/* * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "precompiled.hpp" #include "aot/aotLoader.hpp" #include "classfile/symbolTable.hpp" #include "classfile/stringTable.hpp" #include "classfile/systemDictionary.hpp" #include "classfile/vmSymbols.hpp" #include "code/codeCache.hpp" #include "code/icBuffer.hpp" #include "gc/serial/defNewGeneration.hpp" #include "gc/shared/adaptiveSizePolicy.hpp" #include "gc/shared/cardTableBarrierSet.hpp" #include "gc/shared/cardTableRS.hpp" #include "gc/shared/collectedHeap.inline.hpp" #include "gc/shared/collectorCounters.hpp" #include "gc/shared/gcId.hpp" #include "gc/shared/gcLocker.hpp" #include "gc/shared/gcPolicyCounters.hpp" #include "gc/shared/gcTrace.hpp" #include "gc/shared/gcTraceTime.inline.hpp" #include "gc/shared/genCollectedHeap.hpp" #include "gc/shared/genOopClosures.inline.hpp" #include "gc/shared/generationSpec.hpp" #include "gc/shared/space.hpp" #include "gc/shared/strongRootsScope.hpp" #include "gc/shared/vmGCOperations.hpp" #include "gc/shared/weakProcessor.hpp" #include "gc/shared/workgroup.hpp" #include "memory/filemap.hpp" #include "memory/metaspaceCounters.hpp" #include "memory/resourceArea.hpp" #include "oops/oop.inline.hpp" #include "runtime/biasedLocking.hpp" #include "runtime/flags/flagSetting.hpp" #include "runtime/handles.hpp" #include "runtime/handles.inline.hpp" #include "runtime/java.hpp" #include "runtime/vmThread.hpp" #include "services/management.hpp" #include "services/memoryService.hpp" #include "utilities/debug.hpp" #include "utilities/formatBuffer.hpp" #include "utilities/macros.hpp" #include "utilities/stack.inline.hpp" #include "utilities/vmError.hpp" GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy, Generation::Name young, Generation::Name old, const char* policy_counters_name) : CollectedHeap(), _rem_set(NULL), _young_gen_spec(new GenerationSpec(young, policy->initial_young_size(), policy->max_young_size(), policy->gen_alignment())), _old_gen_spec(new GenerationSpec(old, policy->initial_old_size(), policy->max_old_size(), policy->gen_alignment())), _gen_policy(policy), _soft_ref_gen_policy(), _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)), _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)), _full_collections_completed(0) { } jint GenCollectedHeap::initialize() { // 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"); // Allocate space for the heap. char* heap_address; ReservedSpace heap_rs; size_t heap_alignment = collector_policy()->heap_alignment(); heap_address = allocate(heap_alignment, &heap_rs); if (!heap_rs.is_reserved()) { vm_shutdown_during_initialization( "Could not reserve enough space for object heap"); return JNI_ENOMEM; } initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); _rem_set = create_rem_set(reserved_region()); _rem_set->initialize(); CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set); bs->initialize(); BarrierSet::set_barrier_set(bs); ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size(), false, false); _young_gen = _young_gen_spec->init(young_rs, rem_set()); heap_rs = heap_rs.last_part(_young_gen_spec->max_size()); ReservedSpace old_rs = heap_rs.first_part(_old_gen_spec->max_size(), false, false); _old_gen = _old_gen_spec->init(old_rs, rem_set()); clear_incremental_collection_failed(); return JNI_OK; } CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) { return new CardTableRS(reserved_region, false /* scan_concurrently */); } void GenCollectedHeap::initialize_size_policy(size_t init_eden_size, size_t init_promo_size, size_t init_survivor_size) { const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0; _size_policy = new AdaptiveSizePolicy(init_eden_size, init_promo_size, init_survivor_size, max_gc_pause_sec, GCTimeRatio); } char* GenCollectedHeap::allocate(size_t alignment, ReservedSpace* heap_rs){ // Now figure out the total size. const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size(); assert(alignment % pageSize == 0, "Must be"); // Check for overflow. size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size(); if (total_reserved < _young_gen_spec->max_size()) { vm_exit_during_initialization("The size of the object heap + VM data exceeds " "the maximum representable size"); } assert(total_reserved % alignment == 0, "Gen size; total_reserved=" SIZE_FORMAT ", alignment=" SIZE_FORMAT, total_reserved, alignment); *heap_rs = Universe::reserve_heap(total_reserved, alignment); os::trace_page_sizes("Heap", collector_policy()->min_heap_byte_size(), total_reserved, alignment, heap_rs->base(), heap_rs->size()); return heap_rs->base(); } void GenCollectedHeap::post_initialize() { CollectedHeap::post_initialize(); ref_processing_init(); DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen; initialize_size_policy(def_new_gen->eden()->capacity(), _old_gen->capacity(), def_new_gen->from()->capacity()); MarkSweep::initialize(); } void GenCollectedHeap::ref_processing_init() { _young_gen->ref_processor_init(); _old_gen->ref_processor_init(); } GenerationSpec* GenCollectedHeap::young_gen_spec() const { return _young_gen_spec; } GenerationSpec* GenCollectedHeap::old_gen_spec() const { return _old_gen_spec; } size_t GenCollectedHeap::capacity() const { return _young_gen->capacity() + _old_gen->capacity(); } size_t GenCollectedHeap::used() const { return _young_gen->used() + _old_gen->used(); } void GenCollectedHeap::save_used_regions() { _old_gen->save_used_region(); _young_gen->save_used_region(); } size_t GenCollectedHeap::max_capacity() const { return _young_gen->max_capacity() + _old_gen->max_capacity(); } // 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; } // Return true if any of the following is true: // . the allocation won't fit into the current young gen heap // . gc locker is occupied (jni critical section) // . heap memory is tight -- the most recent previous collection // was a full collection because a partial collection (would // have) failed and is likely to fail again bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const { size_t young_capacity = _young_gen->capacity_before_gc(); return (word_size > heap_word_size(young_capacity)) || GCLocker::is_active_and_needs_gc() || incremental_collection_failed(); } HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) { HeapWord* result = NULL; if (_old_gen->should_allocate(size, is_tlab)) { result = _old_gen->expand_and_allocate(size, is_tlab); } if (result == NULL) { if (_young_gen->should_allocate(size, is_tlab)) { result = _young_gen->expand_and_allocate(size, is_tlab); } } assert(result == NULL || is_in_reserved(result), "result not in heap"); return result; } HeapWord* GenCollectedHeap::mem_allocate_work(size_t size, bool is_tlab, bool* gc_overhead_limit_was_exceeded) { debug_only(check_for_valid_allocation_state()); assert(no_gc_in_progress(), "Allocation during gc not allowed"); // In general gc_overhead_limit_was_exceeded should be false so // set it so here and reset it to true only if the gc time // limit is being exceeded as checked below. *gc_overhead_limit_was_exceeded = false; HeapWord* result = NULL; // Loop until the allocation is satisfied, or unsatisfied after GC. for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) { HandleMark hm; // Discard any handles allocated in each iteration. // First allocation attempt is lock-free. Generation *young = _young_gen; assert(young->supports_inline_contig_alloc(), "Otherwise, must do alloc within heap lock"); if (young->should_allocate(size, is_tlab)) { result = young->par_allocate(size, is_tlab); if (result != NULL) { assert(is_in_reserved(result), "result not in heap"); return result; } } uint gc_count_before; // Read inside the Heap_lock locked region. { MutexLocker ml(Heap_lock); log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation"); // Note that only large objects get a shot at being // allocated in later generations. bool first_only = !should_try_older_generation_allocation(size); result = attempt_allocation(size, is_tlab, first_only); if (result != NULL) { assert(is_in_reserved(result), "result not in heap"); return result; } if (GCLocker::is_active_and_needs_gc()) { if (is_tlab) { return NULL; // Caller will retry allocating individual object. } if (!is_maximal_no_gc()) { // Try and expand heap to satisfy request. result = expand_heap_and_allocate(size, is_tlab); // Result could be null if we are out of space. if (result != NULL) { return result; } } if (gclocker_stalled_count > GCLockerRetryAllocationCount) { return NULL; // We didn't get to do a GC and we didn't get any memory. } // If this thread is not in a jni critical section, we stall // the requestor until the critical section has cleared and // GC allowed. When the critical section clears, a GC is // initiated by the last thread exiting the critical section; so // we retry the allocation sequence from the beginning of the loop, // rather than causing more, now probably unnecessary, GC attempts. JavaThread* jthr = JavaThread::current(); if (!jthr->in_critical()) { MutexUnlocker mul(Heap_lock); // Wait for JNI critical section to be exited GCLocker::stall_until_clear(); gclocker_stalled_count += 1; continue; } else { if (CheckJNICalls) { fatal("Possible deadlock due to allocating while" " in jni critical section"); } return NULL; } } // Read the gc count while the heap lock is held. gc_count_before = total_collections(); } VM_GenCollectForAllocation op(size, is_tlab, gc_count_before); VMThread::execute(&op); if (op.prologue_succeeded()) { result = op.result(); if (op.gc_locked()) { assert(result == NULL, "must be NULL if gc_locked() is true"); continue; // Retry and/or stall as necessary. } // Allocation has failed and a collection // has been done. If the gc time limit was exceeded the // this time, return NULL so that an out-of-memory // will be thrown. Clear gc_overhead_limit_exceeded // so that the overhead exceeded does not persist. const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded(); const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear(); if (limit_exceeded && softrefs_clear) { *gc_overhead_limit_was_exceeded = true; size_policy()->set_gc_overhead_limit_exceeded(false); if (op.result() != NULL) { CollectedHeap::fill_with_object(op.result(), size); } return NULL; } assert(result == NULL || is_in_reserved(result), "result not in heap"); return result; } // Give a warning if we seem to be looping forever. if ((QueuedAllocationWarningCount > 0) && (try_count % QueuedAllocationWarningCount == 0)) { log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times," " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : ""); } } } #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 = NULL; if (_young_gen->should_allocate(size, is_tlab)) { res = _young_gen->allocate(size, is_tlab); if (res != NULL || first_only) { return res; } } if (_old_gen->should_allocate(size, is_tlab)) { res = _old_gen->allocate(size, is_tlab); } return res; } HeapWord* GenCollectedHeap::mem_allocate(size_t size, bool* gc_overhead_limit_was_exceeded) { return mem_allocate_work(size, false /* is_tlab */, gc_overhead_limit_was_exceeded); } bool GenCollectedHeap::must_clear_all_soft_refs() { return _gc_cause == GCCause::_metadata_GC_clear_soft_refs || _gc_cause == GCCause::_wb_full_gc; } void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size, bool is_tlab, bool run_verification, bool clear_soft_refs, bool restore_marks_for_biased_locking) { FormatBuffer<> title("Collect gen: %s", gen->short_name()); GCTraceTime(Trace, gc, phases) t1(title); TraceCollectorStats tcs(gen->counters()); TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause()); gen->stat_record()->invocations++; gen->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(); log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize); if (run_verification && VerifyBeforeGC) { HandleMark hm; // Discard invalid handles created during verification Universe::verify("Before GC"); } COMPILER2_PRESENT(DerivedPointerTable::clear()); if (restore_marks_for_biased_locking) { // 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 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 = gen->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(); rp->setup_policy(clear_soft_refs); } else { // collect() below will enable discovery as appropriate } gen->collect(full, clear_soft_refs, size, is_tlab); if (!rp->enqueuing_is_done()) { ReferenceProcessorPhaseTimes pt(NULL, rp->num_queues()); rp->enqueue_discovered_references(NULL, &pt); pt.print_enqueue_phase(); } else { rp->set_enqueuing_is_done(false); } rp->verify_no_references_recorded(); } COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); gen->stat_record()->accumulated_time.stop(); update_gc_stats(gen, full); if (run_verification && VerifyAfterGC) { HandleMark hm; // Discard invalid handles created during verification Universe::verify("After GC"); } } void GenCollectedHeap::do_collection(bool full, bool clear_all_soft_refs, size_t size, bool is_tlab, GenerationType max_generation) { 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"); if (GCLocker::check_active_before_gc()) { return; // GC is disabled (e.g. JNI GetXXXCritical operation) } GCIdMark gc_id_mark; const bool do_clear_all_soft_refs = clear_all_soft_refs || soft_ref_policy()->should_clear_all_soft_refs(); ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy()); const size_t metadata_prev_used = MetaspaceUtils::used_bytes(); print_heap_before_gc(); { FlagSetting fl(_is_gc_active, true); bool complete = full && (max_generation == OldGen); bool old_collects_young = complete && !ScavengeBeforeFullGC; bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab); FormatBuffer<> gc_string("%s", "Pause "); if (do_young_collection) { gc_string.append("Young"); } else { gc_string.append("Full"); } GCTraceCPUTime tcpu; GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true); gc_prologue(complete); increment_total_collections(complete); size_t young_prev_used = _young_gen->used(); size_t old_prev_used = _old_gen->used(); bool run_verification = total_collections() >= VerifyGCStartAt; bool prepared_for_verification = false; bool collected_old = false; if (do_young_collection) { if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) { prepare_for_verify(); prepared_for_verification = true; } collect_generation(_young_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 0, do_clear_all_soft_refs, false); if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) && size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) { // Allocation request was met by young GC. size = 0; } } bool must_restore_marks_for_biased_locking = false; if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) { if (!complete) { // The full_collections increment was missed above. increment_total_full_collections(); } if (!prepared_for_verification && run_verification && VerifyGCLevel <= 1 && VerifyBeforeGC) { prepare_for_verify(); } if (do_young_collection) { // We did a young GC. Need a new GC id for the old GC. GCIdMark gc_id_mark; GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true); collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); } else { // No young GC done. Use the same GC id as was set up earlier in this method. collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); } must_restore_marks_for_biased_locking = true; collected_old = true; } // Update "complete" boolean wrt what actually transpired -- // for instance, a promotion failure could have led to // a whole heap collection. complete = complete || collected_old; print_heap_change(young_prev_used, old_prev_used); MetaspaceUtils::print_metaspace_change(metadata_prev_used); // Adjust generation sizes. if (collected_old) { _old_gen->compute_new_size(); } _young_gen->compute_new_size(); if (complete) { // Delete metaspaces for unloaded class loaders and clean up loader_data graph ClassLoaderDataGraph::purge(); MetaspaceUtils::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(); } } print_heap_after_gc(); #ifdef TRACESPINNING ParallelTaskTerminator::print_termination_counts(); #endif } void GenCollectedHeap::register_nmethod(nmethod* nm) { CodeCache::register_scavenge_root_nmethod(nm); } void GenCollectedHeap::verify_nmethod(nmethod* nm) { CodeCache::verify_scavenge_root_nmethod(nm); } HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { GCCauseSetter x(this, GCCause::_allocation_failure); HeapWord* result = NULL; assert(size != 0, "Precondition violated"); if (GCLocker::is_active_and_needs_gc()) { // GC locker is active; instead of a collection we will attempt // to expand the heap, if there's room for expansion. if (!is_maximal_no_gc()) { result = expand_heap_and_allocate(size, is_tlab); } return result; // Could be null if we are out of space. } else if (!incremental_collection_will_fail(false /* don't consult_young */)) { // Do an incremental collection. do_collection(false, // full false, // clear_all_soft_refs size, // size is_tlab, // is_tlab GenCollectedHeap::OldGen); // max_generation } else { log_trace(gc)(" :: Trying full because partial may fail :: "); // Try a full collection; see delta for bug id 6266275 // for the original code and why this has been simplified // with from-space allocation criteria modified and // such allocation moved out of the safepoint path. do_collection(true, // full false, // clear_all_soft_refs size, // size is_tlab, // is_tlab GenCollectedHeap::OldGen); // max_generation } result = attempt_allocation(size, is_tlab, false /*first_only*/); if (result != NULL) { assert(is_in_reserved(result), "result not in heap"); return result; } // OK, collection failed, try expansion. result = expand_heap_and_allocate(size, is_tlab); if (result != NULL) { return result; } // If we reach this point, we're really out of memory. Try every trick // we can to reclaim memory. Force collection of soft references. Force // a complete compaction of the heap. Any additional methods for finding // free memory should be here, especially if they are expensive. If this // attempt fails, an OOM exception will be thrown. { UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted do_collection(true, // full true, // clear_all_soft_refs size, // size is_tlab, // is_tlab GenCollectedHeap::OldGen); // max_generation } result = attempt_allocation(size, is_tlab, false /* first_only */); if (result != NULL) { assert(is_in_reserved(result), "result not in heap"); return result; } assert(!soft_ref_policy()->should_clear_all_soft_refs(), "Flag should have been handled and cleared prior to this point"); // What else? We might try synchronous finalization later. If the total // space available is large enough for the allocation, then a more // complete compaction phase than we've tried so far might be // appropriate. return NULL; } #ifdef ASSERT class AssertNonScavengableClosure: public OopClosure { public: virtual void do_oop(oop* p) { assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p), "Referent should not be scavengable."); } virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } }; static AssertNonScavengableClosure assert_is_non_scavengable_closure; #endif void GenCollectedHeap::process_roots(StrongRootsScope* scope, ScanningOption so, OopClosure* strong_roots, OopClosure* weak_roots, CLDClosure* strong_cld_closure, CLDClosure* weak_cld_closure, CodeBlobToOopClosure* code_roots) { // General roots. assert(Threads::thread_claim_parity() != 0, "must have called prologue code"); assert(code_roots != NULL, "code root closure should always be set"); // _n_termination for _process_strong_tasks should be set up stream // in a method not running in a GC worker. Otherwise the GC worker // could be trying to change the termination condition while the task // is executing in another GC worker. if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) { ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure); } // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots; bool is_par = scope->n_threads() > 1; Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p); if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) { Universe::oops_do(strong_roots); } // Global (strong) JNI handles if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) { JNIHandles::oops_do(strong_roots); } if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) { ObjectSynchronizer::oops_do(strong_roots); } if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) { Management::oops_do(strong_roots); } if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) { JvmtiExport::oops_do(strong_roots); } if (UseAOT && !_process_strong_tasks->is_task_claimed(GCH_PS_aot_oops_do)) { AOTLoader::oops_do(strong_roots); } if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) { SystemDictionary::roots_oops_do(strong_roots, weak_roots); } if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) { if (so & SO_ScavengeCodeCache) { assert(code_roots != NULL, "must supply closure for code cache"); // We only visit parts of the CodeCache when scavenging. CodeCache::scavenge_root_nmethods_do(code_roots); } if (so & SO_AllCodeCache) { assert(code_roots != NULL, "must supply closure for code cache"); // CMSCollector uses this to do intermediate-strength collections. // We scan the entire code cache, since CodeCache::do_unloading is not called. CodeCache::blobs_do(code_roots); } // Verify that the code cache contents are not subject to // movement by a scavenging collection. DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations)); DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable)); } } void GenCollectedHeap::process_string_table_roots(StrongRootsScope* scope, OopClosure* root_closure) { assert(root_closure != NULL, "Must be set"); // All threads execute the following. A specific chunk of buckets // from the StringTable are the individual tasks. if (scope->n_threads() > 1) { StringTable::possibly_parallel_oops_do(root_closure); } else { StringTable::oops_do(root_closure); } } void GenCollectedHeap::young_process_roots(StrongRootsScope* scope, OopsInGenClosure* root_closure, OopsInGenClosure* old_gen_closure, CLDClosure* cld_closure) { MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations); process_roots(scope, SO_ScavengeCodeCache, root_closure, root_closure, cld_closure, cld_closure, &mark_code_closure); process_string_table_roots(scope, root_closure); if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { root_closure->reset_generation(); } // When collection is parallel, all threads get to cooperate to do // old generation scanning. old_gen_closure->set_generation(_old_gen); rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads()); old_gen_closure->reset_generation(); _process_strong_tasks->all_tasks_completed(scope->n_threads()); } void GenCollectedHeap::full_process_roots(StrongRootsScope* scope, bool is_adjust_phase, ScanningOption so, bool only_strong_roots, OopsInGenClosure* root_closure, CLDClosure* cld_closure) { MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase); OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure; CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure); if (is_adjust_phase) { // We never treat the string table as roots during marking // for the full gc, so we only need to process it during // the adjust phase. process_string_table_roots(scope, root_closure); } _process_strong_tasks->all_tasks_completed(scope->n_threads()); } void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { WeakProcessor::oops_do(root_closure); _young_gen->ref_processor()->weak_oops_do(root_closure); _old_gen->ref_processor()->weak_oops_do(root_closure); } bool GenCollectedHeap::no_allocs_since_save_marks() { return _young_gen->no_allocs_since_save_marks() && _old_gen->no_allocs_since_save_marks(); } bool GenCollectedHeap::supports_inline_contig_alloc() const { return _young_gen->supports_inline_contig_alloc(); } HeapWord* volatile* GenCollectedHeap::top_addr() const { return _young_gen->top_addr(); } HeapWord** GenCollectedHeap::end_addr() const { return _young_gen->end_addr(); } // public collection interfaces void GenCollectedHeap::collect(GCCause::Cause cause) { if (cause == GCCause::_wb_young_gc) { // Young collection for the WhiteBox API. collect(cause, YoungGen); } else { #ifdef ASSERT if (cause == GCCause::_scavenge_alot) { // Young collection only. collect(cause, YoungGen); } else { // Stop-the-world full collection. collect(cause, OldGen); } #else // Stop-the-world full collection. collect(cause, OldGen); #endif } } void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) { // 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_generation); } 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, OldGen); } // this is the private collection interface // The Heap_lock is expected to be held on entry. void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) { // 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_generation); VMThread::execute(&op); } } void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { do_full_collection(clear_all_soft_refs, OldGen); } void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, GenerationType last_generation) { GenerationType local_last_generation; if (!incremental_collection_will_fail(false /* don't consult_young */) && gc_cause() == GCCause::_gc_locker) { local_last_generation = YoungGen; } else { local_last_generation = last_generation; } do_collection(true, // full clear_all_soft_refs, // clear_all_soft_refs 0, // size false, // is_tlab local_last_generation); // last_generation // 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_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker && incremental_collection_will_fail(false /* don't consult_young */)) { log_debug(gc, jni)("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 OldGen); // last_generation } } bool GenCollectedHeap::is_in_young(oop p) { bool result = ((HeapWord*)p) < _old_gen->reserved().start(); assert(result == _young_gen->is_in_reserved(p), "incorrect test - result=%d, p=" INTPTR_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 { return _young_gen->is_in(p) || _old_gen->is_in(p); } #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 < _young_gen->reserved().end() && p != NULL; } #endif void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) { NoHeaderExtendedOopClosure no_header_cl(cl); oop_iterate(&no_header_cl); } void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) { _young_gen->oop_iterate(cl); _old_gen->oop_iterate(cl); } void GenCollectedHeap::object_iterate(ObjectClosure* cl) { _young_gen->object_iterate(cl); _old_gen->object_iterate(cl); } void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { _young_gen->safe_object_iterate(cl); _old_gen->safe_object_iterate(cl); } Space* GenCollectedHeap::space_containing(const void* addr) const { Space* res = _young_gen->space_containing(addr); if (res != NULL) { return res; } res = _old_gen->space_containing(addr); assert(res != NULL, "Could not find containing space"); return res; } HeapWord* GenCollectedHeap::block_start(const void* addr) const { assert(is_in_reserved(addr), "block_start of address outside of heap"); if (_young_gen->is_in_reserved(addr)) { assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); return _young_gen->block_start(addr); } assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); return _old_gen->block_start(addr); } size_t GenCollectedHeap::block_size(const HeapWord* addr) const { assert(is_in_reserved(addr), "block_size of address outside of heap"); if (_young_gen->is_in_reserved(addr)) { assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); return _young_gen->block_size(addr); } assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); return _old_gen->block_size(addr); } 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"); if (_young_gen->is_in_reserved(addr)) { return _young_gen->block_is_obj(addr); } assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); return _old_gen->block_is_obj(addr); } bool GenCollectedHeap::supports_tlab_allocation() const { assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); return _young_gen->supports_tlab_allocation(); } size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); if (_young_gen->supports_tlab_allocation()) { return _young_gen->tlab_capacity(); } return 0; } size_t GenCollectedHeap::tlab_used(Thread* thr) const { assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); if (_young_gen->supports_tlab_allocation()) { return _young_gen->tlab_used(); } return 0; } size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); if (_young_gen->supports_tlab_allocation()) { return _young_gen->unsafe_max_tlab_alloc(); } return 0; } HeapWord* GenCollectedHeap::allocate_new_tlab(size_t min_size, size_t requested_size, size_t* actual_size) { bool gc_overhead_limit_was_exceeded; HeapWord* result = mem_allocate_work(requested_size /* size */, true /* is_tlab */, &gc_overhead_limit_was_exceeded); if (result != NULL) { *actual_size = requested_size; } 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; _young_gen->contribute_scratch(res, requestor, max_alloc_words); _old_gen->contribute_scratch(res, requestor, max_alloc_words); sort_scratch_list(res); return res; } void GenCollectedHeap::release_scratch() { _young_gen->reset_scratch(); _old_gen->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) { cl->do_generation(_old_gen); cl->do_generation(_young_gen); } else { cl->do_generation(_young_gen); cl->do_generation(_old_gen); } } bool GenCollectedHeap::is_maximal_no_gc() const { return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); } void GenCollectedHeap::save_marks() { _young_gen->save_marks(); _old_gen->save_marks(); } GenCollectedHeap* GenCollectedHeap::heap() { CollectedHeap* heap = Universe::heap(); assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()"); assert(heap->kind() == CollectedHeap::Serial || heap->kind() == CollectedHeap::CMS, "Invalid name"); return (GenCollectedHeap*) heap; } #if INCLUDE_SERIALGC void GenCollectedHeap::prepare_for_compaction() { // Start by compacting into same gen. CompactPoint cp(_old_gen); _old_gen->prepare_for_compaction(&cp); _young_gen->prepare_for_compaction(&cp); } #endif // INCLUDE_SERIALGC void GenCollectedHeap::verify(VerifyOption option /* ignored */) { log_debug(gc, verify)("%s", _old_gen->name()); _old_gen->verify(); log_debug(gc, verify)("%s", _old_gen->name()); _young_gen->verify(); log_debug(gc, verify)("RemSet"); rem_set()->verify(); } void GenCollectedHeap::print_on(outputStream* st) const { _young_gen->print_on(st); _old_gen->print_on(st); MetaspaceUtils::print_on(st); } void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { } void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { } void GenCollectedHeap::print_tracing_info() const { if (log_is_enabled(Debug, gc, heap, exit)) { LogStreamHandle(Debug, gc, heap, exit) lsh; _young_gen->print_summary_info_on(&lsh); _old_gen->print_summary_info_on(&lsh); } } void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const { log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K); log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->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"); // 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) { #if COMPILER2_OR_JVMCI assert(DerivedPointerTable::is_empty(), "derived pointer present"); size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr())); guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps"); #endif // COMPILER2_OR_JVMCI 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(); }; #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 == _old_gen, "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() { // 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 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); jlong retVal = now - tolgc_cl.time(); if (retVal < 0) { log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT ". returning zero instead.", retVal); return 0; } return retVal; }