| /* |
| * Copyright (c) 2001, 2015, 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_implementation/shared/collectorCounters.hpp" |
| #include "gc_implementation/shared/gcPolicyCounters.hpp" |
| #include "gc_implementation/shared/gcHeapSummary.hpp" |
| #include "gc_implementation/shared/gcTimer.hpp" |
| #include "gc_implementation/shared/gcTraceTime.hpp" |
| #include "gc_implementation/shared/gcTrace.hpp" |
| #include "gc_implementation/shared/spaceDecorator.hpp" |
| #include "memory/defNewGeneration.inline.hpp" |
| #include "memory/gcLocker.inline.hpp" |
| #include "memory/genCollectedHeap.hpp" |
| #include "memory/genOopClosures.inline.hpp" |
| #include "memory/genRemSet.hpp" |
| #include "memory/generationSpec.hpp" |
| #include "memory/iterator.hpp" |
| #include "memory/referencePolicy.hpp" |
| #include "memory/space.inline.hpp" |
| #include "oops/instanceRefKlass.hpp" |
| #include "oops/oop.inline.hpp" |
| #include "runtime/atomic.inline.hpp" |
| #include "runtime/java.hpp" |
| #include "runtime/prefetch.inline.hpp" |
| #include "runtime/thread.inline.hpp" |
| #include "utilities/copy.hpp" |
| #include "utilities/globalDefinitions.hpp" |
| #include "utilities/stack.inline.hpp" |
| |
| PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC |
| |
| // |
| // DefNewGeneration functions. |
| |
| // Methods of protected closure types. |
| |
| DefNewGeneration::IsAliveClosure::IsAliveClosure(Generation* g) : _g(g) { |
| assert(g->level() == 0, "Optimized for youngest gen."); |
| } |
| bool DefNewGeneration::IsAliveClosure::do_object_b(oop p) { |
| return (HeapWord*)p >= _g->reserved().end() || p->is_forwarded(); |
| } |
| |
| DefNewGeneration::KeepAliveClosure:: |
| KeepAliveClosure(ScanWeakRefClosure* cl) : _cl(cl) { |
| GenRemSet* rs = GenCollectedHeap::heap()->rem_set(); |
| _rs = (CardTableRS*)rs; |
| } |
| |
| 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::EvacuateFollowersClosure:: |
| EvacuateFollowersClosure(GenCollectedHeap* gch, int level, |
| ScanClosure* cur, ScanClosure* older) : |
| _gch(gch), _level(level), |
| _scan_cur_or_nonheap(cur), _scan_older(older) |
| {} |
| |
| void DefNewGeneration::EvacuateFollowersClosure::do_void() { |
| do { |
| _gch->oop_since_save_marks_iterate(_level, _scan_cur_or_nonheap, |
| _scan_older); |
| } while (!_gch->no_allocs_since_save_marks(_level)); |
| } |
| |
| DefNewGeneration::FastEvacuateFollowersClosure:: |
| FastEvacuateFollowersClosure(GenCollectedHeap* gch, int level, |
| DefNewGeneration* gen, |
| FastScanClosure* cur, FastScanClosure* older) : |
| _gch(gch), _level(level), _gen(gen), |
| _scan_cur_or_nonheap(cur), _scan_older(older) |
| {} |
| |
| void DefNewGeneration::FastEvacuateFollowersClosure::do_void() { |
| do { |
| _gch->oop_since_save_marks_iterate(_level, _scan_cur_or_nonheap, |
| _scan_older); |
| } while (!_gch->no_allocs_since_save_marks(_level)); |
| guarantee(_gen->promo_failure_scan_is_complete(), "Failed to finish scan"); |
| } |
| |
| ScanClosure::ScanClosure(DefNewGeneration* g, bool gc_barrier) : |
| OopsInKlassOrGenClosure(g), _g(g), _gc_barrier(gc_barrier) |
| { |
| assert(_g->level() == 0, "Optimized for youngest generation"); |
| _boundary = _g->reserved().end(); |
| } |
| |
| void ScanClosure::do_oop(oop* p) { ScanClosure::do_oop_work(p); } |
| void ScanClosure::do_oop(narrowOop* p) { ScanClosure::do_oop_work(p); } |
| |
| FastScanClosure::FastScanClosure(DefNewGeneration* g, bool gc_barrier) : |
| OopsInKlassOrGenClosure(g), _g(g), _gc_barrier(gc_barrier) |
| { |
| assert(_g->level() == 0, "Optimized for youngest generation"); |
| _boundary = _g->reserved().end(); |
| } |
| |
| void FastScanClosure::do_oop(oop* p) { FastScanClosure::do_oop_work(p); } |
| void FastScanClosure::do_oop(narrowOop* p) { FastScanClosure::do_oop_work(p); } |
| |
| void KlassScanClosure::do_klass(Klass* klass) { |
| #ifndef PRODUCT |
| if (TraceScavenge) { |
| ResourceMark rm; |
| gclog_or_tty->print_cr("KlassScanClosure::do_klass " PTR_FORMAT ", %s, dirty: %s", |
| klass, |
| klass->external_name(), |
| klass->has_modified_oops() ? "true" : "false"); |
| } |
| #endif |
| |
| // If the klass has not been dirtied we know that there's |
| // no references into the young gen and we can skip it. |
| if (klass->has_modified_oops()) { |
| if (_accumulate_modified_oops) { |
| klass->accumulate_modified_oops(); |
| } |
| |
| // Clear this state since we're going to scavenge all the metadata. |
| klass->clear_modified_oops(); |
| |
| // Tell the closure which Klass is being scanned so that it can be dirtied |
| // if oops are left pointing into the young gen. |
| _scavenge_closure->set_scanned_klass(klass); |
| |
| klass->oops_do(_scavenge_closure); |
| |
| _scavenge_closure->set_scanned_klass(NULL); |
| } |
| } |
| |
| ScanWeakRefClosure::ScanWeakRefClosure(DefNewGeneration* g) : |
| _g(g) |
| { |
| assert(_g->level() == 0, "Optimized for youngest generation"); |
| _boundary = _g->reserved().end(); |
| } |
| |
| void ScanWeakRefClosure::do_oop(oop* p) { ScanWeakRefClosure::do_oop_work(p); } |
| void ScanWeakRefClosure::do_oop(narrowOop* p) { ScanWeakRefClosure::do_oop_work(p); } |
| |
| void FilteringClosure::do_oop(oop* p) { FilteringClosure::do_oop_work(p); } |
| void FilteringClosure::do_oop(narrowOop* p) { FilteringClosure::do_oop_work(p); } |
| |
| KlassScanClosure::KlassScanClosure(OopsInKlassOrGenClosure* scavenge_closure, |
| KlassRemSet* klass_rem_set) |
| : _scavenge_closure(scavenge_closure), |
| _accumulate_modified_oops(klass_rem_set->accumulate_modified_oops()) {} |
| |
| |
| DefNewGeneration::DefNewGeneration(ReservedSpace rs, |
| size_t initial_size, |
| int level, |
| const char* policy) |
| : Generation(rs, initial_size, level), |
| _promo_failure_drain_in_progress(false), |
| _should_allocate_from_space(false) |
| { |
| MemRegion cmr((HeapWord*)_virtual_space.low(), |
| (HeapWord*)_virtual_space.high()); |
| Universe::heap()->barrier_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 = GenCollectedHeap::heap()->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 = (GenCollectorPolicy*) GenCollectedHeap::heap()->collector_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(); |
| _next_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_size_up(minimum_eden_size, alignment); |
| uintx maximum_survivor_size = (size - minimum_eden_size) / 2; |
| uintx unaligned_survivor_size = |
| align_size_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((HeapWord*)eden_start), "checking alignment"); |
| assert(Space::is_aligned((HeapWord*)from_start), "checking alignment"); |
| assert(Space::is_aligned((HeapWord*)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 (GC_locker::is_active()) { |
| if (PrintGC && Verbose) { |
| gclog_or_tty->print_cr("Garbage collection disabled, " |
| "expanded heap instead"); |
| } |
| } |
| |
| return success; |
| } |
| |
| |
| void DefNewGeneration::compute_new_size() { |
| // This is called after a gc that includes the following generation |
| // (which is required to exist.) 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; |
| } |
| |
| int next_level = level() + 1; |
| GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| assert(next_level < gch->_n_gens, |
| "DefNewGeneration cannot be an oldest gen"); |
| |
| Generation* next_gen = gch->get_gen(next_level); |
| size_t old_size = next_gen->capacity(); |
| size_t new_size_before = _virtual_space.committed_size(); |
| size_t min_new_size = spec()->init_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; |
| |
| // Compute desired new generation size based on NewRatio and |
| // NewSizeThreadIncrease |
| size_t desired_new_size = old_size/NewRatio; |
| int threads_count = Threads::number_of_non_daemon_threads(); |
| size_t thread_increase_size = threads_count * NewSizeThreadIncrease; |
| desired_new_size = align_size_up(desired_new_size + thread_increase_size, 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()); |
| Universe::heap()->barrier_set()->resize_covered_region(cmr); |
| if (Verbose && PrintGC) { |
| size_t new_size_after = _virtual_space.committed_size(); |
| size_t eden_size_after = eden()->capacity(); |
| size_t survivor_size_after = from()->capacity(); |
| gclog_or_tty->print("New generation size " SIZE_FORMAT "K->" |
| SIZE_FORMAT "K [eden=" |
| SIZE_FORMAT "K,survivor=" SIZE_FORMAT "K]", |
| new_size_before/K, new_size_after/K, |
| eden_size_after/K, survivor_size_after/K); |
| if (WizardMode) { |
| gclog_or_tty->print("[allowed " SIZE_FORMAT "K extra for %d threads]", |
| thread_increase_size/K, threads_count); |
| } |
| gclog_or_tty->cr(); |
| } |
| } |
| } |
| |
| void DefNewGeneration::younger_refs_iterate(OopsInGenClosure* cl) { |
| 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** 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) { |
| HeapWord* result = NULL; |
| if (Verbose && PrintGCDetails) { |
| gclog_or_tty->print("DefNewGeneration::allocate_from_space(" SIZE_FORMAT "):" |
| " will_fail: %s" |
| " heap_lock: %s" |
| " free: " SIZE_FORMAT, |
| size, |
| GenCollectedHeap::heap()->incremental_collection_will_fail(false /* don't consult_young */) ? |
| "true" : "false", |
| Heap_lock->is_locked() ? "locked" : "unlocked", |
| from()->free()); |
| } |
| if (should_allocate_from_space() || GC_locker::is_active_and_needs_gc()) { |
| if (Heap_lock->owned_by_self() || |
| (SafepointSynchronize::is_at_safepoint() && |
| Thread::current()->is_VM_thread())) { |
| // If the Heap_lock is not locked by this thread, this will be called |
| // again later with the Heap_lock held. |
| result = from()->allocate(size); |
| } else if (PrintGC && Verbose) { |
| gclog_or_tty->print_cr(" Heap_lock is not owned by self"); |
| } |
| } else if (PrintGC && Verbose) { |
| gclog_or_tty->print_cr(" should_allocate_from_space: NOT"); |
| } |
| if (PrintGC && Verbose) { |
| gclog_or_tty->print_cr(" returns %s", 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 |
| _tenuring_threshold = |
| age_table()->compute_tenuring_threshold(to()->capacity()/HeapWordSize); |
| } |
| |
| 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()); |
| |
| _next_gen = gch->next_gen(this); |
| |
| // 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()) { |
| if (Verbose && PrintGCDetails) { |
| gclog_or_tty->print(" :: 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 t1(GCCauseString("GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL, gc_tracer.gc_id()); |
| // Capture heap used before collection (for printing). |
| size_t gch_prev_used = gch->used(); |
| |
| gch->trace_heap_before_gc(&gc_tracer); |
| |
| SpecializationStats::clear(); |
| |
| // 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(0), |
| "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, _level, this, |
| &fsc_with_no_gc_barrier, |
| &fsc_with_gc_barrier); |
| |
| assert(gch->no_allocs_since_save_marks(0), |
| "save marks have not been newly set."); |
| |
| gch->gen_process_roots(_level, |
| true, // Process younger gens, if any, |
| // as strong roots. |
| true, // activate StrongRootsScope |
| SharedHeap::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.gc_id()); |
| gc_tracer.report_gc_reference_stats(stats); |
| |
| 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 minor 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(); |
| if (PrintGCDetails) { |
| gclog_or_tty->print(" (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. |
| _next_gen->promotion_failure_occurred(); |
| gc_tracer.report_promotion_failed(_promotion_failed_info); |
| |
| // Reset the PromotionFailureALot counters. |
| NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();) |
| } |
| if (PrintGC && !PrintGCDetails) { |
| gch->print_heap_change(gch_prev_used); |
| } |
| // 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()); |
| SpecializationStats::print(); |
| |
| // 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_tracer.report_tenuring_threshold(tenuring_threshold()); |
| |
| _gc_timer->register_gc_end(); |
| |
| gc_tracer.report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions()); |
| } |
| |
| class RemoveForwardPointerClosure: public ObjectClosure { |
| public: |
| void do_object(oop obj) { |
| obj->init_mark(); |
| } |
| }; |
| |
| 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() { |
| RemoveForwardPointerClosure rspc; |
| eden()->object_iterate(&rspc); |
| from()->object_iterate(&rspc); |
| |
| // Now restore saved marks, if any. |
| assert(_objs_with_preserved_marks.size() == _preserved_marks_of_objs.size(), |
| "should be the same"); |
| while (!_objs_with_preserved_marks.is_empty()) { |
| oop obj = _objs_with_preserved_marks.pop(); |
| markOop m = _preserved_marks_of_objs.pop(); |
| obj->set_mark(m); |
| } |
| _objs_with_preserved_marks.clear(true); |
| _preserved_marks_of_objs.clear(true); |
| } |
| |
| void DefNewGeneration::preserve_mark(oop obj, markOop m) { |
| assert(_promotion_failed && m->must_be_preserved_for_promotion_failure(obj), |
| "Oversaving!"); |
| _objs_with_preserved_marks.push(obj); |
| _preserved_marks_of_objs.push(m); |
| } |
| |
| void DefNewGeneration::preserve_mark_if_necessary(oop obj, markOop m) { |
| if (m->must_be_preserved_for_promotion_failure(obj)) { |
| preserve_mark(obj, m); |
| } |
| } |
| |
| void DefNewGeneration::handle_promotion_failure(oop old) { |
| if (PrintPromotionFailure && !_promotion_failed) { |
| gclog_or_tty->print(" (promotion failure size = %d) ", |
| old->size()); |
| } |
| _promotion_failed = true; |
| _promotion_failed_info.register_copy_failure(old->size()); |
| preserve_mark_if_necessary(old, old->mark()); |
| // 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 = _next_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(); |
| } |
| |
| #define DefNew_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ |
| \ |
| void DefNewGeneration:: \ |
| oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ |
| cl->set_generation(this); \ |
| eden()->oop_since_save_marks_iterate##nv_suffix(cl); \ |
| to()->oop_since_save_marks_iterate##nv_suffix(cl); \ |
| from()->oop_since_save_marks_iterate##nv_suffix(cl); \ |
| cl->reset_generation(); \ |
| save_marks(); \ |
| } |
| |
| ALL_SINCE_SAVE_MARKS_CLOSURES(DefNew_SINCE_SAVE_MARKS_DEFN) |
| |
| #undef DefNew_SINCE_SAVE_MARKS_DEFN |
| |
| void DefNewGeneration::contribute_scratch(ScratchBlock*& list, Generation* requestor, |
| size_t max_alloc_words) { |
| if (requestor == this || _promotion_failed) return; |
| assert(requestor->level() > level(), "DefNewGeneration must be youngest"); |
| |
| /* $$$ 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()) { |
| if (Verbose && PrintGCDetails) { |
| gclog_or_tty->print(" :: to is not empty :: "); |
| } |
| return false; |
| } |
| if (_next_gen == NULL) { |
| GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| _next_gen = gch->next_gen(this); |
| } |
| return _next_gen->promotion_attempt_is_safe(used()); |
| } |
| |
| void DefNewGeneration::gc_epilogue(bool full) { |
| DEBUG_ONLY(static bool seen_incremental_collection_failed = false;) |
| |
| assert(!GC_locker::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()) { |
| if (Verbose && PrintGCDetails) { |
| gclog_or_tty->print("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 { |
| if (Verbose && PrintGCDetails) { |
| gclog_or_tty->print("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()) { |
| if (Verbose && PrintGCDetails) { |
| gclog_or_tty->print("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) { |
| if (Verbose && PrintGCDetails) { |
| gclog_or_tty->print("DefNewEpilogue: cause(%s), not full, seen_failed, will_clear_seen_failed", |
| GCCause::to_string(gch->gc_cause())); |
| } |
| assert(gch->gc_cause() == GCCause::_scavenge_alot || |
| (gch->gc_cause() == GCCause::_java_lang_system_gc && 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->collector_policy()->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 (CMSEdenChunksRecordAlways && _next_gen != NULL) { |
| _next_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 (CMSEdenChunksRecordAlways && _next_gen != NULL) { |
| _next_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(); |
| } |