/* * Copyright (c) 2000, 2011, 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/vmGCOperations.hpp" #include "gc_interface/collectedHeap.inline.hpp" #include "memory/compactPermGen.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/permGen.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/aprofiler.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" #ifndef SERIALGC #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp" #endif 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() { 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 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_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, err_msg("Gen size; total_reserved=" SIZE_FORMAT ", pageSize=" SIZE_FORMAT, total_reserved, pageSize)); total_reserved += perm_gen_spec->max_size(); assert(total_reserved % pageSize == 0, err_msg("Perm size; total_reserved=" SIZE_FORMAT ", pageSize=" SIZE_FORMAT ", perm gen max=" SIZE_FORMAT, total_reserved, pageSize, perm_gen_spec->max_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. if (UseCompressedOops) { heap_address = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop); *_total_reserved = total_reserved; *_n_covered_regions = n_covered_regions; *heap_rs = ReservedHeapSpace(total_reserved, alignment, UseLargePages, heap_address); if (heap_address != NULL && !heap_rs->is_reserved()) { // Failed to reserve at specified address - the requested memory // region is taken already, for example, by 'java' launcher. // Try again to reserver heap higher. heap_address = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop); *heap_rs = ReservedHeapSpace(total_reserved, alignment, UseLargePages, heap_address); if (heap_address != NULL && !heap_rs->is_reserved()) { // Failed to reserve at specified address again - give up. heap_address = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop); assert(heap_address == NULL, ""); *heap_rs = ReservedHeapSpace(total_reserved, alignment, UseLargePages, heap_address); } } return heap_address; } } *_total_reserved = total_reserved; *_n_covered_regions = n_covered_regions; *heap_rs = ReservedHeapSpace(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* 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 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)) { 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(); // do any pre full gc dumps } // 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(),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; } 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->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 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 (complete) { // We did a "major" collection post_full_gc_dump(); // do any post full gc dumps } 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(); } #ifdef TRACESPINNING ParallelTaskTerminator::print_termination_counts(); #endif 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_n_threads(t); } void GenCollectedHeap:: gen_process_strong_roots(int level, bool younger_gens_as_roots, bool activate_scope, bool collecting_perm_gen, SharedHeap::ScanningOption so, OopsInGenClosure* not_older_gens, bool do_code_roots, OopsInGenClosure* older_gens) { // General strong roots. if (!do_code_roots) { SharedHeap::process_strong_roots(activate_scope, collecting_perm_gen, so, not_older_gens, NULL, older_gens); } 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, collecting_perm_gen, so, not_older_gens, &code_roots, 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, CodeBlobClosure* code_roots, OopClosure* non_root_closure) { SharedHeap::process_weak_roots(root_closure, code_roots, 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) { report_out_of_shared_space(SharedPermGen); } // 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(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, (void*)p)); return result; } // 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 || 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; } if (_perm_gen->as_gen()->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"); // The order of the generations is young (low addr), old, perm (high addr) return p < _gens[_n_gens - 2]->reserved().end() && p != NULL; } #endif 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::safe_object_iterate(ObjectClosure* cl) { for (int i = 0; i < _n_gens; i++) { _gens[i]->safe_object_iterate(cl); } perm_gen()->safe_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; 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); 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, VerifyOption option /* ignored */) { 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(); } 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) { #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); if (!CleanChunkPoolAsync) { Chunk::clean_chunk_pool(); } 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. perm_gen()->record_spaces_top(); } } #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); perm_gen()->ensure_parsability(); } oop GenCollectedHeap::handle_failed_promotion(Generation* gen, oop obj, size_t obj_size) { 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; }