/* * Copyright (c) 2023, 2026, Oracle and/or its affiliates. All rights reserved. * Copyright (c) 2013, 2022, Red Hat, Inc. All rights reserved. * Copyright Amazon.com Inc. 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 "cds/aotMappedHeapWriter.hpp" #include "classfile/systemDictionary.hpp" #include "gc/shared/classUnloadingContext.hpp" #include "gc/shared/fullGCForwarding.hpp" #include "gc/shared/gc_globals.hpp" #include "gc/shared/gcArguments.hpp" #include "gc/shared/gcTimer.hpp" #include "gc/shared/gcTraceTime.inline.hpp" #include "gc/shared/locationPrinter.inline.hpp" #include "gc/shared/memAllocator.hpp" #include "gc/shared/plab.hpp" #include "gc/shared/tlab_globals.hpp" #include "gc/shenandoah/heuristics/shenandoahOldHeuristics.hpp" #include "gc/shenandoah/heuristics/shenandoahYoungHeuristics.hpp" #include "gc/shenandoah/mode/shenandoahGenerationalMode.hpp" #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp" #include "gc/shenandoah/mode/shenandoahSATBMode.hpp" #include "gc/shenandoah/shenandoahAllocRate.inline.hpp" #include "gc/shenandoah/shenandoahAllocRequest.hpp" #include "gc/shenandoah/shenandoahBarrierSet.hpp" #include "gc/shenandoah/shenandoahClosures.inline.hpp" #include "gc/shenandoah/shenandoahCodeRoots.hpp" #include "gc/shenandoah/shenandoahCollectionSet.hpp" #include "gc/shenandoah/shenandoahCollectorPolicy.hpp" #include "gc/shenandoah/shenandoahConcurrentMark.hpp" #include "gc/shenandoah/shenandoahControlThread.hpp" #include "gc/shenandoah/shenandoahFreeSet.hpp" #include "gc/shenandoah/shenandoahGenerationalEvacuationTask.hpp" #include "gc/shenandoah/shenandoahGenerationalHeap.hpp" #include "gc/shenandoah/shenandoahGlobalGeneration.hpp" #include "gc/shenandoah/shenandoahHeap.inline.hpp" #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp" #include "gc/shenandoah/shenandoahHeapRegionClosures.hpp" #include "gc/shenandoah/shenandoahHeapRegionSet.hpp" #include "gc/shenandoah/shenandoahInitLogger.hpp" #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp" #include "gc/shenandoah/shenandoahMemoryPool.hpp" #include "gc/shenandoah/shenandoahMonitoringSupport.hpp" #include "gc/shenandoah/shenandoahObjArrayAllocator.hpp" #include "gc/shenandoah/shenandoahOldGeneration.hpp" #include "gc/shenandoah/shenandoahPadding.hpp" #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp" #include "gc/shenandoah/shenandoahPhaseTimings.hpp" #include "gc/shenandoah/shenandoahReferenceProcessor.hpp" #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp" #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp" #include "gc/shenandoah/shenandoahStackWatermark.hpp" #include "gc/shenandoah/shenandoahSTWMark.hpp" #include "gc/shenandoah/shenandoahUncommitThread.hpp" #include "gc/shenandoah/shenandoahUtils.hpp" #include "gc/shenandoah/shenandoahVerifier.hpp" #include "gc/shenandoah/shenandoahVMOperations.hpp" #include "gc/shenandoah/shenandoahWorkerPolicy.hpp" #include "gc/shenandoah/shenandoahWorkGroup.hpp" #include "gc/shenandoah/shenandoahYoungGeneration.hpp" #include "memory/allocation.hpp" #include "memory/classLoaderMetaspace.hpp" #include "memory/memoryReserver.hpp" #include "memory/metaspaceUtils.hpp" #include "memory/universe.hpp" #include "nmt/mallocTracker.hpp" #include "nmt/memTracker.hpp" #include "oops/compressedOops.inline.hpp" #include "prims/jvmtiTagMap.hpp" #include "runtime/atomic.hpp" #include "runtime/atomicAccess.hpp" #include "runtime/globals.hpp" #include "runtime/interfaceSupport.inline.hpp" #include "runtime/java.hpp" #include "runtime/orderAccess.hpp" #include "runtime/safepointMechanism.hpp" #include "runtime/stackWatermarkSet.hpp" #include "runtime/threads.hpp" #include "runtime/vmThread.hpp" #include "utilities/events.hpp" #include "utilities/globalDefinitions.hpp" #include "utilities/powerOfTwo.hpp" #if INCLUDE_JFR #include "gc/shenandoah/shenandoahJfrSupport.hpp" #endif class ShenandoahPretouchHeapTask : public WorkerTask { private: ShenandoahRegionIterator _regions; const size_t _page_size; public: ShenandoahPretouchHeapTask(size_t page_size) : WorkerTask("Shenandoah Pretouch Heap"), _page_size(page_size) {} virtual void work(uint worker_id) { ShenandoahHeapRegion* r = _regions.next(); while (r != nullptr) { if (r->is_committed()) { os::pretouch_memory(r->bottom(), r->end(), _page_size); } r = _regions.next(); } } }; class ShenandoahPretouchBitmapTask : public WorkerTask { private: ShenandoahRegionIterator _regions; char* _bitmap_base; const size_t _bitmap_size; const size_t _page_size; public: ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) : WorkerTask("Shenandoah Pretouch Bitmap"), _bitmap_base(bitmap_base), _bitmap_size(bitmap_size), _page_size(page_size) {} virtual void work(uint worker_id) { ShenandoahHeapRegion* r = _regions.next(); while (r != nullptr) { size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor(); size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor(); assert (end <= _bitmap_size, "end is sane: %zu < %zu", end, _bitmap_size); if (r->is_committed()) { os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size); } r = _regions.next(); } } }; static ReservedSpace reserve(size_t size, size_t preferred_page_size) { // When a page size is given we don't want to mix large // and normal pages. If the size is not a multiple of the // page size it will be aligned up to achieve this. size_t alignment = os::vm_allocation_granularity(); if (preferred_page_size != os::vm_page_size()) { alignment = MAX2(preferred_page_size, alignment); size = align_up(size, alignment); } const ReservedSpace reserved = MemoryReserver::reserve(size, alignment, preferred_page_size, mtGC); if (!reserved.is_reserved()) { vm_exit_during_initialization("Could not reserve space"); } return reserved; } jint ShenandoahHeap::initialize() { // // Figure out heap sizing // size_t init_byte_size = InitialHeapSize; size_t min_byte_size = MinHeapSize; size_t max_byte_size = MaxHeapSize; size_t heap_alignment = HeapAlignment; size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes(); Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap"); Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap"); _num_regions = ShenandoahHeapRegion::region_count(); assert(_num_regions == (max_byte_size / reg_size_bytes), "Regions should cover entire heap exactly: %zu != %zu/%zu", _num_regions, max_byte_size, reg_size_bytes); size_t num_committed_regions = init_byte_size / reg_size_bytes; num_committed_regions = MIN2(num_committed_regions, _num_regions); assert(num_committed_regions <= _num_regions, "sanity"); _initial_size = num_committed_regions * reg_size_bytes; size_t num_min_regions = min_byte_size / reg_size_bytes; num_min_regions = MIN2(num_min_regions, _num_regions); assert(num_min_regions <= _num_regions, "sanity"); _minimum_size = num_min_regions * reg_size_bytes; _soft_max_size.store_relaxed(clamp(SoftMaxHeapSize, min_capacity(), max_capacity())); _committed.store_relaxed(_initial_size); size_t heap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); size_t bitmap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); size_t region_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); // // Reserve and commit memory for heap // ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment); initialize_reserved_region(heap_rs); _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize); _heap_region_special = heap_rs.special(); assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0, "Misaligned heap: " PTR_FORMAT, p2i(base())); os::trace_page_sizes_for_requested_size("Heap", max_byte_size, heap_alignment, heap_rs.base(), heap_rs.size(), heap_rs.page_size()); #if SHENANDOAH_OPTIMIZED_MARKTASK // The optimized ShenandoahMarkTask takes some bits away from the full object bits. // Fail if we ever attempt to address more than we can. if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) { FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n" "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n" "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).", p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable()); vm_exit_during_initialization("Fatal Error", buf); } #endif ReservedSpace sh_rs = heap_rs.first_part(max_byte_size); if (!_heap_region_special) { os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false, "Cannot commit heap memory"); } BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this, _heap_region)); // Now we know the number of regions and heap sizes, initialize the heuristics. initialize_heuristics(); // If ShenandoahCardBarrier is enabled but it's not generational mode // it means we're under passive mode and we have to initialize old gen // for the purpose of having card table. if (ShenandoahCardBarrier && !(mode()->is_generational())) { _old_generation = new ShenandoahOldGeneration(max_workers()); } assert(_heap_region.byte_size() == heap_rs.size(), "Need to know reserved size for card table"); // // Worker threads must be initialized after the barrier is configured // _workers = new ShenandoahWorkerThreads("ShenWorker", _max_workers); if (_workers == nullptr) { vm_exit_during_initialization("Failed necessary allocation."); } else { _workers->initialize_workers(); } if (ParallelGCThreads > 1) { _safepoint_workers = new ShenandoahWorkerThreads("Safepoint Cleanup Thread", ParallelGCThreads); _safepoint_workers->initialize_workers(); } // // Reserve and commit memory for bitmap(s) // size_t bitmap_size_orig = ShenandoahMarkBitMap::compute_size(heap_rs.size()); _bitmap_size = align_up(bitmap_size_orig, bitmap_page_size); size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor(); guarantee(bitmap_bytes_per_region != 0, "Bitmap bytes per region should not be zero"); guarantee(is_power_of_2(bitmap_bytes_per_region), "Bitmap bytes per region should be power of two: %zu", bitmap_bytes_per_region); if (bitmap_page_size > bitmap_bytes_per_region) { _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region; _bitmap_bytes_per_slice = bitmap_page_size; } else { _bitmap_regions_per_slice = 1; _bitmap_bytes_per_slice = bitmap_bytes_per_region; } guarantee(_bitmap_regions_per_slice >= 1, "Should have at least one region per slice: %zu", _bitmap_regions_per_slice); guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0, "Bitmap slices should be page-granular: bps = %zu, page size = %zu", _bitmap_bytes_per_slice, bitmap_page_size); ReservedSpace bitmap = reserve(_bitmap_size, bitmap_page_size); os::trace_page_sizes_for_requested_size("Mark Bitmap", bitmap_size_orig, bitmap_page_size, bitmap.base(), bitmap.size(), bitmap.page_size()); MemTracker::record_virtual_memory_tag(bitmap, mtGC); _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize); _bitmap_region_special = bitmap.special(); size_t bitmap_init_commit = _bitmap_bytes_per_slice * align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice; bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit); if (!_bitmap_region_special) { os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false, "Cannot commit bitmap memory"); } _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions); if (ShenandoahVerify) { ReservedSpace verify_bitmap = reserve(_bitmap_size, bitmap_page_size); os::trace_page_sizes_for_requested_size("Verify Bitmap", bitmap_size_orig, bitmap_page_size, verify_bitmap.base(), verify_bitmap.size(), verify_bitmap.page_size()); if (!verify_bitmap.special()) { os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false, "Cannot commit verification bitmap memory"); } MemTracker::record_virtual_memory_tag(verify_bitmap, mtGC); MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize); _verification_bit_map.initialize(_heap_region, verify_bitmap_region); _verifier = new ShenandoahVerifier(this, &_verification_bit_map); } // Reserve aux bitmap for use in object_iterate(). We don't commit it here. size_t aux_bitmap_page_size = bitmap_page_size; ReservedSpace aux_bitmap = reserve(_bitmap_size, aux_bitmap_page_size); os::trace_page_sizes_for_requested_size("Aux Bitmap", bitmap_size_orig, aux_bitmap_page_size, aux_bitmap.base(), aux_bitmap.size(), aux_bitmap.page_size()); MemTracker::record_virtual_memory_tag(aux_bitmap, mtGC); _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize); _aux_bitmap_region_special = aux_bitmap.special(); _aux_bit_map.initialize(_heap_region, _aux_bitmap_region); // // Create regions and region sets // size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE); size_t region_storage_size_orig = region_align * _num_regions; size_t region_storage_size = align_up(region_storage_size_orig, MAX2(region_page_size, os::vm_allocation_granularity())); ReservedSpace region_storage = reserve(region_storage_size, region_page_size); os::trace_page_sizes_for_requested_size("Region Storage", region_storage_size_orig, region_page_size, region_storage.base(), region_storage.size(), region_storage.page_size()); MemTracker::record_virtual_memory_tag(region_storage, mtGC); if (!region_storage.special()) { os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false, "Cannot commit region memory"); } // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks. // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there. // If not successful, bite a bullet and allocate at whatever address. { const size_t cset_align = MAX2(os::vm_page_size(), os::vm_allocation_granularity()); const size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align); const size_t cset_page_size = os::vm_page_size(); uintptr_t min = round_up_power_of_2(cset_align); uintptr_t max = (1u << 30u); ReservedSpace cset_rs; for (uintptr_t addr = min; addr <= max; addr <<= 1u) { char* req_addr = (char*)addr; assert(is_aligned(req_addr, cset_align), "Should be aligned"); cset_rs = MemoryReserver::reserve(req_addr, cset_size, cset_align, cset_page_size, mtGC); if (cset_rs.is_reserved()) { assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr); _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base()); break; } } if (_collection_set == nullptr) { cset_rs = MemoryReserver::reserve(cset_size, cset_align, os::vm_page_size(), mtGC); if (!cset_rs.is_reserved()) { vm_exit_during_initialization("Cannot reserve memory for collection set"); } _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base()); } os::trace_page_sizes_for_requested_size("Collection Set", cset_size, cset_page_size, cset_rs.base(), cset_rs.size(), cset_rs.page_size()); } _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC); _affiliations = NEW_C_HEAP_ARRAY(uint8_t, _num_regions, mtGC); { ShenandoahHeapLocker locker(lock()); for (size_t i = 0; i < _num_regions; i++) { HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i; bool is_committed = i < num_committed_regions; void* loc = region_storage.base() + i * region_align; ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed); assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity"); _marking_context->initialize_top_at_mark_start(r); _regions[i] = r; assert(!collection_set()->is_in(i), "New region should not be in collection set"); _affiliations[i] = ShenandoahAffiliation::FREE; } if (mode()->is_generational()) { size_t young_reserve = (soft_max_capacity() * ShenandoahEvacReserve) / 100; young_generation()->set_evacuation_reserve(young_reserve); old_generation()->set_evacuation_reserve((size_t) 0); old_generation()->set_promoted_reserve((size_t) 0); } _free_set = new ShenandoahFreeSet(this, _num_regions); initialize_generations(); // We are initializing free set. We ignore cset region tallies. size_t young_trashed_regions, old_trashed_regions, first_old, last_old, num_old; _free_set->prepare_to_rebuild(young_trashed_regions, old_trashed_regions, first_old, last_old, num_old); if (mode()->is_generational()) { ShenandoahGenerationalHeap* gen_heap = ShenandoahGenerationalHeap::heap(); // We cannot call // gen_heap->young_generation()->heuristics()->bytes_of_allocation_runway_before_gc_trigger(young_cset_regions) // until after the heap is fully initialized. So we make up a safe value here. size_t allocation_runway = InitialHeapSize / 2; gen_heap->compute_old_generation_balance(allocation_runway, old_trashed_regions, young_trashed_regions); } _free_set->finish_rebuild(young_trashed_regions, old_trashed_regions, num_old); } if (AlwaysPreTouch) { // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads, // before initialize() below zeroes it with initializing thread. For any given region, // we touch the region and the corresponding bitmaps from the same thread. ShenandoahPushWorkerScope scope(workers(), _max_workers, false); _pretouch_heap_page_size = heap_page_size; _pretouch_bitmap_page_size = bitmap_page_size; // OS memory managers may want to coalesce back-to-back pages. Make their jobs // simpler by pre-touching continuous spaces (heap and bitmap) separately. ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size); _workers->run_task(&bcl); ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size); _workers->run_task(&hcl); } // // Initialize the rest of GC subsystems // _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC); for (uint worker = 0; worker < _max_workers; worker++) { _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC); Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData)); } // There should probably be Shenandoah-specific options for these, // just as there are G1-specific options. { ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set(); satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent } _monitoring_support = new ShenandoahMonitoringSupport(this); _phase_timings = new ShenandoahPhaseTimings(max_workers()); ShenandoahCodeRoots::initialize(); // Initialization of controller makes use of variables established by initialize_heuristics. initialize_controller(); // Certain initialization of heuristics must be deferred until after controller is initialized. post_initialize_heuristics(); start_idle_span(); if (ShenandoahUncommit) { _uncommit_thread = new ShenandoahUncommitThread(this); } print_init_logger(); FullGCForwarding::initialize(_heap_region); return JNI_OK; } void ShenandoahHeap::initialize_controller() { _control_thread = new ShenandoahControlThread(); } void ShenandoahHeap::print_init_logger() const { ShenandoahInitLogger::print(); } void ShenandoahHeap::initialize_mode() { if (ShenandoahGCMode != nullptr) { if (strcmp(ShenandoahGCMode, "satb") == 0) { _gc_mode = new ShenandoahSATBMode(); } else if (strcmp(ShenandoahGCMode, "passive") == 0) { _gc_mode = new ShenandoahPassiveMode(); } else if (strcmp(ShenandoahGCMode, "generational") == 0) { _gc_mode = new ShenandoahGenerationalMode(); } else { vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option"); } } else { vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option (null)"); } _gc_mode->initialize_flags(); if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) { vm_exit_during_initialization( err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.", _gc_mode->name())); } if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) { vm_exit_during_initialization( err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.", _gc_mode->name())); } } void ShenandoahHeap::initialize_heuristics() { _global_generation = new ShenandoahGlobalGeneration(mode()->is_generational(), max_workers()); _global_generation->initialize_heuristics(mode()); } #ifdef _MSC_VER #pragma warning( push ) #pragma warning( disable:4355 ) // 'this' : used in base member initializer list #endif ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) : CollectedHeap(), _active_generation(nullptr), _initial_size(0), _committed(0), _alloc_rate_decay(&_alloc_rate), _max_workers(MAX3(ConcGCThreads, ParallelGCThreads, 1U)), _workers(nullptr), _safepoint_workers(nullptr), _heap_region_special(false), _num_regions(0), _regions(nullptr), _affiliations(nullptr), _gc_state_changed(false), _gc_no_progress_count(0), _cancel_requested_time(0), _update_refs_iterator(this), _global_generation(nullptr), _control_thread(nullptr), _uncommit_thread(nullptr), _young_generation(nullptr), _old_generation(nullptr), _shenandoah_policy(policy), _gc_mode(nullptr), _free_set(nullptr), _verifier(nullptr), _phase_timings(nullptr), _monitoring_support(nullptr), _memory_pool(nullptr), _stw_memory_manager("Shenandoah Pauses"), _cycle_memory_manager("Shenandoah Cycles"), _gc_timer(new ConcurrentGCTimer()), _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes), _marking_context(nullptr), _bitmap_size(0), _bitmap_regions_per_slice(0), _bitmap_bytes_per_slice(0), _bitmap_region_special(false), _aux_bitmap_region_special(false), _liveness_cache(nullptr), _collection_set(nullptr), _evac_tracker(new ShenandoahEvacuationTracker()) { // Initialize GC mode early, many subsequent initialization procedures depend on it initialize_mode(); _cancelled_gc.set(GCCause::_no_gc); } #ifdef _MSC_VER #pragma warning( pop ) #endif void ShenandoahHeap::print_heap_on(outputStream* st) const { const bool is_generational = mode()->is_generational(); const char* front_spacing = ""; if (is_generational) { st->print_cr("Generational Shenandoah Heap"); st->print_cr(" Young:"); st->print_cr(" " PROPERFMT " max, " PROPERFMT " used", PROPERFMTARGS(young_generation()->max_capacity()), PROPERFMTARGS(young_generation()->used())); st->print_cr(" Old:"); st->print_cr(" " PROPERFMT " max, " PROPERFMT " used", PROPERFMTARGS(old_generation()->max_capacity()), PROPERFMTARGS(old_generation()->used())); st->print_cr(" Entire heap:"); st->print_cr(" " PROPERFMT " soft max, " PROPERFMT " committed", PROPERFMTARGS(soft_max_capacity()), PROPERFMTARGS(committed())); front_spacing = " "; } else { st->print_cr("Shenandoah Heap"); st->print_cr(" " PROPERFMT " max, " PROPERFMT " soft max, " PROPERFMT " committed, " PROPERFMT " used", PROPERFMTARGS(max_capacity()), PROPERFMTARGS(soft_max_capacity()), PROPERFMTARGS(committed()), PROPERFMTARGS(used()) ); } st->print_cr("%s %zu x " PROPERFMT " regions", front_spacing, num_regions(), PROPERFMTARGS(ShenandoahHeapRegion::region_size_bytes())); st->print("Status: "); if (has_forwarded_objects()) st->print("has forwarded objects, "); if (!is_generational) { if (is_concurrent_mark_in_progress()) st->print("marking,"); } else { if (is_concurrent_old_mark_in_progress()) st->print("old marking, "); if (is_concurrent_young_mark_in_progress()) st->print("young marking, "); } if (is_evacuation_in_progress()) st->print("evacuating, "); if (is_update_refs_in_progress()) st->print("updating refs, "); if (is_degenerated_gc_in_progress()) st->print("degenerated gc, "); if (is_full_gc_in_progress()) st->print("full gc, "); if (is_full_gc_move_in_progress()) st->print("full gc move, "); if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, "); if (is_concurrent_strong_root_in_progress() && !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, "); if (cancelled_gc()) { st->print("cancelled"); } else { st->print("not cancelled"); } st->cr(); st->print_cr("Reserved region:"); st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ", p2i(reserved_region().start()), p2i(reserved_region().end())); ShenandoahCollectionSet* cset = collection_set(); st->print_cr("Collection set:"); if (cset != nullptr) { st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address())); st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address())); } else { st->print_cr(" (null)"); } st->cr(); if (Verbose) { st->cr(); print_heap_regions_on(st); } } void ShenandoahHeap::print_gc_on(outputStream* st) const { print_heap_regions_on(st); } class ShenandoahInitWorkerGCLABClosure : public ThreadClosure { public: void do_thread(Thread* thread) { assert(thread != nullptr, "Sanity"); ShenandoahThreadLocalData::initialize_gclab(thread); } }; void ShenandoahHeap::initialize_generations() { _global_generation->post_initialize(this); } // We do not call this explicitly It is called by Hotspot infrastructure. void ShenandoahHeap::post_initialize() { CollectedHeap::post_initialize(); check_soft_max_changed(); // Schedule periodic task to report on gc thread CPU utilization _mmu_tracker.initialize(); // Periodically decay allocation rate to compensate for not being updated when allocation rate // is low. Heuristics are evaluated unconditionally from a dedicated thread so it will continue // to see the last (possibly stale) allocation rate if the allocation rate is low. _alloc_rate_decay.enroll(); MutexLocker ml(Threads_lock); ShenandoahInitWorkerGCLABClosure init_gclabs; _workers->threads_do(&init_gclabs); // gclab can not be initialized early during VM startup, as it can not determinate its max_size. // Now, we will let WorkerThreads to initialize gclab when new worker is created. _workers->set_initialize_gclab(); // Note that the safepoint workers may require gclabs if the threads are used to create a heap dump // during a concurrent evacuation phase. if (_safepoint_workers != nullptr) { _safepoint_workers->threads_do(&init_gclabs); _safepoint_workers->set_initialize_gclab(); } JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers();) } void ShenandoahHeap::post_initialize_heuristics() { _global_generation->post_initialize_heuristics(); } ShenandoahHeuristics* ShenandoahHeap::heuristics() { return _global_generation->heuristics(); } size_t ShenandoahHeap::used() const { return global_generation()->used(); } size_t ShenandoahHeap::committed() const { return _committed.load_relaxed(); } void ShenandoahHeap::increase_committed(size_t bytes) { shenandoah_assert_heaplocked_or_safepoint(); _committed.fetch_then_add(bytes, memory_order_relaxed); } void ShenandoahHeap::decrease_committed(size_t bytes) { shenandoah_assert_heaplocked_or_safepoint(); _committed.fetch_then_sub(bytes, memory_order_relaxed); } size_t ShenandoahHeap::capacity() const { return committed(); } size_t ShenandoahHeap::max_capacity() const { return _num_regions * ShenandoahHeapRegion::region_size_bytes(); } size_t ShenandoahHeap::soft_max_capacity() const { size_t v = _soft_max_size.load_relaxed(); assert(min_capacity() <= v && v <= max_capacity(), "Should be in bounds: %zu <= %zu <= %zu", min_capacity(), v, max_capacity()); return v; } void ShenandoahHeap::set_soft_max_capacity(size_t v) { assert(min_capacity() <= v && v <= max_capacity(), "Should be in bounds: %zu <= %zu <= %zu", min_capacity(), v, max_capacity()); _soft_max_size.store_relaxed(v); heuristics()->compute_headroom_adjustment(); } size_t ShenandoahHeap::min_capacity() const { return _minimum_size; } size_t ShenandoahHeap::initial_capacity() const { return _initial_size; } bool ShenandoahHeap::is_in(const void* p) const { if (!is_in_reserved(p)) { return false; } if (is_full_gc_move_in_progress()) { // Full GC move is running, we do not have a consistent region // information yet. But we know the pointer is in heap. return true; } // Now check if we point to a live section in active region. const ShenandoahHeapRegion* r = heap_region_containing(p); if (p >= r->top()) { return false; } if (r->is_active()) { return true; } // The region is trash, but won't be recycled until after concurrent weak // roots. We also don't allow mutators to allocate from trash regions // during weak roots. Concurrent class unloading may access unmarked oops // in trash regions. return r->is_trash() && is_concurrent_weak_root_in_progress(); } void ShenandoahHeap::notify_soft_max_changed() { if (_uncommit_thread != nullptr) { _uncommit_thread->notify_soft_max_changed(); } } void ShenandoahHeap::notify_explicit_gc_requested() { if (_uncommit_thread != nullptr) { _uncommit_thread->notify_explicit_gc_requested(); } } bool ShenandoahHeap::check_soft_max_changed() { size_t new_soft_max = AtomicAccess::load(&SoftMaxHeapSize); size_t old_soft_max = soft_max_capacity(); if (new_soft_max != old_soft_max) { new_soft_max = clamp(new_soft_max, min_capacity(), max_capacity()); if (new_soft_max != old_soft_max) { log_info(gc)("Soft Max Heap Size: %zu%s -> %zu%s", byte_size_in_proper_unit(old_soft_max), proper_unit_for_byte_size(old_soft_max), byte_size_in_proper_unit(new_soft_max), proper_unit_for_byte_size(new_soft_max) ); set_soft_max_capacity(new_soft_max); return true; } } return false; } void ShenandoahHeap::notify_heap_changed() { // Update monitoring counters when we took a new region. This amortizes the // update costs on slow path. monitoring_support()->notify_heap_changed(); _heap_changed.try_set(); } void ShenandoahHeap::start_idle_span() { heuristics()->start_idle_span(); } void ShenandoahHeap::set_forced_counters_update(bool value) { monitoring_support()->set_forced_counters_update(value); } void ShenandoahHeap::handle_force_counters_update() { monitoring_support()->handle_force_counters_update(); } HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) { // New object should fit the GCLAB size size_t min_size = MAX2(size, PLAB::min_size()); // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively. size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2; new_size = MIN2(new_size, PLAB::max_size()); new_size = MAX2(new_size, PLAB::min_size()); // Record new heuristic value even if we take any shortcut. This captures // the case when moderately-sized objects always take a shortcut. At some point, // heuristics should catch up with them. log_debug(gc, free)("Set new GCLAB size: %zu", new_size); ShenandoahThreadLocalData::set_gclab_size(thread, new_size); if (new_size < size) { // New size still does not fit the object. Fall back to shared allocation. // This avoids retiring perfectly good GCLABs, when we encounter a large object. log_debug(gc, free)("New gclab size (%zu) is too small for %zu", new_size, size); return nullptr; } // Retire current GCLAB, and allocate a new one. PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); gclab->retire(); size_t actual_size = 0; HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size); if (gclab_buf == nullptr) { return nullptr; } assert (size <= actual_size, "allocation should fit"); // ...and clear or zap just allocated TLAB, if needed. if (ZeroTLAB) { Copy::zero_to_words(gclab_buf, actual_size); } else if (ZapTLAB) { // Skip mangling the space corresponding to the object header to // ensure that the returned space is not considered parsable by // any concurrent GC thread. size_t hdr_size = oopDesc::header_size(); Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal); } gclab->set_buf(gclab_buf, actual_size); return gclab->allocate(size); } // Called from stubs in JIT code or interpreter HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size, size_t requested_size, size_t* actual_size) { ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size); HeapWord* res = allocate_memory(req); if (res != nullptr) { *actual_size = req.actual_size(); } else { *actual_size = 0; } return res; } HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size, size_t word_size, size_t* actual_size) { ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size); HeapWord* res = allocate_memory(req); if (res != nullptr) { *actual_size = req.actual_size(); } else { *actual_size = 0; } return res; } HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) { bool in_new_region = false; HeapWord* result = nullptr; if (req.is_mutator_alloc()) { if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) { result = allocate_memory_under_lock(req, in_new_region); } // Check that gc overhead is not exceeded. // // Shenandoah will grind along for quite a while allocating one // object at a time using shared (non-tlab) allocations. This check // is testing that the GC overhead limit has not been exceeded. // This will notify the collector to start a cycle, but will raise // an OOME to the mutator if the last Full GCs have not made progress. // gc_no_progress_count is incremented following each degen or full GC that fails to achieve is_good_progress(). if (result == nullptr && !req.is_lab_alloc() && get_gc_no_progress_count() > ShenandoahNoProgressThreshold) { control_thread()->handle_alloc_failure(req, false); req.set_actual_size(0); return nullptr; } if (result == nullptr) { // Block until control thread reacted, then retry allocation. // // It might happen that one of the threads requesting allocation would unblock // way later after GC happened, only to fail the second allocation, because // other threads have already depleted the free storage. In this case, a better // strategy is to try again, until at least one full GC has completed. // // Stop retrying and return nullptr to cause OOMError exception if our allocation failed even after: // a) We experienced a GC that had good progress, or // b) We experienced at least one Full GC (whether or not it had good progress) const size_t original_count = shenandoah_policy()->full_gc_count(); while (result == nullptr && should_retry_allocation(original_count)) { control_thread()->handle_alloc_failure(req, true); result = allocate_memory_under_lock(req, in_new_region); } if (result != nullptr) { // If our allocation request has been satisfied after it initially failed, we count this as good gc progress notify_gc_progress(); } if (log_develop_is_enabled(Debug, gc, alloc)) { ResourceMark rm; log_debug(gc, alloc)("Thread: %s, Result: " PTR_FORMAT ", Request: %s, Size: %zu" ", Original: %zu, Latest: %zu", Thread::current()->name(), p2i(result), req.type_string(), req.size(), original_count, get_gc_no_progress_count()); } } } else { assert(req.is_gc_alloc(), "Can only accept GC allocs here"); result = allocate_memory_under_lock(req, in_new_region); // Do not call handle_alloc_failure() here, because we cannot block. // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac(). } if (in_new_region) { notify_heap_changed(); } if (result == nullptr) { req.set_actual_size(0); } if (result != nullptr) { size_t requested = req.size(); size_t actual = req.actual_size(); assert (req.is_lab_alloc() || (requested == actual), "Only LAB allocations are elastic: %s, requested = %zu, actual = %zu", req.type_string(), requested, actual); } return result; } inline bool ShenandoahHeap::should_retry_allocation(size_t original_full_gc_count) const { return shenandoah_policy()->full_gc_count() == original_full_gc_count && !shenandoah_policy()->is_at_shutdown(); } HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) { // If we are dealing with mutator allocation, then we may need to block for safepoint. // We cannot block for safepoint for GC allocations, because there is a high chance // we are already running at safepoint or from stack watermark machinery, and we cannot // block again. ShenandoahHeapLocker locker(lock(), req.is_mutator_alloc()); // Make sure the old generation has room for either evacuations or promotions before trying to allocate. if (req.is_old() && !old_generation()->can_allocate(req)) { return nullptr; } // If TLAB request size is greater than available, allocate() will attempt to downsize request to fit within available // memory. HeapWord* result = _free_set->allocate(req, in_new_region); if (result != nullptr) { if (req.is_mutator_alloc()) { _alloc_rate.allocated((req.actual_size() + req.waste()) * HeapWordSize); } if (req.is_old()) { if (req.is_lab_alloc()) { old_generation()->configure_plab_for_current_thread(req); } else if (req.is_promotion()) { const size_t actual_size = req.actual_size() * HeapWordSize; log_debug(gc, plab)("Expend shared promotion of %zu bytes", actual_size); old_generation()->expend_promoted(actual_size); } } } return result; } HeapWord* ShenandoahHeap::mem_allocate(size_t size) { ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size); return allocate_memory(req); } oop ShenandoahHeap::array_allocate(Klass* klass, size_t size, int length, bool do_zero, TRAPS) { ShenandoahObjArrayAllocator allocator(klass, size, length, do_zero, THREAD); return allocator.allocate(); } MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, size_t size, Metaspace::MetadataType mdtype) { MetaWord* result; // Inform metaspace OOM to GC heuristics if class unloading is possible. ShenandoahHeuristics* h = global_generation()->heuristics(); if (h->can_unload_classes()) { h->record_metaspace_oom(); } // Expand and retry allocation result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype); if (result != nullptr) { return result; } // Start full GC collect(GCCause::_metadata_GC_clear_soft_refs); // Retry allocation result = loader_data->metaspace_non_null()->allocate(size, mdtype); if (result != nullptr) { return result; } // Expand and retry allocation result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype); if (result != nullptr) { return result; } // Out of memory return nullptr; } class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure { private: ShenandoahHeap* const _heap; Thread* const _thread; public: ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) : _heap(heap), _thread(Thread::current()) {} void do_object(oop p) { shenandoah_assert_marked(nullptr, p); if (!p->is_forwarded()) { _heap->evacuate_object(p, _thread); } } }; class ShenandoahEvacuationTask : public WorkerTask { private: ShenandoahHeap* const _sh; ShenandoahCollectionSet* const _cs; bool _concurrent; public: ShenandoahEvacuationTask(ShenandoahHeap* sh, ShenandoahCollectionSet* cs, bool concurrent) : WorkerTask("Shenandoah Evacuation"), _sh(sh), _cs(cs), _concurrent(concurrent) {} void work(uint worker_id) { if (_concurrent) { ShenandoahWorkerTimingsTracker timer(ShenandoahPhaseTimings::conc_evac, ShenandoahPhaseTimings::Work, worker_id, true); ShenandoahConcurrentWorkerSession worker_session(worker_id); SuspendibleThreadSetJoiner stsj; do_work(); } else { ShenandoahWorkerTimingsTracker timer(ShenandoahPhaseTimings::degen_gc_evac, ShenandoahPhaseTimings::Work, worker_id, true); ShenandoahParallelWorkerSession worker_session(worker_id); do_work(); } } private: void do_work() { ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh); ShenandoahHeapRegion* r; while ((r =_cs->claim_next()) != nullptr) { assert(r->has_live(), "Region %zu should have been reclaimed early", r->index()); _sh->marked_object_iterate(r, &cl); if (_sh->check_cancelled_gc_and_yield(_concurrent)) { break; } } } }; class ShenandoahRetireGCLABClosure : public ThreadClosure { private: bool const _resize; public: explicit ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {} void do_thread(Thread* thread) override { PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name()); gclab->retire(); if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) { ShenandoahThreadLocalData::set_gclab_size(thread, 0); } if (ShenandoahHeap::heap()->mode()->is_generational()) { ShenandoahPLAB* shenandoah_plab = ShenandoahThreadLocalData::shenandoah_plab(thread); assert(shenandoah_plab != nullptr, "PLAB should be initialized for %s", thread->name()); // There are two reasons to retire all plabs between old-gen evacuation passes. // 1. We need to make the plab memory parsable by remembered-set scanning. // 2. We need to establish a trustworthy UpdateWaterMark value within each old-gen heap region shenandoah_plab->retire(); // Re-enable promotions for the next evacuation phase. shenandoah_plab->enable_promotions(); // Reset the fill size for next evacuation phase. if (_resize && shenandoah_plab->desired_size() > 0) { shenandoah_plab->set_desired_size(0); } } } }; class ShenandoahGCStatePropagatorHandshakeClosure : public HandshakeClosure { public: explicit ShenandoahGCStatePropagatorHandshakeClosure(char gc_state) : HandshakeClosure("Shenandoah GC State Change"), _gc_state(gc_state) {} void do_thread(Thread* thread) override { ShenandoahThreadLocalData::set_gc_state(thread, _gc_state); } private: char _gc_state; }; class ShenandoahPrepareForUpdateRefsHandshakeClosure : public HandshakeClosure { public: explicit ShenandoahPrepareForUpdateRefsHandshakeClosure(char gc_state) : HandshakeClosure("Shenandoah Prepare for Update Refs"), _retire(ResizeTLAB), _propagator(gc_state) {} void do_thread(Thread* thread) override { _propagator.do_thread(thread); if (ShenandoahThreadLocalData::gclab(thread) != nullptr) { _retire.do_thread(thread); } } private: ShenandoahRetireGCLABClosure _retire; ShenandoahGCStatePropagatorHandshakeClosure _propagator; }; void ShenandoahHeap::evacuate_collection_set(ShenandoahGeneration* generation, bool concurrent) { assert(generation->is_global(), "Only global generation expected here"); ShenandoahEvacuationTask task(this, _collection_set, concurrent); workers()->run_task(&task); } void ShenandoahHeap::concurrent_prepare_for_update_refs() { { // Java threads take this lock while they are being attached and added to the list of threads. // If another thread holds this lock before we update the gc state, it will receive a stale // gc state, but they will have been added to the list of java threads and so will be corrected // by the following handshake. MutexLocker lock(Threads_lock); // A cancellation at this point means the degenerated cycle must resume from update-refs. set_gc_state_concurrent(EVACUATION, false); set_gc_state_concurrent(WEAK_ROOTS, false); set_gc_state_concurrent(UPDATE_REFS, true); } // This will propagate the gc state and retire gclabs and plabs for threads that require it. ShenandoahPrepareForUpdateRefsHandshakeClosure prepare_for_update_refs(_gc_state.raw_value()); // The handshake won't touch worker threads (or control thread, or VM thread), so do those separately. Threads::non_java_threads_do(&prepare_for_update_refs); // Now retire gclabs and plabs and propagate gc_state for mutator threads Handshake::execute(&prepare_for_update_refs); _update_refs_iterator.reset(); } void ShenandoahHeap::op_final_roots() { assert(!is_evacuation_in_progress(), "Should not evacuate for abbreviated or old cycles"); set_gc_state_at_safepoint(WEAK_ROOTS, false); propagate_gc_state_to_all_threads(); if (ShenandoahVerify) { verifier()->verify_after_gc(active_generation()); } // Final pause, arm the nmethods to put barriers down. ShenandoahCodeRoots::arm_nmethods(); ShenandoahStackWatermark::change_epoch_id(); } oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) { assert(thread == Thread::current(), "Expected thread parameter to be current thread."); ShenandoahHeapRegion* r = heap_region_containing(p); assert(!r->is_humongous(), "never evacuate humongous objects"); ShenandoahAffiliation target_gen = r->affiliation(); return try_evacuate_object(p, thread, r, target_gen); } oop ShenandoahHeap::try_evacuate_object(oop p, Thread* thread, ShenandoahHeapRegion* from_region, ShenandoahAffiliation target_gen) { assert(target_gen == YOUNG_GENERATION, "Only expect evacuations to young in this mode"); assert(from_region->is_young(), "Only expect evacuations from young in this mode"); bool alloc_from_lab = true; HeapWord* copy = nullptr; size_t size = ShenandoahForwarding::size(p); #ifdef ASSERT if (ShenandoahOOMDuringEvacALot && (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call copy = nullptr; } else { #endif if (UseTLAB) { copy = allocate_from_gclab(thread, size); } if (copy == nullptr) { // If we failed to allocate in LAB, we'll try a shared allocation. ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size, target_gen); copy = allocate_memory(req); alloc_from_lab = false; } #ifdef ASSERT } #endif if (copy == nullptr) { control_thread()->handle_alloc_failure_evac(size); // Install the self-forwarded bit on p so other evacuators/LRBs see // the object as "already handled, do not try to evacuate". The CAS // may fail if another thread concurrently installed a real forwardee // (they succeeded where we failed) or self-forwarded first. markWord old_mark = p->mark(); if (old_mark.is_forwarded()) { return ShenandoahForwarding::get_forwardee(p); } oop winner = ShenandoahForwarding::try_forward_to_self(p, old_mark); if (winner == nullptr) { // We own the self-forwarding. Flag the region so the degen/full GC // entry drain knows to scan it for self_fwd bits to clear. from_region->set_has_self_forwards(); return p; } return winner; } if (ShenandoahEvacTracking) { evac_tracker()->begin_evacuation(thread, size * HeapWordSize, from_region->affiliation(), target_gen); } // Copy the object: Copy::aligned_disjoint_words(cast_from_oop(p), copy, size); oop copy_val = cast_to_oop(copy); // Relativize stack chunks before publishing the copy. After the forwarding CAS, // mutators can see the copy and thaw it via the fast path if flags == 0. We must // relativize derived pointers and set gc_mode before that happens. Skip if the // copy's mark word is already a forwarding pointer (another thread won the race // and overwrote the original's header before we copied it). if (!ShenandoahForwarding::is_forwarded(copy_val)) { ContinuationGCSupport::relativize_stack_chunk(copy_val); } // Try to install the new forwarding pointer. oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val); if (result == copy_val) { // Successfully evacuated. Our copy is now the public one! shenandoah_assert_correct(nullptr, copy_val); if (ShenandoahEvacTracking) { evac_tracker()->end_evacuation(thread, size * HeapWordSize, from_region->affiliation(), target_gen); } return copy_val; } else { // Failed to evacuate. We need to deal with the object that is left behind. Since this // new allocation is certainly after TAMS, it will be considered live in the next cycle. // But if it happens to contain references to evacuated regions, those references would // not get updated for this stale copy during this cycle, and we will crash while scanning // it the next cycle. if (alloc_from_lab) { // For LAB allocations, it is enough to rollback the allocation ptr. Either the next // object will overwrite this stale copy, or the filler object on LAB retirement will // do this. ShenandoahThreadLocalData::gclab(thread)->undo_allocation(copy, size); } else { // For non-LAB allocations, we have no way to retract the allocation, and // have to explicitly overwrite the copy with the filler object. With that overwrite, // we have to keep the fwdptr initialized and pointing to our (stale) copy. assert(size >= ShenandoahHeap::min_fill_size(), "previously allocated object known to be larger than min_size"); fill_with_object(copy, size); shenandoah_assert_correct(nullptr, copy_val); // For non-LAB allocations, the object has already been registered } shenandoah_assert_correct(nullptr, result); return result; } } // Clear the self_fwd bit on a live cset object, if set. Runs at a safepoint, // so a plain store is sufficient — no concurrent writers to the mark word. class ShenandoahUnSelfForwardObjectClosure : public ObjectClosure { public: void do_object(oop obj) override { markWord m = obj->mark(); if (m.is_self_forwarded()) { obj->set_mark(m.unset_self_forwarded()); } } }; // Parallel task over flagged cset regions. Iterates the live objects via the // mark bitmap (skipping evacuated and never-marked memory), clears self_fwd // bits, and resets the region flag once done. class ShenandoahUnSelfForwardTask : public WorkerTask { private: ShenandoahHeap* const _heap; ShenandoahCollectionSet* const _cs; public: ShenandoahUnSelfForwardTask(ShenandoahHeap* heap, ShenandoahCollectionSet* cs) : WorkerTask("Shenandoah Un-Self-Forward"), _heap(heap), _cs(cs) {} void work(uint worker_id) override { ShenandoahParallelWorkerSession worker_session(worker_id); ShenandoahUnSelfForwardObjectClosure cl; ShenandoahHeapRegion* r; while ((r = _cs->claim_next()) != nullptr) { if (r->has_self_forwards()) { _heap->marked_object_iterate(r, &cl); r->clear_has_self_forwards(); } } } }; void ShenandoahHeap::un_self_forward_cset_regions() { assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint"); ShenandoahCollectionSet* cs = collection_set(); if (cs == nullptr || cs->is_empty()) { return; } cs->clear_current_index(); ShenandoahUnSelfForwardTask task(this, cs); workers()->run_task(&task); DEBUG_ONLY(assert_no_self_forwards()); } #ifdef ASSERT void ShenandoahHeap::assert_no_self_forwards() const { assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint"); ShenandoahCollectionSet* cs = collection_set(); if (cs == nullptr) return; cs->clear_current_index(); ShenandoahHeapRegion* r; while ((r = cs->next()) != nullptr) { assert(!r->has_self_forwards(), "region still flagged after drain"); } cs->clear_current_index(); } #endif void ShenandoahHeap::trash_cset_regions() { ShenandoahHeapLocker locker(lock()); ShenandoahCollectionSet* set = collection_set(); ShenandoahHeapRegion* r; set->clear_current_index(); while ((r = set->next()) != nullptr) { r->make_trash(); } collection_set()->clear(); } void ShenandoahHeap::print_heap_regions_on(outputStream* st) const { st->print_cr("Heap Regions:"); st->print_cr("Region state: EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HP=pinned humongous start"); st->print_cr(" HC=humongous continuation, CS=collection set, TR=trash, P=pinned, CSP=pinned collection set"); st->print_cr("BTE=bottom/top/end, TAMS=top-at-mark-start"); st->print_cr("UWM=update watermark, U=used"); st->print_cr("T=TLAB allocs, G=GCLAB allocs"); st->print_cr("S=shared allocs, L=live data"); st->print_cr("CP=critical pins"); for (size_t i = 0; i < num_regions(); i++) { get_region(i)->print_on(st); } } void ShenandoahHeap::process_gc_stats() const { // Commit worker statistics to cycle data phase_timings()->flush_par_workers_to_cycle(); // Print GC stats for current cycle LogTarget(Info, gc, stats) lt; if (lt.is_enabled()) { ResourceMark rm; LogStream ls(lt); phase_timings()->print_cycle_on(&ls); if (ShenandoahEvacTracking) { ShenandoahCycleStats evac_stats = evac_tracker()->flush_cycle_to_global(); evac_tracker()->print_evacuations_on(&ls, &evac_stats.workers, &evac_stats.mutators); } } // Commit statistics to globals phase_timings()->flush_cycle_to_global(); } size_t ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) const { assert(start->is_humongous_start(), "reclaim regions starting with the first one"); assert(!start->has_live(), "liveness must be zero"); // Do not try to get the size of this humongous object. STW collections will // have already unloaded classes, so an unmarked object may have a bad klass pointer. ShenandoahHeapRegion* region = start; size_t index = region->index(); do { assert(region->is_humongous(), "Expect correct humongous start or continuation"); assert(!region->is_cset(), "Humongous region should not be in collection set"); region->make_trash_immediate(); region = get_region(++index); } while (region != nullptr && region->is_humongous_continuation()); // Return number of regions trashed return index - start->index(); } class ShenandoahCheckCleanGCLABClosure : public ThreadClosure { public: ShenandoahCheckCleanGCLABClosure() {} void do_thread(Thread* thread) { PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name()); assert(gclab->words_remaining() == 0, "GCLAB should not need retirement"); if (ShenandoahHeap::heap()->mode()->is_generational()) { ShenandoahPLAB* shenandoah_plab = ShenandoahThreadLocalData::shenandoah_plab(thread); assert(shenandoah_plab != nullptr, "PLAB should be initialized for %s", thread->name()); assert(shenandoah_plab->plab()->words_remaining() == 0, "PLAB should not need retirement"); } } }; void ShenandoahHeap::labs_make_parsable() { assert(UseTLAB, "Only call with UseTLAB"); ShenandoahRetireGCLABClosure cl(false); for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { ThreadLocalAllocBuffer& tlab = t->tlab(); tlab.make_parsable(); if (ZeroTLAB) { t->retire_tlab(); } cl.do_thread(t); } workers()->threads_do(&cl); if (safepoint_workers() != nullptr) { safepoint_workers()->threads_do(&cl); } } void ShenandoahHeap::tlabs_retire(bool resize) { assert(UseTLAB, "Only call with UseTLAB"); assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled"); ThreadLocalAllocStats stats; for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { t->retire_tlab(&stats); if (resize) { t->tlab().resize(); } } stats.publish(); #ifdef ASSERT ShenandoahCheckCleanGCLABClosure cl; for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { cl.do_thread(t); } workers()->threads_do(&cl); #endif } void ShenandoahHeap::gclabs_retire(bool resize) { assert(UseTLAB, "Only call with UseTLAB"); assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled"); ShenandoahRetireGCLABClosure cl(resize); for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { cl.do_thread(t); } workers()->threads_do(&cl); if (safepoint_workers() != nullptr) { safepoint_workers()->threads_do(&cl); } } // Returns size in bytes size_t ShenandoahHeap::unsafe_max_tlab_alloc() const { // Return the max allowed size, and let the allocation path // figure out the safe size for current allocation. return ShenandoahHeapRegion::max_tlab_size_bytes(); } size_t ShenandoahHeap::max_tlab_size() const { // Returns size in words return ShenandoahHeapRegion::max_tlab_size_words(); } void ShenandoahHeap::collect_as_vm_thread(GCCause::Cause cause) { // These requests are ignored because we can't easily have Shenandoah jump into // a synchronous (degenerated or full) cycle while it is in the middle of a concurrent // cycle. We _could_ cancel the concurrent cycle and then try to run a cycle directly // on the VM thread, but this would confuse the control thread mightily and doesn't // seem worth the trouble. Instead, we will have the caller thread run (and wait for) a // concurrent cycle in the prologue of the heap inspect/dump operation (see VM_HeapDumper::doit_prologue). // This is how other concurrent collectors in the JVM handle this scenario as well. assert(Thread::current()->is_VM_thread(), "Should be the VM thread"); guarantee(cause == GCCause::_heap_dump || cause == GCCause::_heap_inspection, "Invalid cause"); } void ShenandoahHeap::collect(GCCause::Cause cause) { control_thread()->request_gc(cause); } void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) { // This method is only called by `CollectedHeap::collect_as_vm_thread`, which we have // overridden to do nothing. See the comment there for an explanation of how heap inspections // work for Shenandoah. ShouldNotReachHere(); } HeapWord* ShenandoahHeap::block_start(const void* addr) const { ShenandoahHeapRegion* r = heap_region_containing(addr); if (r != nullptr) { return r->block_start(addr); } return nullptr; } bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const { ShenandoahHeapRegion* r = heap_region_containing(addr); return r->block_is_obj(addr); } bool ShenandoahHeap::print_location(outputStream* st, void* addr) const { return BlockLocationPrinter::print_location(st, addr); } void ShenandoahHeap::prepare_for_verify() { if (SafepointSynchronize::is_at_safepoint() && UseTLAB) { labs_make_parsable(); } } void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const { if (_shenandoah_policy->is_at_shutdown()) { return; } if (_control_thread != nullptr) { tcl->do_thread(_control_thread); } if (_uncommit_thread != nullptr) { tcl->do_thread(_uncommit_thread); } workers()->threads_do(tcl); if (_safepoint_workers != nullptr) { _safepoint_workers->threads_do(tcl); } } void ShenandoahHeap::print_tracing_info() const { LogTarget(Info, gc, stats) lt; if (lt.is_enabled()) { ResourceMark rm; LogStream ls(lt); if (ShenandoahEvacTracking) { evac_tracker()->print_global_on(&ls); ls.cr(); ls.cr(); } phase_timings()->print_global_on(&ls); ls.cr(); ls.cr(); shenandoah_policy()->print_gc_stats(&ls); ls.cr(); ls.cr(); } } // Active generation may only be set by the VM thread at a safepoint. void ShenandoahHeap::set_active_generation(ShenandoahGeneration* generation) { assert(Thread::current()->is_VM_thread(), "Only the VM Thread"); assert(SafepointSynchronize::is_at_safepoint(), "Only at a safepoint!"); _active_generation = generation; } void ShenandoahHeap::on_cycle_start(GCCause::Cause cause, ShenandoahGeneration* generation, bool is_degenerated, bool is_out_of_cycle) { shenandoah_policy()->record_collection_cause(cause); const GCCause::Cause current = gc_cause(); assert(current == GCCause::_no_gc, "Over-writing cause: %s, with: %s", GCCause::to_string(current), GCCause::to_string(cause)); set_gc_cause(cause); if (is_degenerated) { generation->heuristics()->record_degenerated_cycle_start(is_out_of_cycle); } else { generation->heuristics()->record_cycle_start(); } } void ShenandoahHeap::on_cycle_end(ShenandoahGeneration* generation) { assert(gc_cause() != GCCause::_no_gc, "cause wasn't set"); generation->heuristics()->record_cycle_end(); if (mode()->is_generational() && generation->is_global()) { // If we just completed a GLOBAL GC, claim credit for completion of young-gen and old-gen GC as well young_generation()->heuristics()->record_cycle_end(); old_generation()->heuristics()->record_cycle_end(); } set_gc_cause(GCCause::_no_gc); } void ShenandoahHeap::verify(VerifyOption vo) { if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) { if (ShenandoahVerify) { verifier()->verify_generic(active_generation(), vo); } else { // TODO: Consider allocating verification bitmaps on demand, // and turn this on unconditionally. } } } size_t ShenandoahHeap::tlab_capacity() const { return _free_set->capacity_not_holding_lock(); } class ObjectIterateScanRootClosure : public BasicOopIterateClosure { private: MarkBitMap* _bitmap; ShenandoahScanObjectStack* _oop_stack; ShenandoahHeap* const _heap; ShenandoahMarkingContext* const _marking_context; template void do_oop_work(T* p) { T o = RawAccess<>::oop_load(p); if (!CompressedOops::is_null(o)) { oop obj = CompressedOops::decode_not_null(o); if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) { // There may be dead oops in weak roots in concurrent root phase, do not touch them. return; } obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj); assert(oopDesc::is_oop(obj), "must be a valid oop"); if (!_bitmap->is_marked(obj)) { _bitmap->mark(obj); _oop_stack->push(obj); } } } public: ObjectIterateScanRootClosure(MarkBitMap* bitmap, ShenandoahScanObjectStack* oop_stack) : _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()), _marking_context(_heap->marking_context()) {} void do_oop(oop* p) { do_oop_work(p); } void do_oop(narrowOop* p) { do_oop_work(p); } }; /* * This is public API, used in preparation of object_iterate(). * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can * control, we call SH::tlabs_retire, SH::gclabs_retire. */ void ShenandoahHeap::ensure_parsability(bool retire_tlabs) { // No-op. } /* * Iterates objects in the heap. This is public API, used for, e.g., heap dumping. * * We cannot safely iterate objects by doing a linear scan at random points in time. Linear * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g. * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear * scanning therefore depends on having a valid marking bitmap to support it. However, we only * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid * marking bitmap during marking, after aborted marking or during/after cleanup (when we just * wiped the bitmap in preparation for next marking). * * For all those reasons, we implement object iteration as a single marking traversal, reporting * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap * is allowed to report dead objects, but is not required to do so. */ void ShenandoahHeap::object_iterate(ObjectClosure* cl) { // Reset bitmap if (!prepare_aux_bitmap_for_iteration()) return; ShenandoahScanObjectStack oop_stack; ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack); // Seed the stack with root scan scan_roots_for_iteration(&oop_stack, &oops); // Work through the oop stack to traverse heap while (! oop_stack.is_empty()) { oop obj = oop_stack.pop(); assert(oopDesc::is_oop(obj), "must be a valid oop"); cl->do_object(obj); obj->oop_iterate(&oops); } assert(oop_stack.is_empty(), "should be empty"); // Reclaim bitmap reclaim_aux_bitmap_for_iteration(); } bool ShenandoahHeap::prepare_aux_bitmap_for_iteration() { assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints"); if (!_aux_bitmap_region_special) { bool success = os::commit_memory((char *) _aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false); if (!success) { log_warning(gc)("Auxiliary marking bitmap commit failed: " PTR_FORMAT " (%zu bytes)", p2i(_aux_bitmap_region.start()), _aux_bitmap_region.byte_size()); return false; } } _aux_bit_map.clear(); return true; } void ShenandoahHeap::scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops) { // Process GC roots according to current GC cycle // This populates the work stack with initial objects // It is important to relinquish the associated locks before diving // into heap dumper uint n_workers = safepoint_workers() != nullptr ? safepoint_workers()->active_workers() : 1; ShenandoahHeapIterationRootScanner rp(n_workers); rp.roots_do(oops); } void ShenandoahHeap::reclaim_aux_bitmap_for_iteration() { if (!_aux_bitmap_region_special) { os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size()); } } // Closure for parallelly iterate objects class ShenandoahObjectIterateParScanClosure : public BasicOopIterateClosure { private: MarkBitMap* _bitmap; ShenandoahObjToScanQueue* _queue; ShenandoahHeap* const _heap; ShenandoahMarkingContext* const _marking_context; template void do_oop_work(T* p) { T o = RawAccess<>::oop_load(p); if (!CompressedOops::is_null(o)) { oop obj = CompressedOops::decode_not_null(o); if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) { // There may be dead oops in weak roots in concurrent root phase, do not touch them. return; } obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj); assert(oopDesc::is_oop(obj), "Must be a valid oop"); if (_bitmap->par_mark(obj)) { _queue->push(ShenandoahMarkTask(obj)); } } } public: ShenandoahObjectIterateParScanClosure(MarkBitMap* bitmap, ShenandoahObjToScanQueue* q) : _bitmap(bitmap), _queue(q), _heap(ShenandoahHeap::heap()), _marking_context(_heap->marking_context()) {} void do_oop(oop* p) { do_oop_work(p); } void do_oop(narrowOop* p) { do_oop_work(p); } }; // Object iterator for parallel heap iteraion. // The root scanning phase happenes in construction as a preparation of // parallel marking queues. // Every worker processes it's own marking queue. work-stealing is used // to balance workload. class ShenandoahParallelObjectIterator : public ParallelObjectIteratorImpl { private: uint _num_workers; bool _init_ready; MarkBitMap* _aux_bit_map; ShenandoahHeap* _heap; ShenandoahScanObjectStack _roots_stack; // global roots stack ShenandoahObjToScanQueueSet* _task_queues; public: ShenandoahParallelObjectIterator(uint num_workers, MarkBitMap* bitmap) : _num_workers(num_workers), _init_ready(false), _aux_bit_map(bitmap), _heap(ShenandoahHeap::heap()) { // Initialize bitmap _init_ready = _heap->prepare_aux_bitmap_for_iteration(); if (!_init_ready) { return; } ObjectIterateScanRootClosure oops(_aux_bit_map, &_roots_stack); _heap->scan_roots_for_iteration(&_roots_stack, &oops); _init_ready = prepare_worker_queues(); } ~ShenandoahParallelObjectIterator() { // Reclaim bitmap _heap->reclaim_aux_bitmap_for_iteration(); // Reclaim queue for workers if (_task_queues!= nullptr) { for (uint i = 0; i < _num_workers; ++i) { ShenandoahObjToScanQueue* q = _task_queues->queue(i); if (q != nullptr) { delete q; _task_queues->register_queue(i, nullptr); } } delete _task_queues; _task_queues = nullptr; } } virtual void object_iterate(ObjectClosure* cl, uint worker_id) { if (_init_ready) { object_iterate_parallel(cl, worker_id, _task_queues); } } private: // Divide global root_stack into worker queues bool prepare_worker_queues() { _task_queues = new ShenandoahObjToScanQueueSet((int) _num_workers); // Initialize queues for every workers for (uint i = 0; i < _num_workers; ++i) { ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue(); _task_queues->register_queue(i, task_queue); } // Divide roots among the workers. Assume that object referencing distribution // is related with root kind, use round-robin to make every worker have same chance // to process every kind of roots size_t roots_num = _roots_stack.size(); if (roots_num == 0) { // No work to do return false; } for (uint j = 0; j < roots_num; j++) { uint stack_id = j % _num_workers; oop obj = _roots_stack.pop(); _task_queues->queue(stack_id)->push(ShenandoahMarkTask(obj)); } return true; } void object_iterate_parallel(ObjectClosure* cl, uint worker_id, ShenandoahObjToScanQueueSet* queue_set) { assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints"); assert(queue_set != nullptr, "task queue must not be null"); ShenandoahObjToScanQueue* q = queue_set->queue(worker_id); assert(q != nullptr, "object iterate queue must not be null"); ShenandoahMarkTask t; ShenandoahObjectIterateParScanClosure oops(_aux_bit_map, q); // Work through the queue to traverse heap. // Steal when there is no task in queue. while (q->pop(t) || queue_set->steal(worker_id, t)) { oop obj = t.obj(); assert(oopDesc::is_oop(obj), "must be a valid oop"); cl->do_object(obj); obj->oop_iterate(&oops); } assert(q->is_empty(), "should be empty"); } }; ParallelObjectIteratorImpl* ShenandoahHeap::parallel_object_iterator(uint workers) { return new ShenandoahParallelObjectIterator(workers, &_aux_bit_map); } // Keep alive an object that was loaded with AS_NO_KEEPALIVE. void ShenandoahHeap::keep_alive(oop obj) { if (is_concurrent_mark_in_progress() && (obj != nullptr)) { ShenandoahBarrierSet::barrier_set()->enqueue(obj); } } void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { for (size_t i = 0; i < num_regions(); i++) { ShenandoahHeapRegion* current = get_region(i); blk->heap_region_do(current); } } class ShenandoahHeapRegionIteratorTask : public WorkerTask { private: ShenandoahRegionIterator _regions; ShenandoahHeapRegionClosure* _closure; public: ShenandoahHeapRegionIteratorTask(ShenandoahHeapRegionClosure* closure) : WorkerTask("Shenandoah Heap Region Iterator") , _closure(closure) {} void work(uint worker_id) override { ShenandoahParallelWorkerSession worker_session(worker_id); ShenandoahHeapRegion* region = _regions.next(); while (region != nullptr) { _closure->heap_region_do(region); region = _regions.next(); } } }; class ShenandoahParallelHeapRegionTask : public WorkerTask { private: ShenandoahHeap* const _heap; ShenandoahHeapRegionClosure* const _blk; size_t const _stride; shenandoah_padding(0); Atomic _index; shenandoah_padding(1); public: ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk, size_t stride) : WorkerTask("Shenandoah Parallel Region Operation"), _heap(ShenandoahHeap::heap()), _blk(blk), _stride(stride), _index(0) {} void work(uint worker_id) { ShenandoahParallelWorkerSession worker_session(worker_id); size_t stride = _stride; size_t max = _heap->num_regions(); while (_index.load_relaxed() < max) { size_t cur = _index.fetch_then_add(stride, memory_order_relaxed); size_t start = cur; size_t end = MIN2(cur + stride, max); if (start >= max) break; for (size_t i = cur; i < end; i++) { ShenandoahHeapRegion* current = _heap->get_region(i); _blk->heap_region_do(current); } } } }; void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { assert(blk->is_thread_safe(), "Only thread-safe closures here"); const uint active_workers = workers()->active_workers(); const size_t n_regions = num_regions(); size_t stride = blk->parallel_region_stride(); if (stride == 0 && active_workers > 1) { // Automatically derive the stride to balance the work between threads // evenly. Do not try to split work if below the reasonable threshold. constexpr size_t threshold = 4096; stride = n_regions <= threshold ? threshold : (n_regions + active_workers - 1) / active_workers; } if (n_regions > stride && active_workers > 1) { ShenandoahParallelHeapRegionTask task(blk, stride); workers()->run_task(&task); } else { heap_region_iterate(blk); } } void ShenandoahHeap::heap_region_iterator(ShenandoahHeapRegionClosure* closure) const { ShenandoahHeapRegionIteratorTask task(closure); workers()->run_task(&task); } class ShenandoahRendezvousHandshakeClosure : public HandshakeClosure { public: inline ShenandoahRendezvousHandshakeClosure(const char* name) : HandshakeClosure(name) {} inline void do_thread(Thread* thread) {} }; void ShenandoahHeap::rendezvous_threads(const char* name) { ShenandoahRendezvousHandshakeClosure cl(name); Handshake::execute(&cl); } void ShenandoahHeap::recycle_trash() { free_set()->recycle_trash(); } void ShenandoahHeap::do_class_unloading() { _unloader.unload(); if (mode()->is_generational()) { old_generation()->set_parsable(false); } } void ShenandoahHeap::stw_weak_refs(ShenandoahGeneration* generation, bool full_gc) { // Weak refs processing ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs : ShenandoahPhaseTimings::degen_gc_weakrefs; ShenandoahTimingsTracker t(phase); ShenandoahGCWorkerPhase worker_phase(phase); generation->ref_processor()->process_references(phase, workers(), false /* concurrent */); } void ShenandoahHeap::prepare_update_heap_references() { assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint"); // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to // make them parsable for update code to work correctly. Plus, we can compute new sizes // for future GCLABs here. if (UseTLAB) { ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs); gclabs_retire(ResizeTLAB); } _update_refs_iterator.reset(); } void ShenandoahHeap::propagate_gc_state_to_all_threads() { assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint"); if (_gc_state_changed) { // If we are only marking old, we do not need to process young pointers ShenandoahBarrierSet::satb_mark_queue_set().set_filter_out_young( is_concurrent_old_mark_in_progress() && !is_concurrent_young_mark_in_progress() ); ShenandoahGCStatePropagatorHandshakeClosure propagator(_gc_state.raw_value()); Threads::threads_do(&propagator); _gc_state_changed = false; } } void ShenandoahHeap::set_gc_state_at_safepoint(uint mask, bool value) { assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint"); _gc_state.set_cond(mask, value); _gc_state_changed = true; } void ShenandoahHeap::set_gc_state_concurrent(uint mask, bool value) { // Holding the thread lock here assures that any thread created after we change the gc // state will have the correct state. It also prevents attaching threads from seeing // an inconsistent state. See ShenandoahBarrierSet::on_thread_attach for reference. Established // threads will use their thread local copy of the gc state (changed by a handshake, or on a // safepoint). assert(Threads_lock->is_locked(), "Must hold thread lock for concurrent gc state change"); _gc_state.set_cond(mask, value); } void ShenandoahHeap::set_concurrent_young_mark_in_progress(bool in_progress) { uint mask; assert(!has_forwarded_objects(), "Young marking is not concurrent with evacuation"); if (!in_progress && is_concurrent_old_mark_in_progress()) { assert(mode()->is_generational(), "Only generational GC has old marking"); assert(_gc_state.is_set(MARKING), "concurrent_old_marking_in_progress implies MARKING"); // If old-marking is in progress when we turn off YOUNG_MARKING, leave MARKING (and OLD_MARKING) on mask = YOUNG_MARKING; } else { mask = MARKING | YOUNG_MARKING; } set_gc_state_at_safepoint(mask, in_progress); manage_satb_barrier(in_progress); } void ShenandoahHeap::set_concurrent_old_mark_in_progress(bool in_progress) { #ifdef ASSERT // has_forwarded_objects() iff UPDATE_REFS or EVACUATION bool has_forwarded = has_forwarded_objects(); bool updating_or_evacuating = _gc_state.is_set(UPDATE_REFS | EVACUATION); bool evacuating = _gc_state.is_set(EVACUATION); assert ((has_forwarded == updating_or_evacuating) || (evacuating && !has_forwarded && collection_set()->is_empty()), "Updating or evacuating iff has forwarded objects, or if evacuation phase is promoting in place without forwarding"); #endif if (!in_progress && is_concurrent_young_mark_in_progress()) { // If young-marking is in progress when we turn off OLD_MARKING, leave MARKING (and YOUNG_MARKING) on assert(_gc_state.is_set(MARKING), "concurrent_young_marking_in_progress implies MARKING"); set_gc_state_at_safepoint(OLD_MARKING, in_progress); } else { set_gc_state_at_safepoint(MARKING | OLD_MARKING, in_progress); } manage_satb_barrier(in_progress); } bool ShenandoahHeap::is_prepare_for_old_mark_in_progress() const { return old_generation()->is_preparing_for_mark(); } void ShenandoahHeap::manage_satb_barrier(bool active) { if (is_concurrent_mark_in_progress()) { // Ignore request to deactivate barrier while concurrent mark is in progress. // Do not attempt to re-activate the barrier if it is already active. if (active && !ShenandoahBarrierSet::satb_mark_queue_set().is_active()) { ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(active, !active); } } else { // No concurrent marking is in progress so honor request to deactivate, // but only if the barrier is already active. if (!active && ShenandoahBarrierSet::satb_mark_queue_set().is_active()) { ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(active, !active); } } } void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) { assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint"); set_gc_state_at_safepoint(EVACUATION, in_progress); } void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) { if (in_progress) { _concurrent_strong_root_in_progress.set(); } else { _concurrent_strong_root_in_progress.unset(); } } void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) { set_gc_state_at_safepoint(WEAK_ROOTS, cond); } GCTracer* ShenandoahHeap::tracer() { return shenandoah_policy()->tracer(); } size_t ShenandoahHeap::tlab_used() const { return _free_set->used_not_holding_lock(); } bool ShenandoahHeap::try_cancel_gc(GCCause::Cause cause) { const GCCause::Cause prev = _cancelled_gc.xchg(cause); return prev == GCCause::_no_gc || prev == GCCause::_shenandoah_concurrent_gc; } void ShenandoahHeap::cancel_concurrent_mark() { if (mode()->is_generational()) { young_generation()->cancel_marking(); old_generation()->cancel_marking(); } global_generation()->cancel_marking(); ShenandoahBarrierSet::satb_mark_queue_set().abandon_partial_marking(); } bool ShenandoahHeap::cancel_gc(GCCause::Cause cause) { if (try_cancel_gc(cause)) { FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause)); log_info(gc,thread)("%s", msg.buffer()); Events::log(Thread::current(), "%s", msg.buffer()); _cancel_requested_time = os::elapsedTime(); return true; } return false; } uint ShenandoahHeap::max_workers() { return _max_workers; } void ShenandoahHeap::stop() { // The shutdown sequence should be able to terminate when GC is running. // Step 0. Notify policy to disable event recording and prevent visiting gc threads during shutdown _shenandoah_policy->record_shutdown(); // Step 1. Stop reporting on gc thread cpu utilization mmu_tracker()->stop(); // Step 2. Stop decaying allocation rate. _alloc_rate_decay.disenroll(); // Step 3. Wait until GC worker exits normally (this will cancel any ongoing GC). control_thread()->stop(); // Step 4. Shutdown uncommit thread. if (_uncommit_thread != nullptr) { _uncommit_thread->stop(); } } void ShenandoahHeap::stw_unload_classes(bool full_gc) { if (!unload_classes()) return; ClassUnloadingContext ctx(_workers->active_workers(), true /* unregister_nmethods_during_purge */, false /* lock_nmethod_free_separately */); // Unload classes and purge SystemDictionary. { ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_purge_class_unload : ShenandoahPhaseTimings::degen_gc_purge_class_unload; ShenandoahIsAliveSelector is_alive; { CodeCache::UnlinkingScope scope(is_alive.is_alive_closure()); ShenandoahGCPhase gc_phase(phase); ShenandoahGCWorkerPhase worker_phase(phase); bool unloading_occurred = SystemDictionary::do_unloading(gc_timer()); ShenandoahClassUnloadingTask unlink_task(phase, unloading_occurred); _workers->run_task(&unlink_task); } // Release unloaded nmethods's memory. ClassUnloadingContext::context()->purge_and_free_nmethods(); } { ShenandoahGCPhase phase(full_gc ? ShenandoahPhaseTimings::full_gc_purge_cldg : ShenandoahPhaseTimings::degen_gc_purge_cldg); ClassLoaderDataGraph::purge(true /* at_safepoint */); } // Resize and verify metaspace MetaspaceGC::compute_new_size(); if (mode()->is_generational()) { old_generation()->set_parsable(false); } DEBUG_ONLY(MetaspaceUtils::verify();) } // Weak roots are either pre-evacuated (final mark) or updated (final update refs), // so they should not have forwarded oops. // However, we do need to "null" dead oops in the roots, if can not be done // in concurrent cycles. void ShenandoahHeap::stw_process_weak_roots(bool full_gc) { uint num_workers = _workers->active_workers(); ShenandoahPhaseTimings::Phase timing_phase = full_gc ? ShenandoahPhaseTimings::full_gc_purge_weak_par : ShenandoahPhaseTimings::degen_gc_purge_weak_par; ShenandoahGCPhase phase(timing_phase); ShenandoahGCWorkerPhase worker_phase(timing_phase); // Cleanup weak roots if (has_forwarded_objects()) { ShenandoahForwardedIsAliveClosure is_alive; ShenandoahNonConcUpdateRefsClosure keep_alive; ShenandoahParallelWeakRootsCleaningTask cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers); _workers->run_task(&cleaning_task); } else { ShenandoahIsAliveClosure is_alive; #ifdef ASSERT ShenandoahAssertNotForwardedClosure verify_cl; ShenandoahParallelWeakRootsCleaningTask cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers); #else ShenandoahParallelWeakRootsCleaningTask cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers); #endif _workers->run_task(&cleaning_task); } } void ShenandoahHeap::parallel_cleaning(ShenandoahGeneration* generation, bool full_gc) { assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); assert(is_stw_gc_in_progress(), "Only for Degenerated and Full GC"); ShenandoahGCPhase phase(full_gc ? ShenandoahPhaseTimings::full_gc_purge : ShenandoahPhaseTimings::degen_gc_purge); stw_weak_refs(generation, full_gc); stw_process_weak_roots(full_gc); stw_unload_classes(full_gc); } void ShenandoahHeap::set_has_forwarded_objects(bool cond) { set_gc_state_at_safepoint(HAS_FORWARDED, cond); } void ShenandoahHeap::set_unload_classes(bool uc) { _unload_classes.set_cond(uc); } bool ShenandoahHeap::unload_classes() const { return _unload_classes.is_set(); } address ShenandoahHeap::in_cset_fast_test_addr() { ShenandoahHeap* heap = ShenandoahHeap::heap(); assert(heap->collection_set() != nullptr, "Sanity"); return (address) heap->collection_set()->biased_map_address(); } void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) { _degenerated_gc_in_progress.set_cond(in_progress); } void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) { _full_gc_in_progress.set_cond(in_progress); } void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) { assert (is_full_gc_in_progress(), "should be"); _full_gc_move_in_progress.set_cond(in_progress); } void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) { set_gc_state_at_safepoint(UPDATE_REFS, in_progress); } void ShenandoahHeap::register_nmethod(nmethod* nm) { ShenandoahCodeRoots::register_nmethod(nm); } void ShenandoahHeap::unregister_nmethod(nmethod* nm) { ShenandoahCodeRoots::unregister_nmethod(nm); } void ShenandoahHeap::pin_object(JavaThread* thr, oop o) { heap_region_containing(o)->record_pin(); } void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) { ShenandoahHeapRegion* r = heap_region_containing(o); assert(r != nullptr, "Sanity"); assert(r->pin_count() > 0, "Region %zu should have non-zero pins", r->index()); r->record_unpin(); } void ShenandoahHeap::sync_pinned_region_status() { ShenandoahHeapLocker locker(lock()); for (size_t i = 0; i < num_regions(); i++) { ShenandoahHeapRegion *r = get_region(i); if (r->is_active()) { if (r->is_pinned()) { if (r->pin_count() == 0) { r->make_unpinned(); } } else { if (r->pin_count() > 0) { r->make_pinned(); } } } } assert_pinned_region_status(); } #ifdef ASSERT void ShenandoahHeap::assert_pinned_region_status() const { assert_pinned_region_status(global_generation()); } void ShenandoahHeap::assert_pinned_region_status(ShenandoahGeneration* generation) const { for (size_t i = 0; i < num_regions(); i++) { ShenandoahHeapRegion* r = get_region(i); if (generation->contains(r)) { assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0), "Region %zu pinning status is inconsistent", i); } } } #endif ConcurrentGCTimer* ShenandoahHeap::gc_timer() const { return _gc_timer; } void ShenandoahHeap::prepare_concurrent_roots() { assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); assert(!is_stw_gc_in_progress(), "Only concurrent GC"); set_concurrent_strong_root_in_progress(!collection_set()->is_empty()); set_concurrent_weak_root_in_progress(true); if (unload_classes()) { _unloader.prepare(); } } void ShenandoahHeap::finish_concurrent_roots() { assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); assert(!is_stw_gc_in_progress(), "Only concurrent GC"); if (unload_classes()) { _unloader.finish(); } } #ifdef ASSERT void ShenandoahHeap::assert_gc_workers(uint nworkers) { assert(nworkers > 0 && nworkers <= max_workers(), "Sanity"); if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) { // Use ParallelGCThreads inside safepoints assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads (%u) within safepoint, not %u", ParallelGCThreads, nworkers); } else { // Use ConcGCThreads outside safepoints assert(nworkers == ConcGCThreads, "Use ConcGCThreads (%u) outside safepoints, %u", ConcGCThreads, nworkers); } } #endif ShenandoahVerifier* ShenandoahHeap::verifier() { guarantee(ShenandoahVerify, "Should be enabled"); assert (_verifier != nullptr, "sanity"); return _verifier; } template class ShenandoahUpdateHeapRefsTask : public WorkerTask { private: ShenandoahHeap* _heap; ShenandoahRegionIterator* _regions; public: explicit ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) : WorkerTask("Shenandoah Update References"), _heap(ShenandoahHeap::heap()), _regions(regions) { } void work(uint worker_id) { if (CONCURRENT) { ShenandoahWorkerTimingsTracker timer(ShenandoahPhaseTimings::conc_update_refs, ShenandoahPhaseTimings::Work, worker_id, true); ShenandoahConcurrentWorkerSession worker_session(worker_id); SuspendibleThreadSetJoiner stsj; do_work(worker_id); } else { ShenandoahWorkerTimingsTracker timer(ShenandoahPhaseTimings::degen_gc_update_refs, ShenandoahPhaseTimings::Work, worker_id, true); ShenandoahParallelWorkerSession worker_session(worker_id); do_work(worker_id); } } private: template void do_work(uint worker_id) { if (CONCURRENT && (worker_id == 0)) { // We ask the first worker to replenish the Mutator free set by moving regions previously reserved to hold the // results of evacuation. These reserves are no longer necessary because evacuation has completed. size_t cset_regions = _heap->collection_set()->count(); // Now that evacuation is done, we can reassign any regions that had been reserved to hold the results of evacuation // to the mutator free set. At the end of GC, we will have cset_regions newly evacuated fully empty regions from // which we will be able to replenish the Collector free set and the OldCollector free set in preparation for the // next GC cycle. _heap->free_set()->move_regions_from_collector_to_mutator(cset_regions); } // If !CONCURRENT, there's no value in expanding Mutator free set T cl; ShenandoahHeapRegion* r = _regions->next(); while (r != nullptr) { HeapWord* update_watermark = r->get_update_watermark(); assert (update_watermark >= r->bottom(), "sanity"); if (r->is_active() && !r->is_cset()) { _heap->marked_object_oop_iterate(r, &cl, update_watermark); } if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) { return; } r = _regions->next(); } } }; void ShenandoahHeap::update_heap_references(ShenandoahGeneration* generation, bool concurrent) { assert(generation->is_global(), "Should only get global generation here"); assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC"); if (concurrent) { ShenandoahUpdateHeapRefsTask task(&_update_refs_iterator); workers()->run_task(&task); } else { ShenandoahUpdateHeapRefsTask task(&_update_refs_iterator); workers()->run_task(&task); } } void ShenandoahHeap::update_heap_region_states(bool concurrent) { assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC"); { ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_refs_update_region_states : ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states); final_update_refs_update_region_states(); assert_pinned_region_status(); } { ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_refs_trash_cset : ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset); trash_cset_regions(); } } void ShenandoahHeap::final_update_refs_update_region_states() { ShenandoahSynchronizePinnedRegionStates cl; parallel_heap_region_iterate(&cl); } void ShenandoahHeap::rebuild_free_set_within_phase() { ShenandoahHeapLocker locker(lock()); size_t young_trashed_regions, old_trashed_regions, first_old_region, last_old_region, old_region_count; _free_set->prepare_to_rebuild(young_trashed_regions, old_trashed_regions, first_old_region, last_old_region, old_region_count); // If there are no old regions, first_old_region will be greater than last_old_region assert((first_old_region > last_old_region) || ((last_old_region + 1 - first_old_region >= old_region_count) && get_region(first_old_region)->is_old() && get_region(last_old_region)->is_old()), "sanity: old_region_count: %zu, first_old_region: %zu, last_old_region: %zu", old_region_count, first_old_region, last_old_region); if (mode()->is_generational()) { #ifdef ASSERT if (ShenandoahVerify) { verifier()->verify_before_rebuilding_free_set(); } #endif // The computation of bytes_of_allocation_runway_before_gc_trigger is quite conservative so consider all of this // available for transfer to old. Note that transfer of humongous regions does not impact available. ShenandoahGenerationalHeap* gen_heap = ShenandoahGenerationalHeap::heap(); size_t allocation_runway = gen_heap->young_generation()->heuristics()->bytes_of_allocation_runway_before_gc_trigger(young_trashed_regions); gen_heap->compute_old_generation_balance(allocation_runway, old_trashed_regions, young_trashed_regions); } // Rebuild free set based on adjusted generation sizes. _free_set->finish_rebuild(young_trashed_regions, old_trashed_regions, old_region_count); if (mode()->is_generational()) { ShenandoahGenerationalHeap* gen_heap = ShenandoahGenerationalHeap::heap(); ShenandoahOldGeneration* old_gen = gen_heap->old_generation(); old_gen->heuristics()->evaluate_triggers(first_old_region, last_old_region, old_region_count, num_regions()); } } void ShenandoahHeap::rebuild_free_set(bool concurrent) { ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_refs_rebuild_freeset : ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset); rebuild_free_set_within_phase(); } bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) { size_t slice = r->index() / _bitmap_regions_per_slice; size_t regions_from = _bitmap_regions_per_slice * slice; size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1)); for (size_t g = regions_from; g < regions_to; g++) { assert (g / _bitmap_regions_per_slice == slice, "same slice"); if (skip_self && g == r->index()) continue; if (get_region(g)->is_committed()) { return true; } } return false; } void ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) { shenandoah_assert_heaplocked(); assert(!is_bitmap_region_special(), "Not for special memory"); if (is_bitmap_slice_committed(r, true)) { // Some other region from the group is already committed, meaning the bitmap // slice is already committed, we exit right away. return; } // Commit the bitmap slice: size_t slice = r->index() / _bitmap_regions_per_slice; size_t off = _bitmap_bytes_per_slice * slice; size_t len = _bitmap_bytes_per_slice; char* start = (char*) _bitmap_region.start() + off; os::commit_memory_or_exit(start, len, false, "Unable to commit bitmap slice"); if (AlwaysPreTouch) { os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size); } } void ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) { shenandoah_assert_heaplocked(); assert(!is_bitmap_region_special(), "Not for special memory"); if (is_bitmap_slice_committed(r, true)) { // Some other region from the group is still committed, meaning the bitmap // slice should stay committed, exit right away. return; } // Uncommit the bitmap slice: size_t slice = r->index() / _bitmap_regions_per_slice; size_t off = _bitmap_bytes_per_slice * slice; size_t len = _bitmap_bytes_per_slice; char* addr = (char*) _bitmap_region.start() + off; os::uncommit_memory(addr, len); } void ShenandoahHeap::forbid_uncommit() { if (_uncommit_thread != nullptr) { _uncommit_thread->forbid_uncommit(); } } void ShenandoahHeap::allow_uncommit() { if (_uncommit_thread != nullptr) { _uncommit_thread->allow_uncommit(); } } #ifdef ASSERT bool ShenandoahHeap::is_uncommit_in_progress() { if (_uncommit_thread != nullptr) { return _uncommit_thread->is_uncommit_in_progress(); } return false; } #endif void ShenandoahHeap::safepoint_synchronize_begin() { StackWatermarkSet::safepoint_synchronize_begin(); SuspendibleThreadSet::synchronize(); } void ShenandoahHeap::safepoint_synchronize_end() { SuspendibleThreadSet::desynchronize(); } void ShenandoahHeap::try_inject_alloc_failure() { if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) { _inject_alloc_failure.set(); os::naked_short_sleep(1); if (cancelled_gc()) { log_info(gc)("Allocation failure was successfully injected"); } } } bool ShenandoahHeap::should_inject_alloc_failure() { return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset(); } void ShenandoahHeap::initialize_serviceability() { _memory_pool = new ShenandoahMemoryPool(this); _cycle_memory_manager.add_pool(_memory_pool); _stw_memory_manager.add_pool(_memory_pool); } GrowableArray ShenandoahHeap::memory_managers() { GrowableArray memory_managers(2); memory_managers.append(&_cycle_memory_manager); memory_managers.append(&_stw_memory_manager); return memory_managers; } GrowableArray ShenandoahHeap::memory_pools() { GrowableArray memory_pools(1); memory_pools.append(_memory_pool); return memory_pools; } MemoryUsage ShenandoahHeap::memory_usage() { return shenandoah_memory_usage(_initial_size, used(), committed(), max_capacity()); } ShenandoahRegionIterator::ShenandoahRegionIterator() : _heap(ShenandoahHeap::heap()), _index(0) {} ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) : _heap(heap), _index(0) {} void ShenandoahRegionIterator::reset() { _index.store_relaxed(0); } bool ShenandoahRegionIterator::has_next() const { return _index.load_relaxed() < _heap->num_regions(); } ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) { #ifdef ASSERT assert(_liveness_cache != nullptr, "sanity"); assert(worker_id < _max_workers, "sanity"); for (uint i = 0; i < num_regions(); i++) { assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty"); } #endif return _liveness_cache[worker_id]; } void ShenandoahHeap::flush_liveness_cache(uint worker_id) { assert(worker_id < _max_workers, "sanity"); assert(_liveness_cache != nullptr, "sanity"); ShenandoahLiveData* ld = _liveness_cache[worker_id]; for (uint i = 0; i < num_regions(); i++) { ShenandoahLiveData live = ld[i]; if (live > 0) { ShenandoahHeapRegion* r = get_region(i); r->increase_live_data_gc_words(live); ld[i] = 0; } } } bool ShenandoahHeap::requires_barriers(stackChunkOop obj) const { if (is_idle()) return false; // Objects allocated after marking start are implicitly alive, don't need any barriers during // marking phase. if (is_concurrent_mark_in_progress() && !marking_context()->allocated_after_mark_start(obj)) { return true; } // Can not guarantee obj is deeply good. if (has_forwarded_objects()) { return true; } return false; } HeapWord* ShenandoahHeap::allocate_loaded_archive_space(size_t size) { #if INCLUDE_CDS_JAVA_HEAP // CDS wants a raw continuous memory range to load a bunch of objects itself. // This is an unusual request, since all requested regions should be regular, not humongous. // // CDS would guarantee no objects straddle multiple regions, as long as regions are as large // as MIN_GC_REGION_ALIGNMENT. guarantee(ShenandoahHeapRegion::region_size_bytes() >= AOTMappedHeapWriter::MIN_GC_REGION_ALIGNMENT, "Must be"); ShenandoahAllocRequest req = ShenandoahAllocRequest::for_cds(size); return allocate_memory(req); #else assert(false, "Archive heap loader should not be available, should not be here"); return nullptr; #endif // INCLUDE_CDS_JAVA_HEAP } void ShenandoahHeap::complete_loaded_archive_space(MemRegion archive_space) { // Nothing to do here, except checking that heap looks fine. #ifdef ASSERT HeapWord* start = archive_space.start(); HeapWord* end = archive_space.end(); // No unclaimed space between the objects. // Objects are properly allocated in correct regions. HeapWord* cur = start; while (cur < end) { oop oop = cast_to_oop(cur); shenandoah_assert_in_correct_region(nullptr, oop); cur += oop->size(); } // No unclaimed tail at the end of archive space. assert(cur == end, "Archive space should be fully used: " PTR_FORMAT " " PTR_FORMAT, p2i(cur), p2i(end)); // All regions in contiguous space have good state. size_t begin_reg_idx = heap_region_index_containing(start); size_t end_reg_idx = heap_region_index_containing(end); for (size_t idx = begin_reg_idx; idx <= end_reg_idx; idx++) { ShenandoahHeapRegion* r = get_region(idx); assert(r->is_regular(), "Must be regular"); assert(r->is_young(), "Must be young"); assert(idx == end_reg_idx || r->top() == r->end(), "All regions except the last one should be full: " PTR_FORMAT " " PTR_FORMAT, p2i(r->top()), p2i(r->end())); assert(idx != begin_reg_idx || r->bottom() == start, "Archive space start should be at the bottom of first region: " PTR_FORMAT " " PTR_FORMAT, p2i(r->bottom()), p2i(start)); assert(idx != end_reg_idx || r->top() == end, "Archive space end should be at the top of last region: " PTR_FORMAT " " PTR_FORMAT, p2i(r->top()), p2i(end)); } #endif } ShenandoahGeneration* ShenandoahHeap::generation_for(ShenandoahAffiliation affiliation) const { if (!mode()->is_generational()) { return global_generation(); } else if (affiliation == YOUNG_GENERATION) { return young_generation(); } else if (affiliation == OLD_GENERATION) { return old_generation(); } ShouldNotReachHere(); return nullptr; } void ShenandoahHeap::log_heap_status(const char* msg) const { if (mode()->is_generational()) { young_generation()->log_status(msg); old_generation()->log_status(msg); } else { global_generation()->log_status(msg); } } ShenandoahHeapLocker::ShenandoahHeapLocker(ShenandoahHeapLock* lock, bool allow_block_for_safepoint) : _lock(lock) { #ifdef ASSERT ShenandoahFreeSet* free_set = ShenandoahHeap::heap()->free_set(); // free_set is nullptr only at pre-initialized state assert(free_set == nullptr || !free_set->rebuild_lock()->owned_by_self(), "Dead lock, can't acquire heap lock while holding free-set rebuild lock"); assert(_lock != nullptr, "Must not"); #endif _lock->lock(allow_block_for_safepoint); }