| /* |
| * Copyright 2001-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| * CA 95054 USA or visit www.sun.com if you need additional information or |
| * have any questions. |
| * |
| */ |
| |
| # include "incls/_precompiled.incl" |
| # include "incls/_defNewGeneration.cpp.incl" |
| |
| // |
| // DefNewGeneration functions. |
| |
| // Methods of protected closure types. |
| |
| DefNewGeneration::IsAliveClosure::IsAliveClosure(Generation* g) : _g(g) { |
| assert(g->level() == 0, "Optimized for youngest gen."); |
| } |
| void DefNewGeneration::IsAliveClosure::do_object(oop p) { |
| assert(false, "Do not call."); |
| } |
| 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(); |
| assert(rs->rs_kind() == GenRemSet::CardTable, "Wrong rem set kind."); |
| _rs = (CardTableRS*)rs; |
| } |
| |
| void DefNewGeneration::KeepAliveClosure::do_oop(oop* p) { |
| // We never expect to see a null reference being processed |
| // as a weak reference. |
| assert (*p != NULL, "expected non-null ref"); |
| assert ((*p)->is_oop(), "expected an oop while scanning weak refs"); |
| |
| _cl->do_oop_nv(p); |
| |
| // Card marking is trickier for weak refs. |
| // This oop is a 'next' field which was filled in while we |
| // were discovering weak references. While we might not need |
| // to take a special action to keep this reference alive, we |
| // will need to dirty a card as the field was modified. |
| // |
| // Alternatively, we could create a method which iterates through |
| // each generation, allowing them in turn to examine the modified |
| // field. |
| // |
| // We could check that p is also in an older generation, but |
| // dirty cards in the youngest gen are never scanned, so the |
| // extra check probably isn't worthwhile. |
| if (Universe::heap()->is_in_reserved(p)) { |
| _rs->inline_write_ref_field_gc(p, *p); |
| } |
| } |
| |
| DefNewGeneration::FastKeepAliveClosure:: |
| FastKeepAliveClosure(DefNewGeneration* g, ScanWeakRefClosure* cl) : |
| DefNewGeneration::KeepAliveClosure(cl) { |
| _boundary = g->reserved().end(); |
| } |
| |
| void DefNewGeneration::FastKeepAliveClosure::do_oop(oop* p) { |
| assert (*p != NULL, "expected non-null ref"); |
| assert ((*p)->is_oop(), "expected an oop while scanning weak refs"); |
| |
| _cl->do_oop_nv(p); |
| |
| // Optimized for Defnew generation if it's the youngest generation: |
| // we set a younger_gen card if we have an older->youngest |
| // generation pointer. |
| if (((HeapWord*)(*p) < _boundary) && Universe::heap()->is_in_reserved(p)) { |
| _rs->inline_write_ref_field_gc(p, *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_stack() == NULL |
| || _gen->promo_failure_scan_stack()->length() == 0, |
| "Failed to finish scan"); |
| } |
| |
| ScanClosure::ScanClosure(DefNewGeneration* g, bool gc_barrier) : |
| OopsInGenClosure(g), _g(g), _gc_barrier(gc_barrier) |
| { |
| assert(_g->level() == 0, "Optimized for youngest generation"); |
| _boundary = _g->reserved().end(); |
| } |
| |
| FastScanClosure::FastScanClosure(DefNewGeneration* g, bool gc_barrier) : |
| OopsInGenClosure(g), _g(g), _gc_barrier(gc_barrier) |
| { |
| assert(_g->level() == 0, "Optimized for youngest generation"); |
| _boundary = _g->reserved().end(); |
| } |
| |
| ScanWeakRefClosure::ScanWeakRefClosure(DefNewGeneration* g) : |
| OopClosure(g->ref_processor()), _g(g) |
| { |
| assert(_g->level() == 0, "Optimized for youngest generation"); |
| _boundary = _g->reserved().end(); |
| } |
| |
| |
| DefNewGeneration::DefNewGeneration(ReservedSpace rs, |
| size_t initial_size, |
| int level, |
| const char* policy) |
| : Generation(rs, initial_size, level), |
| _objs_with_preserved_marks(NULL), |
| _preserved_marks_of_objs(NULL), |
| _promo_failure_scan_stack(NULL), |
| _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); |
| |
| if (GenCollectedHeap::heap()->collector_policy()->has_soft_ended_eden()) { |
| _eden_space = new ConcEdenSpace(this); |
| } else { |
| _eden_space = new EdenSpace(this); |
| } |
| _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()->min_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 |
| |
| // Generation counters -- generation 0, 3 subspaces |
| _gen_counters = new GenerationCounters("new", 0, 3, &_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); |
| update_counters(); |
| _next_gen = NULL; |
| _tenuring_threshold = MaxTenuringThreshold; |
| _pretenure_size_threshold_words = PretenureSizeThreshold >> LogHeapWordSize; |
| } |
| |
| void DefNewGeneration::compute_space_boundaries(uintx minimum_eden_size) { |
| uintx alignment = GenCollectedHeap::heap()->collector_policy()->min_alignment(); |
| |
| // 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); |
| |
| eden()->initialize(edenMR, (minimum_eden_size == 0)); |
| // If minumum_eden_size != 0, 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 && (minimum_eden_size != 0)) { |
| eden()->mangle_unused_area(); |
| } |
| from()->initialize(fromMR, true); |
| to()->initialize(toMR , true); |
| 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); |
| bool success = _virtual_space.expand_by(bytes); |
| |
| // 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->_gens[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) { |
| compute_space_boundaries(eden()->used()); |
| 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::object_iterate_since_last_GC(ObjectClosure* cl) { |
| // $$$ This may be wrong in case of "scavenge failure"? |
| eden()->object_iterate(cl); |
| } |
| |
| 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()->min_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 (PrintGC && Verbose) { |
| gclog_or_tty->print("DefNewGeneration::allocate_from_space(%u):" |
| " will_fail: %s" |
| " heap_lock: %s" |
| " free: " SIZE_FORMAT, |
| size, |
| GenCollectedHeap::heap()->incremental_collection_will_fail() ? "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::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(); |
| _next_gen = gch->next_gen(this); |
| assert(_next_gen != NULL, |
| "This must be the youngest gen, and not the only gen"); |
| |
| // If the next generation is too full to accomodate promotion |
| // from this generation, pass on collection; let the next generation |
| // do it. |
| if (!collection_attempt_is_safe()) { |
| gch->set_incremental_collection_will_fail(); |
| return; |
| } |
| assert(to()->is_empty(), "Else not collection_attempt_is_safe"); |
| |
| init_assuming_no_promotion_failure(); |
| |
| TraceTime t1("GC", PrintGC && !PrintGCDetails, true, gclog_or_tty); |
| // Capture heap used before collection (for printing). |
| size_t gch_prev_used = gch->used(); |
| |
| SpecializationStats::clear(); |
| |
| // These can be shared for all code paths |
| IsAliveClosure is_alive(this); |
| ScanWeakRefClosure scan_weak_ref(this); |
| |
| age_table()->clear(); |
| to()->clear(); |
| |
| gch->rem_set()->prepare_for_younger_refs_iterate(false); |
| |
| assert(gch->no_allocs_since_save_marks(0), |
| "save marks have not been newly set."); |
| |
| // Weak refs. |
| // FIXME: Are these storage leaks, or are they resource objects? |
| #ifdef COMPILER2 |
| ReferencePolicy *soft_ref_policy = new LRUMaxHeapPolicy(); |
| #else |
| ReferencePolicy *soft_ref_policy = new LRUCurrentHeapPolicy(); |
| #endif // COMPILER2 |
| |
| // Not very pretty. |
| CollectorPolicy* cp = gch->collector_policy(); |
| |
| FastScanClosure fsc_with_no_gc_barrier(this, false); |
| FastScanClosure fsc_with_gc_barrier(this, true); |
| |
| 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_strong_roots(_level, |
| true, // Process younger gens, if any, as |
| // strong roots. |
| false,// not collecting permanent generation. |
| SharedHeap::SO_AllClasses, |
| &fsc_with_gc_barrier, |
| &fsc_with_no_gc_barrier); |
| |
| // "evacuate followers". |
| evacuate_followers.do_void(); |
| |
| FastKeepAliveClosure keep_alive(this, &scan_weak_ref); |
| ref_processor()->process_discovered_references( |
| soft_ref_policy, &is_alive, &keep_alive, &evacuate_followers, NULL); |
| if (!promotion_failed()) { |
| // Swap the survivor spaces. |
| eden()->clear(); |
| from()->clear(); |
| swap_spaces(); |
| |
| assert(to()->is_empty(), "to space should be empty now"); |
| |
| // Set the desired survivor size to half the real survivor space |
| _tenuring_threshold = |
| age_table()->compute_tenuring_threshold(to()->capacity()/HeapWordSize); |
| |
| if (PrintGC && !PrintGCDetails) { |
| gch->print_heap_change(gch_prev_used); |
| } |
| } else { |
| assert(HandlePromotionFailure, |
| "Should not be here unless promotion failure handling is on"); |
| assert(_promo_failure_scan_stack != NULL && |
| _promo_failure_scan_stack->length() == 0, "post condition"); |
| |
| // deallocate stack and it's elements |
| delete _promo_failure_scan_stack; |
| _promo_failure_scan_stack = NULL; |
| |
| 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 the sake of uniformity wrt ParNewGeneration::collect(). |
| from()->set_next_compaction_space(to()); |
| gch->set_incremental_collection_will_fail(); |
| |
| // Reset the PromotionFailureALot counters. |
| NOT_PRODUCT(Universe::heap()->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()); |
| SpecializationStats::print(); |
| update_time_of_last_gc(os::javaTimeMillis()); |
| } |
| |
| class RemoveForwardPointerClosure: public ObjectClosure { |
| public: |
| void do_object(oop obj) { |
| obj->init_mark(); |
| } |
| }; |
| |
| void DefNewGeneration::init_assuming_no_promotion_failure() { |
| _promotion_failed = false; |
| 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. |
| if (_objs_with_preserved_marks != NULL) { |
| assert(_preserved_marks_of_objs != NULL, "Both or none."); |
| assert(_objs_with_preserved_marks->length() == |
| _preserved_marks_of_objs->length(), "Both or none."); |
| for (int i = 0; i < _objs_with_preserved_marks->length(); i++) { |
| oop obj = _objs_with_preserved_marks->at(i); |
| markOop m = _preserved_marks_of_objs->at(i); |
| obj->set_mark(m); |
| } |
| delete _objs_with_preserved_marks; |
| delete _preserved_marks_of_objs; |
| _objs_with_preserved_marks = NULL; |
| _preserved_marks_of_objs = NULL; |
| } |
| } |
| |
| void DefNewGeneration::preserve_mark_if_necessary(oop obj, markOop m) { |
| if (m->must_be_preserved_for_promotion_failure(obj)) { |
| if (_objs_with_preserved_marks == NULL) { |
| assert(_preserved_marks_of_objs == NULL, "Both or none."); |
| _objs_with_preserved_marks = new (ResourceObj::C_HEAP) |
| GrowableArray<oop>(PreserveMarkStackSize, true); |
| _preserved_marks_of_objs = new (ResourceObj::C_HEAP) |
| GrowableArray<markOop>(PreserveMarkStackSize, true); |
| } |
| _objs_with_preserved_marks->push(obj); |
| _preserved_marks_of_objs->push(m); |
| } |
| } |
| |
| void DefNewGeneration::handle_promotion_failure(oop old) { |
| preserve_mark_if_necessary(old, old->mark()); |
| // forward to self |
| old->forward_to(old); |
| _promotion_failed = true; |
| |
| push_on_promo_failure_scan_stack(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, oop* from) { |
| 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(s); |
| } |
| |
| // Otherwise try allocating obj tenured |
| if (obj == NULL) { |
| obj = _next_gen->promote(old, s, from); |
| if (obj == NULL) { |
| if (!HandlePromotionFailure) { |
| // A failed promotion likely means the MaxLiveObjectEvacuationRatio flag |
| // is incorrectly set. In any case, its seriously wrong to be here! |
| vm_exit_out_of_memory(s*wordSize, "promotion"); |
| } |
| |
| 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::push_on_promo_failure_scan_stack(oop obj) { |
| if (_promo_failure_scan_stack == NULL) { |
| _promo_failure_scan_stack = new (ResourceObj::C_HEAP) |
| GrowableArray<oop>(40, true); |
| } |
| |
| _promo_failure_scan_stack->push(obj); |
| } |
| |
| void DefNewGeneration::drain_promo_failure_scan_stack() { |
| assert(_promo_failure_scan_stack != NULL, "precondition"); |
| |
| while (_promo_failure_scan_stack->length() > 0) { |
| 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; |
| } |
| } |
| |
| bool DefNewGeneration::collection_attempt_is_safe() { |
| if (!to()->is_empty()) { |
| return false; |
| } |
| if (_next_gen == NULL) { |
| GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| _next_gen = gch->next_gen(this); |
| assert(_next_gen != NULL, |
| "This must be the youngest gen, and not the only gen"); |
| } |
| |
| // Decide if there's enough room for a full promotion |
| // When using extremely large edens, we effectively lose a |
| // large amount of old space. Use the "MaxLiveObjectEvacuationRatio" |
| // flag to reduce the minimum evacuation space requirements. If |
| // there is not enough space to evacuate eden during a scavenge, |
| // the VM will immediately exit with an out of memory error. |
| // This flag has not been tested |
| // with collectors other than simple mark & sweep. |
| // |
| // Note that with the addition of promotion failure handling, the |
| // VM will not immediately exit but will undo the young generation |
| // collection. The parameter is left here for compatibility. |
| const double evacuation_ratio = MaxLiveObjectEvacuationRatio / 100.0; |
| |
| // worst_case_evacuation is based on "used()". For the case where this |
| // method is called after a collection, this is still appropriate because |
| // the case that needs to be detected is one in which a full collection |
| // has been done and has overflowed into the young generation. In that |
| // case a minor collection will fail (the overflow of the full collection |
| // means there is no space in the old generation for any promotion). |
| size_t worst_case_evacuation = (size_t)(used() * evacuation_ratio); |
| |
| return _next_gen->promotion_attempt_is_safe(worst_case_evacuation, |
| HandlePromotionFailure); |
| } |
| |
| void DefNewGeneration::gc_epilogue(bool full) { |
| // 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(); |
| clear_should_allocate_from_space(); |
| if (collection_attempt_is_safe()) { |
| gch->clear_incremental_collection_will_fail(); |
| } else { |
| gch->set_incremental_collection_will_fail(); |
| if (full) { // we seem to be running out of space |
| set_should_allocate_from_space(); |
| } |
| } |
| |
| // update the generation and space performance counters |
| update_counters(); |
| gch->collector_policy()->counters()->update_counters(); |
| } |
| |
| 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(bool allow_dirty) { |
| eden()->verify(allow_dirty); |
| from()->verify(allow_dirty); |
| to()->verify(allow_dirty); |
| } |
| |
| 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"; |
| } |