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/*
- * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2023, 2024, 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.
#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/shenandoahAllocRequest.hpp"
#include "gc/shenandoah/shenandoahBarrierSet.hpp"
#include "gc/shenandoah/shenandoahClosures.inline.hpp"
#include "gc/shenandoah/shenandoahCollectionSet.hpp"
#include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
#include "gc/shenandoah/shenandoahConcurrentMark.hpp"
#include "gc/shenandoah/shenandoahMarkingContext.inline.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/shenandoahPhaseTimings.hpp"
#include "gc/shenandoah/shenandoahHeap.inline.hpp"
+ #include "gc/shenandoah/shenandoahHeapRegionClosures.hpp"
#include "gc/shenandoah/shenandoahHeapRegion.inline.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/shenandoahMetrics.hpp"
#include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
+ #include "gc/shenandoah/shenandoahOldGeneration.hpp"
#include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
#include "gc/shenandoah/shenandoahPacer.inline.hpp"
#include "gc/shenandoah/shenandoahPadding.hpp"
#include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
#include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
#include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
+ #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp"
#include "gc/shenandoah/shenandoahSTWMark.hpp"
#include "gc/shenandoah/shenandoahUtils.hpp"
#include "gc/shenandoah/shenandoahVerifier.hpp"
#include "gc/shenandoah/shenandoahCodeRoots.hpp"
#include "gc/shenandoah/shenandoahVMOperations.hpp"
#include "gc/shenandoah/shenandoahWorkGroup.hpp"
#include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
+ #include "gc/shenandoah/shenandoahYoungGeneration.hpp"
+ #include "gc/shenandoah/mode/shenandoahGenerationalMode.hpp"
#include "gc/shenandoah/mode/shenandoahIUMode.hpp"
#include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
#include "gc/shenandoah/mode/shenandoahSATBMode.hpp"
+ #include "utilities/globalDefinitions.hpp"
+
#if INCLUDE_JFR
#include "gc/shenandoah/shenandoahJfrSupport.hpp"
#endif
#include "classfile/systemDictionary.hpp"
_num_regions = ShenandoahHeapRegion::region_count();
assert(_num_regions == (max_byte_size / reg_size_bytes),
"Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT,
_num_regions, max_byte_size, reg_size_bytes);
- // Now we know the number of regions, initialize the heuristics.
- initialize_heuristics();
-
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;
_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_rs.page_size(), heap_alignment,
+ heap_rs.base(), heap_rs.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()) {
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();
+
+ 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("Shenandoah GC Threads", _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)
//
- _bitmap_size = ShenandoahMarkBitMap::compute_size(heap_rs.size());
- _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
+ 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(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
"Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
_bitmap_bytes_per_slice, bitmap_page_size);
ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
+ os::trace_page_sizes_for_requested_size("Mark Bitmap",
+ bitmap_size_orig, bitmap.page_size(), bitmap_page_size,
+ bitmap.base(),
+ bitmap.size());
MemTracker::record_virtual_memory_type(bitmap.base(), 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;
+ 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, _max_workers);
+ _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
if (ShenandoahVerify) {
ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
+ os::trace_page_sizes_for_requested_size("Verify Bitmap",
+ bitmap_size_orig, verify_bitmap.page_size(), bitmap_page_size,
+ verify_bitmap.base(),
+ verify_bitmap.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_type(verify_bitmap.base(), mtGC);
_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.
- ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
+ size_t aux_bitmap_page_size = bitmap_page_size;
+
+ ReservedSpace aux_bitmap(_bitmap_size, aux_bitmap_page_size);
+ os::trace_page_sizes_for_requested_size("Aux Bitmap",
+ bitmap_size_orig, aux_bitmap.page_size(), aux_bitmap_page_size,
+ aux_bitmap.base(), aux_bitmap.size());
MemTracker::record_virtual_memory_type(aux_bitmap.base(), 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 = align_up(region_align * _num_regions, region_page_size);
- region_storage_size = align_up(region_storage_size, os::vm_allocation_granularity());
+ 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(region_storage_size, region_page_size);
+ os::trace_page_sizes_for_requested_size("Region Storage",
+ region_storage_size_orig, region_storage.page_size(), region_page_size,
+ region_storage.base(), region_storage.size());
MemTracker::record_virtual_memory_type(region_storage.base(), 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.
{
- size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity());
- 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_align = MAX2<size_t>(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");
- ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size(), req_addr);
+ cset_rs = ReservedSpace(cset_size, cset_align, cset_page_size, req_addr);
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) {
- ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size());
+ cset_rs = ReservedSpace(cset_size, cset_align, os::vm_page_size());
_collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
}
+ os::trace_page_sizes_for_requested_size("Collection Set",
+ cset_size, cset_rs.page_size(), cset_page_size,
+ cset_rs.base(),
+ cset_rs.size());
}
_regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
+ _affiliations = NEW_C_HEAP_ARRAY(uint8_t, _num_regions, mtGC);
_free_set = new ShenandoahFreeSet(this, _num_regions);
{
ShenandoahHeapLocker locker(lock());
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;
}
// Initialize to complete
_marking_context->mark_complete();
+ size_t young_cset_regions, old_cset_regions;
- _free_set->rebuild();
+ // We are initializing free set. We ignore cset region tallies.
+ size_t first_old, last_old, num_old;
+ _free_set->prepare_to_rebuild(young_cset_regions, old_cset_regions, first_old, last_old, num_old);
+ _free_set->finish_rebuild(young_cset_regions, old_cset_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,
ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
_pretouch_heap_page_size = heap_page_size;
_pretouch_bitmap_page_size = bitmap_page_size;
- #ifdef LINUX
- // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
- // pages. But, the kernel needs to know that every small page is used, in order to coalesce
- // them into huge one. Therefore, we need to pretouch with smaller pages.
- if (UseTransparentHugePages) {
- _pretouch_heap_page_size = (size_t)os::vm_page_size();
- _pretouch_bitmap_page_size = (size_t)os::vm_page_size();
- }
- #endif
-
// 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);
ShenandoahCodeRoots::initialize();
if (ShenandoahPacing) {
_pacer = new ShenandoahPacer(this);
_pacer->setup_for_idle();
- } else {
- _pacer = nullptr;
}
- _control_thread = new ShenandoahControlThread();
+ initialize_controller();
- ShenandoahInitLogger::print();
+ print_init_logger();
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, "iu") == 0) {
_gc_mode = new ShenandoahIUMode();
} 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->name()));
}
}
void ShenandoahHeap::initialize_heuristics() {
- assert(_gc_mode != nullptr, "Must be initialized");
- _heuristics = _gc_mode->initialize_heuristics();
-
- if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
- vm_exit_during_initialization(
- err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
- _heuristics->name()));
- }
- if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
- vm_exit_during_initialization(
- err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
- _heuristics->name()));
- }
+ _global_generation = new ShenandoahGlobalGeneration(mode()->is_generational(), max_workers(), max_capacity(), max_capacity());
+ _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(),
+ _gc_generation(nullptr),
+ _active_generation(nullptr),
_initial_size(0),
- _used(0),
_committed(0),
- _bytes_allocated_since_gc_start(0),
- _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
+ _max_workers(MAX3(ConcGCThreads, ParallelGCThreads, 1U)),
_workers(nullptr),
_safepoint_workers(nullptr),
_heap_region_special(false),
_num_regions(0),
_regions(nullptr),
- _update_refs_iterator(this),
+ _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),
+ _young_generation(nullptr),
+ _old_generation(nullptr),
_shenandoah_policy(policy),
_gc_mode(nullptr),
- _heuristics(nullptr),
_free_set(nullptr),
_pacer(nullptr),
_verifier(nullptr),
_phase_timings(nullptr),
_monitoring_support(nullptr),
_stw_memory_manager("Shenandoah Pauses"),
_cycle_memory_manager("Shenandoah Cycles"),
_gc_timer(new ConcurrentGCTimer()),
_soft_ref_policy(),
_log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
- _ref_processor(new ShenandoahReferenceProcessor(MAX2(_max_workers, 1U))),
_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)
{
- // Initialize GC mode early, so we can adjust barrier support
+ // Initialize GC mode early, many subsequent initialization procedures depend on it
initialize_mode();
- BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
-
- _max_workers = MAX2(_max_workers, 1U);
- _workers = new ShenandoahWorkerThreads("Shenandoah GC Threads", _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();
- }
}
#ifdef _MSC_VER
#pragma warning( pop )
#endif
- class ShenandoahResetBitmapTask : public WorkerTask {
- private:
- ShenandoahRegionIterator _regions;
-
- public:
- ShenandoahResetBitmapTask() :
- WorkerTask("Shenandoah Reset Bitmap") {}
-
- void work(uint worker_id) {
- ShenandoahHeapRegion* region = _regions.next();
- ShenandoahHeap* heap = ShenandoahHeap::heap();
- ShenandoahMarkingContext* const ctx = heap->marking_context();
- while (region != nullptr) {
- if (heap->is_bitmap_slice_committed(region)) {
- ctx->clear_bitmap(region);
- }
- region = _regions.next();
- }
- }
- };
-
- void ShenandoahHeap::reset_mark_bitmap() {
- assert_gc_workers(_workers->active_workers());
- mark_incomplete_marking_context();
-
- ShenandoahResetBitmapTask task;
- _workers->run_task(&task);
- }
-
void ShenandoahHeap::print_on(outputStream* st) const {
st->print_cr("Shenandoah Heap");
st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()),
byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
st->print("Status: ");
if (has_forwarded_objects()) st->print("has forwarded objects, ");
- if (is_concurrent_mark_in_progress()) st->print("marking, ");
+ if (!mode()->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, ");
}
};
void ShenandoahHeap::post_initialize() {
CollectedHeap::post_initialize();
+
+ // Schedule periodic task to report on gc thread CPU utilization
+ _mmu_tracker.initialize();
+
MutexLocker ml(Threads_lock);
ShenandoahInitWorkerGCLABClosure init_gclabs;
_workers->threads_do(&init_gclabs);
if (_safepoint_workers != nullptr) {
_safepoint_workers->threads_do(&init_gclabs);
_safepoint_workers->set_initialize_gclab();
}
- _heuristics->initialize();
-
JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
}
+ ShenandoahHeuristics* ShenandoahHeap::heuristics() {
+ return _global_generation->heuristics();
+ }
+
size_t ShenandoahHeap::used() const {
- return Atomic::load(&_used);
+ return global_generation()->used();
}
size_t ShenandoahHeap::committed() const {
return Atomic::load(&_committed);
}
void ShenandoahHeap::decrease_committed(size_t bytes) {
shenandoah_assert_heaplocked_or_safepoint();
_committed -= bytes;
}
- void ShenandoahHeap::increase_used(size_t bytes) {
- Atomic::add(&_used, bytes, memory_order_relaxed);
+ // For tracking usage based on allocations, it should be the case that:
+ // * The sum of regions::used == heap::used
+ // * The sum of a generation's regions::used == generation::used
+ // * The sum of a generation's humongous regions::free == generation::humongous_waste
+ // These invariants are checked by the verifier on GC safepoints.
+ //
+ // Additional notes:
+ // * When a mutator's allocation request causes a region to be retired, the
+ // free memory left in that region is considered waste. It does not contribute
+ // to the usage, but it _does_ contribute to allocation rate.
+ // * The bottom of a PLAB must be aligned on card size. In some cases this will
+ // require padding in front of the PLAB (a filler object). Because this padding
+ // is included in the region's used memory we include the padding in the usage
+ // accounting as waste.
+ // * Mutator allocations are used to compute an allocation rate. They are also
+ // sent to the Pacer for those purposes.
+ // * There are three sources of waste:
+ // 1. The padding used to align a PLAB on card size
+ // 2. Region's free is less than minimum TLAB size and is retired
+ // 3. The unused portion of memory in the last region of a humongous object
+ void ShenandoahHeap::increase_used(const ShenandoahAllocRequest& req) {
+ size_t actual_bytes = req.actual_size() * HeapWordSize;
+ size_t wasted_bytes = req.waste() * HeapWordSize;
+ ShenandoahGeneration* generation = generation_for(req.affiliation());
+
+ if (req.is_gc_alloc()) {
+ assert(wasted_bytes == 0 || req.type() == ShenandoahAllocRequest::_alloc_plab, "Only PLABs have waste");
+ increase_used(generation, actual_bytes + wasted_bytes);
+ } else {
+ assert(req.is_mutator_alloc(), "Expected mutator alloc here");
+ // padding and actual size both count towards allocation counter
+ generation->increase_allocated(actual_bytes + wasted_bytes);
+
+ // only actual size counts toward usage for mutator allocations
+ increase_used(generation, actual_bytes);
+
+ // notify pacer of both actual size and waste
+ notify_mutator_alloc_words(req.actual_size(), req.waste());
+
+ if (wasted_bytes > 0 && ShenandoahHeapRegion::requires_humongous(req.actual_size())) {
+ increase_humongous_waste(generation,wasted_bytes);
+ }
+ }
}
- void ShenandoahHeap::set_used(size_t bytes) {
- Atomic::store(&_used, bytes);
+ void ShenandoahHeap::increase_humongous_waste(ShenandoahGeneration* generation, size_t bytes) {
+ generation->increase_humongous_waste(bytes);
+ if (!generation->is_global()) {
+ global_generation()->increase_humongous_waste(bytes);
+ }
}
- void ShenandoahHeap::decrease_used(size_t bytes) {
- assert(used() >= bytes, "never decrease heap size by more than we've left");
- Atomic::sub(&_used, bytes, memory_order_relaxed);
+ void ShenandoahHeap::decrease_humongous_waste(ShenandoahGeneration* generation, size_t bytes) {
+ generation->decrease_humongous_waste(bytes);
+ if (!generation->is_global()) {
+ global_generation()->decrease_humongous_waste(bytes);
+ }
}
- void ShenandoahHeap::increase_allocated(size_t bytes) {
- Atomic::add(&_bytes_allocated_since_gc_start, bytes, memory_order_relaxed);
+ void ShenandoahHeap::increase_used(ShenandoahGeneration* generation, size_t bytes) {
+ generation->increase_used(bytes);
+ if (!generation->is_global()) {
+ global_generation()->increase_used(bytes);
+ }
}
- void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
- size_t bytes = words * HeapWordSize;
- if (!waste) {
- increase_used(bytes);
+ void ShenandoahHeap::decrease_used(ShenandoahGeneration* generation, size_t bytes) {
+ generation->decrease_used(bytes);
+ if (!generation->is_global()) {
+ global_generation()->decrease_used(bytes);
}
- increase_allocated(bytes);
+ }
+
+ void ShenandoahHeap::notify_mutator_alloc_words(size_t words, size_t waste) {
if (ShenandoahPacing) {
control_thread()->pacing_notify_alloc(words);
- if (waste) {
- pacer()->claim_for_alloc(words, true);
+ if (waste > 0) {
+ pacer()->claim_for_alloc<true>(waste);
}
}
}
size_t ShenandoahHeap::capacity() const {
size_t ShenandoahHeap::initial_capacity() const {
return _initial_size;
}
- bool ShenandoahHeap::is_in(const void* p) const {
- HeapWord* heap_base = (HeapWord*) base();
- HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
- return p >= heap_base && p < last_region_end;
+ void ShenandoahHeap::maybe_uncommit(double shrink_before, size_t shrink_until) {
+ assert (ShenandoahUncommit, "should be enabled");
+
+ // Determine if there is work to do. This avoids taking heap lock if there is
+ // no work available, avoids spamming logs with superfluous logging messages,
+ // and minimises the amount of work while locks are taken.
+
+ if (committed() <= shrink_until) return;
+
+ bool has_work = false;
+ for (size_t i = 0; i < num_regions(); i++) {
+ ShenandoahHeapRegion* r = get_region(i);
+ if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
+ has_work = true;
+ break;
+ }
+ }
+
+ if (has_work) {
+ static const char* msg = "Concurrent uncommit";
+ ShenandoahConcurrentPhase gcPhase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */);
+ EventMark em("%s", msg);
+
+ op_uncommit(shrink_before, shrink_until);
+ }
}
void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
assert (ShenandoahUncommit, "should be enabled");
}
SpinPause(); // allow allocators to take the lock
}
if (count > 0) {
- control_thread()->notify_heap_changed();
+ notify_heap_changed();
+ }
+ }
+
+ bool ShenandoahHeap::check_soft_max_changed() {
+ size_t new_soft_max = Atomic::load(&SoftMaxHeapSize);
+ size_t old_soft_max = soft_max_capacity();
+ if (new_soft_max != old_soft_max) {
+ new_soft_max = MAX2(min_capacity(), new_soft_max);
+ new_soft_max = MIN2(max_capacity(), new_soft_max);
+ if (new_soft_max != old_soft_max) {
+ log_info(gc)("Soft Max Heap Size: " SIZE_FORMAT "%s -> " SIZE_FORMAT "%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::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: " SIZE_FORMAT, 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 (" SIZE_FORMAT ") is too small for " SIZE_FORMAT, new_size, size);
return nullptr;
}
// Retire current GCLAB, and allocate a new one.
PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
}
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 (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
result = allocate_memory_under_lock(req, in_new_region);
}
- // Allocation failed, block until control thread reacted, then retry allocation.
+ // Check that gc overhead is not exceeded.
//
- // 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, as long as GC makes progress (or until at least
- // one full GC has completed).
- size_t original_count = shenandoah_policy()->full_gc_count();
- while (result == nullptr
- && (_progress_last_gc.is_set() || original_count == shenandoah_policy()->full_gc_count())) {
- control_thread()->handle_alloc_failure(req);
- result = allocate_memory_under_lock(req, in_new_region);
+ // 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)
+
+ size_t original_count = shenandoah_policy()->full_gc_count();
+ while ((result == nullptr) && (original_count == shenandoah_policy()->full_gc_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 satisifed 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: " SIZE_FORMAT
+ ", Original: " SIZE_FORMAT ", Latest: " SIZE_FORMAT,
+ 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) {
- control_thread()->notify_heap_changed();
+ notify_heap_changed();
+ }
+
+ if (result == nullptr) {
+ req.set_actual_size(0);
}
+ // This is called regardless of the outcome of the allocation to account
+ // for any waste created by retiring regions with this request.
+ increase_used(req);
+
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 = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
if (req.is_mutator_alloc()) {
- notify_mutator_alloc_words(actual, false);
-
// If we requested more than we were granted, give the rest back to pacer.
// This only matters if we are in the same pacing epoch: do not try to unpace
// over the budget for the other phase.
if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
}
- } else {
- increase_used(actual*HeapWordSize);
}
}
return result;
}
// 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());
- return _free_set->allocate(req, in_new_region);
+
+ // 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);
+
+ // Record the plab configuration for this result and register the object.
+ if (result != nullptr && req.is_old()) {
+ old_generation()->configure_plab_for_current_thread(req);
+ if (req.type() == ShenandoahAllocRequest::_alloc_shared_gc) {
+ // Register the newly allocated object while we're holding the global lock since there's no synchronization
+ // built in to the implementation of register_object(). There are potential races when multiple independent
+ // threads are allocating objects, some of which might span the same card region. For example, consider
+ // a card table's memory region within which three objects are being allocated by three different threads:
+ //
+ // objects being "concurrently" allocated:
+ // [-----a------][-----b-----][--------------c------------------]
+ // [---- card table memory range --------------]
+ //
+ // Before any objects are allocated, this card's memory range holds no objects. Note that allocation of object a
+ // wants to set the starts-object, first-start, and last-start attributes of the preceding card region.
+ // Allocation of object b wants to set the starts-object, first-start, and last-start attributes of this card region.
+ // Allocation of object c also wants to set the starts-object, first-start, and last-start attributes of this
+ // card region.
+ //
+ // The thread allocating b and the thread allocating c can "race" in various ways, resulting in confusion, such as
+ // last-start representing object b while first-start represents object c. This is why we need to require all
+ // register_object() invocations to be "mutually exclusive" with respect to each card's memory range.
+ old_generation()->card_scan()->register_object(result);
+ }
+ }
+
+ return result;
}
HeapWord* ShenandoahHeap::mem_allocate(size_t size,
bool* gc_overhead_limit_was_exceeded) {
ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
size_t size,
Metaspace::MetadataType mdtype) {
MetaWord* result;
// Inform metaspace OOM to GC heuristics if class unloading is possible.
- if (heuristics()->can_unload_classes()) {
- ShenandoahHeuristics* h = heuristics();
+ 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);
void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
ShenandoahEvacuationTask task(this, _collection_set, concurrent);
workers()->run_task(&task);
}
+ oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) {
+ assert(thread == Thread::current(), "Expected thread parameter to be current thread.");
+ if (ShenandoahThreadLocalData::is_oom_during_evac(thread)) {
+ // This thread went through the OOM during evac protocol. It is safe to return
+ // the forward pointer. It must not attempt to evacuate any other objects.
+ return ShenandoahBarrierSet::resolve_forwarded(p);
+ }
+
+ assert(ShenandoahThreadLocalData::is_evac_allowed(thread), "must be enclosed in oom-evac scope");
+
+ 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 = p->size();
+
+ #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);
+
+ _oom_evac_handler.handle_out_of_memory_during_evacuation();
+
+ return ShenandoahBarrierSet::resolve_forwarded(p);
+ }
+
+ // Copy the object:
+ Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(p), copy, size);
+
+ // Try to install the new forwarding pointer.
+ oop copy_val = cast_to_oop(copy);
+ oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val);
+ if (result == copy_val) {
+ // Successfully evacuated. Our copy is now the public one!
+ ContinuationGCSupport::relativize_stack_chunk(copy_val);
+ shenandoah_assert_correct(nullptr, copy_val);
+ 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;
+ }
+ }
+
void ShenandoahHeap::trash_cset_regions() {
ShenandoahHeapLocker locker(lock());
ShenandoahCollectionSet* set = collection_set();
ShenandoahHeapRegion* r;
for (size_t i = 0; i < num_regions(); i++) {
get_region(i)->print_on(st);
}
}
- void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
+ size_t ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
assert(start->is_humongous_start(), "reclaim regions starting with the first one");
oop humongous_obj = cast_to_oop(start->bottom());
size_t size = humongous_obj->size();
size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
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();
}
+ return required_regions;
}
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()) {
+ PLAB* plab = ShenandoahThreadLocalData::plab(thread);
+ assert(plab != nullptr, "PLAB should be initialized for %s", thread->name());
+ assert(plab->words_remaining() == 0, "PLAB should not need retirement");
+ }
}
};
class ShenandoahRetireGCLABClosure : public ThreadClosure {
private:
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()) {
+ PLAB* plab = ShenandoahThreadLocalData::plab(thread);
+ assert(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
+ ShenandoahGenerationalHeap::heap()->retire_plab(plab, thread);
+ if (_resize && ShenandoahThreadLocalData::plab_size(thread) > 0) {
+ ShenandoahThreadLocalData::set_plab_size(thread, 0);
+ }
+ }
}
};
void ShenandoahHeap::labs_make_parsable() {
assert(UseTLAB, "Only call with UseTLAB");
labs_make_parsable();
}
}
void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
- tcl->do_thread(_control_thread);
+ if (_shenandoah_policy->is_at_shutdown()) {
+ return;
+ }
+
+ if (_control_thread != nullptr) {
+ tcl->do_thread(_control_thread);
+ }
+
workers()->threads_do(tcl);
if (_safepoint_workers != nullptr) {
_safepoint_workers->threads_do(tcl);
}
}
ls.cr();
ls.cr();
}
}
+ void ShenandoahHeap::set_gc_generation(ShenandoahGeneration* generation) {
+ shenandoah_assert_control_or_vm_thread_at_safepoint();
+ _gc_generation = generation;
+ }
+
+ // Active generation may only be set by the VM thread at a safepoint.
+ void ShenandoahHeap::set_active_generation() {
+ assert(Thread::current()->is_VM_thread(), "Only the VM Thread");
+ assert(SafepointSynchronize::is_at_safepoint(), "Only at a safepoint!");
+ assert(_gc_generation != nullptr, "Will set _active_generation to nullptr");
+ _active_generation = _gc_generation;
+ }
+
+ void ShenandoahHeap::on_cycle_start(GCCause::Cause cause, ShenandoahGeneration* generation) {
+ shenandoah_policy()->record_collection_cause(cause);
+
+ assert(gc_cause() == GCCause::_no_gc, "Over-writing cause");
+ assert(_gc_generation == nullptr, "Over-writing _gc_generation");
+
+ set_gc_cause(cause);
+ set_gc_generation(generation);
+
+ generation->heuristics()->record_cycle_start();
+ }
+
+ void ShenandoahHeap::on_cycle_end(ShenandoahGeneration* generation) {
+ assert(gc_cause() != GCCause::_no_gc, "cause wasn't set");
+ assert(_gc_generation != nullptr, "_gc_generation 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_generation(nullptr);
+ set_gc_cause(GCCause::_no_gc);
+ }
+
void ShenandoahHeap::verify(VerifyOption vo) {
if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
if (ShenandoahVerify) {
verifier()->verify_generic(vo);
} else {
} else {
heap_region_iterate(blk);
}
}
- class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
- private:
- ShenandoahMarkingContext* const _ctx;
- public:
- ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
-
- void heap_region_do(ShenandoahHeapRegion* r) {
- assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
- if (r->is_active()) {
- // Check if region needs updating its TAMS. We have updated it already during concurrent
- // reset, so it is very likely we don't need to do another write here.
- if (_ctx->top_at_mark_start(r) != r->top()) {
- _ctx->capture_top_at_mark_start(r);
- }
- } else {
- assert(_ctx->top_at_mark_start(r) == r->top(),
- "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
- }
- }
-
- bool is_thread_safe() { return true; }
- };
-
class ShenandoahRendezvousClosure : public HandshakeClosure {
public:
inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {}
inline void do_thread(Thread* thread) {}
};
void ShenandoahHeap::recycle_trash() {
free_set()->recycle_trash();
}
- class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
- private:
- ShenandoahMarkingContext* const _ctx;
- public:
- ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
-
- void heap_region_do(ShenandoahHeapRegion* r) {
- if (r->is_active()) {
- // Reset live data and set TAMS optimistically. We would recheck these under the pause
- // anyway to capture any updates that happened since now.
- r->clear_live_data();
- _ctx->capture_top_at_mark_start(r);
- }
- }
-
- bool is_thread_safe() { return true; }
- };
-
- void ShenandoahHeap::prepare_gc() {
- reset_mark_bitmap();
-
- ShenandoahResetUpdateRegionStateClosure cl;
- parallel_heap_region_iterate(&cl);
- }
-
- class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
- private:
- ShenandoahMarkingContext* const _ctx;
- ShenandoahHeapLock* const _lock;
-
- public:
- ShenandoahFinalMarkUpdateRegionStateClosure() :
- _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
-
- void heap_region_do(ShenandoahHeapRegion* r) {
- if (r->is_active()) {
- // All allocations past TAMS are implicitly live, adjust the region data.
- // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
- HeapWord *tams = _ctx->top_at_mark_start(r);
- HeapWord *top = r->top();
- if (top > tams) {
- r->increase_live_data_alloc_words(pointer_delta(top, tams));
- }
-
- // We are about to select the collection set, make sure it knows about
- // current pinning status. Also, this allows trashing more regions that
- // now have their pinning status dropped.
- if (r->is_pinned()) {
- if (r->pin_count() == 0) {
- ShenandoahHeapLocker locker(_lock);
- r->make_unpinned();
- }
- } else {
- if (r->pin_count() > 0) {
- ShenandoahHeapLocker locker(_lock);
- r->make_pinned();
- }
- }
-
- // Remember limit for updating refs. It's guaranteed that we get no
- // from-space-refs written from here on.
- r->set_update_watermark_at_safepoint(r->top());
- } else {
- assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
- assert(_ctx->top_at_mark_start(r) == r->top(),
- "Region " SIZE_FORMAT " should have correct TAMS", r->index());
- }
- }
-
- bool is_thread_safe() { return true; }
- };
-
- void ShenandoahHeap::prepare_regions_and_collection_set(bool concurrent) {
- assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
- {
- ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_region_states :
- ShenandoahPhaseTimings::degen_gc_final_update_region_states);
- ShenandoahFinalMarkUpdateRegionStateClosure cl;
- parallel_heap_region_iterate(&cl);
-
- assert_pinned_region_status();
- }
-
- {
- ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::choose_cset :
- ShenandoahPhaseTimings::degen_gc_choose_cset);
- ShenandoahHeapLocker locker(lock());
- _collection_set->clear();
- heuristics()->choose_collection_set(_collection_set);
- }
-
- {
- ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_rebuild_freeset :
- ShenandoahPhaseTimings::degen_gc_final_rebuild_freeset);
- ShenandoahHeapLocker locker(lock());
- _free_set->rebuild();
- }
- }
-
void ShenandoahHeap::do_class_unloading() {
_unloader.unload();
+ if (mode()->is_generational()) {
+ old_generation()->set_parsable(false);
+ }
}
void ShenandoahHeap::stw_weak_refs(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);
- ref_processor()->process_references(phase, workers(), false /* concurrent */);
+ shenandoah_assert_generations_reconciled();
+ gc_generation()->ref_processor()->process_references(phase, workers(), false /* concurrent */);
}
void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint");
_gc_state.set_cond(mask, value);
_gc_state_changed = true;
}
- void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
- assert(!has_forwarded_objects(), "Not expected before/after mark phase");
- set_gc_state(MARKING, in_progress);
- ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
+ 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(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 UPDATEREFS or EVACUATION
+ bool has_forwarded = has_forwarded_objects();
+ bool updating_or_evacuating = _gc_state.is_set(UPDATEREFS | 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(OLD_MARKING, in_progress);
+ } else {
+ set_gc_state(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(EVACUATION, in_progress);
bool ShenandoahHeap::try_cancel_gc() {
jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
return prev == CANCELLABLE;
}
+ 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();
+ }
+
void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
if (try_cancel_gc()) {
FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
log_info(gc)("%s", msg.buffer());
Events::log(Thread::current(), "%s", msg.buffer());
+ _cancel_requested_time = os::elapsedTime();
}
}
uint ShenandoahHeap::max_workers() {
return _max_workers;
// The shutdown sequence should be able to terminate when GC is running.
// Step 0. Notify policy to disable event recording.
_shenandoah_policy->record_shutdown();
+ // Step 0a. Stop reporting on gc thread cpu utilization
+ mmu_tracker()->stop();
+
// Step 1. Notify control thread that we are in shutdown.
// Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
// Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
control_thread()->prepare_for_graceful_shutdown();
ShenandoahHeap* heap = ShenandoahHeap::heap();
assert(heap->collection_set() != nullptr, "Sanity");
return (address) heap->collection_set()->biased_map_address();
}
- size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
- return Atomic::load(&_bytes_allocated_since_gc_start);
- }
-
void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
- Atomic::store(&_bytes_allocated_since_gc_start, (size_t)0);
+ if (mode()->is_generational()) {
+ young_generation()->reset_bytes_allocated_since_gc_start();
+ old_generation()->reset_bytes_allocated_since_gc_start();
+ }
+
+ global_generation()->reset_bytes_allocated_since_gc_start();
}
void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
_degenerated_gc_in_progress.set_cond(in_progress);
}
#ifdef ASSERT
void ShenandoahHeap::assert_pinned_region_status() {
for (size_t i = 0; i < num_regions(); i++) {
ShenandoahHeapRegion* r = get_region(i);
- assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
- "Region " SIZE_FORMAT " pinning status is inconsistent", i);
+ shenandoah_assert_generations_reconciled();
+ if (gc_generation()->contains(r)) {
+ assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
+ "Region " SIZE_FORMAT " pinning status is inconsistent", i);
+ }
}
}
#endif
ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
#ifdef ASSERT
void ShenandoahHeap::assert_gc_workers(uint nworkers) {
assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
- if (UseDynamicNumberOfGCThreads) {
- assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
- } else {
- // Use ParallelGCThreads inside safepoints
- assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
- }
+ // Use ParallelGCThreads inside safepoints
+ assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads (%u) within safepoint, not %u",
+ ParallelGCThreads, nworkers);
} else {
- if (UseDynamicNumberOfGCThreads) {
- assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
- } else {
- // Use ConcGCThreads outside safepoints
- assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
- }
+ // Use ConcGCThreads outside safepoints
+ assert(nworkers == ConcGCThreads, "Use ConcGCThreads (%u) outside safepoints, %u",
+ ConcGCThreads, nworkers);
}
}
#endif
ShenandoahVerifier* ShenandoahHeap::verifier() {
class ShenandoahUpdateHeapRefsTask : public WorkerTask {
private:
ShenandoahHeap* _heap;
ShenandoahRegionIterator* _regions;
public:
- ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) :
+ explicit ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) :
WorkerTask("Shenandoah Update References"),
_heap(ShenandoahHeap::heap()),
_regions(regions) {
}
void work(uint worker_id) {
if (CONCURRENT) {
ShenandoahConcurrentWorkerSession worker_session(worker_id);
ShenandoahSuspendibleThreadSetJoiner stsj;
- do_work<ShenandoahConcUpdateRefsClosure>();
+ do_work<ShenandoahConcUpdateRefsClosure>(worker_id);
} else {
ShenandoahParallelWorkerSession worker_session(worker_id);
- do_work<ShenandoahSTWUpdateRefsClosure>();
+ do_work<ShenandoahSTWUpdateRefsClosure>(worker_id);
}
}
private:
template<class T>
- void do_work() {
+ 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();
- ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
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 (ShenandoahPacing) {
- _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
+ if (ShenandoahPacing) {
+ _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
+ }
}
if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
return;
}
r = _regions->next();
ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator);
workers()->run_task(&task);
}
}
-
- class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
- private:
- ShenandoahHeapLock* const _lock;
-
- public:
- ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
-
- void heap_region_do(ShenandoahHeapRegion* r) {
- // Drop unnecessary "pinned" state from regions that does not have CP marks
- // anymore, as this would allow trashing them.
-
- if (r->is_active()) {
- if (r->is_pinned()) {
- if (r->pin_count() == 0) {
- ShenandoahHeapLocker locker(_lock);
- r->make_unpinned();
- }
- } else {
- if (r->pin_count() > 0) {
- ShenandoahHeapLocker locker(_lock);
- r->make_pinned();
- }
- }
- }
- }
-
- bool is_thread_safe() { return true; }
- };
-
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);
- ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
- parallel_heap_region_iterate(&cl);
+
+ final_update_refs_update_region_states();
assert_pinned_region_status();
}
{
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(bool concurrent) {
- {
- ShenandoahGCPhase phase(concurrent ?
- ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
- ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
- ShenandoahHeapLocker locker(lock());
- _free_set->rebuild();
+ ShenandoahGCPhase phase(concurrent ?
+ ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
+ ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
+ ShenandoahHeapLocker locker(lock());
+ size_t young_cset_regions, old_cset_regions;
+ size_t first_old_region, last_old_region, old_region_count;
+ _free_set->prepare_to_rebuild(young_cset_regions, old_cset_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: " SIZE_FORMAT ", first_old_region: " SIZE_FORMAT ", last_old_region: " SIZE_FORMAT,
+ 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_cset_regions);
+ gen_heap->compute_old_generation_balance(allocation_runway, old_cset_regions);
+
+ // Total old_available may have been expanded to hold anticipated promotions. We trigger if the fragmented available
+ // memory represents more than 16 regions worth of data. Note that fragmentation may increase when we promote regular
+ // regions in place when many of these regular regions have an abundant amount of available memory within them. Fragmentation
+ // will decrease as promote-by-copy consumes the available memory within these partially consumed regions.
+ //
+ // We consider old-gen to have excessive fragmentation if more than 12.5% of old-gen is free memory that resides
+ // within partially consumed regions of memory.
+ }
+ // Rebuild free set based on adjusted generation sizes.
+ _free_set->finish_rebuild(young_cset_regions, old_cset_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::print_extended_on(outputStream *st) const {
print_on(st);
void ShenandoahHeap::safepoint_synchronize_end() {
SuspendibleThreadSet::desynchronize();
}
- void ShenandoahHeap::entry_uncommit(double shrink_before, size_t shrink_until) {
- static const char *msg = "Concurrent uncommit";
- ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */);
- EventMark em("%s", msg);
-
- op_uncommit(shrink_before, shrink_until);
- }
-
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()) {
memory_pools.append(_memory_pool);
return memory_pools;
}
MemoryUsage ShenandoahHeap::memory_usage() {
- return _memory_pool->get_memory_usage();
+ return MemoryUsage(_initial_size, used(), committed(), max_capacity());
}
ShenandoahRegionIterator::ShenandoahRegionIterator() :
_heap(ShenandoahHeap::heap()),
_index(0) {}
return true;
}
return false;
}
+
+ 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);
+ }
+ }
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