Mercurial > hg > graal-compiler
diff src/share/vm/memory/genCollectedHeap.cpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | ba764ed4b6f2 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/memory/genCollectedHeap.cpp Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,1368 @@ +/* + * Copyright 2000-2007 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/_genCollectedHeap.cpp.incl" + +GenCollectedHeap* GenCollectedHeap::_gch; +NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;) + +// The set of potentially parallel tasks in strong root scanning. +enum GCH_process_strong_roots_tasks { + // We probably want to parallelize both of these internally, but for now... + GCH_PS_younger_gens, + // Leave this one last. + GCH_PS_NumElements +}; + +GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) : + SharedHeap(policy), + _gen_policy(policy), + _gen_process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)), + _full_collections_completed(0) +{ + if (_gen_process_strong_tasks == NULL || + !_gen_process_strong_tasks->valid()) { + vm_exit_during_initialization("Failed necessary allocation."); + } + assert(policy != NULL, "Sanity check"); + _preloading_shared_classes = false; +} + +jint GenCollectedHeap::initialize() { + int i; + _n_gens = gen_policy()->number_of_generations(); + + // While there are no constraints in the GC code that HeapWordSize + // be any particular value, there are multiple other areas in the + // system which believe this to be true (e.g. oop->object_size in some + // cases incorrectly returns the size in wordSize units rather than + // HeapWordSize). + guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); + + // The heap must be at least as aligned as generations. + size_t alignment = Generation::GenGrain; + + _gen_specs = gen_policy()->generations(); + PermanentGenerationSpec *perm_gen_spec = + collector_policy()->permanent_generation(); + + // Make sure the sizes are all aligned. + for (i = 0; i < _n_gens; i++) { + _gen_specs[i]->align(alignment); + } + perm_gen_spec->align(alignment); + + // If we are dumping the heap, then allocate a wasted block of address + // space in order to push the heap to a lower address. This extra + // address range allows for other (or larger) libraries to be loaded + // without them occupying the space required for the shared spaces. + + if (DumpSharedSpaces) { + uintx reserved = 0; + uintx block_size = 64*1024*1024; + while (reserved < SharedDummyBlockSize) { + char* dummy = os::reserve_memory(block_size); + reserved += block_size; + } + } + + // Allocate space for the heap. + + char* heap_address; + size_t total_reserved = 0; + int n_covered_regions = 0; + ReservedSpace heap_rs(0); + + heap_address = allocate(alignment, perm_gen_spec, &total_reserved, + &n_covered_regions, &heap_rs); + + if (UseSharedSpaces) { + if (!heap_rs.is_reserved() || heap_address != heap_rs.base()) { + if (heap_rs.is_reserved()) { + heap_rs.release(); + } + FileMapInfo* mapinfo = FileMapInfo::current_info(); + mapinfo->fail_continue("Unable to reserve shared region."); + allocate(alignment, perm_gen_spec, &total_reserved, &n_covered_regions, + &heap_rs); + } + } + + if (!heap_rs.is_reserved()) { + vm_shutdown_during_initialization( + "Could not reserve enough space for object heap"); + return JNI_ENOMEM; + } + + _reserved = MemRegion((HeapWord*)heap_rs.base(), + (HeapWord*)(heap_rs.base() + heap_rs.size())); + + // It is important to do this in a way such that concurrent readers can't + // temporarily think somethings in the heap. (Seen this happen in asserts.) + _reserved.set_word_size(0); + _reserved.set_start((HeapWord*)heap_rs.base()); + size_t actual_heap_size = heap_rs.size() - perm_gen_spec->misc_data_size() + - perm_gen_spec->misc_code_size(); + _reserved.set_end((HeapWord*)(heap_rs.base() + actual_heap_size)); + + _rem_set = collector_policy()->create_rem_set(_reserved, n_covered_regions); + set_barrier_set(rem_set()->bs()); + _gch = this; + + for (i = 0; i < _n_gens; i++) { + ReservedSpace this_rs = heap_rs.first_part(_gen_specs[i]->max_size(), + UseSharedSpaces, UseSharedSpaces); + _gens[i] = _gen_specs[i]->init(this_rs, i, rem_set()); + heap_rs = heap_rs.last_part(_gen_specs[i]->max_size()); + } + _perm_gen = perm_gen_spec->init(heap_rs, PermSize, rem_set()); + + clear_incremental_collection_will_fail(); + clear_last_incremental_collection_failed(); + +#ifndef SERIALGC + // If we are running CMS, create the collector responsible + // for collecting the CMS generations. + if (collector_policy()->is_concurrent_mark_sweep_policy()) { + bool success = create_cms_collector(); + if (!success) return JNI_ENOMEM; + } +#endif // SERIALGC + + return JNI_OK; +} + + +char* GenCollectedHeap::allocate(size_t alignment, + PermanentGenerationSpec* perm_gen_spec, + size_t* _total_reserved, + int* _n_covered_regions, + ReservedSpace* heap_rs){ + const char overflow_msg[] = "The size of the object heap + VM data exceeds " + "the maximum representable size"; + + // Now figure out the total size. + size_t total_reserved = 0; + int n_covered_regions = 0; + const size_t pageSize = UseLargePages ? + os::large_page_size() : os::vm_page_size(); + + for (int i = 0; i < _n_gens; i++) { + total_reserved += _gen_specs[i]->max_size(); + if (total_reserved < _gen_specs[i]->max_size()) { + vm_exit_during_initialization(overflow_msg); + } + n_covered_regions += _gen_specs[i]->n_covered_regions(); + } + assert(total_reserved % pageSize == 0, "Gen size"); + total_reserved += perm_gen_spec->max_size(); + assert(total_reserved % pageSize == 0, "Perm Gen size"); + + if (total_reserved < perm_gen_spec->max_size()) { + vm_exit_during_initialization(overflow_msg); + } + n_covered_regions += perm_gen_spec->n_covered_regions(); + + // Add the size of the data area which shares the same reserved area + // as the heap, but which is not actually part of the heap. + size_t s = perm_gen_spec->misc_data_size() + perm_gen_spec->misc_code_size(); + + total_reserved += s; + if (total_reserved < s) { + vm_exit_during_initialization(overflow_msg); + } + + if (UseLargePages) { + assert(total_reserved != 0, "total_reserved cannot be 0"); + total_reserved = round_to(total_reserved, os::large_page_size()); + if (total_reserved < os::large_page_size()) { + vm_exit_during_initialization(overflow_msg); + } + } + + // Calculate the address at which the heap must reside in order for + // the shared data to be at the required address. + + char* heap_address; + if (UseSharedSpaces) { + + // Calculate the address of the first word beyond the heap. + FileMapInfo* mapinfo = FileMapInfo::current_info(); + int lr = CompactingPermGenGen::n_regions - 1; + size_t capacity = align_size_up(mapinfo->space_capacity(lr), alignment); + heap_address = mapinfo->region_base(lr) + capacity; + + // Calculate the address of the first word of the heap. + heap_address -= total_reserved; + } else { + heap_address = NULL; // any address will do. + } + + *_total_reserved = total_reserved; + *_n_covered_regions = n_covered_regions; + *heap_rs = ReservedSpace(total_reserved, alignment, + UseLargePages, heap_address); + + return heap_address; +} + + +void GenCollectedHeap::post_initialize() { + SharedHeap::post_initialize(); + TwoGenerationCollectorPolicy *policy = + (TwoGenerationCollectorPolicy *)collector_policy(); + guarantee(policy->is_two_generation_policy(), "Illegal policy type"); + DefNewGeneration* def_new_gen = (DefNewGeneration*) get_gen(0); + assert(def_new_gen->kind() == Generation::DefNew || + def_new_gen->kind() == Generation::ParNew || + def_new_gen->kind() == Generation::ASParNew, + "Wrong generation kind"); + + Generation* old_gen = get_gen(1); + assert(old_gen->kind() == Generation::ConcurrentMarkSweep || + old_gen->kind() == Generation::ASConcurrentMarkSweep || + old_gen->kind() == Generation::MarkSweepCompact, + "Wrong generation kind"); + + policy->initialize_size_policy(def_new_gen->eden()->capacity(), + old_gen->capacity(), + def_new_gen->from()->capacity()); + policy->initialize_gc_policy_counters(); +} + +void GenCollectedHeap::ref_processing_init() { + SharedHeap::ref_processing_init(); + for (int i = 0; i < _n_gens; i++) { + _gens[i]->ref_processor_init(); + } +} + +size_t GenCollectedHeap::capacity() const { + size_t res = 0; + for (int i = 0; i < _n_gens; i++) { + res += _gens[i]->capacity(); + } + return res; +} + +size_t GenCollectedHeap::used() const { + size_t res = 0; + for (int i = 0; i < _n_gens; i++) { + res += _gens[i]->used(); + } + return res; +} + +// Save the "used_region" for generations level and lower, +// and, if perm is true, for perm gen. +void GenCollectedHeap::save_used_regions(int level, bool perm) { + assert(level < _n_gens, "Illegal level parameter"); + for (int i = level; i >= 0; i--) { + _gens[i]->save_used_region(); + } + if (perm) { + perm_gen()->save_used_region(); + } +} + +size_t GenCollectedHeap::max_capacity() const { + size_t res = 0; + for (int i = 0; i < _n_gens; i++) { + res += _gens[i]->max_capacity(); + } + return res; +} + +// Update the _full_collections_completed counter +// at the end of a stop-world full GC. +unsigned int GenCollectedHeap::update_full_collections_completed() { + MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); + assert(_full_collections_completed <= _total_full_collections, + "Can't complete more collections than were started"); + _full_collections_completed = _total_full_collections; + ml.notify_all(); + return _full_collections_completed; +} + +// Update the _full_collections_completed counter, as appropriate, +// at the end of a concurrent GC cycle. Note the conditional update +// below to allow this method to be called by a concurrent collector +// without synchronizing in any manner with the VM thread (which +// may already have initiated a STW full collection "concurrently"). +unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) { + MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); + assert((_full_collections_completed <= _total_full_collections) && + (count <= _total_full_collections), + "Can't complete more collections than were started"); + if (count > _full_collections_completed) { + _full_collections_completed = count; + ml.notify_all(); + } + return _full_collections_completed; +} + + +#ifndef PRODUCT +// Override of memory state checking method in CollectedHeap: +// Some collectors (CMS for example) can't have badHeapWordVal written +// in the first two words of an object. (For instance , in the case of +// CMS these words hold state used to synchronize between certain +// (concurrent) GC steps and direct allocating mutators.) +// The skip_header_HeapWords() method below, allows us to skip +// over the requisite number of HeapWord's. Note that (for +// generational collectors) this means that those many words are +// skipped in each object, irrespective of the generation in which +// that object lives. The resultant loss of precision seems to be +// harmless and the pain of avoiding that imprecision appears somewhat +// higher than we are prepared to pay for such rudimentary debugging +// support. +void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, + size_t size) { + if (CheckMemoryInitialization && ZapUnusedHeapArea) { + // We are asked to check a size in HeapWords, + // but the memory is mangled in juint words. + juint* start = (juint*) (addr + skip_header_HeapWords()); + juint* end = (juint*) (addr + size); + for (juint* slot = start; slot < end; slot += 1) { + assert(*slot == badHeapWordVal, + "Found non badHeapWordValue in pre-allocation check"); + } + } +} +#endif + +HeapWord* GenCollectedHeap::attempt_allocation(size_t size, + bool is_tlab, + bool first_only) { + HeapWord* res; + for (int i = 0; i < _n_gens; i++) { + if (_gens[i]->should_allocate(size, is_tlab)) { + res = _gens[i]->allocate(size, is_tlab); + if (res != NULL) return res; + else if (first_only) break; + } + } + // Otherwise... + return NULL; +} + +HeapWord* GenCollectedHeap::mem_allocate(size_t size, + bool is_large_noref, + bool is_tlab, + bool* gc_overhead_limit_was_exceeded) { + return collector_policy()->mem_allocate_work(size, + is_tlab, + gc_overhead_limit_was_exceeded); +} + +bool GenCollectedHeap::must_clear_all_soft_refs() { + return _gc_cause == GCCause::_last_ditch_collection; +} + +bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { + return (cause == GCCause::_java_lang_system_gc || + cause == GCCause::_gc_locker) && + UseConcMarkSweepGC && ExplicitGCInvokesConcurrent; +} + +void GenCollectedHeap::do_collection(bool full, + bool clear_all_soft_refs, + size_t size, + bool is_tlab, + int max_level) { + bool prepared_for_verification = false; + ResourceMark rm; + DEBUG_ONLY(Thread* my_thread = Thread::current();) + + assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); + assert(my_thread->is_VM_thread() || + my_thread->is_ConcurrentGC_thread(), + "incorrect thread type capability"); + assert(Heap_lock->is_locked(), "the requesting thread should have the Heap_lock"); + guarantee(!is_gc_active(), "collection is not reentrant"); + assert(max_level < n_gens(), "sanity check"); + + if (GC_locker::check_active_before_gc()) { + return; // GC is disabled (e.g. JNI GetXXXCritical operation) + } + + const size_t perm_prev_used = perm_gen()->used(); + + if (PrintHeapAtGC) { + Universe::print_heap_before_gc(); + if (Verbose) { + gclog_or_tty->print_cr("GC Cause: %s", GCCause::to_string(gc_cause())); + } + } + + { + FlagSetting fl(_is_gc_active, true); + + bool complete = full && (max_level == (n_gens()-1)); + const char* gc_cause_str = "GC "; + if (complete) { + GCCause::Cause cause = gc_cause(); + if (cause == GCCause::_java_lang_system_gc) { + gc_cause_str = "Full GC (System) "; + } else { + gc_cause_str = "Full GC "; + } + } + gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); + TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); + TraceTime t(gc_cause_str, PrintGCDetails, false, gclog_or_tty); + + gc_prologue(complete); + increment_total_collections(complete); + + size_t gch_prev_used = used(); + + int starting_level = 0; + if (full) { + // Search for the oldest generation which will collect all younger + // generations, and start collection loop there. + for (int i = max_level; i >= 0; i--) { + if (_gens[i]->full_collects_younger_generations()) { + starting_level = i; + break; + } + } + } + + bool must_restore_marks_for_biased_locking = false; + + int max_level_collected = starting_level; + for (int i = starting_level; i <= max_level; i++) { + if (_gens[i]->should_collect(full, size, is_tlab)) { + // Timer for individual generations. Last argument is false: no CR + TraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, gclog_or_tty); + TraceCollectorStats tcs(_gens[i]->counters()); + TraceMemoryManagerStats tmms(_gens[i]->kind()); + + size_t prev_used = _gens[i]->used(); + _gens[i]->stat_record()->invocations++; + _gens[i]->stat_record()->accumulated_time.start(); + + if (PrintGC && Verbose) { + gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT, + i, + _gens[i]->stat_record()->invocations, + size*HeapWordSize); + } + + if (VerifyBeforeGC && i >= VerifyGCLevel && + total_collections() >= VerifyGCStartAt) { + HandleMark hm; // Discard invalid handles created during verification + if (!prepared_for_verification) { + prepare_for_verify(); + prepared_for_verification = true; + } + gclog_or_tty->print(" VerifyBeforeGC:"); + Universe::verify(true); + } + COMPILER2_PRESENT(DerivedPointerTable::clear()); + + if (!must_restore_marks_for_biased_locking && + _gens[i]->performs_in_place_marking()) { + // We perform this mark word preservation work lazily + // because it's only at this point that we know whether we + // absolutely have to do it; we want to avoid doing it for + // scavenge-only collections where it's unnecessary + must_restore_marks_for_biased_locking = true; + BiasedLocking::preserve_marks(); + } + + // Do collection work + { + // Note on ref discovery: For what appear to be historical reasons, + // GCH enables and disabled (by enqueing) refs discovery. + // In the future this should be moved into the generation's + // collect method so that ref discovery and enqueueing concerns + // are local to a generation. The collect method could return + // an appropriate indication in the case that notification on + // the ref lock was needed. This will make the treatment of + // weak refs more uniform (and indeed remove such concerns + // from GCH). XXX + + HandleMark hm; // Discard invalid handles created during gc + save_marks(); // save marks for all gens + // We want to discover references, but not process them yet. + // This mode is disabled in process_discovered_references if the + // generation does some collection work, or in + // enqueue_discovered_references if the generation returns + // without doing any work. + ReferenceProcessor* rp = _gens[i]->ref_processor(); + // If the discovery of ("weak") refs in this generation is + // atomic wrt other collectors in this configuration, we + // are guaranteed to have empty discovered ref lists. + if (rp->discovery_is_atomic()) { + rp->verify_no_references_recorded(); + rp->enable_discovery(); + } else { + // collect() will enable discovery as appropriate + } + _gens[i]->collect(full, clear_all_soft_refs, size, is_tlab); + if (!rp->enqueuing_is_done()) { + rp->enqueue_discovered_references(); + } else { + rp->set_enqueuing_is_done(false); + } + rp->verify_no_references_recorded(); + } + max_level_collected = i; + + // Determine if allocation request was met. + if (size > 0) { + if (!is_tlab || _gens[i]->supports_tlab_allocation()) { + if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) { + size = 0; + } + } + } + + COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); + + _gens[i]->stat_record()->accumulated_time.stop(); + + update_gc_stats(i, full); + + if (VerifyAfterGC && i >= VerifyGCLevel && + total_collections() >= VerifyGCStartAt) { + HandleMark hm; // Discard invalid handles created during verification + gclog_or_tty->print(" VerifyAfterGC:"); + Universe::verify(false); + } + + if (PrintGCDetails) { + gclog_or_tty->print(":"); + _gens[i]->print_heap_change(prev_used); + } + } + } + + // Update "complete" boolean wrt what actually transpired -- + // for instance, a promotion failure could have led to + // a whole heap collection. + complete = complete || (max_level_collected == n_gens() - 1); + + if (PrintGCDetails) { + print_heap_change(gch_prev_used); + + // Print perm gen info for full GC with PrintGCDetails flag. + if (complete) { + print_perm_heap_change(perm_prev_used); + } + } + + for (int j = max_level_collected; j >= 0; j -= 1) { + // Adjust generation sizes. + _gens[j]->compute_new_size(); + } + + if (complete) { + // Ask the permanent generation to adjust size for full collections + perm()->compute_new_size(); + update_full_collections_completed(); + } + + // Track memory usage and detect low memory after GC finishes + MemoryService::track_memory_usage(); + + gc_epilogue(complete); + + if (must_restore_marks_for_biased_locking) { + BiasedLocking::restore_marks(); + } + } + + AdaptiveSizePolicy* sp = gen_policy()->size_policy(); + AdaptiveSizePolicyOutput(sp, total_collections()); + + if (PrintHeapAtGC) { + Universe::print_heap_after_gc(); + } + + if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) { + tty->print_cr("Stopping after GC #%d", ExitAfterGCNum); + vm_exit(-1); + } +} + +HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { + return collector_policy()->satisfy_failed_allocation(size, is_tlab); +} + +void GenCollectedHeap::set_par_threads(int t) { + SharedHeap::set_par_threads(t); + _gen_process_strong_tasks->set_par_threads(t); +} + +class AssertIsPermClosure: public OopClosure { +public: + void do_oop(oop* p) { + assert((*p) == NULL || (*p)->is_perm(), "Referent should be perm."); + } +}; +static AssertIsPermClosure assert_is_perm_closure; + +void GenCollectedHeap:: +gen_process_strong_roots(int level, + bool younger_gens_as_roots, + bool collecting_perm_gen, + SharedHeap::ScanningOption so, + OopsInGenClosure* older_gens, + OopsInGenClosure* not_older_gens) { + // General strong roots. + SharedHeap::process_strong_roots(collecting_perm_gen, so, + not_older_gens, older_gens); + + if (younger_gens_as_roots) { + if (!_gen_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { + for (int i = 0; i < level; i++) { + not_older_gens->set_generation(_gens[i]); + _gens[i]->oop_iterate(not_older_gens); + } + not_older_gens->reset_generation(); + } + } + // When collection is parallel, all threads get to cooperate to do + // older-gen scanning. + for (int i = level+1; i < _n_gens; i++) { + older_gens->set_generation(_gens[i]); + rem_set()->younger_refs_iterate(_gens[i], older_gens); + older_gens->reset_generation(); + } + + _gen_process_strong_tasks->all_tasks_completed(); +} + +void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure, + OopClosure* non_root_closure) { + SharedHeap::process_weak_roots(root_closure, non_root_closure); + // "Local" "weak" refs + for (int i = 0; i < _n_gens; i++) { + _gens[i]->ref_processor()->weak_oops_do(root_closure); + } +} + +#define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ +void GenCollectedHeap:: \ +oop_since_save_marks_iterate(int level, \ + OopClosureType* cur, \ + OopClosureType* older) { \ + _gens[level]->oop_since_save_marks_iterate##nv_suffix(cur); \ + for (int i = level+1; i < n_gens(); i++) { \ + _gens[i]->oop_since_save_marks_iterate##nv_suffix(older); \ + } \ + perm_gen()->oop_since_save_marks_iterate##nv_suffix(older); \ +} + +ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN) + +#undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN + +bool GenCollectedHeap::no_allocs_since_save_marks(int level) { + for (int i = level; i < _n_gens; i++) { + if (!_gens[i]->no_allocs_since_save_marks()) return false; + } + return perm_gen()->no_allocs_since_save_marks(); +} + +bool GenCollectedHeap::supports_inline_contig_alloc() const { + return _gens[0]->supports_inline_contig_alloc(); +} + +HeapWord** GenCollectedHeap::top_addr() const { + return _gens[0]->top_addr(); +} + +HeapWord** GenCollectedHeap::end_addr() const { + return _gens[0]->end_addr(); +} + +size_t GenCollectedHeap::unsafe_max_alloc() { + return _gens[0]->unsafe_max_alloc_nogc(); +} + +// public collection interfaces + +void GenCollectedHeap::collect(GCCause::Cause cause) { + if (should_do_concurrent_full_gc(cause)) { +#ifndef SERIALGC + // mostly concurrent full collection + collect_mostly_concurrent(cause); +#else // SERIALGC + ShouldNotReachHere(); +#endif // SERIALGC + } else { +#ifdef ASSERT + if (cause == GCCause::_scavenge_alot) { + // minor collection only + collect(cause, 0); + } else { + // Stop-the-world full collection + collect(cause, n_gens() - 1); + } +#else + // Stop-the-world full collection + collect(cause, n_gens() - 1); +#endif + } +} + +void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) { + // The caller doesn't have the Heap_lock + assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); + MutexLocker ml(Heap_lock); + collect_locked(cause, max_level); +} + +// This interface assumes that it's being called by the +// vm thread. It collects the heap assuming that the +// heap lock is already held and that we are executing in +// the context of the vm thread. +void GenCollectedHeap::collect_as_vm_thread(GCCause::Cause cause) { + assert(Thread::current()->is_VM_thread(), "Precondition#1"); + assert(Heap_lock->is_locked(), "Precondition#2"); + GCCauseSetter gcs(this, cause); + switch (cause) { + case GCCause::_heap_inspection: + case GCCause::_heap_dump: { + HandleMark hm; + do_full_collection(false, // don't clear all soft refs + n_gens() - 1); + break; + } + default: // XXX FIX ME + ShouldNotReachHere(); // Unexpected use of this function + } +} + +void GenCollectedHeap::collect_locked(GCCause::Cause cause) { + // The caller has the Heap_lock + assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock"); + collect_locked(cause, n_gens() - 1); +} + +// this is the private collection interface +// The Heap_lock is expected to be held on entry. + +void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) { + if (_preloading_shared_classes) { + warning("\nThe permanent generation is not large enough to preload " + "requested classes.\nUse -XX:PermSize= to increase the initial " + "size of the permanent generation.\n"); + vm_exit(2); + } + // Read the GC count while holding the Heap_lock + unsigned int gc_count_before = total_collections(); + unsigned int full_gc_count_before = total_full_collections(); + { + MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back + VM_GenCollectFull op(gc_count_before, full_gc_count_before, + cause, max_level); + VMThread::execute(&op); + } +} + +#ifndef SERIALGC +bool GenCollectedHeap::create_cms_collector() { + + assert(((_gens[1]->kind() == Generation::ConcurrentMarkSweep) || + (_gens[1]->kind() == Generation::ASConcurrentMarkSweep)) && + _perm_gen->as_gen()->kind() == Generation::ConcurrentMarkSweep, + "Unexpected generation kinds"); + // Skip two header words in the block content verification + NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();) + CMSCollector* collector = new CMSCollector( + (ConcurrentMarkSweepGeneration*)_gens[1], + (ConcurrentMarkSweepGeneration*)_perm_gen->as_gen(), + _rem_set->as_CardTableRS(), + (ConcurrentMarkSweepPolicy*) collector_policy()); + + if (collector == NULL || !collector->completed_initialization()) { + if (collector) { + delete collector; // Be nice in embedded situation + } + vm_shutdown_during_initialization("Could not create CMS collector"); + return false; + } + return true; // success +} + +void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) { + assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock"); + + MutexLocker ml(Heap_lock); + // Read the GC counts while holding the Heap_lock + unsigned int full_gc_count_before = total_full_collections(); + unsigned int gc_count_before = total_collections(); + { + MutexUnlocker mu(Heap_lock); + VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause); + VMThread::execute(&op); + } +} +#endif // SERIALGC + + +void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, + int max_level) { + int local_max_level; + if (!incremental_collection_will_fail() && + gc_cause() == GCCause::_gc_locker) { + local_max_level = 0; + } else { + local_max_level = max_level; + } + + do_collection(true /* full */, + clear_all_soft_refs /* clear_all_soft_refs */, + 0 /* size */, + false /* is_tlab */, + local_max_level /* max_level */); + // Hack XXX FIX ME !!! + // A scavenge may not have been attempted, or may have + // been attempted and failed, because the old gen was too full + if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker && + incremental_collection_will_fail()) { + if (PrintGCDetails) { + gclog_or_tty->print_cr("GC locker: Trying a full collection " + "because scavenge failed"); + } + // This time allow the old gen to be collected as well + do_collection(true /* full */, + clear_all_soft_refs /* clear_all_soft_refs */, + 0 /* size */, + false /* is_tlab */, + n_gens() - 1 /* max_level */); + } +} + +// Returns "TRUE" iff "p" points into the allocated area of the heap. +bool GenCollectedHeap::is_in(const void* p) const { + #ifndef ASSERT + guarantee(VerifyBeforeGC || + VerifyDuringGC || + VerifyBeforeExit || + VerifyAfterGC, "too expensive"); + #endif + // This might be sped up with a cache of the last generation that + // answered yes. + for (int i = 0; i < _n_gens; i++) { + if (_gens[i]->is_in(p)) return true; + } + if (_perm_gen->as_gen()->is_in(p)) return true; + // Otherwise... + return false; +} + +// Returns "TRUE" iff "p" points into the allocated area of the heap. +bool GenCollectedHeap::is_in_youngest(void* p) { + return _gens[0]->is_in(p); +} + +void GenCollectedHeap::oop_iterate(OopClosure* cl) { + for (int i = 0; i < _n_gens; i++) { + _gens[i]->oop_iterate(cl); + } +} + +void GenCollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl) { + for (int i = 0; i < _n_gens; i++) { + _gens[i]->oop_iterate(mr, cl); + } +} + +void GenCollectedHeap::object_iterate(ObjectClosure* cl) { + for (int i = 0; i < _n_gens; i++) { + _gens[i]->object_iterate(cl); + } + perm_gen()->object_iterate(cl); +} + +void GenCollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) { + for (int i = 0; i < _n_gens; i++) { + _gens[i]->object_iterate_since_last_GC(cl); + } +} + +Space* GenCollectedHeap::space_containing(const void* addr) const { + for (int i = 0; i < _n_gens; i++) { + Space* res = _gens[i]->space_containing(addr); + if (res != NULL) return res; + } + Space* res = perm_gen()->space_containing(addr); + if (res != NULL) return res; + // Otherwise... + assert(false, "Could not find containing space"); + return NULL; +} + + +HeapWord* GenCollectedHeap::block_start(const void* addr) const { + assert(is_in_reserved(addr), "block_start of address outside of heap"); + for (int i = 0; i < _n_gens; i++) { + if (_gens[i]->is_in_reserved(addr)) { + assert(_gens[i]->is_in(addr), + "addr should be in allocated part of generation"); + return _gens[i]->block_start(addr); + } + } + if (perm_gen()->is_in_reserved(addr)) { + assert(perm_gen()->is_in(addr), + "addr should be in allocated part of perm gen"); + return perm_gen()->block_start(addr); + } + assert(false, "Some generation should contain the address"); + return NULL; +} + +size_t GenCollectedHeap::block_size(const HeapWord* addr) const { + assert(is_in_reserved(addr), "block_size of address outside of heap"); + for (int i = 0; i < _n_gens; i++) { + if (_gens[i]->is_in_reserved(addr)) { + assert(_gens[i]->is_in(addr), + "addr should be in allocated part of generation"); + return _gens[i]->block_size(addr); + } + } + if (perm_gen()->is_in_reserved(addr)) { + assert(perm_gen()->is_in(addr), + "addr should be in allocated part of perm gen"); + return perm_gen()->block_size(addr); + } + assert(false, "Some generation should contain the address"); + return 0; +} + +bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { + assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); + assert(block_start(addr) == addr, "addr must be a block start"); + for (int i = 0; i < _n_gens; i++) { + if (_gens[i]->is_in_reserved(addr)) { + return _gens[i]->block_is_obj(addr); + } + } + if (perm_gen()->is_in_reserved(addr)) { + return perm_gen()->block_is_obj(addr); + } + assert(false, "Some generation should contain the address"); + return false; +} + +bool GenCollectedHeap::supports_tlab_allocation() const { + for (int i = 0; i < _n_gens; i += 1) { + if (_gens[i]->supports_tlab_allocation()) { + return true; + } + } + return false; +} + +size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { + size_t result = 0; + for (int i = 0; i < _n_gens; i += 1) { + if (_gens[i]->supports_tlab_allocation()) { + result += _gens[i]->tlab_capacity(); + } + } + return result; +} + +size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { + size_t result = 0; + for (int i = 0; i < _n_gens; i += 1) { + if (_gens[i]->supports_tlab_allocation()) { + result += _gens[i]->unsafe_max_tlab_alloc(); + } + } + return result; +} + +HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) { + bool gc_overhead_limit_was_exceeded; + HeapWord* result = mem_allocate(size /* size */, + false /* is_large_noref */, + true /* is_tlab */, + &gc_overhead_limit_was_exceeded); + return result; +} + +// Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size +// from the list headed by "*prev_ptr". +static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { + bool first = true; + size_t min_size = 0; // "first" makes this conceptually infinite. + ScratchBlock **smallest_ptr, *smallest; + ScratchBlock *cur = *prev_ptr; + while (cur) { + assert(*prev_ptr == cur, "just checking"); + if (first || cur->num_words < min_size) { + smallest_ptr = prev_ptr; + smallest = cur; + min_size = smallest->num_words; + first = false; + } + prev_ptr = &cur->next; + cur = cur->next; + } + smallest = *smallest_ptr; + *smallest_ptr = smallest->next; + return smallest; +} + +// Sort the scratch block list headed by res into decreasing size order, +// and set "res" to the result. +static void sort_scratch_list(ScratchBlock*& list) { + ScratchBlock* sorted = NULL; + ScratchBlock* unsorted = list; + while (unsorted) { + ScratchBlock *smallest = removeSmallestScratch(&unsorted); + smallest->next = sorted; + sorted = smallest; + } + list = sorted; +} + +ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, + size_t max_alloc_words) { + ScratchBlock* res = NULL; + for (int i = 0; i < _n_gens; i++) { + _gens[i]->contribute_scratch(res, requestor, max_alloc_words); + } + sort_scratch_list(res); + return res; +} + +size_t GenCollectedHeap::large_typearray_limit() { + return gen_policy()->large_typearray_limit(); +} + +class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure { + void do_generation(Generation* gen) { + gen->prepare_for_verify(); + } +}; + +void GenCollectedHeap::prepare_for_verify() { + ensure_parsability(false); // no need to retire TLABs + GenPrepareForVerifyClosure blk; + generation_iterate(&blk, false); + perm_gen()->prepare_for_verify(); +} + + +void GenCollectedHeap::generation_iterate(GenClosure* cl, + bool old_to_young) { + if (old_to_young) { + for (int i = _n_gens-1; i >= 0; i--) { + cl->do_generation(_gens[i]); + } + } else { + for (int i = 0; i < _n_gens; i++) { + cl->do_generation(_gens[i]); + } + } +} + +void GenCollectedHeap::space_iterate(SpaceClosure* cl) { + for (int i = 0; i < _n_gens; i++) { + _gens[i]->space_iterate(cl, true); + } + perm_gen()->space_iterate(cl, true); +} + +bool GenCollectedHeap::is_maximal_no_gc() const { + for (int i = 0; i < _n_gens; i++) { // skip perm gen + if (!_gens[i]->is_maximal_no_gc()) { + return false; + } + } + return true; +} + +void GenCollectedHeap::save_marks() { + for (int i = 0; i < _n_gens; i++) { + _gens[i]->save_marks(); + } + perm_gen()->save_marks(); +} + +void GenCollectedHeap::compute_new_generation_sizes(int collectedGen) { + for (int i = 0; i <= collectedGen; i++) { + _gens[i]->compute_new_size(); + } +} + +GenCollectedHeap* GenCollectedHeap::heap() { + assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()"); + assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap"); + return _gch; +} + + +void GenCollectedHeap::prepare_for_compaction() { + Generation* scanning_gen = _gens[_n_gens-1]; + // Start by compacting into same gen. + CompactPoint cp(scanning_gen, NULL, NULL); + while (scanning_gen != NULL) { + scanning_gen->prepare_for_compaction(&cp); + scanning_gen = prev_gen(scanning_gen); + } +} + +GCStats* GenCollectedHeap::gc_stats(int level) const { + return _gens[level]->gc_stats(); +} + +void GenCollectedHeap::verify(bool allow_dirty, bool silent) { + if (!silent) { + gclog_or_tty->print("permgen "); + } + perm_gen()->verify(allow_dirty); + for (int i = _n_gens-1; i >= 0; i--) { + Generation* g = _gens[i]; + if (!silent) { + gclog_or_tty->print(g->name()); + gclog_or_tty->print(" "); + } + g->verify(allow_dirty); + } + if (!silent) { + gclog_or_tty->print("remset "); + } + rem_set()->verify(); + if (!silent) { + gclog_or_tty->print("ref_proc "); + } + ReferenceProcessor::verify(); +} + +void GenCollectedHeap::print() const { print_on(tty); } +void GenCollectedHeap::print_on(outputStream* st) const { + for (int i = 0; i < _n_gens; i++) { + _gens[i]->print_on(st); + } + perm_gen()->print_on(st); +} + +void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { + if (workers() != NULL) { + workers()->threads_do(tc); + } +#ifndef SERIALGC + if (UseConcMarkSweepGC) { + ConcurrentMarkSweepThread::threads_do(tc); + } +#endif // SERIALGC +} + +void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { +#ifndef SERIALGC + if (UseParNewGC) { + workers()->print_worker_threads_on(st); + } + if (UseConcMarkSweepGC) { + ConcurrentMarkSweepThread::print_all_on(st); + } +#endif // SERIALGC +} + +void GenCollectedHeap::print_tracing_info() const { + if (TraceGen0Time) { + get_gen(0)->print_summary_info(); + } + if (TraceGen1Time) { + get_gen(1)->print_summary_info(); + } +} + +void GenCollectedHeap::print_heap_change(size_t prev_used) const { + if (PrintGCDetails && Verbose) { + gclog_or_tty->print(" " SIZE_FORMAT + "->" SIZE_FORMAT + "(" SIZE_FORMAT ")", + prev_used, used(), capacity()); + } else { + gclog_or_tty->print(" " SIZE_FORMAT "K" + "->" SIZE_FORMAT "K" + "(" SIZE_FORMAT "K)", + prev_used / K, used() / K, capacity() / K); + } +} + +//New method to print perm gen info with PrintGCDetails flag +void GenCollectedHeap::print_perm_heap_change(size_t perm_prev_used) const { + gclog_or_tty->print(", [%s :", perm_gen()->short_name()); + perm_gen()->print_heap_change(perm_prev_used); + gclog_or_tty->print("]"); +} + +class GenGCPrologueClosure: public GenCollectedHeap::GenClosure { + private: + bool _full; + public: + void do_generation(Generation* gen) { + gen->gc_prologue(_full); + } + GenGCPrologueClosure(bool full) : _full(full) {}; +}; + +void GenCollectedHeap::gc_prologue(bool full) { + assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); + + always_do_update_barrier = false; + // Fill TLAB's and such + CollectedHeap::accumulate_statistics_all_tlabs(); + ensure_parsability(true); // retire TLABs + + // Call allocation profiler + AllocationProfiler::iterate_since_last_gc(); + // Walk generations + GenGCPrologueClosure blk(full); + generation_iterate(&blk, false); // not old-to-young. + perm_gen()->gc_prologue(full); +}; + +class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure { + private: + bool _full; + public: + void do_generation(Generation* gen) { + gen->gc_epilogue(_full); + } + GenGCEpilogueClosure(bool full) : _full(full) {}; +}; + +void GenCollectedHeap::gc_epilogue(bool full) { + // Remember if a partial collection of the heap failed, and + // we did a complete collection. + if (full && incremental_collection_will_fail()) { + set_last_incremental_collection_failed(); + } else { + clear_last_incremental_collection_failed(); + } + // Clear the flag, if set; the generation gc_epilogues will set the + // flag again if the condition persists despite the collection. + clear_incremental_collection_will_fail(); + +#ifdef COMPILER2 + assert(DerivedPointerTable::is_empty(), "derived pointer present"); + size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr())); + guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps"); +#endif /* COMPILER2 */ + + resize_all_tlabs(); + + GenGCEpilogueClosure blk(full); + generation_iterate(&blk, false); // not old-to-young. + perm_gen()->gc_epilogue(full); + + always_do_update_barrier = UseConcMarkSweepGC; +}; + +class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure { + public: + void do_generation(Generation* gen) { + gen->ensure_parsability(); + } +}; + +void GenCollectedHeap::ensure_parsability(bool retire_tlabs) { + CollectedHeap::ensure_parsability(retire_tlabs); + GenEnsureParsabilityClosure ep_cl; + generation_iterate(&ep_cl, false); + perm_gen()->ensure_parsability(); +} + +oop GenCollectedHeap::handle_failed_promotion(Generation* gen, + oop obj, + size_t obj_size, + oop* ref) { + assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); + HeapWord* result = NULL; + + // First give each higher generation a chance to allocate the promoted object. + Generation* allocator = next_gen(gen); + if (allocator != NULL) { + do { + result = allocator->allocate(obj_size, false); + } while (result == NULL && (allocator = next_gen(allocator)) != NULL); + } + + if (result == NULL) { + // Then give gen and higher generations a chance to expand and allocate the + // object. + do { + result = gen->expand_and_allocate(obj_size, false); + } while (result == NULL && (gen = next_gen(gen)) != NULL); + } + + if (result != NULL) { + Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); + } + return oop(result); +} + +class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure { + jlong _time; // in ms + jlong _now; // in ms + + public: + GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { } + + jlong time() { return _time; } + + void do_generation(Generation* gen) { + _time = MIN2(_time, gen->time_of_last_gc(_now)); + } +}; + +jlong GenCollectedHeap::millis_since_last_gc() { + jlong now = os::javaTimeMillis(); + GenTimeOfLastGCClosure tolgc_cl(now); + // iterate over generations getting the oldest + // time that a generation was collected + generation_iterate(&tolgc_cl, false); + tolgc_cl.do_generation(perm_gen()); + // XXX Despite the assert above, since javaTimeMillis() + // doesnot guarantee monotonically increasing return + // values (note, i didn't say "strictly monotonic"), + // we need to guard against getting back a time + // later than now. This should be fixed by basing + // on someting like gethrtime() which guarantees + // monotonicity. Note that cond_wait() is susceptible + // to a similar problem, because its interface is + // based on absolute time in the form of the + // system time's notion of UCT. See also 4506635 + // for yet another problem of similar nature. XXX + jlong retVal = now - tolgc_cl.time(); + if (retVal < 0) { + NOT_PRODUCT(warning("time warp: %d", retVal);) + return 0; + } + return retVal; +}