19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #include "precompiled.hpp"
27 #include "memory/allocation.hpp"
28 #include "memory/universe.hpp"
29
30 #include "gc/shared/gcArguments.hpp"
31 #include "gc/shared/gcTimer.hpp"
32 #include "gc/shared/gcTraceTime.inline.hpp"
33 #include "gc/shared/locationPrinter.inline.hpp"
34 #include "gc/shared/memAllocator.hpp"
35 #include "gc/shared/plab.hpp"
36 #include "gc/shared/tlab_globals.hpp"
37
38 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
39 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
40 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
41 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
42 #include "gc/shenandoah/shenandoahConcurrentMark.hpp"
43 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
44 #include "gc/shenandoah/shenandoahControlThread.hpp"
45 #include "gc/shenandoah/shenandoahFreeSet.hpp"
46 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
47 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
48 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
49 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
50 #include "gc/shenandoah/shenandoahInitLogger.hpp"
51 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
52 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
53 #include "gc/shenandoah/shenandoahMetrics.hpp"
54 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
55 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
56 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
57 #include "gc/shenandoah/shenandoahPadding.hpp"
58 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
59 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
60 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
61 #include "gc/shenandoah/shenandoahStringDedup.hpp"
62 #include "gc/shenandoah/shenandoahSTWMark.hpp"
63 #include "gc/shenandoah/shenandoahUtils.hpp"
64 #include "gc/shenandoah/shenandoahVerifier.hpp"
65 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
66 #include "gc/shenandoah/shenandoahVMOperations.hpp"
67 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
68 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
69 #include "gc/shenandoah/mode/shenandoahIUMode.hpp"
70 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
71 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp"
72 #if INCLUDE_JFR
73 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
74 #endif
75
76 #include "classfile/systemDictionary.hpp"
77 #include "code/codeCache.hpp"
78 #include "memory/classLoaderMetaspace.hpp"
79 #include "memory/metaspaceUtils.hpp"
80 #include "oops/compressedOops.inline.hpp"
81 #include "prims/jvmtiTagMap.hpp"
82 #include "runtime/atomic.hpp"
83 #include "runtime/globals.hpp"
84 #include "runtime/interfaceSupport.inline.hpp"
85 #include "runtime/java.hpp"
86 #include "runtime/orderAccess.hpp"
87 #include "runtime/safepointMechanism.hpp"
88 #include "runtime/vmThread.hpp"
89 #include "services/mallocTracker.hpp"
90 #include "services/memTracker.hpp"
91 #include "utilities/events.hpp"
92 #include "utilities/powerOfTwo.hpp"
93
94 class ShenandoahPretouchHeapTask : public WorkerTask {
95 private:
143 jint ShenandoahHeap::initialize() {
144 //
145 // Figure out heap sizing
146 //
147
148 size_t init_byte_size = InitialHeapSize;
149 size_t min_byte_size = MinHeapSize;
150 size_t max_byte_size = MaxHeapSize;
151 size_t heap_alignment = HeapAlignment;
152
153 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
154
155 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
156 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
157
158 _num_regions = ShenandoahHeapRegion::region_count();
159 assert(_num_regions == (max_byte_size / reg_size_bytes),
160 "Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT,
161 _num_regions, max_byte_size, reg_size_bytes);
162
163 // Now we know the number of regions, initialize the heuristics.
164 initialize_heuristics();
165
166 size_t num_committed_regions = init_byte_size / reg_size_bytes;
167 num_committed_regions = MIN2(num_committed_regions, _num_regions);
168 assert(num_committed_regions <= _num_regions, "sanity");
169 _initial_size = num_committed_regions * reg_size_bytes;
170
171 size_t num_min_regions = min_byte_size / reg_size_bytes;
172 num_min_regions = MIN2(num_min_regions, _num_regions);
173 assert(num_min_regions <= _num_regions, "sanity");
174 _minimum_size = num_min_regions * reg_size_bytes;
175
176 // Default to max heap size.
177 _soft_max_size = _num_regions * reg_size_bytes;
178
179 _committed = _initial_size;
180
181 size_t heap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
182 size_t bitmap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
183 size_t region_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
184
185 //
186 // Reserve and commit memory for heap
187 //
188
189 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
190 initialize_reserved_region(heap_rs);
191 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
192 _heap_region_special = heap_rs.special();
193
194 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
195 "Misaligned heap: " PTR_FORMAT, p2i(base()));
196
197 #if SHENANDOAH_OPTIMIZED_MARKTASK
198 // The optimized ShenandoahMarkTask takes some bits away from the full object bits.
199 // Fail if we ever attempt to address more than we can.
200 if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) {
201 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
202 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
203 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
204 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable());
205 vm_exit_during_initialization("Fatal Error", buf);
206 }
207 #endif
208
209 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
210 if (!_heap_region_special) {
211 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
212 "Cannot commit heap memory");
213 }
214
215 //
216 // Reserve and commit memory for bitmap(s)
217 //
218
219 _bitmap_size = ShenandoahMarkBitMap::compute_size(heap_rs.size());
220 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
221
222 size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor();
223
224 guarantee(bitmap_bytes_per_region != 0,
225 "Bitmap bytes per region should not be zero");
226 guarantee(is_power_of_2(bitmap_bytes_per_region),
227 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
228
229 if (bitmap_page_size > bitmap_bytes_per_region) {
230 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
231 _bitmap_bytes_per_slice = bitmap_page_size;
232 } else {
233 _bitmap_regions_per_slice = 1;
234 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
238 "Should have at least one region per slice: " SIZE_FORMAT,
239 _bitmap_regions_per_slice);
240
241 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
242 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
243 _bitmap_bytes_per_slice, bitmap_page_size);
244
245 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
246 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
247 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
248 _bitmap_region_special = bitmap.special();
249
250 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
251 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
252 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
253 if (!_bitmap_region_special) {
254 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
255 "Cannot commit bitmap memory");
256 }
257
258 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions, _max_workers);
259
260 if (ShenandoahVerify) {
261 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
262 if (!verify_bitmap.special()) {
263 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
264 "Cannot commit verification bitmap memory");
265 }
266 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
267 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
268 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
269 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
270 }
271
272 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
273 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
274 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
275 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
276 _aux_bitmap_region_special = aux_bitmap.special();
277 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
278
301 uintptr_t max = (1u << 30u);
302
303 for (uintptr_t addr = min; addr <= max; addr <<= 1u) {
304 char* req_addr = (char*)addr;
305 assert(is_aligned(req_addr, cset_align), "Should be aligned");
306 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size(), req_addr);
307 if (cset_rs.is_reserved()) {
308 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr);
309 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
310 break;
311 }
312 }
313
314 if (_collection_set == nullptr) {
315 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size());
316 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
317 }
318 }
319
320 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
321 _free_set = new ShenandoahFreeSet(this, _num_regions);
322
323 {
324 ShenandoahHeapLocker locker(lock());
325
326 for (size_t i = 0; i < _num_regions; i++) {
327 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
328 bool is_committed = i < num_committed_regions;
329 void* loc = region_storage.base() + i * region_align;
330
331 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
332 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
333
334 _marking_context->initialize_top_at_mark_start(r);
335 _regions[i] = r;
336 assert(!collection_set()->is_in(i), "New region should not be in collection set");
337 }
338
339 // Initialize to complete
340 _marking_context->mark_complete();
341
342 _free_set->rebuild();
343 }
344
345 if (AlwaysPreTouch) {
346 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
347 // before initialize() below zeroes it with initializing thread. For any given region,
348 // we touch the region and the corresponding bitmaps from the same thread.
349 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
350
351 _pretouch_heap_page_size = heap_page_size;
352 _pretouch_bitmap_page_size = bitmap_page_size;
353
354 #ifdef LINUX
355 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
356 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
384 // There should probably be Shenandoah-specific options for these,
385 // just as there are G1-specific options.
386 {
387 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
388 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
389 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
390 }
391
392 _monitoring_support = new ShenandoahMonitoringSupport(this);
393 _phase_timings = new ShenandoahPhaseTimings(max_workers());
394 ShenandoahCodeRoots::initialize();
395
396 if (ShenandoahPacing) {
397 _pacer = new ShenandoahPacer(this);
398 _pacer->setup_for_idle();
399 } else {
400 _pacer = nullptr;
401 }
402
403 _control_thread = new ShenandoahControlThread();
404
405 ShenandoahInitLogger::print();
406
407 return JNI_OK;
408 }
409
410 void ShenandoahHeap::initialize_mode() {
411 if (ShenandoahGCMode != nullptr) {
412 if (strcmp(ShenandoahGCMode, "satb") == 0) {
413 _gc_mode = new ShenandoahSATBMode();
414 } else if (strcmp(ShenandoahGCMode, "iu") == 0) {
415 _gc_mode = new ShenandoahIUMode();
416 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
417 _gc_mode = new ShenandoahPassiveMode();
418 } else {
419 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
420 }
421 } else {
422 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option (null)");
423 }
424 _gc_mode->initialize_flags();
425 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
426 vm_exit_during_initialization(
427 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
428 _gc_mode->name()));
429 }
430 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
431 vm_exit_during_initialization(
432 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
433 _gc_mode->name()));
434 }
435 }
436
437 void ShenandoahHeap::initialize_heuristics() {
438 assert(_gc_mode != nullptr, "Must be initialized");
439 _heuristics = _gc_mode->initialize_heuristics();
440
441 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
442 vm_exit_during_initialization(
443 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
444 _heuristics->name()));
445 }
446 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
447 vm_exit_during_initialization(
448 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
449 _heuristics->name()));
450 }
451 }
452
453 #ifdef _MSC_VER
454 #pragma warning( push )
455 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
456 #endif
457
458 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
459 CollectedHeap(),
460 _initial_size(0),
461 _used(0),
462 _committed(0),
463 _bytes_allocated_since_gc_start(0),
464 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
465 _workers(nullptr),
466 _safepoint_workers(nullptr),
467 _heap_region_special(false),
468 _num_regions(0),
469 _regions(nullptr),
470 _update_refs_iterator(this),
471 _control_thread(nullptr),
472 _shenandoah_policy(policy),
473 _gc_mode(nullptr),
474 _heuristics(nullptr),
475 _free_set(nullptr),
476 _pacer(nullptr),
477 _verifier(nullptr),
478 _phase_timings(nullptr),
479 _monitoring_support(nullptr),
480 _memory_pool(nullptr),
481 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
482 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
483 _gc_timer(new ConcurrentGCTimer()),
484 _soft_ref_policy(),
485 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
486 _ref_processor(new ShenandoahReferenceProcessor(MAX2(_max_workers, 1U))),
487 _marking_context(nullptr),
488 _bitmap_size(0),
489 _bitmap_regions_per_slice(0),
490 _bitmap_bytes_per_slice(0),
491 _bitmap_region_special(false),
492 _aux_bitmap_region_special(false),
493 _liveness_cache(nullptr),
494 _collection_set(nullptr)
495 {
496 // Initialize GC mode early, so we can adjust barrier support
497 initialize_mode();
498 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
499
500 _max_workers = MAX2(_max_workers, 1U);
501 _workers = new ShenandoahWorkerThreads("Shenandoah GC Threads", _max_workers);
502 if (_workers == nullptr) {
503 vm_exit_during_initialization("Failed necessary allocation.");
504 } else {
505 _workers->initialize_workers();
506 }
507
508 if (ParallelGCThreads > 1) {
509 _safepoint_workers = new ShenandoahWorkerThreads("Safepoint Cleanup Thread",
510 ParallelGCThreads);
511 _safepoint_workers->initialize_workers();
512 }
513 }
514
515 #ifdef _MSC_VER
516 #pragma warning( pop )
517 #endif
518
519 class ShenandoahResetBitmapTask : public WorkerTask {
520 private:
521 ShenandoahRegionIterator _regions;
522
523 public:
524 ShenandoahResetBitmapTask() :
525 WorkerTask("Shenandoah Reset Bitmap") {}
526
527 void work(uint worker_id) {
528 ShenandoahHeapRegion* region = _regions.next();
529 ShenandoahHeap* heap = ShenandoahHeap::heap();
530 ShenandoahMarkingContext* const ctx = heap->marking_context();
531 while (region != nullptr) {
532 if (heap->is_bitmap_slice_committed(region)) {
533 ctx->clear_bitmap(region);
534 }
535 region = _regions.next();
536 }
537 }
538 };
539
540 void ShenandoahHeap::reset_mark_bitmap() {
541 assert_gc_workers(_workers->active_workers());
542 mark_incomplete_marking_context();
543
544 ShenandoahResetBitmapTask task;
545 _workers->run_task(&task);
546 }
547
548 void ShenandoahHeap::print_on(outputStream* st) const {
549 st->print_cr("Shenandoah Heap");
550 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
551 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
552 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()),
553 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
554 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
555 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
556 num_regions(),
557 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
558 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
559
560 st->print("Status: ");
561 if (has_forwarded_objects()) st->print("has forwarded objects, ");
562 if (is_concurrent_mark_in_progress()) st->print("marking, ");
563 if (is_evacuation_in_progress()) st->print("evacuating, ");
564 if (is_update_refs_in_progress()) st->print("updating refs, ");
565 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
566 if (is_full_gc_in_progress()) st->print("full gc, ");
567 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
568 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, ");
569 if (is_concurrent_strong_root_in_progress() &&
570 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, ");
571
572 if (cancelled_gc()) {
573 st->print("cancelled");
574 } else {
575 st->print("not cancelled");
576 }
577 st->cr();
578
579 st->print_cr("Reserved region:");
580 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
581 p2i(reserved_region().start()),
582 p2i(reserved_region().end()));
592
593 st->cr();
594 MetaspaceUtils::print_on(st);
595
596 if (Verbose) {
597 print_heap_regions_on(st);
598 }
599 }
600
601 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
602 public:
603 void do_thread(Thread* thread) {
604 assert(thread != nullptr, "Sanity");
605 assert(thread->is_Worker_thread(), "Only worker thread expected");
606 ShenandoahThreadLocalData::initialize_gclab(thread);
607 }
608 };
609
610 void ShenandoahHeap::post_initialize() {
611 CollectedHeap::post_initialize();
612 MutexLocker ml(Threads_lock);
613
614 ShenandoahInitWorkerGCLABClosure init_gclabs;
615 _workers->threads_do(&init_gclabs);
616
617 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
618 // Now, we will let WorkerThreads to initialize gclab when new worker is created.
619 _workers->set_initialize_gclab();
620 if (_safepoint_workers != nullptr) {
621 _safepoint_workers->threads_do(&init_gclabs);
622 _safepoint_workers->set_initialize_gclab();
623 }
624
625 _heuristics->initialize();
626
627 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
628 }
629
630 size_t ShenandoahHeap::used() const {
631 return Atomic::load(&_used);
632 }
633
634 size_t ShenandoahHeap::committed() const {
635 return Atomic::load(&_committed);
636 }
637
638 void ShenandoahHeap::increase_committed(size_t bytes) {
639 shenandoah_assert_heaplocked_or_safepoint();
640 _committed += bytes;
641 }
642
643 void ShenandoahHeap::decrease_committed(size_t bytes) {
644 shenandoah_assert_heaplocked_or_safepoint();
645 _committed -= bytes;
646 }
647
648 void ShenandoahHeap::increase_used(size_t bytes) {
649 Atomic::add(&_used, bytes, memory_order_relaxed);
650 }
651
652 void ShenandoahHeap::set_used(size_t bytes) {
653 Atomic::store(&_used, bytes);
654 }
655
656 void ShenandoahHeap::decrease_used(size_t bytes) {
657 assert(used() >= bytes, "never decrease heap size by more than we've left");
658 Atomic::sub(&_used, bytes, memory_order_relaxed);
659 }
660
661 void ShenandoahHeap::increase_allocated(size_t bytes) {
662 Atomic::add(&_bytes_allocated_since_gc_start, bytes, memory_order_relaxed);
663 }
664
665 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
666 size_t bytes = words * HeapWordSize;
667 if (!waste) {
668 increase_used(bytes);
669 }
670 increase_allocated(bytes);
671 if (ShenandoahPacing) {
672 control_thread()->pacing_notify_alloc(words);
673 if (waste) {
674 pacer()->claim_for_alloc(words, true);
675 }
676 }
677 }
678
679 size_t ShenandoahHeap::capacity() const {
680 return committed();
681 }
682
683 size_t ShenandoahHeap::max_capacity() const {
684 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
685 }
686
687 size_t ShenandoahHeap::soft_max_capacity() const {
688 size_t v = Atomic::load(&_soft_max_size);
689 assert(min_capacity() <= v && v <= max_capacity(),
690 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
691 min_capacity(), v, max_capacity());
692 return v;
693 }
694
695 void ShenandoahHeap::set_soft_max_capacity(size_t v) {
696 assert(min_capacity() <= v && v <= max_capacity(),
697 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
698 min_capacity(), v, max_capacity());
699 Atomic::store(&_soft_max_size, v);
700 }
701
702 size_t ShenandoahHeap::min_capacity() const {
703 return _minimum_size;
704 }
705
706 size_t ShenandoahHeap::initial_capacity() const {
707 return _initial_size;
708 }
709
710 bool ShenandoahHeap::is_in(const void* p) const {
711 HeapWord* heap_base = (HeapWord*) base();
712 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
713 return p >= heap_base && p < last_region_end;
714 }
715
716 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
717 assert (ShenandoahUncommit, "should be enabled");
718
719 // Application allocates from the beginning of the heap, and GC allocates at
720 // the end of it. It is more efficient to uncommit from the end, so that applications
721 // could enjoy the near committed regions. GC allocations are much less frequent,
722 // and therefore can accept the committing costs.
723
724 size_t count = 0;
725 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
726 ShenandoahHeapRegion* r = get_region(i - 1);
727 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
728 ShenandoahHeapLocker locker(lock());
729 if (r->is_empty_committed()) {
730 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) {
731 break;
732 }
733
734 r->make_uncommitted();
735 count++;
736 }
737 }
738 SpinPause(); // allow allocators to take the lock
739 }
740
741 if (count > 0) {
742 control_thread()->notify_heap_changed();
743 }
744 }
745
746 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
747 // New object should fit the GCLAB size
748 size_t min_size = MAX2(size, PLAB::min_size());
749
750 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
751 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
752 new_size = MIN2(new_size, PLAB::max_size());
753 new_size = MAX2(new_size, PLAB::min_size());
754
755 // Record new heuristic value even if we take any shortcut. This captures
756 // the case when moderately-sized objects always take a shortcut. At some point,
757 // heuristics should catch up with them.
758 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
759
760 if (new_size < size) {
761 // New size still does not fit the object. Fall back to shared allocation.
762 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
763 return nullptr;
764 }
765
766 // Retire current GCLAB, and allocate a new one.
767 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
768 gclab->retire();
769
770 size_t actual_size = 0;
771 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
772 if (gclab_buf == nullptr) {
773 return nullptr;
774 }
775
776 assert (size <= actual_size, "allocation should fit");
777
778 if (ZeroTLAB) {
779 // ..and clear it.
780 Copy::zero_to_words(gclab_buf, actual_size);
781 } else {
782 // ...and zap just allocated object.
783 #ifdef ASSERT
784 // Skip mangling the space corresponding to the object header to
785 // ensure that the returned space is not considered parsable by
786 // any concurrent GC thread.
787 size_t hdr_size = oopDesc::header_size();
788 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
789 #endif // ASSERT
790 }
791 gclab->set_buf(gclab_buf, actual_size);
792 return gclab->allocate(size);
793 }
794
795 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
796 size_t requested_size,
797 size_t* actual_size) {
798 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
799 HeapWord* res = allocate_memory(req);
800 if (res != nullptr) {
801 *actual_size = req.actual_size();
802 } else {
803 *actual_size = 0;
804 }
805 return res;
806 }
807
808 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
809 size_t word_size,
810 size_t* actual_size) {
811 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
812 HeapWord* res = allocate_memory(req);
813 if (res != nullptr) {
814 *actual_size = req.actual_size();
815 } else {
816 *actual_size = 0;
817 }
818 return res;
819 }
820
821 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
822 intptr_t pacer_epoch = 0;
823 bool in_new_region = false;
824 HeapWord* result = nullptr;
825
826 if (req.is_mutator_alloc()) {
827 if (ShenandoahPacing) {
828 pacer()->pace_for_alloc(req.size());
829 pacer_epoch = pacer()->epoch();
830 }
831
832 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
833 result = allocate_memory_under_lock(req, in_new_region);
834 }
835
836 // Allocation failed, block until control thread reacted, then retry allocation.
837 //
838 // It might happen that one of the threads requesting allocation would unblock
839 // way later after GC happened, only to fail the second allocation, because
840 // other threads have already depleted the free storage. In this case, a better
841 // strategy is to try again, as long as GC makes progress.
842 //
843 // Then, we need to make sure the allocation was retried after at least one
844 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
845
846 size_t tries = 0;
847
848 while (result == nullptr && _progress_last_gc.is_set()) {
849 tries++;
850 control_thread()->handle_alloc_failure(req);
851 result = allocate_memory_under_lock(req, in_new_region);
852 }
853
854 while (result == nullptr && tries <= ShenandoahFullGCThreshold) {
855 tries++;
856 control_thread()->handle_alloc_failure(req);
857 result = allocate_memory_under_lock(req, in_new_region);
858 }
859
860 } else {
861 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
862 result = allocate_memory_under_lock(req, in_new_region);
863 // Do not call handle_alloc_failure() here, because we cannot block.
864 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
865 }
866
867 if (in_new_region) {
868 control_thread()->notify_heap_changed();
869 }
870
871 if (result != nullptr) {
872 size_t requested = req.size();
873 size_t actual = req.actual_size();
874
875 assert (req.is_lab_alloc() || (requested == actual),
876 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
877 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
878
879 if (req.is_mutator_alloc()) {
880 notify_mutator_alloc_words(actual, false);
881
882 // If we requested more than we were granted, give the rest back to pacer.
883 // This only matters if we are in the same pacing epoch: do not try to unpace
884 // over the budget for the other phase.
885 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
886 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
887 }
888 } else {
889 increase_used(actual*HeapWordSize);
890 }
891 }
892
893 return result;
894 }
895
896 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
897 ShenandoahHeapLocker locker(lock());
898 return _free_set->allocate(req, in_new_region);
899 }
900
901 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
902 bool* gc_overhead_limit_was_exceeded) {
903 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
904 return allocate_memory(req);
905 }
906
907 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
908 size_t size,
909 Metaspace::MetadataType mdtype) {
910 MetaWord* result;
911
912 // Inform metaspace OOM to GC heuristics if class unloading is possible.
913 if (heuristics()->can_unload_classes()) {
914 ShenandoahHeuristics* h = heuristics();
915 h->record_metaspace_oom();
916 }
917
918 // Expand and retry allocation
919 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
920 if (result != nullptr) {
921 return result;
922 }
923
924 // Start full GC
925 collect(GCCause::_metadata_GC_clear_soft_refs);
926
927 // Retry allocation
928 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
929 if (result != nullptr) {
930 return result;
931 }
932
933 // Expand and retry allocation
934 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
973
974 void work(uint worker_id) {
975 if (_concurrent) {
976 ShenandoahConcurrentWorkerSession worker_session(worker_id);
977 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
978 ShenandoahEvacOOMScope oom_evac_scope;
979 do_work();
980 } else {
981 ShenandoahParallelWorkerSession worker_session(worker_id);
982 ShenandoahEvacOOMScope oom_evac_scope;
983 do_work();
984 }
985 }
986
987 private:
988 void do_work() {
989 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
990 ShenandoahHeapRegion* r;
991 while ((r =_cs->claim_next()) != nullptr) {
992 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
993 _sh->marked_object_iterate(r, &cl);
994
995 if (ShenandoahPacing) {
996 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
997 }
998
999 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
1000 break;
1001 }
1002 }
1003 }
1004 };
1005
1006 void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
1007 ShenandoahEvacuationTask task(this, _collection_set, concurrent);
1008 workers()->run_task(&task);
1009 }
1010
1011 void ShenandoahHeap::trash_cset_regions() {
1012 ShenandoahHeapLocker locker(lock());
1013
1014 ShenandoahCollectionSet* set = collection_set();
1015 ShenandoahHeapRegion* r;
1016 set->clear_current_index();
1017 while ((r = set->next()) != nullptr) {
1018 r->make_trash();
1019 }
1020 collection_set()->clear();
1021 }
1022
1023 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1024 st->print_cr("Heap Regions:");
1025 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
1026 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
1027 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark");
1028 st->print_cr("SN=alloc sequence number");
1029
1030 for (size_t i = 0; i < num_regions(); i++) {
1031 get_region(i)->print_on(st);
1032 }
1033 }
1034
1035 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1036 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1037
1038 oop humongous_obj = cast_to_oop(start->bottom());
1039 size_t size = humongous_obj->size();
1040 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1041 size_t index = start->index() + required_regions - 1;
1042
1043 assert(!start->has_live(), "liveness must be zero");
1044
1045 for(size_t i = 0; i < required_regions; i++) {
1046 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1047 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1048 ShenandoahHeapRegion* region = get_region(index --);
1049
1050 assert(region->is_humongous(), "expect correct humongous start or continuation");
1051 assert(!region->is_cset(), "Humongous region should not be in collection set");
1052
1053 region->make_trash_immediate();
1054 }
1055 }
1056
1057 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1058 public:
1059 ShenandoahCheckCleanGCLABClosure() {}
1060 void do_thread(Thread* thread) {
1061 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1062 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1063 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
1064 }
1065 };
1066
1067 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1068 private:
1069 bool const _resize;
1070 public:
1071 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1072 void do_thread(Thread* thread) {
1073 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1074 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1075 gclab->retire();
1076 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1077 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1078 }
1079 }
1080 };
1081
1082 void ShenandoahHeap::labs_make_parsable() {
1083 assert(UseTLAB, "Only call with UseTLAB");
1084
1085 ShenandoahRetireGCLABClosure cl(false);
1086
1087 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1088 ThreadLocalAllocBuffer& tlab = t->tlab();
1089 tlab.make_parsable();
1090 cl.do_thread(t);
1091 }
1092
1093 workers()->threads_do(&cl);
1094 }
1095
1096 void ShenandoahHeap::tlabs_retire(bool resize) {
1097 assert(UseTLAB, "Only call with UseTLAB");
1098 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1116 }
1117 workers()->threads_do(&cl);
1118 #endif
1119 }
1120
1121 void ShenandoahHeap::gclabs_retire(bool resize) {
1122 assert(UseTLAB, "Only call with UseTLAB");
1123 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1124
1125 ShenandoahRetireGCLABClosure cl(resize);
1126 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1127 cl.do_thread(t);
1128 }
1129 workers()->threads_do(&cl);
1130
1131 if (safepoint_workers() != nullptr) {
1132 safepoint_workers()->threads_do(&cl);
1133 }
1134 }
1135
1136 // Returns size in bytes
1137 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1138 if (ShenandoahElasticTLAB) {
1139 // With Elastic TLABs, return the max allowed size, and let the allocation path
1140 // figure out the safe size for current allocation.
1141 return ShenandoahHeapRegion::max_tlab_size_bytes();
1142 } else {
1143 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1144 }
1145 }
1146
1147 size_t ShenandoahHeap::max_tlab_size() const {
1148 // Returns size in words
1149 return ShenandoahHeapRegion::max_tlab_size_words();
1150 }
1151
1152 void ShenandoahHeap::collect(GCCause::Cause cause) {
1153 control_thread()->request_gc(cause);
1154 }
1155
1156 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1157 //assert(false, "Shouldn't need to do full collections");
1158 }
1159
1160 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1161 ShenandoahHeapRegion* r = heap_region_containing(addr);
1164 }
1165 return nullptr;
1166 }
1167
1168 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1169 ShenandoahHeapRegion* r = heap_region_containing(addr);
1170 return r->block_is_obj(addr);
1171 }
1172
1173 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1174 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1175 }
1176
1177 void ShenandoahHeap::prepare_for_verify() {
1178 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) {
1179 labs_make_parsable();
1180 }
1181 }
1182
1183 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1184 tcl->do_thread(_control_thread);
1185 workers()->threads_do(tcl);
1186 if (_safepoint_workers != nullptr) {
1187 _safepoint_workers->threads_do(tcl);
1188 }
1189 if (ShenandoahStringDedup::is_enabled()) {
1190 ShenandoahStringDedup::threads_do(tcl);
1191 }
1192 }
1193
1194 void ShenandoahHeap::print_tracing_info() const {
1195 LogTarget(Info, gc, stats) lt;
1196 if (lt.is_enabled()) {
1197 ResourceMark rm;
1198 LogStream ls(lt);
1199
1200 phase_timings()->print_global_on(&ls);
1201
1202 ls.cr();
1203 ls.cr();
1204
1205 shenandoah_policy()->print_gc_stats(&ls);
1206
1207 ls.cr();
1208 ls.cr();
1209 }
1210 }
1211
1212 void ShenandoahHeap::verify(VerifyOption vo) {
1213 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1214 if (ShenandoahVerify) {
1215 verifier()->verify_generic(vo);
1216 } else {
1217 // TODO: Consider allocating verification bitmaps on demand,
1218 // and turn this on unconditionally.
1219 }
1220 }
1221 }
1222 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1223 return _free_set->capacity();
1224 }
1225
1226 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1227 private:
1228 MarkBitMap* _bitmap;
1229 ShenandoahScanObjectStack* _oop_stack;
1230 ShenandoahHeap* const _heap;
1231 ShenandoahMarkingContext* const _marking_context;
1513 if (start >= max) break;
1514
1515 for (size_t i = cur; i < end; i++) {
1516 ShenandoahHeapRegion* current = _heap->get_region(i);
1517 _blk->heap_region_do(current);
1518 }
1519 }
1520 }
1521 };
1522
1523 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1524 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1525 if (num_regions() > ShenandoahParallelRegionStride) {
1526 ShenandoahParallelHeapRegionTask task(blk);
1527 workers()->run_task(&task);
1528 } else {
1529 heap_region_iterate(blk);
1530 }
1531 }
1532
1533 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1534 private:
1535 ShenandoahMarkingContext* const _ctx;
1536 public:
1537 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1538
1539 void heap_region_do(ShenandoahHeapRegion* r) {
1540 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1541 if (r->is_active()) {
1542 // Check if region needs updating its TAMS. We have updated it already during concurrent
1543 // reset, so it is very likely we don't need to do another write here.
1544 if (_ctx->top_at_mark_start(r) != r->top()) {
1545 _ctx->capture_top_at_mark_start(r);
1546 }
1547 } else {
1548 assert(_ctx->top_at_mark_start(r) == r->top(),
1549 "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
1550 }
1551 }
1552
1553 bool is_thread_safe() { return true; }
1554 };
1555
1556 class ShenandoahRendezvousClosure : public HandshakeClosure {
1557 public:
1558 inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {}
1559 inline void do_thread(Thread* thread) {}
1560 };
1561
1562 void ShenandoahHeap::rendezvous_threads() {
1563 ShenandoahRendezvousClosure cl;
1564 Handshake::execute(&cl);
1565 }
1566
1567 void ShenandoahHeap::recycle_trash() {
1568 free_set()->recycle_trash();
1569 }
1570
1571 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1572 private:
1573 ShenandoahMarkingContext* const _ctx;
1574 public:
1575 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1576
1577 void heap_region_do(ShenandoahHeapRegion* r) {
1578 if (r->is_active()) {
1579 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1580 // anyway to capture any updates that happened since now.
1581 r->clear_live_data();
1582 _ctx->capture_top_at_mark_start(r);
1583 }
1584 }
1585
1586 bool is_thread_safe() { return true; }
1587 };
1588
1589 void ShenandoahHeap::prepare_gc() {
1590 reset_mark_bitmap();
1591
1592 ShenandoahResetUpdateRegionStateClosure cl;
1593 parallel_heap_region_iterate(&cl);
1594 }
1595
1596 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1597 private:
1598 ShenandoahMarkingContext* const _ctx;
1599 ShenandoahHeapLock* const _lock;
1600
1601 public:
1602 ShenandoahFinalMarkUpdateRegionStateClosure() :
1603 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1604
1605 void heap_region_do(ShenandoahHeapRegion* r) {
1606 if (r->is_active()) {
1607 // All allocations past TAMS are implicitly live, adjust the region data.
1608 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1609 HeapWord *tams = _ctx->top_at_mark_start(r);
1610 HeapWord *top = r->top();
1611 if (top > tams) {
1612 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1613 }
1614
1615 // We are about to select the collection set, make sure it knows about
1616 // current pinning status. Also, this allows trashing more regions that
1617 // now have their pinning status dropped.
1618 if (r->is_pinned()) {
1619 if (r->pin_count() == 0) {
1620 ShenandoahHeapLocker locker(_lock);
1621 r->make_unpinned();
1622 }
1623 } else {
1624 if (r->pin_count() > 0) {
1625 ShenandoahHeapLocker locker(_lock);
1626 r->make_pinned();
1627 }
1628 }
1629
1630 // Remember limit for updating refs. It's guaranteed that we get no
1631 // from-space-refs written from here on.
1632 r->set_update_watermark_at_safepoint(r->top());
1633 } else {
1634 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1635 assert(_ctx->top_at_mark_start(r) == r->top(),
1636 "Region " SIZE_FORMAT " should have correct TAMS", r->index());
1637 }
1638 }
1639
1640 bool is_thread_safe() { return true; }
1641 };
1642
1643 void ShenandoahHeap::prepare_regions_and_collection_set(bool concurrent) {
1644 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
1645 {
1646 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_region_states :
1647 ShenandoahPhaseTimings::degen_gc_final_update_region_states);
1648 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1649 parallel_heap_region_iterate(&cl);
1650
1651 assert_pinned_region_status();
1652 }
1653
1654 {
1655 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::choose_cset :
1656 ShenandoahPhaseTimings::degen_gc_choose_cset);
1657 ShenandoahHeapLocker locker(lock());
1658 _collection_set->clear();
1659 heuristics()->choose_collection_set(_collection_set);
1660 }
1661
1662 {
1663 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_rebuild_freeset :
1664 ShenandoahPhaseTimings::degen_gc_final_rebuild_freeset);
1665 ShenandoahHeapLocker locker(lock());
1666 _free_set->rebuild();
1667 }
1668 }
1669
1670 void ShenandoahHeap::do_class_unloading() {
1671 _unloader.unload();
1672 }
1673
1674 void ShenandoahHeap::stw_weak_refs(bool full_gc) {
1675 // Weak refs processing
1676 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs
1677 : ShenandoahPhaseTimings::degen_gc_weakrefs;
1678 ShenandoahTimingsTracker t(phase);
1679 ShenandoahGCWorkerPhase worker_phase(phase);
1680 ref_processor()->process_references(phase, workers(), false /* concurrent */);
1681 }
1682
1683 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
1684 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
1685
1686 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to
1687 // make them parsable for update code to work correctly. Plus, we can compute new sizes
1688 // for future GCLABs here.
1689 if (UseTLAB) {
1690 ShenandoahGCPhase phase(concurrent ?
1691 ShenandoahPhaseTimings::init_update_refs_manage_gclabs :
1692 ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs);
1693 gclabs_retire(ResizeTLAB);
1694 }
1695
1696 _update_refs_iterator.reset();
1697 }
1698
1699 void ShenandoahHeap::set_gc_state_all_threads(char state) {
1700 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1701 ShenandoahThreadLocalData::set_gc_state(t, state);
1702 }
1703 }
1704
1705 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1706 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1707 _gc_state.set_cond(mask, value);
1708 set_gc_state_all_threads(_gc_state.raw_value());
1709 }
1710
1711 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1712 assert(!has_forwarded_objects(), "Not expected before/after mark phase");
1713 set_gc_state_mask(MARKING, in_progress);
1714 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1715 }
1716
1717 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1718 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1719 set_gc_state_mask(EVACUATION, in_progress);
1720 }
1721
1722 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
1723 if (in_progress) {
1724 _concurrent_strong_root_in_progress.set();
1725 } else {
1726 _concurrent_strong_root_in_progress.unset();
1727 }
1728 }
1729
1730 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) {
1731 set_gc_state_mask(WEAK_ROOTS, cond);
1732 }
1733
1734 GCTracer* ShenandoahHeap::tracer() {
1739 return _free_set->used();
1740 }
1741
1742 bool ShenandoahHeap::try_cancel_gc() {
1743 while (true) {
1744 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
1745 if (prev == CANCELLABLE) return true;
1746 else if (prev == CANCELLED) return false;
1747 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
1748 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
1749 Thread* thread = Thread::current();
1750 if (thread->is_Java_thread()) {
1751 // We need to provide a safepoint here, otherwise we might
1752 // spin forever if a SP is pending.
1753 ThreadBlockInVM sp(JavaThread::cast(thread));
1754 SpinPause();
1755 }
1756 }
1757 }
1758
1759 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1760 if (try_cancel_gc()) {
1761 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1762 log_info(gc)("%s", msg.buffer());
1763 Events::log(Thread::current(), "%s", msg.buffer());
1764 }
1765 }
1766
1767 uint ShenandoahHeap::max_workers() {
1768 return _max_workers;
1769 }
1770
1771 void ShenandoahHeap::stop() {
1772 // The shutdown sequence should be able to terminate when GC is running.
1773
1774 // Step 0. Notify policy to disable event recording.
1775 _shenandoah_policy->record_shutdown();
1776
1777 // Step 1. Notify control thread that we are in shutdown.
1778 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1779 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1780 control_thread()->prepare_for_graceful_shutdown();
1781
1782 // Step 2. Notify GC workers that we are cancelling GC.
1783 cancel_gc(GCCause::_shenandoah_stop_vm);
1784
1785 // Step 3. Wait until GC worker exits normally.
1786 control_thread()->stop();
1787 }
1788
1789 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
1790 if (!unload_classes()) return;
1791 // Unload classes and purge SystemDictionary.
1792 {
1793 ShenandoahPhaseTimings::Phase phase = full_gc ?
1794 ShenandoahPhaseTimings::full_gc_purge_class_unload :
1795 ShenandoahPhaseTimings::degen_gc_purge_class_unload;
1796 ShenandoahIsAliveSelector is_alive;
1797 CodeCache::UnloadingScope scope(is_alive.is_alive_closure());
1798 ShenandoahGCPhase gc_phase(phase);
1799 ShenandoahGCWorkerPhase worker_phase(phase);
1800 bool purged_class = SystemDictionary::do_unloading(gc_timer());
1801
1802 uint num_workers = _workers->active_workers();
1803 ShenandoahClassUnloadingTask unlink_task(phase, num_workers, purged_class);
1804 _workers->run_task(&unlink_task);
1805 }
1859 }
1860
1861 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
1862 set_gc_state_mask(HAS_FORWARDED, cond);
1863 }
1864
1865 void ShenandoahHeap::set_unload_classes(bool uc) {
1866 _unload_classes.set_cond(uc);
1867 }
1868
1869 bool ShenandoahHeap::unload_classes() const {
1870 return _unload_classes.is_set();
1871 }
1872
1873 address ShenandoahHeap::in_cset_fast_test_addr() {
1874 ShenandoahHeap* heap = ShenandoahHeap::heap();
1875 assert(heap->collection_set() != nullptr, "Sanity");
1876 return (address) heap->collection_set()->biased_map_address();
1877 }
1878
1879 address ShenandoahHeap::cancelled_gc_addr() {
1880 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
1881 }
1882
1883 address ShenandoahHeap::gc_state_addr() {
1884 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
1885 }
1886
1887 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
1888 return Atomic::load(&_bytes_allocated_since_gc_start);
1889 }
1890
1891 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
1892 Atomic::store(&_bytes_allocated_since_gc_start, (size_t)0);
1893 }
1894
1895 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
1896 _degenerated_gc_in_progress.set_cond(in_progress);
1897 }
1898
1899 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
1900 _full_gc_in_progress.set_cond(in_progress);
1901 }
1902
1903 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
1904 assert (is_full_gc_in_progress(), "should be");
1905 _full_gc_move_in_progress.set_cond(in_progress);
1906 }
1907
1908 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
1909 set_gc_state_mask(UPDATEREFS, in_progress);
1910 }
1911
1912 void ShenandoahHeap::register_nmethod(nmethod* nm) {
1936 if (r->is_active()) {
1937 if (r->is_pinned()) {
1938 if (r->pin_count() == 0) {
1939 r->make_unpinned();
1940 }
1941 } else {
1942 if (r->pin_count() > 0) {
1943 r->make_pinned();
1944 }
1945 }
1946 }
1947 }
1948
1949 assert_pinned_region_status();
1950 }
1951
1952 #ifdef ASSERT
1953 void ShenandoahHeap::assert_pinned_region_status() {
1954 for (size_t i = 0; i < num_regions(); i++) {
1955 ShenandoahHeapRegion* r = get_region(i);
1956 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
1957 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
1958 }
1959 }
1960 #endif
1961
1962 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
1963 return _gc_timer;
1964 }
1965
1966 void ShenandoahHeap::prepare_concurrent_roots() {
1967 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1968 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1969 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
1970 set_concurrent_weak_root_in_progress(true);
1971 if (unload_classes()) {
1972 _unloader.prepare();
1973 }
1974 }
1975
1976 void ShenandoahHeap::finish_concurrent_roots() {
1977 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1997 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
1998 } else {
1999 // Use ConcGCThreads outside safepoints
2000 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2001 }
2002 }
2003 }
2004 #endif
2005
2006 ShenandoahVerifier* ShenandoahHeap::verifier() {
2007 guarantee(ShenandoahVerify, "Should be enabled");
2008 assert (_verifier != nullptr, "sanity");
2009 return _verifier;
2010 }
2011
2012 template<bool CONCURRENT>
2013 class ShenandoahUpdateHeapRefsTask : public WorkerTask {
2014 private:
2015 ShenandoahHeap* _heap;
2016 ShenandoahRegionIterator* _regions;
2017 public:
2018 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) :
2019 WorkerTask("Shenandoah Update References"),
2020 _heap(ShenandoahHeap::heap()),
2021 _regions(regions) {
2022 }
2023
2024 void work(uint worker_id) {
2025 if (CONCURRENT) {
2026 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2027 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2028 do_work<ShenandoahConcUpdateRefsClosure>();
2029 } else {
2030 ShenandoahParallelWorkerSession worker_session(worker_id);
2031 do_work<ShenandoahSTWUpdateRefsClosure>();
2032 }
2033 }
2034
2035 private:
2036 template<class T>
2037 void do_work() {
2038 T cl;
2039 ShenandoahHeapRegion* r = _regions->next();
2040 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2041 while (r != nullptr) {
2042 HeapWord* update_watermark = r->get_update_watermark();
2043 assert (update_watermark >= r->bottom(), "sanity");
2044 if (r->is_active() && !r->is_cset()) {
2045 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2046 }
2047 if (ShenandoahPacing) {
2048 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2049 }
2050 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
2051 return;
2052 }
2053 r = _regions->next();
2054 }
2055 }
2056 };
2057
2058 void ShenandoahHeap::update_heap_references(bool concurrent) {
2059 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2060
2061 if (concurrent) {
2062 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator);
2063 workers()->run_task(&task);
2064 } else {
2065 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator);
2066 workers()->run_task(&task);
2067 }
2068 }
2069
2070
2071 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2072 private:
2073 ShenandoahHeapLock* const _lock;
2074
2075 public:
2076 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2077
2078 void heap_region_do(ShenandoahHeapRegion* r) {
2079 // Drop unnecessary "pinned" state from regions that does not have CP marks
2080 // anymore, as this would allow trashing them.
2081
2082 if (r->is_active()) {
2083 if (r->is_pinned()) {
2084 if (r->pin_count() == 0) {
2085 ShenandoahHeapLocker locker(_lock);
2086 r->make_unpinned();
2087 }
2088 } else {
2089 if (r->pin_count() > 0) {
2090 ShenandoahHeapLocker locker(_lock);
2091 r->make_pinned();
2092 }
2093 }
2094 }
2095 }
2096
2097 bool is_thread_safe() { return true; }
2098 };
2099
2100 void ShenandoahHeap::update_heap_region_states(bool concurrent) {
2101 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2102 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2103
2104 {
2105 ShenandoahGCPhase phase(concurrent ?
2106 ShenandoahPhaseTimings::final_update_refs_update_region_states :
2107 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states);
2108 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2109 parallel_heap_region_iterate(&cl);
2110
2111 assert_pinned_region_status();
2112 }
2113
2114 {
2115 ShenandoahGCPhase phase(concurrent ?
2116 ShenandoahPhaseTimings::final_update_refs_trash_cset :
2117 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset);
2118 trash_cset_regions();
2119 }
2120 }
2121
2122 void ShenandoahHeap::rebuild_free_set(bool concurrent) {
2123 {
2124 ShenandoahGCPhase phase(concurrent ?
2125 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
2126 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
2127 ShenandoahHeapLocker locker(lock());
2128 _free_set->rebuild();
2222 EventMark em("%s", msg);
2223
2224 op_uncommit(shrink_before, shrink_until);
2225 }
2226
2227 void ShenandoahHeap::try_inject_alloc_failure() {
2228 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2229 _inject_alloc_failure.set();
2230 os::naked_short_sleep(1);
2231 if (cancelled_gc()) {
2232 log_info(gc)("Allocation failure was successfully injected");
2233 }
2234 }
2235 }
2236
2237 bool ShenandoahHeap::should_inject_alloc_failure() {
2238 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2239 }
2240
2241 void ShenandoahHeap::initialize_serviceability() {
2242 _memory_pool = new ShenandoahMemoryPool(this);
2243 _cycle_memory_manager.add_pool(_memory_pool);
2244 _stw_memory_manager.add_pool(_memory_pool);
2245 }
2246
2247 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2248 GrowableArray<GCMemoryManager*> memory_managers(2);
2249 memory_managers.append(&_cycle_memory_manager);
2250 memory_managers.append(&_stw_memory_manager);
2251 return memory_managers;
2252 }
2253
2254 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2255 GrowableArray<MemoryPool*> memory_pools(1);
2256 memory_pools.append(_memory_pool);
2257 return memory_pools;
2258 }
2259
2260 MemoryUsage ShenandoahHeap::memory_usage() {
2261 return _memory_pool->get_memory_usage();
2262 }
2263
2264 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2265 _heap(ShenandoahHeap::heap()),
2266 _index(0) {}
2267
2268 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2269 _heap(heap),
2270 _index(0) {}
2271
2272 void ShenandoahRegionIterator::reset() {
2273 _index = 0;
2274 }
2275
2276 bool ShenandoahRegionIterator::has_next() const {
2277 return _index < _heap->num_regions();
2278 }
2279
2280 char ShenandoahHeap::gc_state() const {
2281 return _gc_state.raw_value();
2282 }
2283
2284 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2285 #ifdef ASSERT
2286 assert(_liveness_cache != nullptr, "sanity");
2287 assert(worker_id < _max_workers, "sanity");
2288 for (uint i = 0; i < num_regions(); i++) {
2289 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2290 }
2291 #endif
2292 return _liveness_cache[worker_id];
2293 }
2294
2295 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2296 assert(worker_id < _max_workers, "sanity");
2297 assert(_liveness_cache != nullptr, "sanity");
2298 ShenandoahLiveData* ld = _liveness_cache[worker_id];
2299 for (uint i = 0; i < num_regions(); i++) {
2300 ShenandoahLiveData live = ld[i];
2301 if (live > 0) {
2302 ShenandoahHeapRegion* r = get_region(i);
2303 r->increase_live_data_gc_words(live);
2304 ld[i] = 0;
2305 }
2306 }
2307 }
2308
2309 bool ShenandoahHeap::requires_barriers(stackChunkOop obj) const {
2310 if (is_idle()) return false;
2311
2312 // Objects allocated after marking start are implicitly alive, don't need any barriers during
2313 // marking phase.
2314 if (is_concurrent_mark_in_progress() &&
2315 !marking_context()->allocated_after_mark_start(obj)) {
2316 return true;
2317 }
2318
2319 // Can not guarantee obj is deeply good.
2320 if (has_forwarded_objects()) {
2321 return true;
2322 }
2323
2324 return false;
2325 }
|
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #include "precompiled.hpp"
27 #include "memory/allocation.hpp"
28 #include "memory/universe.hpp"
29
30 #include "gc/shared/gcArguments.hpp"
31 #include "gc/shared/gcTimer.hpp"
32 #include "gc/shared/gcTraceTime.inline.hpp"
33 #include "gc/shared/locationPrinter.inline.hpp"
34 #include "gc/shared/memAllocator.hpp"
35 #include "gc/shared/plab.hpp"
36 #include "gc/shared/tlab_globals.hpp"
37
38 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
39 #include "gc/shenandoah/shenandoahCardTable.hpp"
40 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
41 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
42 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
43 #include "gc/shenandoah/shenandoahConcurrentMark.hpp"
44 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
45 #include "gc/shenandoah/shenandoahControlThread.hpp"
46 #include "gc/shenandoah/shenandoahRegulatorThread.hpp"
47 #include "gc/shenandoah/shenandoahFreeSet.hpp"
48 #include "gc/shenandoah/shenandoahGlobalGeneration.hpp"
49 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
50 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
51 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
52 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
53 #include "gc/shenandoah/shenandoahInitLogger.hpp"
54 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
55 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
56 #include "gc/shenandoah/shenandoahMetrics.hpp"
57 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
58 #include "gc/shenandoah/shenandoahOldGeneration.hpp"
59 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
60 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
61 #include "gc/shenandoah/shenandoahPadding.hpp"
62 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
63 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
64 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
65 #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp"
66 #include "gc/shenandoah/shenandoahStringDedup.hpp"
67 #include "gc/shenandoah/shenandoahSTWMark.hpp"
68 #include "gc/shenandoah/shenandoahUtils.hpp"
69 #include "gc/shenandoah/shenandoahVerifier.hpp"
70 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
71 #include "gc/shenandoah/shenandoahVMOperations.hpp"
72 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
73 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
74 #include "gc/shenandoah/shenandoahYoungGeneration.hpp"
75 #include "gc/shenandoah/mode/shenandoahGenerationalMode.hpp"
76 #include "gc/shenandoah/mode/shenandoahIUMode.hpp"
77 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
78 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp"
79
80 #if INCLUDE_JFR
81 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
82 #endif
83
84 #include "gc/shenandoah/heuristics/shenandoahOldHeuristics.hpp"
85
86 #include "classfile/systemDictionary.hpp"
87 #include "code/codeCache.hpp"
88 #include "memory/classLoaderMetaspace.hpp"
89 #include "memory/metaspaceUtils.hpp"
90 #include "oops/compressedOops.inline.hpp"
91 #include "prims/jvmtiTagMap.hpp"
92 #include "runtime/atomic.hpp"
93 #include "runtime/globals.hpp"
94 #include "runtime/interfaceSupport.inline.hpp"
95 #include "runtime/java.hpp"
96 #include "runtime/orderAccess.hpp"
97 #include "runtime/safepointMechanism.hpp"
98 #include "runtime/vmThread.hpp"
99 #include "services/mallocTracker.hpp"
100 #include "services/memTracker.hpp"
101 #include "utilities/events.hpp"
102 #include "utilities/powerOfTwo.hpp"
103
104 class ShenandoahPretouchHeapTask : public WorkerTask {
105 private:
153 jint ShenandoahHeap::initialize() {
154 //
155 // Figure out heap sizing
156 //
157
158 size_t init_byte_size = InitialHeapSize;
159 size_t min_byte_size = MinHeapSize;
160 size_t max_byte_size = MaxHeapSize;
161 size_t heap_alignment = HeapAlignment;
162
163 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
164
165 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
166 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
167
168 _num_regions = ShenandoahHeapRegion::region_count();
169 assert(_num_regions == (max_byte_size / reg_size_bytes),
170 "Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT,
171 _num_regions, max_byte_size, reg_size_bytes);
172
173 size_t num_committed_regions = init_byte_size / reg_size_bytes;
174 num_committed_regions = MIN2(num_committed_regions, _num_regions);
175 assert(num_committed_regions <= _num_regions, "sanity");
176 _initial_size = num_committed_regions * reg_size_bytes;
177
178 size_t num_min_regions = min_byte_size / reg_size_bytes;
179 num_min_regions = MIN2(num_min_regions, _num_regions);
180 assert(num_min_regions <= _num_regions, "sanity");
181 _minimum_size = num_min_regions * reg_size_bytes;
182
183 // Default to max heap size.
184 _soft_max_size = _num_regions * reg_size_bytes;
185
186 _committed = _initial_size;
187
188 // Now we know the number of regions and heap sizes, initialize the heuristics.
189 initialize_generations();
190 initialize_heuristics();
191
192 size_t heap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
193 size_t bitmap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
194 size_t region_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
195
196 //
197 // Reserve and commit memory for heap
198 //
199
200 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
201 initialize_reserved_region(heap_rs);
202 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
203 _heap_region_special = heap_rs.special();
204
205 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
206 "Misaligned heap: " PTR_FORMAT, p2i(base()));
207
208 #if SHENANDOAH_OPTIMIZED_MARKTASK
209 // The optimized ShenandoahMarkTask takes some bits away from the full object bits.
210 // Fail if we ever attempt to address more than we can.
211 if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) {
212 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
213 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
214 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
215 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable());
216 vm_exit_during_initialization("Fatal Error", buf);
217 }
218 #endif
219
220 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
221 if (!_heap_region_special) {
222 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
223 "Cannot commit heap memory");
224 }
225
226 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this, _heap_region));
227
228 //
229 // After reserving the Java heap, create the card table, barriers, and workers, in dependency order
230 //
231 if (mode()->is_generational()) {
232 ShenandoahDirectCardMarkRememberedSet *rs;
233 ShenandoahCardTable* card_table = ShenandoahBarrierSet::barrier_set()->card_table();
234 size_t card_count = card_table->cards_required(heap_rs.size() / HeapWordSize);
235 rs = new ShenandoahDirectCardMarkRememberedSet(ShenandoahBarrierSet::barrier_set()->card_table(), card_count);
236 _card_scan = new ShenandoahScanRemembered<ShenandoahDirectCardMarkRememberedSet>(rs);
237 }
238
239 _workers = new ShenandoahWorkerThreads("Shenandoah GC Threads", _max_workers);
240 if (_workers == nullptr) {
241 vm_exit_during_initialization("Failed necessary allocation.");
242 } else {
243 _workers->initialize_workers();
244 }
245
246 if (ParallelGCThreads > 1) {
247 _safepoint_workers = new ShenandoahWorkerThreads("Safepoint Cleanup Thread", ParallelGCThreads);
248 _safepoint_workers->initialize_workers();
249 }
250
251 //
252 // Reserve and commit memory for bitmap(s)
253 //
254
255 _bitmap_size = ShenandoahMarkBitMap::compute_size(heap_rs.size());
256 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
257
258 size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor();
259
260 guarantee(bitmap_bytes_per_region != 0,
261 "Bitmap bytes per region should not be zero");
262 guarantee(is_power_of_2(bitmap_bytes_per_region),
263 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
264
265 if (bitmap_page_size > bitmap_bytes_per_region) {
266 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
267 _bitmap_bytes_per_slice = bitmap_page_size;
268 } else {
269 _bitmap_regions_per_slice = 1;
270 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
274 "Should have at least one region per slice: " SIZE_FORMAT,
275 _bitmap_regions_per_slice);
276
277 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
278 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
279 _bitmap_bytes_per_slice, bitmap_page_size);
280
281 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
282 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
283 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
284 _bitmap_region_special = bitmap.special();
285
286 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
287 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
288 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
289 if (!_bitmap_region_special) {
290 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
291 "Cannot commit bitmap memory");
292 }
293
294 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
295
296 if (ShenandoahVerify) {
297 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
298 if (!verify_bitmap.special()) {
299 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
300 "Cannot commit verification bitmap memory");
301 }
302 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
303 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
304 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
305 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
306 }
307
308 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
309 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
310 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
311 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
312 _aux_bitmap_region_special = aux_bitmap.special();
313 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
314
337 uintptr_t max = (1u << 30u);
338
339 for (uintptr_t addr = min; addr <= max; addr <<= 1u) {
340 char* req_addr = (char*)addr;
341 assert(is_aligned(req_addr, cset_align), "Should be aligned");
342 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size(), req_addr);
343 if (cset_rs.is_reserved()) {
344 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr);
345 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
346 break;
347 }
348 }
349
350 if (_collection_set == nullptr) {
351 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size());
352 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
353 }
354 }
355
356 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
357 _affiliations = NEW_C_HEAP_ARRAY(uint8_t, _num_regions, mtGC);
358 _free_set = new ShenandoahFreeSet(this, _num_regions);
359
360 {
361 ShenandoahHeapLocker locker(lock());
362
363
364 for (size_t i = 0; i < _num_regions; i++) {
365 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
366 bool is_committed = i < num_committed_regions;
367 void* loc = region_storage.base() + i * region_align;
368
369 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
370 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
371
372 _marking_context->initialize_top_at_mark_start(r);
373 _regions[i] = r;
374 assert(!collection_set()->is_in(i), "New region should not be in collection set");
375
376 _affiliations[i] = ShenandoahRegionAffiliation::FREE;
377 }
378
379 // Initialize to complete
380 _marking_context->mark_complete();
381
382 _free_set->rebuild();
383 }
384
385 if (AlwaysPreTouch) {
386 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
387 // before initialize() below zeroes it with initializing thread. For any given region,
388 // we touch the region and the corresponding bitmaps from the same thread.
389 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
390
391 _pretouch_heap_page_size = heap_page_size;
392 _pretouch_bitmap_page_size = bitmap_page_size;
393
394 #ifdef LINUX
395 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
396 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
424 // There should probably be Shenandoah-specific options for these,
425 // just as there are G1-specific options.
426 {
427 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
428 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
429 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
430 }
431
432 _monitoring_support = new ShenandoahMonitoringSupport(this);
433 _phase_timings = new ShenandoahPhaseTimings(max_workers());
434 ShenandoahCodeRoots::initialize();
435
436 if (ShenandoahPacing) {
437 _pacer = new ShenandoahPacer(this);
438 _pacer->setup_for_idle();
439 } else {
440 _pacer = nullptr;
441 }
442
443 _control_thread = new ShenandoahControlThread();
444 _regulator_thread = new ShenandoahRegulatorThread(_control_thread);
445
446 ShenandoahInitLogger::print();
447
448 return JNI_OK;
449 }
450
451 size_t ShenandoahHeap::max_size_for(ShenandoahGeneration* generation) const {
452 switch (generation->generation_mode()) {
453 case YOUNG: return _generation_sizer.max_young_size();
454 case OLD: return max_capacity() - _generation_sizer.min_young_size();
455 case GLOBAL: return max_capacity();
456 default:
457 ShouldNotReachHere();
458 return 0;
459 }
460 }
461
462 size_t ShenandoahHeap::min_size_for(ShenandoahGeneration* generation) const {
463 switch (generation->generation_mode()) {
464 case YOUNG: return _generation_sizer.min_young_size();
465 case OLD: return max_capacity() - _generation_sizer.max_young_size();
466 case GLOBAL: return min_capacity();
467 default:
468 ShouldNotReachHere();
469 return 0;
470 }
471 }
472
473 void ShenandoahHeap::initialize_generations() {
474 // Max capacity is the maximum _allowed_ capacity. That is, the maximum allowed capacity
475 // for old would be total heap - minimum capacity of young. This means the sum of the maximum
476 // allowed for old and young could exceed the total heap size. It remains the case that the
477 // _actual_ capacity of young + old = total.
478 _generation_sizer.heap_size_changed(soft_max_capacity());
479 size_t initial_capacity_young = _generation_sizer.max_young_size();
480 size_t max_capacity_young = _generation_sizer.max_young_size();
481 size_t initial_capacity_old = max_capacity() - max_capacity_young;
482 size_t max_capacity_old = max_capacity() - initial_capacity_young;
483
484 _young_generation = new ShenandoahYoungGeneration(_max_workers, max_capacity_young, initial_capacity_young);
485 _old_generation = new ShenandoahOldGeneration(_max_workers, max_capacity_old, initial_capacity_old);
486 _global_generation = new ShenandoahGlobalGeneration(_max_workers, soft_max_capacity(), soft_max_capacity());
487 }
488
489 void ShenandoahHeap::initialize_heuristics() {
490 if (ShenandoahGCMode != nullptr) {
491 if (strcmp(ShenandoahGCMode, "satb") == 0) {
492 _gc_mode = new ShenandoahSATBMode();
493 } else if (strcmp(ShenandoahGCMode, "iu") == 0) {
494 _gc_mode = new ShenandoahIUMode();
495 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
496 _gc_mode = new ShenandoahPassiveMode();
497 } else if (strcmp(ShenandoahGCMode, "generational") == 0) {
498 _gc_mode = new ShenandoahGenerationalMode();
499 } else {
500 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
501 }
502 } else {
503 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option (null)");
504 }
505 _gc_mode->initialize_flags();
506 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
507 vm_exit_during_initialization(
508 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
509 _gc_mode->name()));
510 }
511 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
512 vm_exit_during_initialization(
513 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
514 _gc_mode->name()));
515 }
516
517 _global_generation->initialize_heuristics(_gc_mode);
518 if (mode()->is_generational()) {
519 _young_generation->initialize_heuristics(_gc_mode);
520 _old_generation->initialize_heuristics(_gc_mode);
521
522 ShenandoahEvacWaste = ShenandoahGenerationalEvacWaste;
523 }
524 }
525
526 #ifdef _MSC_VER
527 #pragma warning( push )
528 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
529 #endif
530
531 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
532 CollectedHeap(),
533 _gc_generation(nullptr),
534 _prepare_for_old_mark(false),
535 _initial_size(0),
536 _used(0),
537 _committed(0),
538 _max_workers(MAX3(ConcGCThreads, ParallelGCThreads, 1U)),
539 _workers(nullptr),
540 _safepoint_workers(nullptr),
541 _heap_region_special(false),
542 _num_regions(0),
543 _regions(nullptr),
544 _affiliations(nullptr),
545 _update_refs_iterator(this),
546 _alloc_supplement_reserve(0),
547 _promoted_reserve(0),
548 _old_evac_reserve(0),
549 _old_evac_expended(0),
550 _young_evac_reserve(0),
551 _captured_old_usage(0),
552 _previous_promotion(0),
553 _cancel_requested_time(0),
554 _young_generation(nullptr),
555 _global_generation(nullptr),
556 _old_generation(nullptr),
557 _control_thread(nullptr),
558 _regulator_thread(nullptr),
559 _shenandoah_policy(policy),
560 _free_set(nullptr),
561 _pacer(nullptr),
562 _verifier(nullptr),
563 _phase_timings(nullptr),
564 _evac_tracker(new ShenandoahEvacuationTracker()),
565 _mmu_tracker(),
566 _generation_sizer(&_mmu_tracker),
567 _monitoring_support(nullptr),
568 _memory_pool(nullptr),
569 _young_gen_memory_pool(nullptr),
570 _old_gen_memory_pool(nullptr),
571 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
572 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
573 _gc_timer(new ConcurrentGCTimer()),
574 _soft_ref_policy(),
575 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
576 _marking_context(nullptr),
577 _bitmap_size(0),
578 _bitmap_regions_per_slice(0),
579 _bitmap_bytes_per_slice(0),
580 _bitmap_region_special(false),
581 _aux_bitmap_region_special(false),
582 _liveness_cache(nullptr),
583 _collection_set(nullptr),
584 _card_scan(nullptr)
585 {
586 }
587
588 #ifdef _MSC_VER
589 #pragma warning( pop )
590 #endif
591
592 void ShenandoahHeap::print_on(outputStream* st) const {
593 st->print_cr("Shenandoah Heap");
594 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
595 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
596 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()),
597 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
598 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
599 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
600 num_regions(),
601 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
602 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
603
604 st->print("Status: ");
605 if (has_forwarded_objects()) st->print("has forwarded objects, ");
606 if (is_concurrent_old_mark_in_progress()) st->print("old marking, ");
607 if (is_concurrent_young_mark_in_progress()) st->print("young marking, ");
608 if (is_evacuation_in_progress()) st->print("evacuating, ");
609 if (is_update_refs_in_progress()) st->print("updating refs, ");
610 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
611 if (is_full_gc_in_progress()) st->print("full gc, ");
612 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
613 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, ");
614 if (is_concurrent_strong_root_in_progress() &&
615 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, ");
616
617 if (cancelled_gc()) {
618 st->print("cancelled");
619 } else {
620 st->print("not cancelled");
621 }
622 st->cr();
623
624 st->print_cr("Reserved region:");
625 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
626 p2i(reserved_region().start()),
627 p2i(reserved_region().end()));
637
638 st->cr();
639 MetaspaceUtils::print_on(st);
640
641 if (Verbose) {
642 print_heap_regions_on(st);
643 }
644 }
645
646 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
647 public:
648 void do_thread(Thread* thread) {
649 assert(thread != nullptr, "Sanity");
650 assert(thread->is_Worker_thread(), "Only worker thread expected");
651 ShenandoahThreadLocalData::initialize_gclab(thread);
652 }
653 };
654
655 void ShenandoahHeap::post_initialize() {
656 CollectedHeap::post_initialize();
657 _mmu_tracker.initialize();
658
659 MutexLocker ml(Threads_lock);
660
661 ShenandoahInitWorkerGCLABClosure init_gclabs;
662 _workers->threads_do(&init_gclabs);
663
664 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
665 // Now, we will let WorkerThreads to initialize gclab when new worker is created.
666 _workers->set_initialize_gclab();
667 if (_safepoint_workers != nullptr) {
668 _safepoint_workers->threads_do(&init_gclabs);
669 _safepoint_workers->set_initialize_gclab();
670 }
671
672 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
673 }
674
675
676 ShenandoahOldHeuristics* ShenandoahHeap::old_heuristics() {
677 return (ShenandoahOldHeuristics*) _old_generation->heuristics();
678 }
679
680 bool ShenandoahHeap::doing_mixed_evacuations() {
681 return _old_generation->state() == ShenandoahOldGeneration::WAITING_FOR_EVAC;
682 }
683
684 bool ShenandoahHeap::is_old_bitmap_stable() const {
685 ShenandoahOldGeneration::State state = _old_generation->state();
686 return state != ShenandoahOldGeneration::MARKING
687 && state != ShenandoahOldGeneration::BOOTSTRAPPING;
688 }
689
690 bool ShenandoahHeap::is_gc_generation_young() const {
691 return _gc_generation != nullptr && _gc_generation->generation_mode() == YOUNG;
692 }
693
694 size_t ShenandoahHeap::used() const {
695 return Atomic::load(&_used);
696 }
697
698 size_t ShenandoahHeap::committed() const {
699 return Atomic::load(&_committed);
700 }
701
702 void ShenandoahHeap::increase_committed(size_t bytes) {
703 shenandoah_assert_heaplocked_or_safepoint();
704 _committed += bytes;
705 }
706
707 void ShenandoahHeap::decrease_committed(size_t bytes) {
708 shenandoah_assert_heaplocked_or_safepoint();
709 _committed -= bytes;
710 }
711
712 void ShenandoahHeap::increase_used(size_t bytes) {
713 Atomic::add(&_used, bytes, memory_order_relaxed);
714 }
715
716 void ShenandoahHeap::set_used(size_t bytes) {
717 Atomic::store(&_used, bytes);
718 }
719
720 void ShenandoahHeap::decrease_used(size_t bytes) {
721 assert(used() >= bytes, "never decrease heap size by more than we've left");
722 Atomic::sub(&_used, bytes, memory_order_relaxed);
723 }
724
725 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
726 size_t bytes = words * HeapWordSize;
727 if (!waste) {
728 increase_used(bytes);
729 }
730
731 if (ShenandoahPacing) {
732 control_thread()->pacing_notify_alloc(words);
733 if (waste) {
734 pacer()->claim_for_alloc(words, true);
735 }
736 }
737 }
738
739 size_t ShenandoahHeap::capacity() const {
740 return committed();
741 }
742
743 size_t ShenandoahHeap::max_capacity() const {
744 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
745 }
746
747 size_t ShenandoahHeap::soft_max_capacity() const {
748 size_t v = Atomic::load(&_soft_max_size);
749 assert(min_capacity() <= v && v <= max_capacity(),
750 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
751 min_capacity(), v, max_capacity());
752 return v;
753 }
754
755 void ShenandoahHeap::set_soft_max_capacity(size_t v) {
756 assert(min_capacity() <= v && v <= max_capacity(),
757 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
758 min_capacity(), v, max_capacity());
759 Atomic::store(&_soft_max_size, v);
760
761 if (mode()->is_generational()) {
762 _generation_sizer.heap_size_changed(_soft_max_size);
763 size_t soft_max_capacity_young = _generation_sizer.max_young_size();
764 size_t soft_max_capacity_old = _soft_max_size - soft_max_capacity_young;
765 _young_generation->set_soft_max_capacity(soft_max_capacity_young);
766 _old_generation->set_soft_max_capacity(soft_max_capacity_old);
767 }
768 }
769
770 size_t ShenandoahHeap::min_capacity() const {
771 return _minimum_size;
772 }
773
774 size_t ShenandoahHeap::initial_capacity() const {
775 return _initial_size;
776 }
777
778 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
779 assert (ShenandoahUncommit, "should be enabled");
780
781 // Application allocates from the beginning of the heap, and GC allocates at
782 // the end of it. It is more efficient to uncommit from the end, so that applications
783 // could enjoy the near committed regions. GC allocations are much less frequent,
784 // and therefore can accept the committing costs.
785
786 size_t count = 0;
787 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
788 ShenandoahHeapRegion* r = get_region(i - 1);
789 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
790 ShenandoahHeapLocker locker(lock());
791 if (r->is_empty_committed()) {
792 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) {
793 break;
794 }
795
796 r->make_uncommitted();
797 count++;
798 }
799 }
800 SpinPause(); // allow allocators to take the lock
801 }
802
803 if (count > 0) {
804 control_thread()->notify_heap_changed();
805 regulator_thread()->notify_heap_changed();
806 }
807 }
808
809 void ShenandoahHeap::handle_old_evacuation(HeapWord* obj, size_t words, bool promotion) {
810 // Only register the copy of the object that won the evacuation race.
811 card_scan()->register_object_wo_lock(obj);
812
813 // Mark the entire range of the evacuated object as dirty. At next remembered set scan,
814 // we will clear dirty bits that do not hold interesting pointers. It's more efficient to
815 // do this in batch, in a background GC thread than to try to carefully dirty only cards
816 // that hold interesting pointers right now.
817 card_scan()->mark_range_as_dirty(obj, words);
818
819 if (promotion) {
820 // This evacuation was a promotion, track this as allocation against old gen
821 old_generation()->increase_allocated(words * HeapWordSize);
822 }
823 }
824
825 void ShenandoahHeap::handle_old_evacuation_failure() {
826 if (_old_gen_oom_evac.try_set()) {
827 log_info(gc)("Old gen evac failure.");
828 }
829 }
830
831 void ShenandoahHeap::handle_promotion_failure() {
832 old_heuristics()->handle_promotion_failure();
833 }
834
835 void ShenandoahHeap::report_promotion_failure(Thread* thread, size_t size) {
836 // We squelch excessive reports to reduce noise in logs. Squelch enforcement is not "perfect" because
837 // this same code can be in-lined in multiple contexts, and each context will have its own copy of the static
838 // last_report_epoch and this_epoch_report_count variables.
839 const size_t MaxReportsPerEpoch = 4;
840 static size_t last_report_epoch = 0;
841 static size_t epoch_report_count = 0;
842
843 size_t promotion_reserve;
844 size_t promotion_expended;
845
846 size_t gc_id = control_thread()->get_gc_id();
847
848 if ((gc_id != last_report_epoch) || (epoch_report_count++ < MaxReportsPerEpoch)) {
849 {
850 // Promotion failures should be very rare. Invest in providing useful diagnostic info.
851 ShenandoahHeapLocker locker(lock());
852 promotion_reserve = get_promoted_reserve();
853 promotion_expended = get_promoted_expended();
854 }
855 PLAB* plab = ShenandoahThreadLocalData::plab(thread);
856 size_t words_remaining = (plab == nullptr)? 0: plab->words_remaining();
857 const char* promote_enabled = ShenandoahThreadLocalData::allow_plab_promotions(thread)? "enabled": "disabled";
858
859 log_info(gc, ergo)("Promotion failed, size " SIZE_FORMAT ", has plab? %s, PLAB remaining: " SIZE_FORMAT
860 ", plab promotions %s, promotion reserve: " SIZE_FORMAT ", promotion expended: " SIZE_FORMAT,
861 size, plab == nullptr? "no": "yes",
862 words_remaining, promote_enabled, promotion_reserve, promotion_expended);
863 if ((gc_id == last_report_epoch) && (epoch_report_count >= MaxReportsPerEpoch)) {
864 log_info(gc, ergo)("Squelching additional promotion failure reports for current epoch");
865 } else if (gc_id != last_report_epoch) {
866 last_report_epoch = gc_id;;
867 epoch_report_count = 1;
868 }
869 }
870 }
871
872 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
873 // New object should fit the GCLAB size
874 size_t min_size = MAX2(size, PLAB::min_size());
875
876 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
877 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
878
879 // Limit growth of GCLABs to ShenandoahMaxEvacLABRatio * the minimum size. This enables more equitable distribution of
880 // available evacuation buidget between the many threads that are coordinating in the evacuation effort.
881 if (ShenandoahMaxEvacLABRatio > 0) {
882 log_debug(gc, free)("Allocate new gclab: " SIZE_FORMAT ", " SIZE_FORMAT, new_size, PLAB::min_size() * ShenandoahMaxEvacLABRatio);
883 new_size = MIN2(new_size, PLAB::min_size() * ShenandoahMaxEvacLABRatio);
884 }
885
886 new_size = MIN2(new_size, PLAB::max_size());
887 new_size = MAX2(new_size, PLAB::min_size());
888
889 // Record new heuristic value even if we take any shortcut. This captures
890 // the case when moderately-sized objects always take a shortcut. At some point,
891 // heuristics should catch up with them.
892 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
893
894 if (new_size < size) {
895 // New size still does not fit the object. Fall back to shared allocation.
896 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
897 log_debug(gc, free)("New gclab size (" SIZE_FORMAT ") is too small for " SIZE_FORMAT, new_size, size);
898 return nullptr;
899 }
900
901 // Retire current GCLAB, and allocate a new one.
902 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
903 gclab->retire();
904
905 size_t actual_size = 0;
906 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
907 if (gclab_buf == nullptr) {
908 return nullptr;
909 }
910
911 assert (size <= actual_size, "allocation should fit");
912
913 if (ZeroTLAB) {
914 // ..and clear it.
915 Copy::zero_to_words(gclab_buf, actual_size);
916 } else {
917 // ...and zap just allocated object.
918 #ifdef ASSERT
919 // Skip mangling the space corresponding to the object header to
920 // ensure that the returned space is not considered parsable by
921 // any concurrent GC thread.
922 size_t hdr_size = oopDesc::header_size();
923 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
924 #endif // ASSERT
925 }
926 gclab->set_buf(gclab_buf, actual_size);
927 return gclab->allocate(size);
928 }
929
930 // Establish a new PLAB and allocate size HeapWords within it.
931 HeapWord* ShenandoahHeap::allocate_from_plab_slow(Thread* thread, size_t size, bool is_promotion) {
932 // New object should fit the PLAB size
933 size_t min_size = MAX2(size, PLAB::min_size());
934
935 // Figure out size of new PLAB, looking back at heuristics. Expand aggressively.
936 size_t cur_size = ShenandoahThreadLocalData::plab_size(thread);
937 if (cur_size == 0) {
938 cur_size = PLAB::min_size();
939 }
940 size_t future_size = cur_size * 2;
941 // Limit growth of PLABs to ShenandoahMaxEvacLABRatio * the minimum size. This enables more equitable distribution of
942 // available evacuation buidget between the many threads that are coordinating in the evacuation effort.
943 if (ShenandoahMaxEvacLABRatio > 0) {
944 future_size = MIN2(future_size, PLAB::min_size() * ShenandoahMaxEvacLABRatio);
945 }
946 future_size = MIN2(future_size, PLAB::max_size());
947 future_size = MAX2(future_size, PLAB::min_size());
948
949 size_t unalignment = future_size % CardTable::card_size_in_words();
950 if (unalignment != 0) {
951 future_size = future_size - unalignment + CardTable::card_size_in_words();
952 }
953
954 // Record new heuristic value even if we take any shortcut. This captures
955 // the case when moderately-sized objects always take a shortcut. At some point,
956 // heuristics should catch up with them. Note that the requested cur_size may
957 // not be honored, but we remember that this is the preferred size.
958 ShenandoahThreadLocalData::set_plab_size(thread, future_size);
959 if (cur_size < size) {
960 // The PLAB to be allocated is still not large enough to hold the object. Fall back to shared allocation.
961 // This avoids retiring perfectly good PLABs in order to represent a single large object allocation.
962 return nullptr;
963 }
964
965 // Retire current PLAB, and allocate a new one.
966 PLAB* plab = ShenandoahThreadLocalData::plab(thread);
967 if (plab->words_remaining() < PLAB::min_size()) {
968 // Retire current PLAB, and allocate a new one.
969 // CAUTION: retire_plab may register the remnant filler object with the remembered set scanner without a lock. This
970 // is safe iff it is assured that each PLAB is a whole-number multiple of card-mark memory size and each PLAB is
971 // aligned with the start of a card's memory range.
972
973 retire_plab(plab, thread);
974
975 size_t actual_size = 0;
976 // allocate_new_plab resets plab_evacuated and plab_promoted and disables promotions if old-gen available is
977 // less than the remaining evacuation need. It also adjusts plab_preallocated and expend_promoted if appropriate.
978 HeapWord* plab_buf = allocate_new_plab(min_size, cur_size, &actual_size);
979 if (plab_buf == nullptr) {
980 return nullptr;
981 } else {
982 ShenandoahThreadLocalData::enable_plab_retries(thread);
983 }
984 assert (size <= actual_size, "allocation should fit");
985 if (ZeroTLAB) {
986 // ..and clear it.
987 Copy::zero_to_words(plab_buf, actual_size);
988 } else {
989 // ...and zap just allocated object.
990 #ifdef ASSERT
991 // Skip mangling the space corresponding to the object header to
992 // ensure that the returned space is not considered parsable by
993 // any concurrent GC thread.
994 size_t hdr_size = oopDesc::header_size();
995 Copy::fill_to_words(plab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
996 #endif // ASSERT
997 }
998 plab->set_buf(plab_buf, actual_size);
999
1000 if (is_promotion && !ShenandoahThreadLocalData::allow_plab_promotions(thread)) {
1001 return nullptr;
1002 }
1003 return plab->allocate(size);
1004 } else {
1005 // If there's still at least min_size() words available within the current plab, don't retire it. Let's gnaw
1006 // away on this plab as long as we can. Meanwhile, return nullptr to force this particular allocation request
1007 // to be satisfied with a shared allocation. By packing more promotions into the previously allocated PLAB, we
1008 // reduce the likelihood of evacuation failures, and we we reduce the need for downsizing our PLABs.
1009 return nullptr;
1010 }
1011 }
1012
1013 // TODO: It is probably most efficient to register all objects (both promotions and evacuations) that were allocated within
1014 // this plab at the time we retire the plab. A tight registration loop will run within both code and data caches. This change
1015 // would allow smaller and faster in-line implementation of alloc_from_plab(). Since plabs are aligned on card-table boundaries,
1016 // this object registration loop can be performed without acquiring a lock.
1017 void ShenandoahHeap::retire_plab(PLAB* plab, Thread* thread) {
1018 // We don't enforce limits on plab_evacuated. We let it consume all available old-gen memory in order to reduce
1019 // probability of an evacuation failure. We do enforce limits on promotion, to make sure that excessive promotion
1020 // does not result in an old-gen evacuation failure. Note that a failed promotion is relatively harmless. Any
1021 // object that fails to promote in the current cycle will be eligible for promotion in a subsequent cycle.
1022
1023 // When the plab was instantiated, its entirety was treated as if the entire buffer was going to be dedicated to
1024 // promotions. Now that we are retiring the buffer, we adjust for the reality that the plab is not entirely promotions.
1025 // 1. Some of the plab may have been dedicated to evacuations.
1026 // 2. Some of the plab may have been abandoned due to waste (at the end of the plab).
1027 size_t not_promoted =
1028 ShenandoahThreadLocalData::get_plab_preallocated_promoted(thread) - ShenandoahThreadLocalData::get_plab_promoted(thread);
1029 ShenandoahThreadLocalData::reset_plab_promoted(thread);
1030 ShenandoahThreadLocalData::reset_plab_evacuated(thread);
1031 ShenandoahThreadLocalData::set_plab_preallocated_promoted(thread, 0);
1032 if (not_promoted > 0) {
1033 unexpend_promoted(not_promoted);
1034 }
1035 size_t waste = plab->waste();
1036 HeapWord* top = plab->top();
1037 plab->retire();
1038 if (top != nullptr && plab->waste() > waste && is_in_old(top)) {
1039 // If retiring the plab created a filler object, then we
1040 // need to register it with our card scanner so it can
1041 // safely walk the region backing the plab.
1042 log_debug(gc)("retire_plab() is registering remnant of size " SIZE_FORMAT " at " PTR_FORMAT,
1043 plab->waste() - waste, p2i(top));
1044 card_scan()->register_object_wo_lock(top);
1045 }
1046 }
1047
1048 void ShenandoahHeap::retire_plab(PLAB* plab) {
1049 Thread* thread = Thread::current();
1050 retire_plab(plab, thread);
1051 }
1052
1053 void ShenandoahHeap::cancel_old_gc() {
1054 shenandoah_assert_safepoint();
1055 assert(_old_generation != nullptr, "Should only have mixed collections in generation mode.");
1056 log_info(gc)("Terminating old gc cycle.");
1057
1058 // Stop marking
1059 old_generation()->cancel_marking();
1060 // Stop coalescing undead objects
1061 set_prepare_for_old_mark_in_progress(false);
1062 // Stop tracking old regions
1063 old_heuristics()->abandon_collection_candidates();
1064 // Remove old generation access to young generation mark queues
1065 young_generation()->set_old_gen_task_queues(nullptr);
1066 // Transition to IDLE now.
1067 _old_generation->transition_to(ShenandoahOldGeneration::IDLE);
1068 }
1069
1070 bool ShenandoahHeap::is_old_gc_active() {
1071 return _old_generation->state() != ShenandoahOldGeneration::IDLE;
1072 }
1073
1074 void ShenandoahHeap::coalesce_and_fill_old_regions() {
1075 class ShenandoahGlobalCoalesceAndFill : public ShenandoahHeapRegionClosure {
1076 public:
1077 virtual void heap_region_do(ShenandoahHeapRegion* region) override {
1078 // old region is not in the collection set and was not immediately trashed
1079 if (region->is_old() && region->is_active() && !region->is_humongous()) {
1080 // Reset the coalesce and fill boundary because this is a global collect
1081 // and cannot be preempted by young collects. We want to be sure the entire
1082 // region is coalesced here and does not resume from a previously interrupted
1083 // or completed coalescing.
1084 region->begin_preemptible_coalesce_and_fill();
1085 region->oop_fill_and_coalesce();
1086 }
1087 }
1088
1089 virtual bool is_thread_safe() override {
1090 return true;
1091 }
1092 };
1093 ShenandoahGlobalCoalesceAndFill coalesce;
1094 parallel_heap_region_iterate(&coalesce);
1095 }
1096
1097 bool ShenandoahHeap::adjust_generation_sizes() {
1098 if (mode()->is_generational()) {
1099 return _generation_sizer.adjust_generation_sizes();
1100 }
1101 return false;
1102 }
1103
1104 // Called from stubs in JIT code or interpreter
1105 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
1106 size_t requested_size,
1107 size_t* actual_size) {
1108 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
1109 HeapWord* res = allocate_memory(req, false);
1110 if (res != nullptr) {
1111 *actual_size = req.actual_size();
1112 } else {
1113 *actual_size = 0;
1114 }
1115 return res;
1116 }
1117
1118 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
1119 size_t word_size,
1120 size_t* actual_size) {
1121 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
1122 HeapWord* res = allocate_memory(req, false);
1123 if (res != nullptr) {
1124 *actual_size = req.actual_size();
1125 } else {
1126 *actual_size = 0;
1127 }
1128 return res;
1129 }
1130
1131 HeapWord* ShenandoahHeap::allocate_new_plab(size_t min_size,
1132 size_t word_size,
1133 size_t* actual_size) {
1134 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_plab(min_size, word_size);
1135 // Note that allocate_memory() sets a thread-local flag to prohibit further promotions by this thread
1136 // if we are at risk of exceeding the old-gen evacuation budget.
1137 HeapWord* res = allocate_memory(req, false);
1138 if (res != nullptr) {
1139 *actual_size = req.actual_size();
1140 } else {
1141 *actual_size = 0;
1142 }
1143 return res;
1144 }
1145
1146 // is_promotion is true iff this allocation is known for sure to hold the result of young-gen evacuation
1147 // to old-gen. plab allocates are not known as such, since they may hold old-gen evacuations.
1148 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req, bool is_promotion) {
1149 intptr_t pacer_epoch = 0;
1150 bool in_new_region = false;
1151 HeapWord* result = nullptr;
1152
1153 if (req.is_mutator_alloc()) {
1154 if (ShenandoahPacing) {
1155 pacer()->pace_for_alloc(req.size());
1156 pacer_epoch = pacer()->epoch();
1157 }
1158
1159 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
1160 result = allocate_memory_under_lock(req, in_new_region, is_promotion);
1161 }
1162
1163 // Allocation failed, block until control thread reacted, then retry allocation.
1164 //
1165 // It might happen that one of the threads requesting allocation would unblock
1166 // way later after GC happened, only to fail the second allocation, because
1167 // other threads have already depleted the free storage. In this case, a better
1168 // strategy is to try again, as long as GC makes progress.
1169 //
1170 // Then, we need to make sure the allocation was retried after at least one
1171 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
1172 size_t tries = 0;
1173 while (result == nullptr && _progress_last_gc.is_set()) {
1174 tries++;
1175 control_thread()->handle_alloc_failure(req);
1176 result = allocate_memory_under_lock(req, in_new_region, is_promotion);
1177 }
1178 while (result == nullptr && tries <= ShenandoahFullGCThreshold) {
1179 tries++;
1180 control_thread()->handle_alloc_failure(req);
1181 result = allocate_memory_under_lock(req, in_new_region, is_promotion);
1182 }
1183 } else {
1184 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
1185 result = allocate_memory_under_lock(req, in_new_region, is_promotion);
1186 // Do not call handle_alloc_failure() here, because we cannot block.
1187 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
1188 }
1189
1190 if (in_new_region) {
1191 control_thread()->notify_heap_changed();
1192 regulator_thread()->notify_heap_changed();
1193 }
1194
1195 if (result != nullptr) {
1196 ShenandoahGeneration* alloc_generation = generation_for(req.affiliation());
1197 size_t requested = req.size();
1198 size_t actual = req.actual_size();
1199 size_t actual_bytes = actual * HeapWordSize;
1200
1201 assert (req.is_lab_alloc() || (requested == actual),
1202 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
1203 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
1204
1205 if (req.is_mutator_alloc()) {
1206 notify_mutator_alloc_words(actual, false);
1207 alloc_generation->increase_allocated(actual_bytes);
1208
1209 // If we requested more than we were granted, give the rest back to pacer.
1210 // This only matters if we are in the same pacing epoch: do not try to unpace
1211 // over the budget for the other phase.
1212 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
1213 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
1214 }
1215 } else {
1216 increase_used(actual_bytes);
1217 }
1218 }
1219
1220 return result;
1221 }
1222
1223 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region, bool is_promotion) {
1224 bool try_smaller_lab_size = false;
1225 size_t smaller_lab_size;
1226 {
1227 // promotion_eligible pertains only to PLAB allocations, denoting that the PLAB is allowed to allocate for promotions.
1228 bool promotion_eligible = false;
1229 bool allow_allocation = true;
1230 bool plab_alloc = false;
1231 size_t requested_bytes = req.size() * HeapWordSize;
1232 HeapWord* result = nullptr;
1233 ShenandoahHeapLocker locker(lock());
1234 Thread* thread = Thread::current();
1235
1236 if (mode()->is_generational()) {
1237 if (req.affiliation() == YOUNG_GENERATION) {
1238 if (req.is_mutator_alloc()) {
1239 size_t young_available = young_generation()->adjusted_available();
1240 if (requested_bytes > young_available) {
1241 // We know this is not a GCLAB. This must be a TLAB or a shared allocation.
1242 if (req.is_lab_alloc() && (young_available >= req.min_size())) {
1243 try_smaller_lab_size = true;
1244 smaller_lab_size = young_available / HeapWordSize;
1245 } else {
1246 // Can't allocate because even min_size() is larger than remaining young_available
1247 log_info(gc, ergo)("Unable to shrink %s alloc request of minimum size: " SIZE_FORMAT
1248 ", young available: " SIZE_FORMAT,
1249 req.is_lab_alloc()? "TLAB": "shared",
1250 HeapWordSize * (req.is_lab_alloc()? req.min_size(): req.size()), young_available);
1251 return nullptr;
1252 }
1253 }
1254 }
1255 } else { // reg.affiliation() == OLD_GENERATION
1256 assert(req.type() != ShenandoahAllocRequest::_alloc_gclab, "GCLAB pertains only to young-gen memory");
1257 if (req.type() == ShenandoahAllocRequest::_alloc_plab) {
1258 plab_alloc = true;
1259 size_t promotion_avail = get_promoted_reserve();
1260 size_t promotion_expended = get_promoted_expended();
1261 if (promotion_expended + requested_bytes > promotion_avail) {
1262 promotion_avail = 0;
1263 if (get_old_evac_reserve() == 0) {
1264 // There are no old-gen evacuations in this pass. There's no value in creating a plab that cannot
1265 // be used for promotions.
1266 allow_allocation = false;
1267 }
1268 } else {
1269 promotion_avail = promotion_avail - (promotion_expended + requested_bytes);
1270 promotion_eligible = true;
1271 }
1272 } else if (is_promotion) {
1273 // This is a shared alloc for promotion
1274 size_t promotion_avail = get_promoted_reserve();
1275 size_t promotion_expended = get_promoted_expended();
1276 if (promotion_expended + requested_bytes > promotion_avail) {
1277 promotion_avail = 0;
1278 } else {
1279 promotion_avail = promotion_avail - (promotion_expended + requested_bytes);
1280 }
1281 if (promotion_avail == 0) {
1282 // We need to reserve the remaining memory for evacuation. Reject this allocation. The object will be
1283 // evacuated to young-gen memory and promoted during a future GC pass.
1284 return nullptr;
1285 }
1286 // Else, we'll allow the allocation to proceed. (Since we hold heap lock, the tested condition remains true.)
1287 } else {
1288 // This is a shared allocation for evacuation. Memory has already been reserved for this purpose.
1289 }
1290 }
1291 } // This ends the is_generational() block
1292
1293 if (!try_smaller_lab_size) {
1294 result = (allow_allocation)? _free_set->allocate(req, in_new_region): nullptr;
1295 if (result != nullptr) {
1296 if (req.affiliation() == ShenandoahRegionAffiliation::OLD_GENERATION) {
1297 ShenandoahThreadLocalData::reset_plab_promoted(thread);
1298 if (req.is_gc_alloc()) {
1299 if (req.type() == ShenandoahAllocRequest::_alloc_plab) {
1300 if (promotion_eligible) {
1301 size_t actual_size = req.actual_size() * HeapWordSize;
1302 // Assume the entirety of this PLAB will be used for promotion. This prevents promotion from overreach.
1303 // When we retire this plab, we'll unexpend what we don't really use.
1304 ShenandoahThreadLocalData::enable_plab_promotions(thread);
1305 expend_promoted(actual_size);
1306 assert(get_promoted_expended() <= get_promoted_reserve(), "Do not expend more promotion than budgeted");
1307 ShenandoahThreadLocalData::set_plab_preallocated_promoted(thread, actual_size);
1308 } else {
1309 // Disable promotions in this thread because entirety of this PLAB must be available to hold old-gen evacuations.
1310 ShenandoahThreadLocalData::disable_plab_promotions(thread);
1311 ShenandoahThreadLocalData::set_plab_preallocated_promoted(thread, 0);
1312 }
1313 } else if (is_promotion) {
1314 // Shared promotion. Assume size is requested_bytes.
1315 expend_promoted(requested_bytes);
1316 assert(get_promoted_expended() <= get_promoted_reserve(), "Do not expend more promotion than budgeted");
1317 }
1318 }
1319
1320 // Register the newly allocated object while we're holding the global lock since there's no synchronization
1321 // built in to the implementation of register_object(). There are potential races when multiple independent
1322 // threads are allocating objects, some of which might span the same card region. For example, consider
1323 // a card table's memory region within which three objects are being allocated by three different threads:
1324 //
1325 // objects being "concurrently" allocated:
1326 // [-----a------][-----b-----][--------------c------------------]
1327 // [---- card table memory range --------------]
1328 //
1329 // Before any objects are allocated, this card's memory range holds no objects. Note that allocation of object a
1330 // wants to set the has-object, first-start, and last-start attributes of the preceding card region.
1331 // allocation of object b wants to set the has-object, first-start, and last-start attributes of this card region.
1332 // allocation of object c also wants to set the has-object, first-start, and last-start attributes of this card region.
1333 //
1334 // The thread allocating b and the thread allocating c can "race" in various ways, resulting in confusion, such as
1335 // last-start representing object b while first-start represents object c. This is why we need to require all
1336 // register_object() invocations to be "mutually exclusive" with respect to each card's memory range.
1337 ShenandoahHeap::heap()->card_scan()->register_object(result);
1338 }
1339 } else {
1340 // The allocation failed. If this was a plab allocation, We've already retired it and no longer have a plab.
1341 if ((req.affiliation() == ShenandoahRegionAffiliation::OLD_GENERATION) && req.is_gc_alloc() &&
1342 (req.type() == ShenandoahAllocRequest::_alloc_plab)) {
1343 // We don't need to disable PLAB promotions because there is no PLAB. We leave promotions enabled because
1344 // this allows the surrounding infrastructure to retry alloc_plab_slow() with a smaller PLAB size.
1345 ShenandoahThreadLocalData::set_plab_preallocated_promoted(thread, 0);
1346 }
1347 }
1348 return result;
1349 }
1350 // else, try_smaller_lab_size is true so we fall through and recurse with a smaller lab size
1351 } // This closes the block that holds the heap lock. This releases the lock.
1352
1353 // We arrive here if the tlab allocation request can be resized to fit within young_available
1354 assert((req.affiliation() == YOUNG_GENERATION) && req.is_lab_alloc() && req.is_mutator_alloc() &&
1355 (smaller_lab_size < req.size()), "Only shrink allocation request size for TLAB allocations");
1356
1357 // By convention, ShenandoahAllocationRequest is primarily read-only. The only mutable instance data is represented by
1358 // actual_size(), which is overwritten with the size of the allocaion when the allocation request is satisfied. We use a
1359 // recursive call here rather than introducing new methods to mutate the existing ShenandoahAllocationRequest argument.
1360 // Mutation of the existing object might result in astonishing results if calling contexts assume the content of immutable
1361 // fields remain constant. The original TLAB allocation request was for memory that exceeded the current capacity. We'll
1362 // attempt to allocate a smaller TLAB. If this is successful, we'll update actual_size() of our incoming
1363 // ShenandoahAllocRequest. If the recursive request fails, we'll simply return nullptr.
1364
1365 // Note that we've relinquished the HeapLock and some other thread may perform additional allocation before our recursive
1366 // call reacquires the lock. If that happens, we will need another recursive call to further reduce the size of our request
1367 // for each time another thread allocates young memory during the brief intervals that the heap lock is available to
1368 // interfering threads. We expect this interference to be rare. The recursion bottoms out when young_available is
1369 // smaller than req.min_size(). The inner-nested call to allocate_memory_under_lock() uses the same min_size() value
1370 // as this call, but it uses a preferred size() that is smaller than our preferred size, and is no larger than what we most
1371 // recently saw as the memory currently available within the young generation.
1372
1373 // TODO: At the expense of code clarity, we could rewrite this recursive solution to use iteration. We need at most one
1374 // extra instance of the ShenandoahAllocRequest, which we can re-initialize multiple times inside a loop, with one iteration
1375 // of the loop required for each time the existing solution would recurse. An iterative solution would be more efficient
1376 // in CPU time and stack memory utilization. The expectation is that it is very rare that we would recurse more than once
1377 // so making this change is not currently seen as a high priority.
1378
1379 ShenandoahAllocRequest smaller_req = ShenandoahAllocRequest::for_tlab(req.min_size(), smaller_lab_size);
1380
1381 // Note that shrinking the preferred size gets us past the gatekeeper that checks whether there's available memory to
1382 // satisfy the allocation request. The reality is the actual TLAB size is likely to be even smaller, because it will
1383 // depend on how much memory is available within mutator regions that are not yet fully used.
1384 HeapWord* result = allocate_memory_under_lock(smaller_req, in_new_region, is_promotion);
1385 if (result != nullptr) {
1386 req.set_actual_size(smaller_req.actual_size());
1387 }
1388 return result;
1389 }
1390
1391 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
1392 bool* gc_overhead_limit_was_exceeded) {
1393 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
1394 return allocate_memory(req, false);
1395 }
1396
1397 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
1398 size_t size,
1399 Metaspace::MetadataType mdtype) {
1400 MetaWord* result;
1401
1402 // Inform metaspace OOM to GC heuristics if class unloading is possible.
1403 ShenandoahHeuristics* h = global_generation()->heuristics();
1404 if (h->can_unload_classes()) {
1405 h->record_metaspace_oom();
1406 }
1407
1408 // Expand and retry allocation
1409 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
1410 if (result != nullptr) {
1411 return result;
1412 }
1413
1414 // Start full GC
1415 collect(GCCause::_metadata_GC_clear_soft_refs);
1416
1417 // Retry allocation
1418 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
1419 if (result != nullptr) {
1420 return result;
1421 }
1422
1423 // Expand and retry allocation
1424 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
1463
1464 void work(uint worker_id) {
1465 if (_concurrent) {
1466 ShenandoahConcurrentWorkerSession worker_session(worker_id);
1467 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
1468 ShenandoahEvacOOMScope oom_evac_scope;
1469 do_work();
1470 } else {
1471 ShenandoahParallelWorkerSession worker_session(worker_id);
1472 ShenandoahEvacOOMScope oom_evac_scope;
1473 do_work();
1474 }
1475 }
1476
1477 private:
1478 void do_work() {
1479 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
1480 ShenandoahHeapRegion* r;
1481 while ((r =_cs->claim_next()) != nullptr) {
1482 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
1483
1484 _sh->marked_object_iterate(r, &cl);
1485
1486 if (ShenandoahPacing) {
1487 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
1488 }
1489 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
1490 break;
1491 }
1492 }
1493 }
1494 };
1495
1496 // Unlike ShenandoahEvacuationTask, this iterates over all regions rather than just the collection set.
1497 // This is needed in order to promote humongous start regions if age() >= tenure threshold.
1498 class ShenandoahGenerationalEvacuationTask : public WorkerTask {
1499 private:
1500 ShenandoahHeap* const _sh;
1501 ShenandoahRegionIterator *_regions;
1502 bool _concurrent;
1503 public:
1504 ShenandoahGenerationalEvacuationTask(ShenandoahHeap* sh,
1505 ShenandoahRegionIterator* iterator,
1506 bool concurrent) :
1507 WorkerTask("Shenandoah Evacuation"),
1508 _sh(sh),
1509 _regions(iterator),
1510 _concurrent(concurrent)
1511 {}
1512
1513 void work(uint worker_id) {
1514 if (_concurrent) {
1515 ShenandoahConcurrentWorkerSession worker_session(worker_id);
1516 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
1517 ShenandoahEvacOOMScope oom_evac_scope;
1518 do_work();
1519 } else {
1520 ShenandoahParallelWorkerSession worker_session(worker_id);
1521 ShenandoahEvacOOMScope oom_evac_scope;
1522 do_work();
1523 }
1524 }
1525
1526 private:
1527 void do_work() {
1528 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
1529 ShenandoahHeapRegion* r;
1530 while ((r = _regions->next()) != nullptr) {
1531 log_debug(gc)("GenerationalEvacuationTask do_work(), looking at %s region " SIZE_FORMAT ", (age: %d) [%s, %s]",
1532 r->is_old()? "old": r->is_young()? "young": "free", r->index(), r->age(),
1533 r->is_active()? "active": "inactive",
1534 r->is_humongous()? (r->is_humongous_start()? "humongous_start": "humongous_continuation"): "regular");
1535 if (r->is_cset()) {
1536 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
1537 _sh->marked_object_iterate(r, &cl);
1538 if (ShenandoahPacing) {
1539 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
1540 }
1541 } else if (r->is_young() && r->is_active() && r->is_humongous_start() && (r->age() > InitialTenuringThreshold)) {
1542 // We promote humongous_start regions along with their affiliated continuations during evacuation rather than
1543 // doing this work during a safepoint. We cannot put humongous regions into the collection set because that
1544 // triggers the load-reference barrier (LRB) to copy on reference fetch.
1545 if (r->promote_humongous() == 0) {
1546 // We chose not to promote because old-gen is out of memory. Report and handle the promotion failure because
1547 // this suggests need for expanding old-gen and/or performing collection of old-gen.
1548 ShenandoahHeap* heap = ShenandoahHeap::heap();
1549 oop obj = cast_to_oop(r->bottom());
1550 size_t size = obj->size();
1551 Thread* thread = Thread::current();
1552 heap->report_promotion_failure(thread, size);
1553 heap->handle_promotion_failure();
1554 }
1555 }
1556 // else, region is free, or OLD, or not in collection set, or humongous_continuation,
1557 // or is young humongous_start that is too young to be promoted
1558
1559 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
1560 break;
1561 }
1562 }
1563 }
1564 };
1565
1566 void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
1567 if (ShenandoahHeap::heap()->mode()->is_generational()) {
1568 ShenandoahRegionIterator regions;
1569 ShenandoahGenerationalEvacuationTask task(this, ®ions, concurrent);
1570 workers()->run_task(&task);
1571 } else {
1572 ShenandoahEvacuationTask task(this, _collection_set, concurrent);
1573 workers()->run_task(&task);
1574 }
1575 }
1576
1577 void ShenandoahHeap::trash_cset_regions() {
1578 ShenandoahHeapLocker locker(lock());
1579
1580 ShenandoahCollectionSet* set = collection_set();
1581 ShenandoahHeapRegion* r;
1582 set->clear_current_index();
1583 while ((r = set->next()) != nullptr) {
1584 r->make_trash();
1585 }
1586 collection_set()->clear();
1587 }
1588
1589 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1590 st->print_cr("Heap Regions:");
1591 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
1592 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
1593 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark");
1594 st->print_cr("SN=alloc sequence number");
1595
1596 for (size_t i = 0; i < num_regions(); i++) {
1597 get_region(i)->print_on(st);
1598 }
1599 }
1600
1601 size_t ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1602 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1603
1604 oop humongous_obj = cast_to_oop(start->bottom());
1605 size_t size = humongous_obj->size();
1606 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1607 size_t index = start->index() + required_regions - 1;
1608
1609 assert(!start->has_live(), "liveness must be zero");
1610
1611 for(size_t i = 0; i < required_regions; i++) {
1612 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1613 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1614 ShenandoahHeapRegion* region = get_region(index --);
1615
1616 assert(region->is_humongous(), "expect correct humongous start or continuation");
1617 assert(!region->is_cset(), "Humongous region should not be in collection set");
1618
1619 region->make_trash_immediate();
1620 }
1621 return required_regions;
1622 }
1623
1624 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1625 public:
1626 ShenandoahCheckCleanGCLABClosure() {}
1627 void do_thread(Thread* thread) {
1628 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1629 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1630 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
1631
1632 PLAB* plab = ShenandoahThreadLocalData::plab(thread);
1633 assert(plab != nullptr, "PLAB should be initialized for %s", thread->name());
1634 assert(plab->words_remaining() == 0, "PLAB should not need retirement");
1635 }
1636 };
1637
1638 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1639 private:
1640 bool const _resize;
1641 public:
1642 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1643 void do_thread(Thread* thread) {
1644 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1645 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1646 gclab->retire();
1647 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1648 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1649 }
1650
1651 PLAB* plab = ShenandoahThreadLocalData::plab(thread);
1652 assert(plab != nullptr, "PLAB should be initialized for %s", thread->name());
1653
1654 // There are two reasons to retire all plabs between old-gen evacuation passes.
1655 // 1. We need to make the plab memory parseable by remembered-set scanning.
1656 // 2. We need to establish a trustworthy UpdateWaterMark value within each old-gen heap region
1657 ShenandoahHeap::heap()->retire_plab(plab, thread);
1658 if (_resize && ShenandoahThreadLocalData::plab_size(thread) > 0) {
1659 ShenandoahThreadLocalData::set_plab_size(thread, 0);
1660 }
1661 }
1662 };
1663
1664 void ShenandoahHeap::labs_make_parsable() {
1665 assert(UseTLAB, "Only call with UseTLAB");
1666
1667 ShenandoahRetireGCLABClosure cl(false);
1668
1669 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1670 ThreadLocalAllocBuffer& tlab = t->tlab();
1671 tlab.make_parsable();
1672 cl.do_thread(t);
1673 }
1674
1675 workers()->threads_do(&cl);
1676 }
1677
1678 void ShenandoahHeap::tlabs_retire(bool resize) {
1679 assert(UseTLAB, "Only call with UseTLAB");
1680 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1698 }
1699 workers()->threads_do(&cl);
1700 #endif
1701 }
1702
1703 void ShenandoahHeap::gclabs_retire(bool resize) {
1704 assert(UseTLAB, "Only call with UseTLAB");
1705 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1706
1707 ShenandoahRetireGCLABClosure cl(resize);
1708 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1709 cl.do_thread(t);
1710 }
1711 workers()->threads_do(&cl);
1712
1713 if (safepoint_workers() != nullptr) {
1714 safepoint_workers()->threads_do(&cl);
1715 }
1716 }
1717
1718 class ShenandoahTagGCLABClosure : public ThreadClosure {
1719 public:
1720 void do_thread(Thread* thread) {
1721 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1722 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1723 if (gclab->words_remaining() > 0) {
1724 ShenandoahHeapRegion* r = ShenandoahHeap::heap()->heap_region_containing(gclab->allocate(0));
1725 r->set_young_lab_flag();
1726 }
1727 }
1728 };
1729
1730 void ShenandoahHeap::set_young_lab_region_flags() {
1731 if (!UseTLAB) {
1732 return;
1733 }
1734 for (size_t i = 0; i < _num_regions; i++) {
1735 _regions[i]->clear_young_lab_flags();
1736 }
1737 ShenandoahTagGCLABClosure cl;
1738 workers()->threads_do(&cl);
1739 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1740 cl.do_thread(t);
1741 ThreadLocalAllocBuffer& tlab = t->tlab();
1742 if (tlab.end() != nullptr) {
1743 ShenandoahHeapRegion* r = heap_region_containing(tlab.start());
1744 r->set_young_lab_flag();
1745 }
1746 }
1747 }
1748
1749 // Returns size in bytes
1750 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1751 if (ShenandoahElasticTLAB) {
1752 if (mode()->is_generational()) {
1753 return MIN2(ShenandoahHeapRegion::max_tlab_size_bytes(), young_generation()->adjusted_available());
1754 } else {
1755 // With Elastic TLABs, return the max allowed size, and let the allocation path
1756 // figure out the safe size for current allocation.
1757 return ShenandoahHeapRegion::max_tlab_size_bytes();
1758 }
1759 } else {
1760 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1761 }
1762 }
1763
1764 size_t ShenandoahHeap::max_tlab_size() const {
1765 // Returns size in words
1766 return ShenandoahHeapRegion::max_tlab_size_words();
1767 }
1768
1769 void ShenandoahHeap::collect(GCCause::Cause cause) {
1770 control_thread()->request_gc(cause);
1771 }
1772
1773 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1774 //assert(false, "Shouldn't need to do full collections");
1775 }
1776
1777 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1778 ShenandoahHeapRegion* r = heap_region_containing(addr);
1781 }
1782 return nullptr;
1783 }
1784
1785 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1786 ShenandoahHeapRegion* r = heap_region_containing(addr);
1787 return r->block_is_obj(addr);
1788 }
1789
1790 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1791 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1792 }
1793
1794 void ShenandoahHeap::prepare_for_verify() {
1795 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) {
1796 labs_make_parsable();
1797 }
1798 }
1799
1800 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1801 if (_shenandoah_policy->is_at_shutdown()) {
1802 return;
1803 }
1804
1805 tcl->do_thread(_control_thread);
1806 tcl->do_thread(_regulator_thread);
1807 workers()->threads_do(tcl);
1808 if (_safepoint_workers != nullptr) {
1809 _safepoint_workers->threads_do(tcl);
1810 }
1811 if (ShenandoahStringDedup::is_enabled()) {
1812 ShenandoahStringDedup::threads_do(tcl);
1813 }
1814 }
1815
1816 void ShenandoahHeap::print_tracing_info() const {
1817 LogTarget(Info, gc, stats) lt;
1818 if (lt.is_enabled()) {
1819 ResourceMark rm;
1820 LogStream ls(lt);
1821
1822 phase_timings()->print_global_on(&ls);
1823
1824 ls.cr();
1825 ls.cr();
1826
1827 shenandoah_policy()->print_gc_stats(&ls);
1828
1829 ls.cr();
1830
1831 evac_tracker()->print_global_on(&ls);
1832
1833 ls.cr();
1834 ls.cr();
1835 }
1836 }
1837
1838 void ShenandoahHeap::on_cycle_start(GCCause::Cause cause, ShenandoahGeneration* generation) {
1839 set_gc_cause(cause);
1840 set_gc_generation(generation);
1841
1842 shenandoah_policy()->record_cycle_start();
1843 generation->heuristics()->record_cycle_start();
1844
1845 // When a cycle starts, attribute any thread activity when the collector
1846 // is idle to the global generation.
1847 _mmu_tracker.record(global_generation());
1848 }
1849
1850 void ShenandoahHeap::on_cycle_end(ShenandoahGeneration* generation) {
1851 generation->heuristics()->record_cycle_end();
1852
1853 if (mode()->is_generational() &&
1854 ((generation->generation_mode() == GLOBAL) || upgraded_to_full())) {
1855 // If we just completed a GLOBAL GC, claim credit for completion of young-gen and old-gen GC as well
1856 young_generation()->heuristics()->record_cycle_end();
1857 old_generation()->heuristics()->record_cycle_end();
1858 }
1859 set_gc_cause(GCCause::_no_gc);
1860
1861 // When a cycle ends, the thread activity is attributed to the respective generation
1862 _mmu_tracker.record(generation);
1863 }
1864
1865 void ShenandoahHeap::verify(VerifyOption vo) {
1866 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1867 if (ShenandoahVerify) {
1868 verifier()->verify_generic(vo);
1869 } else {
1870 // TODO: Consider allocating verification bitmaps on demand,
1871 // and turn this on unconditionally.
1872 }
1873 }
1874 }
1875 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1876 return _free_set->capacity();
1877 }
1878
1879 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1880 private:
1881 MarkBitMap* _bitmap;
1882 ShenandoahScanObjectStack* _oop_stack;
1883 ShenandoahHeap* const _heap;
1884 ShenandoahMarkingContext* const _marking_context;
2166 if (start >= max) break;
2167
2168 for (size_t i = cur; i < end; i++) {
2169 ShenandoahHeapRegion* current = _heap->get_region(i);
2170 _blk->heap_region_do(current);
2171 }
2172 }
2173 }
2174 };
2175
2176 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
2177 assert(blk->is_thread_safe(), "Only thread-safe closures here");
2178 if (num_regions() > ShenandoahParallelRegionStride) {
2179 ShenandoahParallelHeapRegionTask task(blk);
2180 workers()->run_task(&task);
2181 } else {
2182 heap_region_iterate(blk);
2183 }
2184 }
2185
2186 class ShenandoahRendezvousClosure : public HandshakeClosure {
2187 public:
2188 inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {}
2189 inline void do_thread(Thread* thread) {}
2190 };
2191
2192 void ShenandoahHeap::rendezvous_threads() {
2193 ShenandoahRendezvousClosure cl;
2194 Handshake::execute(&cl);
2195 }
2196
2197 void ShenandoahHeap::recycle_trash() {
2198 free_set()->recycle_trash();
2199 }
2200
2201 void ShenandoahHeap::do_class_unloading() {
2202 _unloader.unload();
2203 }
2204
2205 void ShenandoahHeap::stw_weak_refs(bool full_gc) {
2206 // Weak refs processing
2207 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs
2208 : ShenandoahPhaseTimings::degen_gc_weakrefs;
2209 ShenandoahTimingsTracker t(phase);
2210 ShenandoahGCWorkerPhase worker_phase(phase);
2211 active_generation()->ref_processor()->process_references(phase, workers(), false /* concurrent */);
2212 }
2213
2214 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
2215 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2216
2217 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to
2218 // make them parsable for update code to work correctly. Plus, we can compute new sizes
2219 // for future GCLABs here.
2220 if (UseTLAB) {
2221 ShenandoahGCPhase phase(concurrent ?
2222 ShenandoahPhaseTimings::init_update_refs_manage_gclabs :
2223 ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs);
2224 gclabs_retire(ResizeTLAB);
2225 }
2226
2227 _update_refs_iterator.reset();
2228 }
2229
2230 void ShenandoahHeap::set_gc_state_all_threads(char state) {
2231 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2232 ShenandoahThreadLocalData::set_gc_state(t, state);
2233 }
2234 }
2235
2236 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
2237 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
2238 _gc_state.set_cond(mask, value);
2239 set_gc_state_all_threads(_gc_state.raw_value());
2240 }
2241
2242 void ShenandoahHeap::set_concurrent_young_mark_in_progress(bool in_progress) {
2243 if (has_forwarded_objects()) {
2244 set_gc_state_mask(YOUNG_MARKING | UPDATEREFS, in_progress);
2245 } else {
2246 set_gc_state_mask(YOUNG_MARKING, in_progress);
2247 }
2248
2249 manage_satb_barrier(in_progress);
2250 }
2251
2252 void ShenandoahHeap::set_concurrent_old_mark_in_progress(bool in_progress) {
2253 if (has_forwarded_objects()) {
2254 set_gc_state_mask(OLD_MARKING | UPDATEREFS, in_progress);
2255 } else {
2256 set_gc_state_mask(OLD_MARKING, in_progress);
2257 }
2258
2259 manage_satb_barrier(in_progress);
2260 }
2261
2262 void ShenandoahHeap::set_prepare_for_old_mark_in_progress(bool in_progress) {
2263 // Unlike other set-gc-state functions, this may happen outside safepoint.
2264 // Is only set and queried by control thread, so no coherence issues.
2265 _prepare_for_old_mark = in_progress;
2266 }
2267
2268 void ShenandoahHeap::set_aging_cycle(bool in_progress) {
2269 _is_aging_cycle.set_cond(in_progress);
2270 }
2271
2272 void ShenandoahHeap::manage_satb_barrier(bool active) {
2273 if (is_concurrent_mark_in_progress()) {
2274 // Ignore request to deactivate barrier while concurrent mark is in progress.
2275 // Do not attempt to re-activate the barrier if it is already active.
2276 if (active && !ShenandoahBarrierSet::satb_mark_queue_set().is_active()) {
2277 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(active, !active);
2278 }
2279 } else {
2280 // No concurrent marking is in progress so honor request to deactivate,
2281 // but only if the barrier is already active.
2282 if (!active && ShenandoahBarrierSet::satb_mark_queue_set().is_active()) {
2283 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(active, !active);
2284 }
2285 }
2286 }
2287
2288 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
2289 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
2290 set_gc_state_mask(EVACUATION, in_progress);
2291 }
2292
2293 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
2294 if (in_progress) {
2295 _concurrent_strong_root_in_progress.set();
2296 } else {
2297 _concurrent_strong_root_in_progress.unset();
2298 }
2299 }
2300
2301 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) {
2302 set_gc_state_mask(WEAK_ROOTS, cond);
2303 }
2304
2305 GCTracer* ShenandoahHeap::tracer() {
2310 return _free_set->used();
2311 }
2312
2313 bool ShenandoahHeap::try_cancel_gc() {
2314 while (true) {
2315 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
2316 if (prev == CANCELLABLE) return true;
2317 else if (prev == CANCELLED) return false;
2318 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
2319 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
2320 Thread* thread = Thread::current();
2321 if (thread->is_Java_thread()) {
2322 // We need to provide a safepoint here, otherwise we might
2323 // spin forever if a SP is pending.
2324 ThreadBlockInVM sp(JavaThread::cast(thread));
2325 SpinPause();
2326 }
2327 }
2328 }
2329
2330 void ShenandoahHeap::cancel_concurrent_mark() {
2331 _young_generation->cancel_marking();
2332 _old_generation->cancel_marking();
2333 _global_generation->cancel_marking();
2334
2335 ShenandoahBarrierSet::satb_mark_queue_set().abandon_partial_marking();
2336 }
2337
2338 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
2339 if (try_cancel_gc()) {
2340 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
2341 log_info(gc)("%s", msg.buffer());
2342 Events::log(Thread::current(), "%s", msg.buffer());
2343 _cancel_requested_time = os::elapsedTime();
2344 if (cause == GCCause::_shenandoah_upgrade_to_full_gc) {
2345 _upgraded_to_full = true;
2346 }
2347 }
2348 }
2349
2350 uint ShenandoahHeap::max_workers() {
2351 return _max_workers;
2352 }
2353
2354 void ShenandoahHeap::stop() {
2355 // The shutdown sequence should be able to terminate when GC is running.
2356
2357 // Step 1. Notify policy to disable event recording and prevent visiting gc threads during shutdown
2358 _shenandoah_policy->record_shutdown();
2359
2360 // Step 2. Stop requesting collections.
2361 regulator_thread()->stop();
2362
2363 // Step 3. Notify control thread that we are in shutdown.
2364 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
2365 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
2366 control_thread()->prepare_for_graceful_shutdown();
2367
2368 // Step 4. Notify GC workers that we are cancelling GC.
2369 cancel_gc(GCCause::_shenandoah_stop_vm);
2370
2371 // Step 5. Wait until GC worker exits normally.
2372 control_thread()->stop();
2373 }
2374
2375 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
2376 if (!unload_classes()) return;
2377 // Unload classes and purge SystemDictionary.
2378 {
2379 ShenandoahPhaseTimings::Phase phase = full_gc ?
2380 ShenandoahPhaseTimings::full_gc_purge_class_unload :
2381 ShenandoahPhaseTimings::degen_gc_purge_class_unload;
2382 ShenandoahIsAliveSelector is_alive;
2383 CodeCache::UnloadingScope scope(is_alive.is_alive_closure());
2384 ShenandoahGCPhase gc_phase(phase);
2385 ShenandoahGCWorkerPhase worker_phase(phase);
2386 bool purged_class = SystemDictionary::do_unloading(gc_timer());
2387
2388 uint num_workers = _workers->active_workers();
2389 ShenandoahClassUnloadingTask unlink_task(phase, num_workers, purged_class);
2390 _workers->run_task(&unlink_task);
2391 }
2445 }
2446
2447 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2448 set_gc_state_mask(HAS_FORWARDED, cond);
2449 }
2450
2451 void ShenandoahHeap::set_unload_classes(bool uc) {
2452 _unload_classes.set_cond(uc);
2453 }
2454
2455 bool ShenandoahHeap::unload_classes() const {
2456 return _unload_classes.is_set();
2457 }
2458
2459 address ShenandoahHeap::in_cset_fast_test_addr() {
2460 ShenandoahHeap* heap = ShenandoahHeap::heap();
2461 assert(heap->collection_set() != nullptr, "Sanity");
2462 return (address) heap->collection_set()->biased_map_address();
2463 }
2464
2465 address ShenandoahHeap::gc_state_addr() {
2466 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
2467 }
2468
2469 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2470 if (mode()->is_generational()) {
2471 young_generation()->reset_bytes_allocated_since_gc_start();
2472 old_generation()->reset_bytes_allocated_since_gc_start();
2473 }
2474
2475 global_generation()->reset_bytes_allocated_since_gc_start();
2476 }
2477
2478 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2479 _degenerated_gc_in_progress.set_cond(in_progress);
2480 }
2481
2482 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2483 _full_gc_in_progress.set_cond(in_progress);
2484 }
2485
2486 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2487 assert (is_full_gc_in_progress(), "should be");
2488 _full_gc_move_in_progress.set_cond(in_progress);
2489 }
2490
2491 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2492 set_gc_state_mask(UPDATEREFS, in_progress);
2493 }
2494
2495 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2519 if (r->is_active()) {
2520 if (r->is_pinned()) {
2521 if (r->pin_count() == 0) {
2522 r->make_unpinned();
2523 }
2524 } else {
2525 if (r->pin_count() > 0) {
2526 r->make_pinned();
2527 }
2528 }
2529 }
2530 }
2531
2532 assert_pinned_region_status();
2533 }
2534
2535 #ifdef ASSERT
2536 void ShenandoahHeap::assert_pinned_region_status() {
2537 for (size_t i = 0; i < num_regions(); i++) {
2538 ShenandoahHeapRegion* r = get_region(i);
2539 if (active_generation()->contains(r)) {
2540 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2541 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2542 }
2543 }
2544 }
2545 #endif
2546
2547 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
2548 return _gc_timer;
2549 }
2550
2551 void ShenandoahHeap::prepare_concurrent_roots() {
2552 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2553 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
2554 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
2555 set_concurrent_weak_root_in_progress(true);
2556 if (unload_classes()) {
2557 _unloader.prepare();
2558 }
2559 }
2560
2561 void ShenandoahHeap::finish_concurrent_roots() {
2562 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2582 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2583 } else {
2584 // Use ConcGCThreads outside safepoints
2585 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2586 }
2587 }
2588 }
2589 #endif
2590
2591 ShenandoahVerifier* ShenandoahHeap::verifier() {
2592 guarantee(ShenandoahVerify, "Should be enabled");
2593 assert (_verifier != nullptr, "sanity");
2594 return _verifier;
2595 }
2596
2597 template<bool CONCURRENT>
2598 class ShenandoahUpdateHeapRefsTask : public WorkerTask {
2599 private:
2600 ShenandoahHeap* _heap;
2601 ShenandoahRegionIterator* _regions;
2602 ShenandoahRegionChunkIterator* _work_chunks;
2603
2604 public:
2605 explicit ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions,
2606 ShenandoahRegionChunkIterator* work_chunks) :
2607 WorkerTask("Shenandoah Update References"),
2608 _heap(ShenandoahHeap::heap()),
2609 _regions(regions),
2610 _work_chunks(work_chunks)
2611 {
2612 }
2613
2614 void work(uint worker_id) {
2615 if (CONCURRENT) {
2616 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2617 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2618 do_work<ShenandoahConcUpdateRefsClosure>(worker_id);
2619 } else {
2620 ShenandoahParallelWorkerSession worker_session(worker_id);
2621 do_work<ShenandoahSTWUpdateRefsClosure>(worker_id);
2622 }
2623 }
2624
2625 private:
2626 template<class T>
2627 void do_work(uint worker_id) {
2628 T cl;
2629 ShenandoahHeapRegion* r = _regions->next();
2630 // We update references for global, old, and young collections.
2631 assert(_heap->active_generation()->is_mark_complete(), "Expected complete marking");
2632 ShenandoahMarkingContext* const ctx = _heap->marking_context();
2633 bool is_mixed = _heap->collection_set()->has_old_regions();
2634 while (r != nullptr) {
2635 HeapWord* update_watermark = r->get_update_watermark();
2636 assert (update_watermark >= r->bottom(), "sanity");
2637
2638 log_debug(gc)("ShenandoahUpdateHeapRefsTask::do_work(%u) looking at region " SIZE_FORMAT, worker_id, r->index());
2639 bool region_progress = false;
2640 if (r->is_active() && !r->is_cset()) {
2641 if (!_heap->mode()->is_generational() || (r->affiliation() == ShenandoahRegionAffiliation::YOUNG_GENERATION)) {
2642 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2643 region_progress = true;
2644 } else if (r->affiliation() == ShenandoahRegionAffiliation::OLD_GENERATION) {
2645 if (_heap->active_generation()->generation_mode() == GLOBAL) {
2646 // Note that GLOBAL collection is not as effectively balanced as young and mixed cycles. This is because
2647 // concurrent GC threads are parceled out entire heap regions of work at a time and there
2648 // is no "catchup phase" consisting of remembered set scanning, during which parcels of work are smaller
2649 // and more easily distributed more fairly across threads.
2650
2651 // TODO: Consider an improvement to load balance GLOBAL GC.
2652 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2653 region_progress = true;
2654 }
2655 // Otherwise, this is an old region in a young or mixed cycle. Process it during a second phase, below.
2656 // Don't bother to report pacing progress in this case.
2657 } else {
2658 // Because updating of references runs concurrently, it is possible that a FREE inactive region transitions
2659 // to a non-free active region while this loop is executing. Whenever this happens, the changing of a region's
2660 // active status may propagate at a different speed than the changing of the region's affiliation.
2661
2662 // When we reach this control point, it is because a race has allowed a region's is_active() status to be seen
2663 // by this thread before the region's affiliation() is seen by this thread.
2664
2665 // It's ok for this race to occur because the newly transformed region does not have any references to be
2666 // updated.
2667
2668 assert(r->get_update_watermark() == r->bottom(),
2669 "%s Region " SIZE_FORMAT " is_active but not recognized as YOUNG or OLD so must be newly transitioned from FREE",
2670 affiliation_name(r->affiliation()), r->index());
2671 }
2672 }
2673 if (region_progress && ShenandoahPacing) {
2674 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2675 }
2676 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
2677 return;
2678 }
2679 r = _regions->next();
2680 }
2681
2682 if (_heap->mode()->is_generational() && (_heap->active_generation()->generation_mode() != GLOBAL)) {
2683 // Since this is generational and not GLOBAL, we have to process the remembered set. There's no remembered
2684 // set processing if not in generational mode or if GLOBAL mode.
2685
2686 // After this thread has exhausted its traditional update-refs work, it continues with updating refs within remembered set.
2687 // The remembered set workload is better balanced between threads, so threads that are "behind" can catch up with other
2688 // threads during this phase, allowing all threads to work more effectively in parallel.
2689 struct ShenandoahRegionChunk assignment;
2690 RememberedScanner* scanner = _heap->card_scan();
2691
2692 while (!_heap->check_cancelled_gc_and_yield(CONCURRENT) && _work_chunks->next(&assignment)) {
2693 // Keep grabbing next work chunk to process until finished, or asked to yield
2694 ShenandoahHeapRegion* r = assignment._r;
2695 if (r->is_active() && !r->is_cset() && (r->affiliation() == ShenandoahRegionAffiliation::OLD_GENERATION)) {
2696 HeapWord* start_of_range = r->bottom() + assignment._chunk_offset;
2697 HeapWord* end_of_range = r->get_update_watermark();
2698 if (end_of_range > start_of_range + assignment._chunk_size) {
2699 end_of_range = start_of_range + assignment._chunk_size;
2700 }
2701
2702 // Old region in a young cycle or mixed cycle.
2703 if (is_mixed) {
2704 // TODO: For mixed evac, consider building an old-gen remembered set that allows restricted updating
2705 // within old-gen HeapRegions. This remembered set can be constructed by old-gen concurrent marking
2706 // and augmented by card marking. For example, old-gen concurrent marking can remember for each old-gen
2707 // card which other old-gen regions it refers to: none, one-other specifically, multiple-other non-specific.
2708 // Update-references when _mixed_evac processess each old-gen memory range that has a traditional DIRTY
2709 // card or if the "old-gen remembered set" indicates that this card holds pointers specifically to an
2710 // old-gen region in the most recent collection set, or if this card holds pointers to other non-specific
2711 // old-gen heap regions.
2712
2713 if (r->is_humongous()) {
2714 if (start_of_range < end_of_range) {
2715 // Need to examine both dirty and clean cards during mixed evac.
2716 r->oop_iterate_humongous_slice(&cl, false, start_of_range, assignment._chunk_size, true);
2717 }
2718 } else {
2719 // Since this is mixed evacuation, old regions that are candidates for collection have not been coalesced
2720 // and filled. Use mark bits to find objects that need to be updated.
2721 //
2722 // Future TODO: establish a second remembered set to identify which old-gen regions point to other old-gen
2723 // regions which are in the collection set for a particular mixed evacuation.
2724 if (start_of_range < end_of_range) {
2725 HeapWord* p = nullptr;
2726 size_t card_index = scanner->card_index_for_addr(start_of_range);
2727 // In case last object in my range spans boundary of my chunk, I may need to scan all the way to top()
2728 ShenandoahObjectToOopBoundedClosure<T> objs(&cl, start_of_range, r->top());
2729
2730 // Any object that begins in a previous range is part of a different scanning assignment. Any object that
2731 // starts after end_of_range is also not my responsibility. (Either allocated during evacuation, so does
2732 // not hold pointers to from-space, or is beyond the range of my assigned work chunk.)
2733
2734 // Find the first object that begins in my range, if there is one.
2735 p = start_of_range;
2736 oop obj = cast_to_oop(p);
2737 HeapWord* tams = ctx->top_at_mark_start(r);
2738 if (p >= tams) {
2739 // We cannot use ctx->is_marked(obj) to test whether an object begins at this address. Instead,
2740 // we need to use the remembered set crossing map to advance p to the first object that starts
2741 // within the enclosing card.
2742
2743 while (true) {
2744 HeapWord* first_object = scanner->first_object_in_card(card_index);
2745 if (first_object != nullptr) {
2746 p = first_object;
2747 break;
2748 } else if (scanner->addr_for_card_index(card_index + 1) < end_of_range) {
2749 card_index++;
2750 } else {
2751 // Force the loop that follows to immediately terminate.
2752 p = end_of_range;
2753 break;
2754 }
2755 }
2756 obj = cast_to_oop(p);
2757 // Note: p may be >= end_of_range
2758 } else if (!ctx->is_marked(obj)) {
2759 p = ctx->get_next_marked_addr(p, tams);
2760 obj = cast_to_oop(p);
2761 // If there are no more marked objects before tams, this returns tams.
2762 // Note that tams is either >= end_of_range, or tams is the start of an object that is marked.
2763 }
2764 while (p < end_of_range) {
2765 // p is known to point to the beginning of marked object obj
2766 objs.do_object(obj);
2767 HeapWord* prev_p = p;
2768 p += obj->size();
2769 if (p < tams) {
2770 p = ctx->get_next_marked_addr(p, tams);
2771 // If there are no more marked objects before tams, this returns tams. Note that tams is
2772 // either >= end_of_range, or tams is the start of an object that is marked.
2773 }
2774 assert(p != prev_p, "Lack of forward progress");
2775 obj = cast_to_oop(p);
2776 }
2777 }
2778 }
2779 } else {
2780 // This is a young evac..
2781 if (start_of_range < end_of_range) {
2782 size_t cluster_size =
2783 CardTable::card_size_in_words() * ShenandoahCardCluster<ShenandoahDirectCardMarkRememberedSet>::CardsPerCluster;
2784 size_t clusters = assignment._chunk_size / cluster_size;
2785 assert(clusters * cluster_size == assignment._chunk_size, "Chunk assignment must align on cluster boundaries");
2786 scanner->process_region_slice(r, assignment._chunk_offset, clusters, end_of_range, &cl, true, worker_id);
2787 }
2788 }
2789 if (ShenandoahPacing && (start_of_range < end_of_range)) {
2790 _heap->pacer()->report_updaterefs(pointer_delta(end_of_range, start_of_range));
2791 }
2792 }
2793 }
2794 }
2795 }
2796 };
2797
2798 void ShenandoahHeap::update_heap_references(bool concurrent) {
2799 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2800 uint nworkers = workers()->active_workers();
2801 ShenandoahRegionChunkIterator work_list(nworkers);
2802
2803 if (concurrent) {
2804 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator, &work_list);
2805 workers()->run_task(&task);
2806 } else {
2807 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator, &work_list);
2808 workers()->run_task(&task);
2809 }
2810 if (ShenandoahEnableCardStats && card_scan()!=nullptr) { // generational check proxy
2811 card_scan()->log_card_stats(nworkers, CARD_STAT_UPDATE_REFS);
2812 }
2813 }
2814
2815 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2816 private:
2817 ShenandoahMarkingContext* _ctx;
2818 ShenandoahHeapLock* const _lock;
2819 bool _is_generational;
2820
2821 public:
2822 ShenandoahFinalUpdateRefsUpdateRegionStateClosure(
2823 ShenandoahMarkingContext* ctx) : _ctx(ctx), _lock(ShenandoahHeap::heap()->lock()),
2824 _is_generational(ShenandoahHeap::heap()->mode()->is_generational()) { }
2825
2826 void heap_region_do(ShenandoahHeapRegion* r) {
2827
2828 // Maintenance of region age must follow evacuation in order to account for evacuation allocations within survivor
2829 // regions. We consult region age during the subsequent evacuation to determine whether certain objects need to
2830 // be promoted.
2831 if (_is_generational && r->is_young()) {
2832 HeapWord *tams = _ctx->top_at_mark_start(r);
2833 HeapWord *top = r->top();
2834
2835 // Allocations move the watermark when top moves. However compacting
2836 // objects will sometimes lower top beneath the watermark, after which,
2837 // attempts to read the watermark will assert out (watermark should not be
2838 // higher than top).
2839 if (top > tams) {
2840 // There have been allocations in this region since the start of the cycle.
2841 // Any objects new to this region must not assimilate elevated age.
2842 r->reset_age();
2843 } else if (ShenandoahHeap::heap()->is_aging_cycle()) {
2844 r->increment_age();
2845 }
2846 }
2847
2848 // Drop unnecessary "pinned" state from regions that does not have CP marks
2849 // anymore, as this would allow trashing them.
2850 if (r->is_active()) {
2851 if (r->is_pinned()) {
2852 if (r->pin_count() == 0) {
2853 ShenandoahHeapLocker locker(_lock);
2854 r->make_unpinned();
2855 }
2856 } else {
2857 if (r->pin_count() > 0) {
2858 ShenandoahHeapLocker locker(_lock);
2859 r->make_pinned();
2860 }
2861 }
2862 }
2863 }
2864
2865 bool is_thread_safe() { return true; }
2866 };
2867
2868 void ShenandoahHeap::update_heap_region_states(bool concurrent) {
2869 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2870 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2871
2872 {
2873 ShenandoahGCPhase phase(concurrent ?
2874 ShenandoahPhaseTimings::final_update_refs_update_region_states :
2875 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states);
2876 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl (active_generation()->complete_marking_context());
2877 parallel_heap_region_iterate(&cl);
2878
2879 assert_pinned_region_status();
2880 }
2881
2882 {
2883 ShenandoahGCPhase phase(concurrent ?
2884 ShenandoahPhaseTimings::final_update_refs_trash_cset :
2885 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset);
2886 trash_cset_regions();
2887 }
2888 }
2889
2890 void ShenandoahHeap::rebuild_free_set(bool concurrent) {
2891 {
2892 ShenandoahGCPhase phase(concurrent ?
2893 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
2894 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
2895 ShenandoahHeapLocker locker(lock());
2896 _free_set->rebuild();
2990 EventMark em("%s", msg);
2991
2992 op_uncommit(shrink_before, shrink_until);
2993 }
2994
2995 void ShenandoahHeap::try_inject_alloc_failure() {
2996 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2997 _inject_alloc_failure.set();
2998 os::naked_short_sleep(1);
2999 if (cancelled_gc()) {
3000 log_info(gc)("Allocation failure was successfully injected");
3001 }
3002 }
3003 }
3004
3005 bool ShenandoahHeap::should_inject_alloc_failure() {
3006 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
3007 }
3008
3009 void ShenandoahHeap::initialize_serviceability() {
3010 if (mode()->is_generational()) {
3011 _young_gen_memory_pool = new ShenandoahYoungGenMemoryPool(this);
3012 _old_gen_memory_pool = new ShenandoahOldGenMemoryPool(this);
3013 _cycle_memory_manager.add_pool(_young_gen_memory_pool);
3014 _cycle_memory_manager.add_pool(_old_gen_memory_pool);
3015 _stw_memory_manager.add_pool(_young_gen_memory_pool);
3016 _stw_memory_manager.add_pool(_old_gen_memory_pool);
3017 } else {
3018 _memory_pool = new ShenandoahMemoryPool(this);
3019 _cycle_memory_manager.add_pool(_memory_pool);
3020 _stw_memory_manager.add_pool(_memory_pool);
3021 }
3022 }
3023
3024 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
3025 GrowableArray<GCMemoryManager*> memory_managers(2);
3026 memory_managers.append(&_cycle_memory_manager);
3027 memory_managers.append(&_stw_memory_manager);
3028 return memory_managers;
3029 }
3030
3031 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
3032 GrowableArray<MemoryPool*> memory_pools(1);
3033 if (mode()->is_generational()) {
3034 memory_pools.append(_young_gen_memory_pool);
3035 memory_pools.append(_old_gen_memory_pool);
3036 } else {
3037 memory_pools.append(_memory_pool);
3038 }
3039 return memory_pools;
3040 }
3041
3042 MemoryUsage ShenandoahHeap::memory_usage() {
3043 return MemoryUsage(_initial_size, used(), committed(), max_capacity());
3044 }
3045
3046 ShenandoahRegionIterator::ShenandoahRegionIterator() :
3047 _heap(ShenandoahHeap::heap()),
3048 _index(0) {}
3049
3050 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
3051 _heap(heap),
3052 _index(0) {}
3053
3054 void ShenandoahRegionIterator::reset() {
3055 _index = 0;
3056 }
3057
3058 bool ShenandoahRegionIterator::has_next() const {
3059 return _index < _heap->num_regions();
3060 }
3061
3062 char ShenandoahHeap::gc_state() const {
3063 return _gc_state.raw_value();
3064 }
3065
3066 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
3067 #ifdef ASSERT
3068 assert(_liveness_cache != nullptr, "sanity");
3069 assert(worker_id < _max_workers, "sanity");
3070 for (uint i = 0; i < num_regions(); i++) {
3071 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
3072 }
3073 #endif
3074 return _liveness_cache[worker_id];
3075 }
3076
3077 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
3078 assert(worker_id < _max_workers, "sanity");
3079 assert(_liveness_cache != nullptr, "sanity");
3080 ShenandoahLiveData* ld = _liveness_cache[worker_id];
3081
3082 for (uint i = 0; i < num_regions(); i++) {
3083 ShenandoahLiveData live = ld[i];
3084 if (live > 0) {
3085 ShenandoahHeapRegion* r = get_region(i);
3086 r->increase_live_data_gc_words(live);
3087 ld[i] = 0;
3088 }
3089 }
3090 }
3091
3092 bool ShenandoahHeap::requires_barriers(stackChunkOop obj) const {
3093 if (is_idle()) return false;
3094
3095 // Objects allocated after marking start are implicitly alive, don't need any barriers during
3096 // marking phase.
3097 if (is_concurrent_mark_in_progress() &&
3098 !marking_context()->allocated_after_mark_start(obj)) {
3099 return true;
3100 }
3101
3102 // Can not guarantee obj is deeply good.
3103 if (has_forwarded_objects()) {
3104 return true;
3105 }
3106
3107 return false;
3108 }
3109
3110 void ShenandoahHeap::transfer_old_pointers_from_satb() {
3111 _old_generation->transfer_pointers_from_satb();
3112 }
3113
3114 template<>
3115 void ShenandoahGenerationRegionClosure<YOUNG>::heap_region_do(ShenandoahHeapRegion* region) {
3116 // Visit young and free regions
3117 if (region->affiliation() != OLD_GENERATION) {
3118 _cl->heap_region_do(region);
3119 }
3120 }
3121
3122 template<>
3123 void ShenandoahGenerationRegionClosure<OLD>::heap_region_do(ShenandoahHeapRegion* region) {
3124 // Visit old and free regions
3125 if (region->affiliation() != YOUNG_GENERATION) {
3126 _cl->heap_region_do(region);
3127 }
3128 }
3129
3130 template<>
3131 void ShenandoahGenerationRegionClosure<GLOBAL>::heap_region_do(ShenandoahHeapRegion* region) {
3132 _cl->heap_region_do(region);
3133 }
3134
3135 // Assure that the remember set has a dirty card everywhere there is an interesting pointer.
3136 // This examines the read_card_table between bottom() and top() since all PLABS are retired
3137 // before the safepoint for init_mark. Actually, we retire them before update-references and don't
3138 // restore them until the start of evacuation.
3139 void ShenandoahHeap::verify_rem_set_at_mark() {
3140 shenandoah_assert_safepoint();
3141 assert(mode()->is_generational(), "Only verify remembered set for generational operational modes");
3142
3143 ShenandoahRegionIterator iterator;
3144 RememberedScanner* scanner = card_scan();
3145 ShenandoahVerifyRemSetClosure check_interesting_pointers(true);
3146 ShenandoahMarkingContext* ctx;
3147
3148 log_debug(gc)("Verifying remembered set at %s mark", doing_mixed_evacuations()? "mixed": "young");
3149
3150 if (is_old_bitmap_stable() || active_generation()->generation_mode() == GLOBAL) {
3151 ctx = complete_marking_context();
3152 } else {
3153 ctx = nullptr;
3154 }
3155
3156 while (iterator.has_next()) {
3157 ShenandoahHeapRegion* r = iterator.next();
3158 HeapWord* tams = ctx? ctx->top_at_mark_start(r): nullptr;
3159 if (r == nullptr)
3160 break;
3161 if (r->is_old() && r->is_active()) {
3162 HeapWord* obj_addr = r->bottom();
3163 if (r->is_humongous_start()) {
3164 oop obj = cast_to_oop(obj_addr);
3165 if (!ctx || ctx->is_marked(obj)) {
3166 // For humongous objects, the typical object is an array, so the following checks may be overkill
3167 // For regular objects (not object arrays), if the card holding the start of the object is dirty,
3168 // we do not need to verify that cards spanning interesting pointers within this object are dirty.
3169 if (!scanner->is_card_dirty(obj_addr) || obj->is_objArray()) {
3170 obj->oop_iterate(&check_interesting_pointers);
3171 }
3172 // else, object's start is marked dirty and obj is not an objArray, so any interesting pointers are covered
3173 }
3174 // else, this humongous object is not marked so no need to verify its internal pointers
3175 if (!scanner->verify_registration(obj_addr, ctx)) {
3176 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, obj_addr, nullptr,
3177 "Verify init-mark remembered set violation", "object not properly registered", __FILE__, __LINE__);
3178 }
3179 } else if (!r->is_humongous()) {
3180 HeapWord* top = r->top();
3181 while (obj_addr < top) {
3182 oop obj = cast_to_oop(obj_addr);
3183 // ctx->is_marked() returns true if mark bit set (TAMS not relevant during init mark)
3184 if (!ctx || ctx->is_marked(obj)) {
3185 // For regular objects (not object arrays), if the card holding the start of the object is dirty,
3186 // we do not need to verify that cards spanning interesting pointers within this object are dirty.
3187 if (!scanner->is_card_dirty(obj_addr) || obj->is_objArray()) {
3188 obj->oop_iterate(&check_interesting_pointers);
3189 }
3190 // else, object's start is marked dirty and obj is not an objArray, so any interesting pointers are covered
3191 if (!scanner->verify_registration(obj_addr, ctx)) {
3192 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, obj_addr, nullptr,
3193 "Verify init-mark remembered set violation", "object not properly registered", __FILE__, __LINE__);
3194 }
3195 obj_addr += obj->size();
3196 } else {
3197 // This object is not live so we don't verify dirty cards contained therein
3198 assert(tams != nullptr, "If object is not live, ctx and tams should be non-null");
3199 obj_addr = ctx->get_next_marked_addr(obj_addr, tams);
3200 }
3201 }
3202 } // else, we ignore humongous continuation region
3203 } // else, this is not an OLD region so we ignore it
3204 } // all regions have been processed
3205 }
3206
3207 void ShenandoahHeap::help_verify_region_rem_set(ShenandoahHeapRegion* r, ShenandoahMarkingContext* ctx, HeapWord* from,
3208 HeapWord* top, HeapWord* registration_watermark, const char* message) {
3209 RememberedScanner* scanner = card_scan();
3210 ShenandoahVerifyRemSetClosure check_interesting_pointers(false);
3211
3212 HeapWord* obj_addr = from;
3213 if (r->is_humongous_start()) {
3214 oop obj = cast_to_oop(obj_addr);
3215 if (!ctx || ctx->is_marked(obj)) {
3216 size_t card_index = scanner->card_index_for_addr(obj_addr);
3217 // For humongous objects, the typical object is an array, so the following checks may be overkill
3218 // For regular objects (not object arrays), if the card holding the start of the object is dirty,
3219 // we do not need to verify that cards spanning interesting pointers within this object are dirty.
3220 if (!scanner->is_write_card_dirty(card_index) || obj->is_objArray()) {
3221 obj->oop_iterate(&check_interesting_pointers);
3222 }
3223 // else, object's start is marked dirty and obj is not an objArray, so any interesting pointers are covered
3224 }
3225 // else, this humongous object is not live so no need to verify its internal pointers
3226
3227 if ((obj_addr < registration_watermark) && !scanner->verify_registration(obj_addr, ctx)) {
3228 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, obj_addr, nullptr, message,
3229 "object not properly registered", __FILE__, __LINE__);
3230 }
3231 } else if (!r->is_humongous()) {
3232 while (obj_addr < top) {
3233 oop obj = cast_to_oop(obj_addr);
3234 // ctx->is_marked() returns true if mark bit set or if obj above TAMS.
3235 if (!ctx || ctx->is_marked(obj)) {
3236 size_t card_index = scanner->card_index_for_addr(obj_addr);
3237 // For regular objects (not object arrays), if the card holding the start of the object is dirty,
3238 // we do not need to verify that cards spanning interesting pointers within this object are dirty.
3239 if (!scanner->is_write_card_dirty(card_index) || obj->is_objArray()) {
3240 obj->oop_iterate(&check_interesting_pointers);
3241 }
3242 // else, object's start is marked dirty and obj is not an objArray, so any interesting pointers are covered
3243
3244 if ((obj_addr < registration_watermark) && !scanner->verify_registration(obj_addr, ctx)) {
3245 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, obj_addr, nullptr, message,
3246 "object not properly registered", __FILE__, __LINE__);
3247 }
3248 obj_addr += obj->size();
3249 } else {
3250 // This object is not live so we don't verify dirty cards contained therein
3251 HeapWord* tams = ctx->top_at_mark_start(r);
3252 obj_addr = ctx->get_next_marked_addr(obj_addr, tams);
3253 }
3254 }
3255 }
3256 }
3257
3258 void ShenandoahHeap::verify_rem_set_after_full_gc() {
3259 shenandoah_assert_safepoint();
3260 assert(mode()->is_generational(), "Only verify remembered set for generational operational modes");
3261
3262 ShenandoahRegionIterator iterator;
3263
3264 while (iterator.has_next()) {
3265 ShenandoahHeapRegion* r = iterator.next();
3266 if (r == nullptr)
3267 break;
3268 if (r->is_old() && !r->is_cset()) {
3269 help_verify_region_rem_set(r, nullptr, r->bottom(), r->top(), r->top(), "Remembered set violation at end of Full GC");
3270 }
3271 }
3272 }
3273
3274 // Assure that the remember set has a dirty card everywhere there is an interesting pointer. Even though
3275 // the update-references scan of remembered set only examines cards up to update_watermark, the remembered
3276 // set should be valid through top. This examines the write_card_table between bottom() and top() because
3277 // all PLABS are retired immediately before the start of update refs.
3278 void ShenandoahHeap::verify_rem_set_at_update_ref() {
3279 shenandoah_assert_safepoint();
3280 assert(mode()->is_generational(), "Only verify remembered set for generational operational modes");
3281
3282 ShenandoahRegionIterator iterator;
3283 ShenandoahMarkingContext* ctx;
3284
3285 if (is_old_bitmap_stable() || active_generation()->generation_mode() == GLOBAL) {
3286 ctx = complete_marking_context();
3287 } else {
3288 ctx = nullptr;
3289 }
3290
3291 while (iterator.has_next()) {
3292 ShenandoahHeapRegion* r = iterator.next();
3293 if (r == nullptr)
3294 break;
3295 if (r->is_old() && !r->is_cset()) {
3296 help_verify_region_rem_set(r, ctx, r->bottom(), r->top(), r->get_update_watermark(),
3297 "Remembered set violation at init-update-references");
3298 }
3299 }
3300 }
3301
3302 ShenandoahGeneration* ShenandoahHeap::generation_for(ShenandoahRegionAffiliation affiliation) const {
3303 if (!mode()->is_generational()) {
3304 return global_generation();
3305 } else if (affiliation == YOUNG_GENERATION) {
3306 return young_generation();
3307 } else if (affiliation == OLD_GENERATION) {
3308 return old_generation();
3309 }
3310
3311 ShouldNotReachHere();
3312 return nullptr;
3313 }
3314
3315 void ShenandoahHeap::log_heap_status(const char* msg) const {
3316 if (mode()->is_generational()) {
3317 young_generation()->log_status(msg);
3318 old_generation()->log_status(msg);
3319 } else {
3320 global_generation()->log_status(msg);
3321 }
3322 }
3323
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