); } FastScanClosure::FastScanClosure(DefNewGeneration* g, bool gc_barrier) : OopsInClassLoaderDataOrGenClosure(g), _g(g), _gc_barrier(gc_barrier) { _boundary = _g->reserved().end(); } void CLDScanClosure::do_cld(ClassLoaderData* cld) { NOT_PRODUCT(ResourceMark rm); log_develop_trace(gc, scavenge)("CLDScanClosure::do_cld " PTR_FORMAT ", %s, dirty: %s", p2i(cld), cld->loader_name_and_id(), cld->has_modified_oops() ? "true" : "false"); // If the cld has not been dirtied we know that there's // no references into the young gen and we can skip it. if (cld->has_modified_oops()) { if (_accumulate_modified_oops) { cld->accumulate_modified_oops(); } // Tell the closure which CLD is being scanned so that it can be dirtied // if oops are left pointing into the young gen. _scavenge_closure->set_scanned_cld(cld); // Clean the cld since we're going to scavenge all the metadata. cld->oops_do(_scavenge_closure, false, /*clear_modified_oops*/true); _scavenge_closure->set_scanned_cld(NULL); } } ScanWeakRefClosure::ScanWeakRefClosure(DefNewGeneration* g) : _g(g) { _boundary = _g->reserved().end(); } DefNewGeneration::DefNewGeneration(ReservedSpace rs, size_t initial_size, const char* policy) : Generation(rs, initial_size), _preserved_marks_set(false /* in_c_heap */), _promo_failure_drain_in_progress(false), _should_allocate_from_space(false) { MemRegion cmr((HeapWord*)_virtual_space.low(), (HeapWord*)_virtual_space.high()); GenCollectedHeap* gch = GenCollectedHeap::heap(); gch->rem_set()->resize_covered_region(cmr); _eden_space = new ContiguousSpace(); _from_space = new ContiguousSpace(); _to_space = new ContiguousSpace(); if (_eden_space == NULL || _from_space == NULL || _to_space == NULL) { vm_exit_during_initialization("Could not allocate a new gen space"); } // Compute the maximum eden and survivor space sizes. These sizes // are computed assuming the entire reserved space is committed. // These values are exported as performance counters. uintx alignment = gch->collector_policy()->space_alignment(); uintx size = _virtual_space.reserved_size(); _max_survivor_size = compute_survivor_size(size, alignment); _max_eden_size = size - (2*_max_survivor_size); // allocate the performance counters GenCollectorPolicy* gcp = gch->gen_policy(); // Generation counters -- generation 0, 3 subspaces _gen_counters = new GenerationCounters("new", 0, 3, gcp->min_young_size(), gcp->max_young_size(), &_virtual_space); _gc_counters = new CollectorCounters(policy, 0); _eden_counters = new CSpaceCounters("eden", 0, _max_eden_size, _eden_space, _gen_counters); _from_counters = new CSpaceCounters("s0", 1, _max_survivor_size, _from_space, _gen_counters); _to_counters = new CSpaceCounters("s1", 2, _max_survivor_size, _to_space, _gen_counters); compute_space_boundaries(0, SpaceDecorator::Clear, SpaceDecorator::Mangle); update_counters(); _old_gen = NULL; _tenuring_threshold = MaxTenuringThreshold; _pretenure_size_threshold_words = PretenureSizeThreshold >> LogHeapWordSize; _gc_timer = new (ResourceObj::C_HEAP, mtGC) STWGCTimer(); } void DefNewGeneration::compute_space_boundaries(uintx minimum_eden_size, bool clear_space, bool mangle_space) { uintx alignment = GenCollectedHeap::heap()->collector_policy()->space_alignment(); // If the spaces are being cleared (only done at heap initialization // currently), the survivor spaces need not be empty. // Otherwise, no care is taken for used areas in the survivor spaces // so check. assert(clear_space || (to()->is_empty() && from()->is_empty()), "Initialization of the survivor spaces assumes these are empty"); // Compute sizes uintx size = _virtual_space.committed_size(); uintx survivor_size = compute_survivor_size(size, alignment); uintx eden_size = size - (2*survivor_size); assert(eden_size > 0 && survivor_size <= eden_size, "just checking"); if (eden_size < minimum_eden_size) { // May happen due to 64Kb rounding, if so adjust eden size back up minimum_eden_size = align_up(minimum_eden_size, alignment); uintx maximum_survivor_size = (size - minimum_eden_size) / 2; uintx unaligned_survivor_size = align_down(maximum_survivor_size, alignment); survivor_size = MAX2(unaligned_survivor_size, alignment); eden_size = size - (2*survivor_size); assert(eden_size > 0 && survivor_size <= eden_size, "just checking"); assert(eden_size >= minimum_eden_size, "just checking"); } char *eden_start = _virtual_space.low(); char *from_start = eden_start + eden_size; char *to_start = from_start + survivor_size; char *to_end = to_start + survivor_size; assert(to_end == _virtual_space.high(), "just checking"); assert(Space::is_aligned(eden_start), "checking alignment"); assert(Space::is_aligned(from_start), "checking alignment"); assert(Space::is_aligned(to_start), "checking alignment"); MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)from_start); MemRegion fromMR((HeapWord*)from_start, (HeapWord*)to_start); MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end); // A minimum eden size implies that there is a part of eden that // is being used and that affects the initialization of any // newly formed eden. bool live_in_eden = minimum_eden_size > 0; // If not clearing the spaces, do some checking to verify that // the space are already mangled. if (!clear_space) { // Must check mangling before the spaces are reshaped. Otherwise, // the bottom or end of one space may have moved into another // a failure of the check may not correctly indicate which space // is not properly mangled. if (ZapUnusedHeapArea) { HeapWord* limit = (HeapWord*) _virtual_space.high(); eden()->check_mangled_unused_area(limit); from()->check_mangled_unused_area(limit); to()->check_mangled_unused_area(limit); } } // Reset the spaces for their new regions. eden()->initialize(edenMR, clear_space && !live_in_eden, SpaceDecorator::Mangle); // If clear_space and live_in_eden, we will not have cleared any // portion of eden above its top. This can cause newly // expanded space not to be mangled if using ZapUnusedHeapArea. // We explicitly do such mangling here. if (ZapUnusedHeapArea && clear_space && live_in_eden && mangle_space) { eden()->mangle_unused_area(); } from()->initialize(fromMR, clear_space, mangle_space); to()->initialize(toMR, clear_space, mangle_space); // Set next compaction spaces. eden()->set_next_compaction_space(from()); // The to-space is normally empty before a compaction so need // not be considered. The exception is during promotion // failure handling when to-space can contain live objects. from()->set_next_compaction_space(NULL); } void DefNewGeneration::swap_spaces() { ContiguousSpace* s = from(); _from_space = to(); _to_space = s; eden()->set_next_compaction_space(from()); // The to-space is normally empty before a compaction so need // not be considered. The exception is during promotion // failure handling when to-space can contain live objects. from()->set_next_compaction_space(NULL); if (UsePerfData) { CSpaceCounters* c = _from_counters; _from_counters = _to_counters; _to_counters = c; } } bool DefNewGeneration::expand(size_t bytes) { MutexLocker x(ExpandHeap_lock); HeapWord* prev_high = (HeapWord*) _virtual_space.high(); bool success = _virtual_space.expand_by(bytes); if (success && ZapUnusedHeapArea) { // Mangle newly committed space immediately because it // can be done here more simply that after the new // spaces have been computed. HeapWord* new_high = (HeapWord*) _virtual_space.high(); MemRegion mangle_region(prev_high, new_high); SpaceMangler::mangle_region(mangle_region); } // Do not attempt an expand-to-the reserve size. The // request should properly observe the maximum size of // the generation so an expand-to-reserve should be // unnecessary. Also a second call to expand-to-reserve // value potentially can cause an undue expansion. // For example if the first expand fail for unknown reasons, // but the second succeeds and expands the heap to its maximum // value. if (GCLocker::is_active()) { log_debug(gc)("Garbage collection disabled, expanded heap instead"); } return success; } size_t DefNewGeneration::adjust_for_thread_increase(size_t new_size_candidate, size_t new_size_before, size_t alignment) const { size_t desired_new_size = new_size_before; if (NewSizeThreadIncrease > 0) { int threads_count; size_t thread_increase_size = 0; // 1. Check an overflow at 'threads_count * NewSizeThreadIncrease'. threads_count = Threads::number_of_non_daemon_threads(); if (threads_count > 0 && NewSizeThreadIncrease <= max_uintx / threads_count) { thread_increase_size = threads_count * NewSizeThreadIncrease; // 2. Check an overflow at 'new_size_candidate + thread_increase_size'. if (new_size_candidate <= max_uintx - thread_increase_size) { new_size_candidate += thread_increase_size; // 3. Check an overflow at 'align_up'. size_t aligned_max = ((max_uintx - alignment) & ~(alignment-1)); if (new_size_candidate <= aligned_max) { desired_new_size = align_up(new_size_candidate, alignment); } } } } return desired_new_size; } void DefNewGeneration::compute_new_size() { // This is called after a GC that includes the old generation, so from-space // will normally be empty. // Note that we check both spaces, since if scavenge failed they revert roles. // If not we bail out (otherwise we would have to relocate the objects). if (!from()->is_empty() || !to()->is_empty()) { return; } GenCollectedHeap* gch = GenCollectedHeap::heap(); size_t old_size = gch->old_gen()->capacity(); size_t new_size_before = _virtual_space.committed_size(); size_t min_new_size = initial_size(); size_t max_new_size = reserved().byte_size(); assert(min_new_size <= new_size_before && new_size_before <= max_new_size, "just checking"); // All space sizes must be multiples of Generation::GenGrain. size_t alignment = Generation::GenGrain; int threads_count = 0; size_t thread_increase_size = 0; size_t new_size_candidate = old_size / NewRatio; // Compute desired new generation size based on NewRatio and NewSizeThreadIncrease // and reverts to previous value if any overflow happens size_t desired_new_size = adjust_for_thread_increase(new_size_candidate, new_size_before, alignment); // Adjust new generation size desired_new_size = MAX2(MIN2(desired_new_size, max_new_size), min_new_size); assert(desired_new_size <= max_new_size, "just checking"); bool changed = false; if (desired_new_size > new_size_before) { size_t change = desired_new_size - new_size_before; assert(change % alignment == 0, "just checking"); if (expand(change)) { changed = true; } // If the heap failed to expand to the desired size, // "changed" will be false. If the expansion failed // (and at this point it was expected to succeed), // ignore the failure (leaving "changed" as false). } if (desired_new_size < new_size_before && eden()->is_empty()) { // bail out of shrinking if objects in eden size_t change = new_size_before - desired_new_size; assert(change % alignment == 0, "just checking"); _virtual_space.shrink_by(change); changed = true; } if (changed) { // The spaces have already been mangled at this point but // may not have been cleared (set top = bottom) and should be. // Mangling was done when the heap was being expanded. compute_space_boundaries(eden()->used(), SpaceDecorator::Clear, SpaceDecorator::DontMangle); MemRegion cmr((HeapWord*)_virtual_space.low(), (HeapWord*)_virtual_space.high()); gch->rem_set()->resize_covered_region(cmr); log_debug(gc, ergo, heap)( "New generation size " SIZE_FORMAT "K->" SIZE_FORMAT "K [eden=" SIZE_FORMAT "K,survivor=" SIZE_FORMAT "K]", new_size_before/K, _virtual_space.committed_size()/K, eden()->capacity()/K, from()->capacity()/K); log_trace(gc, ergo, heap)( " [allowed " SIZE_FORMAT "K extra for %d threads]", thread_increase_size/K, threads_count); } } void DefNewGeneration::younger_refs_iterate(OopsInGenClosure* cl, uint n_threads) { assert(false, "NYI -- are you sure you want to call this?"); } size_t DefNewGeneration::capacity() const { return eden()->capacity() + from()->capacity(); // to() is only used during scavenge } size_t DefNewGeneration::used() const { return eden()->used() + from()->used(); // to() is only used during scavenge } size_t DefNewGeneration::free() const { return eden()->free() + from()->free(); // to() is only used during scavenge } size_t DefNewGeneration::max_capacity() const { const size_t alignment = GenCollectedHeap::heap()->collector_policy()->space_alignment(); const size_t reserved_bytes = reserved().byte_size(); return reserved_bytes - compute_survivor_size(reserved_bytes, alignment); } size_t DefNewGeneration::unsafe_max_alloc_nogc() const { return eden()->free(); } size_t DefNewGeneration::capacity_before_gc() const { return eden()->capacity(); } size_t DefNewGeneration::contiguous_available() const { return eden()->free(); } HeapWord* volatile* DefNewGeneration::top_addr() const { return eden()->top_addr(); } HeapWord** DefNewGeneration::end_addr() const { return eden()->end_addr(); } void DefNewGeneration::object_iterate(ObjectClosure* blk) { eden()->object_iterate(blk); from()->object_iterate(blk); } void DefNewGeneration::space_iterate(SpaceClosure* blk, bool usedOnly) { blk->do_space(eden()); blk->do_space(from()); blk->do_space(to()); } // The last collection bailed out, we are running out of heap space, // so we try to allocate the from-space, too. HeapWord* DefNewGeneration::allocate_from_space(size_t size) { bool should_try_alloc = should_allocate_from_space() || GCLocker::is_active_and_needs_gc(); // If the Heap_lock is not locked by this thread, this will be called // again later with the Heap_lock held. bool do_alloc = should_try_alloc && (Heap_lock->owned_by_self() || (SafepointSynchronize::is_at_safepoint() && Thread::current()->is_VM_thread())); HeapWord* result = NULL; if (do_alloc) { result = from()->allocate(size); } log_trace(gc, alloc)("DefNewGeneration::allocate_from_space(" SIZE_FORMAT "): will_fail: %s heap_lock: %s free: " SIZE_FORMAT "%s%s returns %s", size, GenCollectedHeap::heap()->incremental_collection_will_fail(false /* don't consult_young */) ? "true" : "false", Heap_lock->is_locked() ? "locked" : "unlocked", from()->free(), should_try_alloc ? "" : " should_allocate_from_space: NOT", do_alloc ? " Heap_lock is not owned by self" : "", result == NULL ? "NULL" : "object"); return result; } HeapWord* DefNewGeneration::expand_and_allocate(size_t size, bool is_tlab, bool parallel) { // We don't attempt to expand the young generation (but perhaps we should.) return allocate(size, is_tlab); } void DefNewGeneration::adjust_desired_tenuring_threshold() { // Set the desired survivor size to half the real survivor space size_t const survivor_capacity = to()->capacity() / HeapWordSize; size_t const desired_survivor_size = (size_t)((((double)survivor_capacity) * TargetSurvivorRatio) / 100); _tenuring_threshold = age_table()->compute_tenuring_threshold(desired_survivor_size); if (UsePerfData) { GCPolicyCounters* gc_counters = GenCollectedHeap::heap()->counters(); gc_counters->tenuring_threshold()->set_value(_tenuring_threshold); gc_counters->desired_survivor_size()->set_value(desired_survivor_size * oopSize); } age_table()->print_age_table(_tenuring_threshold); } 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"); SerialHeap* heap = SerialHeap::heap(); _gc_timer->register_gc_start(); DefNewTracer gc_tracer; gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer->gc_start()); _old_gen = heap->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 ::"); heap->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, phases) tm("DefNew", NULL, heap->gc_cause()); heap->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); // The preserved marks should be empty at the start of the GC. _preserved_marks_set.init(1); heap->rem_set()->prepare_for_younger_refs_iterate(false); assert(heap->no_allocs_since_save_marks(), "save marks have not been newly set."); FastScanClosure fsc_with_no_gc_barrier(this, false); FastScanClosure fsc_with_gc_barrier(this, true); CLDScanClosure cld_scan_closure(&fsc_with_no_gc_barrier, heap->rem_set()->cld_rem_set()->accumulate_modified_oops()); set_promo_failure_scan_stack_closure(&fsc_with_no_gc_barrier); FastEvacuateFollowersClosure evacuate_followers(heap, &fsc_with_no_gc_barrier, &fsc_with_gc_barrier); assert(heap->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: CardTableRS::non_clean_card_iterate_possibly_parallel. StrongRootsScope srs(0); heap->young_process_roots(&srs, &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); ReferenceProcessorPhaseTimes pt(_gc_timer, rp->max_num_queues()); const ReferenceProcessorStats& stats = rp->process_discovered_references(&is_alive, &keep_alive, &evacuate_followers, NULL, &pt); gc_tracer.report_gc_reference_stats(stats); gc_tracer.report_tenuring_threshold(tenuring_threshold()); pt.print_all_references(); assert(heap->no_allocs_since_save_marks(), "save marks have not been newly set."); WeakProcessor::weak_oops_do(&is_alive, &keep_alive); // Verify that the usage of keep_alive didn't copy any objects. assert(heap->no_allocs_since_save_marks(), "save marks have not been newly set."); 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 = heap->size_policy(); size_policy->reset_gc_overhead_limit_count(); assert(!heap->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_info(gc, promotion)("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()); heap->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(heap->reset_promotion_should_fail();) } // We should have processed and cleared all the preserved marks. _preserved_marks_set.reclaim(); // 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); heap->trace_heap_after_gc(&gc_tracer); _gc_timer->register_gc_end(); gc_tracer.report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions()); } void DefNewGeneration::init_assuming_no_promotion_failure() { _promotion_failed = false; _promotion_failed_info.reset(); from()->set_next_compaction_space(NULL); } void DefNewGeneration::remove_forwarding_pointers() { RemoveForwardedPointerClosure rspc; eden()->object_iterate(&rspc); from()->object_iterate(&rspc); restore_preserved_marks(); } void DefNewGeneration::restore_preserved_marks() { SharedRestorePreservedMarksTaskExecutor task_executor(NULL); _preserved_marks_set.restore(&task_executor); } void DefNewGeneration::handle_promotion_failure(oop old) { log_debug(gc, promotion)("Promotion failure size = %d) ", old->size()); _promotion_failed = true; _promotion_failed_info.register_copy_failure(old->size()); _preserved_marks_set.get()->push_if_necessary(old, old->mark_raw()); // forward to self old->forward_to(old); _promo_failure_scan_stack.push(old); if (!_promo_failure_drain_in_progress) { // prevent recursion in copy_to_survivor_space() _promo_failure_drain_in_progress = true; drain_promo_failure_scan_stack(); _promo_failure_drain_in_progress = false; } } oop DefNewGeneration::copy_to_survivor_space(oop old) { assert(is_in_reserved(old) && !old->is_forwarded(), "shouldn't be scavenging this oop"); size_t s = old->size(); oop obj = NULL; // Try allocating obj in to-space (unless too old) if (old->age() < tenuring_threshold()) { obj = (oop) to()->allocate_aligned(s); } // Otherwise try allocating obj tenured if (obj == NULL) { obj = _old_gen->promote(old, s); if (obj == NULL) { handle_promotion_failure(old); return old; } } else { // Prefetch beyond obj const intx interval = PrefetchCopyIntervalInBytes; Prefetch::write(obj, interval); // Copy obj Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)obj, s); // Increment age if obj still in new generation obj->incr_age(); age_table()->add(obj, s); } // Done, insert forward pointer to obj in this header old->forward_to(obj); return obj; } void DefNewGeneration::drain_promo_failure_scan_stack() { while (!_promo_failure_scan_stack.is_empty()) { oop obj = _promo_failure_scan_stack.pop(); obj->oop_iterate(_promo_failure_scan_stack_closure); } } void DefNewGeneration::save_marks() { eden()->set_saved_mark(); to()->set_saved_mark(); from()->set_saved_mark(); } void DefNewGeneration::reset_saved_marks() { eden()->reset_saved_mark(); to()->reset_saved_mark(); from()->reset_saved_mark(); } bool DefNewGeneration::no_allocs_since_save_marks() { assert(eden()->saved_mark_at_top(), "Violated spec - alloc in eden"); assert(from()->saved_mark_at_top(), "Violated spec - alloc in from"); return to()->saved_mark_at_top(); } void DefNewGeneration::contribute_scratch(ScratchBlock*& list, Generation* requestor, size_t max_alloc_words) { if (requestor == this || _promotion_failed) { return; } assert(GenCollectedHeap::heap()->is_old_gen(requestor), "We should not call our own generation"); /* $$$ Assert this? "trace" is a "MarkSweep" function so that's not appropriate. if (to_space->top() > to_space->bottom()) { trace("to_space not empty when contribute_scratch called"); } */ ContiguousSpace* to_space = to(); assert(to_space->end() >= to_space->top(), "pointers out of order"); size_t free_words = pointer_delta(to_space->end(), to_space->top()); if (free_words >= MinFreeScratchWords) { ScratchBlock* sb = (ScratchBlock*)to_space->top(); sb->num_words = free_words; sb->next = list; list = sb; } } void DefNewGeneration::reset_scratch() { // If contributing scratch in to_space, mangle all of // to_space if ZapUnusedHeapArea. This is needed because // top is not maintained while using to-space as scratch. if (ZapUnusedHeapArea) { to()->mangle_unused_area_complete(); } } bool DefNewGeneration::collection_attempt_is_safe() { if (!to()->is_empty()) { log_trace(gc)(":: to is not empty ::"); return false; } if (_old_gen == NULL) { GenCollectedHeap* gch = GenCollectedHeap::heap(); _old_gen = gch->old_gen(); } return _old_gen->promotion_attempt_is_safe(used()); } void DefNewGeneration::gc_epilogue(bool full) { DEBUG_ONLY(static bool seen_incremental_collection_failed = false;) assert(!GCLocker::is_active(), "We should not be executing here"); // Check if the heap is approaching full after a collection has // been done. Generally the young generation is empty at // a minimum at the end of a collection. If it is not, then // the heap is approaching full. GenCollectedHeap* gch = GenCollectedHeap::heap(); if (full) { DEBUG_ONLY(seen_incremental_collection_failed = false;) if (!collection_attempt_is_safe() && !_eden_space->is_empty()) { log_trace(gc)("DefNewEpilogue: cause(%s), full, not safe, set_failed, set_alloc_from, clear_seen", GCCause::to_string(gch->gc_cause())); gch->set_incremental_collection_failed(); // Slight lie: a full gc left us in that state set_should_allocate_from_space(); // we seem to be running out of space } else { log_trace(gc)("DefNewEpilogue: cause(%s), full, safe, clear_failed, clear_alloc_from, clear_seen", GCCause::to_string(gch->gc_cause())); gch->clear_incremental_collection_failed(); // We just did a full collection clear_should_allocate_from_space(); // if set } } else { #ifdef ASSERT // It is possible that incremental_collection_failed() == true // here, because an attempted scavenge did not succeed. The policy // is normally expected to cause a full collection which should // clear that condition, so we should not be here twice in a row // with incremental_collection_failed() == true without having done // a full collection in between. if (!seen_incremental_collection_failed && gch->incremental_collection_failed()) { log_trace(gc)("DefNewEpilogue: cause(%s), not full, not_seen_failed, failed, set_seen_failed", GCCause::to_string(gch->gc_cause())); seen_incremental_collection_failed = true; } else if (seen_incremental_collection_failed) { log_trace(gc)("DefNewEpilogue: cause(%s), not full, seen_failed, will_clear_seen_failed", GCCause::to_string(gch->gc_cause())); assert(gch->gc_cause() == GCCause::_scavenge_alot || (GCCause::is_user_requested_gc(gch->gc_cause()) && UseConcMarkSweepGC && ExplicitGCInvokesConcurrent) || !gch->incremental_collection_failed(), "Twice in a row"); seen_incremental_collection_failed = false; } #endif // ASSERT } if (ZapUnusedHeapArea) { eden()->check_mangled_unused_area_complete(); from()->check_mangled_unused_area_complete(); to()->check_mangled_unused_area_complete(); } if (!CleanChunkPoolAsync) { Chunk::clean_chunk_pool(); } // update the generation and space performance counters update_counters(); gch->counters()->update_counters(); } void DefNewGeneration::record_spaces_top() { assert(ZapUnusedHeapArea, "Not mangling unused space"); eden()->set_top_for_allocations(); to()->set_top_for_allocations(); from()->set_top_for_allocations(); } void DefNewGeneration::ref_processor_init() { Generation::ref_processor_init(); } void DefNewGeneration::update_counters() { if (UsePerfData) { _eden_counters->update_all(); _from_counters->update_all(); _to_counters->update_all(); _gen_counters->update_all(); } } void DefNewGeneration::verify() { eden()->verify(); from()->verify(); to()->verify(); } void DefNewGeneration::print_on(outputStream* st) const { Generation::print_on(st); st->print(" eden"); eden()->print_on(st); st->print(" from"); from()->print_on(st); st->print(" to "); to()->print_on(st); } const char* DefNewGeneration::name() const { return "def new generation"; } // Moved from inline file as they are not called inline CompactibleSpace* DefNewGeneration::first_compaction_space() const { return eden(); } HeapWord* DefNewGeneration::allocate(size_t word_size, bool is_tlab) { // This is the slow-path allocation for the DefNewGeneration. // Most allocations are fast-path in compiled code. // We try to allocate from the eden. If that works, we are happy. // Note that since DefNewGeneration supports lock-free allocation, we // have to use it here, as well. HeapWord* result = eden()->par_allocate(word_size); if (result != NULL) { if (_old_gen != NULL) { _old_gen->sample_eden_chunk(); } } else { // If the eden is full and the last collection bailed out, we are running // out of heap space, and we try to allocate the from-space, too. // allocate_from_space can't be inlined because that would introduce a // circular dependency at compile time. result = allocate_from_space(word_size); } return result; } HeapWord* DefNewGeneration::par_allocate(size_t word_size, bool is_tlab) { HeapWord* res = eden()->par_allocate(word_size); if (_old_gen != NULL) { _old_gen->sample_eden_chunk(); } return res; } size_t DefNewGeneration::tlab_capacity() const { return eden()->capacity(); } size_t DefNewGeneration::tlab_used() const { return eden()->used(); } size_t DefNewGeneration::unsafe_max_tlab_alloc() const { return unsafe_max_alloc_nogc(); }