diff -r 000000000000 -r f90c822e73f8 src/share/vm/memory/genCollectedHeap.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/memory/genCollectedHeap.cpp Wed Apr 27 01:25:04 2016 +0800 @@ -0,0 +1,1298 @@ +/* + * Copyright (c) 2000, 2014, 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 "classfile/symbolTable.hpp" +#include "classfile/systemDictionary.hpp" +#include "classfile/vmSymbols.hpp" +#include "code/icBuffer.hpp" +#include "gc_implementation/shared/collectorCounters.hpp" +#include "gc_implementation/shared/gcTraceTime.hpp" +#include "gc_implementation/shared/vmGCOperations.hpp" +#include "gc_interface/collectedHeap.inline.hpp" +#include "memory/filemap.hpp" +#include "memory/gcLocker.inline.hpp" +#include "memory/genCollectedHeap.hpp" +#include "memory/genOopClosures.inline.hpp" +#include "memory/generation.inline.hpp" +#include "memory/generationSpec.hpp" +#include "memory/resourceArea.hpp" +#include "memory/sharedHeap.hpp" +#include "memory/space.hpp" +#include "oops/oop.inline.hpp" +#include "oops/oop.inline2.hpp" +#include "runtime/biasedLocking.hpp" +#include "runtime/fprofiler.hpp" +#include "runtime/handles.hpp" +#include "runtime/handles.inline.hpp" +#include "runtime/java.hpp" +#include "runtime/vmThread.hpp" +#include "services/memoryService.hpp" +#include "utilities/vmError.hpp" +#include "utilities/workgroup.hpp" +#include "utilities/macros.hpp" +#if INCLUDE_ALL_GCS +#include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" +#include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp" +#endif // INCLUDE_ALL_GCS + +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"); +} + +jint GenCollectedHeap::initialize() { + CollectedHeap::pre_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 gen_alignment = Generation::GenGrain; + + _gen_specs = gen_policy()->generations(); + + // Make sure the sizes are all aligned. + for (i = 0; i < _n_gens; i++) { + _gen_specs[i]->align(gen_alignment); + } + + // Allocate space for the heap. + + char* heap_address; + size_t total_reserved = 0; + int n_covered_regions = 0; + ReservedSpace heap_rs; + + size_t heap_alignment = collector_policy()->heap_alignment(); + + heap_address = allocate(heap_alignment, &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(); + _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(), false, false); + _gens[i] = _gen_specs[i]->init(this_rs, i, rem_set()); + heap_rs = heap_rs.last_part(_gen_specs[i]->max_size()); + } + clear_incremental_collection_failed(); + +#if INCLUDE_ALL_GCS + // 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 // INCLUDE_ALL_GCS + + return JNI_OK; +} + + +char* GenCollectedHeap::allocate(size_t alignment, + 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(); + + assert(alignment % pageSize == 0, "Must be"); + + 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 % alignment == 0, + err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment=" + SIZE_FORMAT, total_reserved, alignment)); + + // Needed until the cardtable is fixed to have the right number + // of covered regions. + n_covered_regions += 2; + + *_total_reserved = total_reserved; + *_n_covered_regions = n_covered_regions; + + *heap_rs = Universe::reserve_heap(total_reserved, alignment); + return heap_rs->base(); +} + + +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. +void GenCollectedHeap::save_used_regions(int level) { + assert(level < _n_gens, "Illegal level parameter"); + for (int i = level; i >= 0; i--) { + _gens[i]->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* gc_overhead_limit_was_exceeded) { + return collector_policy()->mem_allocate_work(size, + false /* 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 UseConcMarkSweepGC && + ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) || + (cause == GCCause::_java_lang_system_gc && 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 bool do_clear_all_soft_refs = clear_all_soft_refs || + collector_policy()->should_clear_all_soft_refs(); + + ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); + + const size_t metadata_prev_used = MetaspaceAux::used_bytes(); + + print_heap_before_gc(); + + { + FlagSetting fl(_is_gc_active, true); + + bool complete = full && (max_level == (n_gens()-1)); + const char* gc_cause_prefix = complete ? "Full GC" : "GC"; + gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); + TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); + GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL); + + 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)) { + if (i == n_gens() - 1) { // a major collection is to happen + if (!complete) { + // The full_collections increment was missed above. + increment_total_full_collections(); + } + pre_full_gc_dump(NULL); // do any pre full gc dumps + } + // Timer for individual generations. Last argument is false: no CR + // FIXME: We should try to start the timing earlier to cover more of the GC pause + GCTraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, NULL); + TraceCollectorStats tcs(_gens[i]->counters()); + TraceMemoryManagerStats tmms(_gens[i]->kind(),gc_cause()); + + size_t prev_used = _gens[i]->used(); + _gens[i]->stat_record()->invocations++; + _gens[i]->stat_record()->accumulated_time.start(); + + // Must be done anew before each collection because + // a previous collection will do mangling and will + // change top of some spaces. + record_gen_tops_before_GC(); + + 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; + } + Universe::verify(" VerifyBeforeGC:"); + } + 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->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); + rp->setup_policy(do_clear_all_soft_refs); + } else { + // collect() below will enable discovery as appropriate + } + _gens[i]->collect(full, do_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 + Universe::verify(" VerifyAfterGC:"); + } + + 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 (complete) { // We did a "major" collection + // FIXME: See comment at pre_full_gc_dump call + post_full_gc_dump(NULL); // do any post full gc dumps + } + + if (PrintGCDetails) { + print_heap_change(gch_prev_used); + + // Print metaspace info for full GC with PrintGCDetails flag. + if (complete) { + MetaspaceAux::print_metaspace_change(metadata_prev_used); + } + } + + for (int j = max_level_collected; j >= 0; j -= 1) { + // Adjust generation sizes. + _gens[j]->compute_new_size(); + } + + if (complete) { + // Delete metaspaces for unloaded class loaders and clean up loader_data graph + ClassLoaderDataGraph::purge(); + MetaspaceAux::verify_metrics(); + // Resize the metaspace capacity after full collections + MetaspaceGC::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()); + + print_heap_after_gc(); + +#ifdef TRACESPINNING + ParallelTaskTerminator::print_termination_counts(); +#endif +} + +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(uint t) { + SharedHeap::set_par_threads(t); + _gen_process_strong_tasks->set_n_threads(t); +} + +void GenCollectedHeap:: +gen_process_strong_roots(int level, + bool younger_gens_as_roots, + bool activate_scope, + bool is_scavenging, + SharedHeap::ScanningOption so, + OopsInGenClosure* not_older_gens, + bool do_code_roots, + OopsInGenClosure* older_gens, + KlassClosure* klass_closure) { + // General strong roots. + + if (!do_code_roots) { + SharedHeap::process_strong_roots(activate_scope, is_scavenging, so, + not_older_gens, NULL, klass_closure); + } else { + bool do_code_marking = (activate_scope || nmethod::oops_do_marking_is_active()); + CodeBlobToOopClosure code_roots(not_older_gens, /*do_marking=*/ do_code_marking); + SharedHeap::process_strong_roots(activate_scope, is_scavenging, so, + not_older_gens, &code_roots, klass_closure); + } + + 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, + CodeBlobClosure* code_roots) { + SharedHeap::process_weak_roots(root_closure, code_roots); + // "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); \ + } \ +} + +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 true; +} + +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)) { +#if INCLUDE_ALL_GCS + // mostly concurrent full collection + collect_mostly_concurrent(cause); +#else // INCLUDE_ALL_GCS + ShouldNotReachHere(); +#endif // INCLUDE_ALL_GCS + } 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); +} + +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) { + // 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); + } +} + +#if INCLUDE_ALL_GCS +bool GenCollectedHeap::create_cms_collector() { + + assert(((_gens[1]->kind() == Generation::ConcurrentMarkSweep) || + (_gens[1]->kind() == Generation::ASConcurrentMarkSweep)), + "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], + _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 // INCLUDE_ALL_GCS + +void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { + do_full_collection(clear_all_soft_refs, _n_gens - 1); +} + +void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, + int max_level) { + int local_max_level; + if (!incremental_collection_will_fail(false /* don't consult_young */) && + 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(false /* don't consult_young */)) { + 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 */); + } +} + +bool GenCollectedHeap::is_in_young(oop p) { + bool result = ((HeapWord*)p) < _gens[_n_gens - 1]->reserved().start(); + assert(result == _gens[0]->is_in_reserved(p), + err_msg("incorrect test - result=%d, p=" PTR_FORMAT, result, p2i((void*)p))); + return result; +} + +// Returns "TRUE" iff "p" points into the committed areas of the heap. +bool GenCollectedHeap::is_in(const void* p) const { + #ifndef ASSERT + guarantee(VerifyBeforeGC || + VerifyDuringGC || + VerifyBeforeExit || + VerifyDuringStartup || + PrintAssembly || + tty->count() != 0 || // already printing + VerifyAfterGC || + VMError::fatal_error_in_progress(), "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; + } + // Otherwise... + return false; +} + +#ifdef ASSERT +// Don't implement this by using is_in_young(). This method is used +// in some cases to check that is_in_young() is correct. +bool GenCollectedHeap::is_in_partial_collection(const void* p) { + assert(is_in_reserved(p) || p == NULL, + "Does not work if address is non-null and outside of the heap"); + return p < _gens[_n_gens - 2]->reserved().end() && p != NULL; +} +#endif + +void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) { + for (int i = 0; i < _n_gens; i++) { + _gens[i]->oop_iterate(cl); + } +} + +void GenCollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* 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); + } +} + +void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { + for (int i = 0; i < _n_gens; i++) { + _gens[i]->safe_object_iterate(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; + } + // 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); + } + } + 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); + } + } + 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); + } + } + 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::tlab_used(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_used(); + } + } + 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; + return collector_policy()->mem_allocate_work(size /* size */, + true /* is_tlab */, + &gc_overhead_limit_was_exceeded); +} + +// 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; +} + +void GenCollectedHeap::release_scratch() { + for (int i = 0; i < _n_gens; i++) { + _gens[i]->reset_scratch(); + } +} + +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); +} + + +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); + } +} + +bool GenCollectedHeap::is_maximal_no_gc() const { + for (int i = 0; i < _n_gens; i++) { + 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(); + } +} + +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() { + guarantee(_n_gens = 2, "Wrong number of generations"); + Generation* old_gen = _gens[1]; + // Start by compacting into same gen. + CompactPoint cp(old_gen, NULL, NULL); + old_gen->prepare_for_compaction(&cp); + Generation* young_gen = _gens[0]; + young_gen->prepare_for_compaction(&cp); +} + +GCStats* GenCollectedHeap::gc_stats(int level) const { + return _gens[level]->gc_stats(); +} + +void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) { + for (int i = _n_gens-1; i >= 0; i--) { + Generation* g = _gens[i]; + if (!silent) { + gclog_or_tty->print("%s", g->name()); + gclog_or_tty->print(" "); + } + g->verify(); + } + if (!silent) { + gclog_or_tty->print("remset "); + } + rem_set()->verify(); +} + +void GenCollectedHeap::print_on(outputStream* st) const { + for (int i = 0; i < _n_gens; i++) { + _gens[i]->print_on(st); + } + MetaspaceAux::print_on(st); +} + +void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { + if (workers() != NULL) { + workers()->threads_do(tc); + } +#if INCLUDE_ALL_GCS + if (UseConcMarkSweepGC) { + ConcurrentMarkSweepThread::threads_do(tc); + } +#endif // INCLUDE_ALL_GCS +} + +void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { +#if INCLUDE_ALL_GCS + if (UseParNewGC) { + workers()->print_worker_threads_on(st); + } + if (UseConcMarkSweepGC) { + ConcurrentMarkSweepThread::print_all_on(st); + } +#endif // INCLUDE_ALL_GCS +} + +void GenCollectedHeap::print_on_error(outputStream* st) const { + this->CollectedHeap::print_on_error(st); + +#if INCLUDE_ALL_GCS + if (UseConcMarkSweepGC) { + st->cr(); + CMSCollector::print_on_error(st); + } +#endif // INCLUDE_ALL_GCS +} + +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); + } +} + +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 + + // Walk generations + GenGCPrologueClosure blk(full); + generation_iterate(&blk, false); // not old-to-young. +}; + +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) { +#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. + + if (!CleanChunkPoolAsync) { + Chunk::clean_chunk_pool(); + } + + MetaspaceCounters::update_performance_counters(); + CompressedClassSpaceCounters::update_performance_counters(); + + always_do_update_barrier = UseConcMarkSweepGC; +}; + +#ifndef PRODUCT +class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure { + private: + public: + void do_generation(Generation* gen) { + gen->record_spaces_top(); + } +}; + +void GenCollectedHeap::record_gen_tops_before_GC() { + if (ZapUnusedHeapArea) { + GenGCSaveTopsBeforeGCClosure blk; + generation_iterate(&blk, false); // not old-to-young. + } +} +#endif // not PRODUCT + +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); +} + +oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen, + oop obj, + size_t obj_size) { + guarantee(old_gen->level() == 1, "We only get here with an old generation"); + assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); + HeapWord* result = NULL; + + result = old_gen->expand_and_allocate(obj_size, false); + + 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() { + // We need a monotonically non-deccreasing time in ms but + // os::javaTimeMillis() does not guarantee monotonicity. + jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; + GenTimeOfLastGCClosure tolgc_cl(now); + // iterate over generations getting the oldest + // time that a generation was collected + generation_iterate(&tolgc_cl, false); + + // javaTimeNanos() is guaranteed to be monotonically non-decreasing + // provided the underlying platform provides such a time source + // (and it is bug free). So we still have to guard against getting + // back a time later than 'now'. + jlong retVal = now - tolgc_cl.time(); + if (retVal < 0) { + NOT_PRODUCT(warning("time warp: "INT64_FORMAT, (int64_t) retVal);) + return 0; + } + return retVal; +}