1 /*
2 * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2013, 2022, Red Hat, Inc. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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/classUnloadingContext.hpp"
31 #include "gc/shared/gcArguments.hpp"
32 #include "gc/shared/gcTimer.hpp"
33 #include "gc/shared/gcTraceTime.inline.hpp"
34 #include "gc/shared/locationPrinter.inline.hpp"
35 #include "gc/shared/memAllocator.hpp"
36 #include "gc/shared/plab.hpp"
37 #include "gc/shared/tlab_globals.hpp"
38
39 #include "gc/shenandoah/shenandoahBarrierSet.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/shenandoahFreeSet.hpp"
47 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
48 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
49 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
50 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
51 #include "gc/shenandoah/shenandoahInitLogger.hpp"
52 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
53 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
54 #include "gc/shenandoah/shenandoahMetrics.hpp"
55 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
56 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
57 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
58 #include "gc/shenandoah/shenandoahPadding.hpp"
59 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
60 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
61 #include "gc/shenandoah/shenandoahRootProcessor.inline.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"
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;
235 }
236
237 guarantee(_bitmap_regions_per_slice >= 1,
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
279 //
280 // Create regions and region sets
281 //
282 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
283 size_t region_storage_size = align_up(region_align * _num_regions, region_page_size);
284 region_storage_size = align_up(region_storage_size, os::vm_allocation_granularity());
285
286 ReservedSpace region_storage(region_storage_size, region_page_size);
287 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC);
288 if (!region_storage.special()) {
289 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false,
290 "Cannot commit region memory");
291 }
292
293 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks.
294 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there.
295 // If not successful, bite a bullet and allocate at whatever address.
296 {
297 size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity());
298 size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align);
299
300 uintptr_t min = round_up_power_of_2(cset_align);
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
357 // them into huge one. Therefore, we need to pretouch with smaller pages.
358 if (UseTransparentHugePages) {
359 _pretouch_heap_page_size = (size_t)os::vm_page_size();
360 _pretouch_bitmap_page_size = (size_t)os::vm_page_size();
361 }
362 #endif
363
364 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
365 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
366
367 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size);
368 _workers->run_task(&bcl);
369
370 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size);
371 _workers->run_task(&hcl);
372 }
373
374 //
375 // Initialize the rest of GC subsystems
376 //
377
378 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC);
379 for (uint worker = 0; worker < _max_workers; worker++) {
380 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC);
381 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData));
382 }
383
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 _gc_state_changed(false),
472 _control_thread(nullptr),
473 _shenandoah_policy(policy),
474 _gc_mode(nullptr),
475 _heuristics(nullptr),
476 _free_set(nullptr),
477 _pacer(nullptr),
478 _verifier(nullptr),
479 _phase_timings(nullptr),
480 _monitoring_support(nullptr),
481 _memory_pool(nullptr),
482 _stw_memory_manager("Shenandoah Pauses"),
483 _cycle_memory_manager("Shenandoah Cycles"),
484 _gc_timer(new ConcurrentGCTimer()),
485 _soft_ref_policy(),
486 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
487 _ref_processor(new ShenandoahReferenceProcessor(MAX2(_max_workers, 1U))),
488 _marking_context(nullptr),
489 _bitmap_size(0),
490 _bitmap_regions_per_slice(0),
491 _bitmap_bytes_per_slice(0),
492 _bitmap_region_special(false),
493 _aux_bitmap_region_special(false),
494 _liveness_cache(nullptr),
495 _collection_set(nullptr)
496 {
497 // Initialize GC mode early, so we can adjust barrier support
498 initialize_mode();
499 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
500
501 _max_workers = MAX2(_max_workers, 1U);
502 _workers = new ShenandoahWorkerThreads("Shenandoah GC Threads", _max_workers);
503 if (_workers == nullptr) {
504 vm_exit_during_initialization("Failed necessary allocation.");
505 } else {
506 _workers->initialize_workers();
507 }
508
509 if (ParallelGCThreads > 1) {
510 _safepoint_workers = new ShenandoahWorkerThreads("Safepoint Cleanup Thread",
511 ParallelGCThreads);
512 _safepoint_workers->initialize_workers();
513 }
514 }
515
516 #ifdef _MSC_VER
517 #pragma warning( pop )
518 #endif
519
520 class ShenandoahResetBitmapTask : public WorkerTask {
521 private:
522 ShenandoahRegionIterator _regions;
523
524 public:
525 ShenandoahResetBitmapTask() :
526 WorkerTask("Shenandoah Reset Bitmap") {}
527
528 void work(uint worker_id) {
529 ShenandoahHeapRegion* region = _regions.next();
530 ShenandoahHeap* heap = ShenandoahHeap::heap();
531 ShenandoahMarkingContext* const ctx = heap->marking_context();
532 while (region != nullptr) {
533 if (heap->is_bitmap_slice_committed(region)) {
534 ctx->clear_bitmap(region);
535 }
536 region = _regions.next();
537 }
538 }
539 };
540
541 void ShenandoahHeap::reset_mark_bitmap() {
542 assert_gc_workers(_workers->active_workers());
543 mark_incomplete_marking_context();
544
545 ShenandoahResetBitmapTask task;
546 _workers->run_task(&task);
547 }
548
549 void ShenandoahHeap::print_on(outputStream* st) const {
550 st->print_cr("Shenandoah Heap");
551 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
552 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
553 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()),
554 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
555 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
556 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
557 num_regions(),
558 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
559 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
560
561 st->print("Status: ");
562 if (has_forwarded_objects()) st->print("has forwarded objects, ");
563 if (is_concurrent_mark_in_progress()) st->print("marking, ");
564 if (is_evacuation_in_progress()) st->print("evacuating, ");
565 if (is_update_refs_in_progress()) st->print("updating refs, ");
566 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
567 if (is_full_gc_in_progress()) st->print("full gc, ");
568 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
569 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, ");
570 if (is_concurrent_strong_root_in_progress() &&
571 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, ");
572
573 if (cancelled_gc()) {
574 st->print("cancelled");
575 } else {
576 st->print("not cancelled");
577 }
578 st->cr();
579
580 st->print_cr("Reserved region:");
581 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
582 p2i(reserved_region().start()),
583 p2i(reserved_region().end()));
594 st->cr();
595 MetaspaceUtils::print_on(st);
596
597 if (Verbose) {
598 st->cr();
599 print_heap_regions_on(st);
600 }
601 }
602
603 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
604 public:
605 void do_thread(Thread* thread) {
606 assert(thread != nullptr, "Sanity");
607 assert(thread->is_Worker_thread(), "Only worker thread expected");
608 ShenandoahThreadLocalData::initialize_gclab(thread);
609 }
610 };
611
612 void ShenandoahHeap::post_initialize() {
613 CollectedHeap::post_initialize();
614 MutexLocker ml(Threads_lock);
615
616 ShenandoahInitWorkerGCLABClosure init_gclabs;
617 _workers->threads_do(&init_gclabs);
618
619 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
620 // Now, we will let WorkerThreads to initialize gclab when new worker is created.
621 _workers->set_initialize_gclab();
622 if (_safepoint_workers != nullptr) {
623 _safepoint_workers->threads_do(&init_gclabs);
624 _safepoint_workers->set_initialize_gclab();
625 }
626
627 _heuristics->initialize();
628
629 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
630 }
631
632 size_t ShenandoahHeap::used() const {
633 return Atomic::load(&_used);
634 }
635
636 size_t ShenandoahHeap::committed() const {
637 return Atomic::load(&_committed);
638 }
639
640 void ShenandoahHeap::increase_committed(size_t bytes) {
641 shenandoah_assert_heaplocked_or_safepoint();
642 _committed += bytes;
643 }
644
645 void ShenandoahHeap::decrease_committed(size_t bytes) {
646 shenandoah_assert_heaplocked_or_safepoint();
647 _committed -= bytes;
648 }
649
650 void ShenandoahHeap::increase_used(size_t bytes) {
651 Atomic::add(&_used, bytes, memory_order_relaxed);
652 }
653
654 void ShenandoahHeap::set_used(size_t bytes) {
655 Atomic::store(&_used, bytes);
656 }
657
658 void ShenandoahHeap::decrease_used(size_t bytes) {
659 assert(used() >= bytes, "never decrease heap size by more than we've left");
660 Atomic::sub(&_used, bytes, memory_order_relaxed);
661 }
662
663 void ShenandoahHeap::increase_allocated(size_t bytes) {
664 Atomic::add(&_bytes_allocated_since_gc_start, bytes, memory_order_relaxed);
665 }
666
667 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
668 size_t bytes = words * HeapWordSize;
669 if (!waste) {
670 increase_used(bytes);
671 }
672 increase_allocated(bytes);
673 if (ShenandoahPacing) {
674 control_thread()->pacing_notify_alloc(words);
675 if (waste) {
676 pacer()->claim_for_alloc(words, true);
677 }
678 }
679 }
680
681 size_t ShenandoahHeap::capacity() const {
682 return committed();
683 }
684
685 size_t ShenandoahHeap::max_capacity() const {
686 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
687 }
688
689 size_t ShenandoahHeap::soft_max_capacity() const {
690 size_t v = Atomic::load(&_soft_max_size);
691 assert(min_capacity() <= v && v <= max_capacity(),
692 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
693 min_capacity(), v, max_capacity());
694 return v;
695 }
696
697 void ShenandoahHeap::set_soft_max_capacity(size_t v) {
698 assert(min_capacity() <= v && v <= max_capacity(),
699 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
700 min_capacity(), v, max_capacity());
701 Atomic::store(&_soft_max_size, v);
702 }
703
704 size_t ShenandoahHeap::min_capacity() const {
705 return _minimum_size;
706 }
707
708 size_t ShenandoahHeap::initial_capacity() const {
709 return _initial_size;
710 }
711
712 bool ShenandoahHeap::is_in(const void* p) const {
713 HeapWord* heap_base = (HeapWord*) base();
714 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
715 return p >= heap_base && p < last_region_end;
716 }
717
718 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
719 assert (ShenandoahUncommit, "should be enabled");
720
721 // Application allocates from the beginning of the heap, and GC allocates at
722 // the end of it. It is more efficient to uncommit from the end, so that applications
723 // could enjoy the near committed regions. GC allocations are much less frequent,
724 // and therefore can accept the committing costs.
725
726 size_t count = 0;
727 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
728 ShenandoahHeapRegion* r = get_region(i - 1);
729 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
730 ShenandoahHeapLocker locker(lock());
731 if (r->is_empty_committed()) {
732 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) {
733 break;
734 }
735
736 r->make_uncommitted();
737 count++;
738 }
739 }
740 SpinPause(); // allow allocators to take the lock
741 }
742
743 if (count > 0) {
744 control_thread()->notify_heap_changed();
745 }
746 }
747
748 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
749 // New object should fit the GCLAB size
750 size_t min_size = MAX2(size, PLAB::min_size());
751
752 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
753 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
754 new_size = MIN2(new_size, PLAB::max_size());
755 new_size = MAX2(new_size, PLAB::min_size());
756
757 // Record new heuristic value even if we take any shortcut. This captures
758 // the case when moderately-sized objects always take a shortcut. At some point,
759 // heuristics should catch up with them.
760 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
761
762 if (new_size < size) {
763 // New size still does not fit the object. Fall back to shared allocation.
764 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
765 return nullptr;
766 }
767
768 // Retire current GCLAB, and allocate a new one.
769 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
770 gclab->retire();
771
772 size_t actual_size = 0;
773 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
774 if (gclab_buf == nullptr) {
775 return nullptr;
776 }
777
778 assert (size <= actual_size, "allocation should fit");
779
780 // ...and clear or zap just allocated TLAB, if needed.
781 if (ZeroTLAB) {
782 Copy::zero_to_words(gclab_buf, actual_size);
783 } else if (ZapTLAB) {
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 }
790 gclab->set_buf(gclab_buf, actual_size);
791 return gclab->allocate(size);
792 }
793
794 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
795 size_t requested_size,
796 size_t* actual_size) {
797 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
798 HeapWord* res = allocate_memory(req);
799 if (res != nullptr) {
800 *actual_size = req.actual_size();
801 } else {
802 *actual_size = 0;
803 }
804 return res;
805 }
806
807 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
808 size_t word_size,
809 size_t* actual_size) {
810 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
811 HeapWord* res = allocate_memory(req);
812 if (res != nullptr) {
813 *actual_size = req.actual_size();
815 *actual_size = 0;
816 }
817 return res;
818 }
819
820 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
821 intptr_t pacer_epoch = 0;
822 bool in_new_region = false;
823 HeapWord* result = nullptr;
824
825 if (req.is_mutator_alloc()) {
826 if (ShenandoahPacing) {
827 pacer()->pace_for_alloc(req.size());
828 pacer_epoch = pacer()->epoch();
829 }
830
831 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
832 result = allocate_memory_under_lock(req, in_new_region);
833 }
834
835 // Allocation failed, block until control thread reacted, then retry allocation.
836 //
837 // It might happen that one of the threads requesting allocation would unblock
838 // way later after GC happened, only to fail the second allocation, because
839 // other threads have already depleted the free storage. In this case, a better
840 // strategy is to try again, as long as GC makes progress (or until at least
841 // one full GC has completed).
842 size_t original_count = shenandoah_policy()->full_gc_count();
843 while (result == nullptr
844 && (_progress_last_gc.is_set() || original_count == shenandoah_policy()->full_gc_count())) {
845 control_thread()->handle_alloc_failure(req);
846 result = allocate_memory_under_lock(req, in_new_region);
847 }
848 } else {
849 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
850 result = allocate_memory_under_lock(req, in_new_region);
851 // Do not call handle_alloc_failure() here, because we cannot block.
852 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
853 }
854
855 if (in_new_region) {
856 control_thread()->notify_heap_changed();
857 }
858
859 if (result != nullptr) {
860 size_t requested = req.size();
861 size_t actual = req.actual_size();
862
863 assert (req.is_lab_alloc() || (requested == actual),
864 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
865 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
866
867 if (req.is_mutator_alloc()) {
868 notify_mutator_alloc_words(actual, false);
869
870 // If we requested more than we were granted, give the rest back to pacer.
871 // This only matters if we are in the same pacing epoch: do not try to unpace
872 // over the budget for the other phase.
873 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
874 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
875 }
876 } else {
877 increase_used(actual*HeapWordSize);
878 }
879 }
880
881 return result;
882 }
883
884 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
885 // If we are dealing with mutator allocation, then we may need to block for safepoint.
886 // We cannot block for safepoint for GC allocations, because there is a high chance
887 // we are already running at safepoint or from stack watermark machinery, and we cannot
888 // block again.
889 ShenandoahHeapLocker locker(lock(), req.is_mutator_alloc());
890 return _free_set->allocate(req, in_new_region);
891 }
892
893 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
894 bool* gc_overhead_limit_was_exceeded) {
895 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
896 return allocate_memory(req);
897 }
898
899 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
900 size_t size,
901 Metaspace::MetadataType mdtype) {
902 MetaWord* result;
903
904 // Inform metaspace OOM to GC heuristics if class unloading is possible.
905 if (heuristics()->can_unload_classes()) {
906 ShenandoahHeuristics* h = heuristics();
907 h->record_metaspace_oom();
908 }
909
910 // Expand and retry allocation
911 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
912 if (result != nullptr) {
913 return result;
914 }
915
916 // Start full GC
917 collect(GCCause::_metadata_GC_clear_soft_refs);
918
919 // Retry allocation
920 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
921 if (result != nullptr) {
922 return result;
923 }
924
925 // Expand and retry allocation
926 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
983 while ((r =_cs->claim_next()) != nullptr) {
984 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
985 _sh->marked_object_iterate(r, &cl);
986
987 if (ShenandoahPacing) {
988 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
989 }
990
991 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
992 break;
993 }
994 }
995 }
996 };
997
998 void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
999 ShenandoahEvacuationTask task(this, _collection_set, concurrent);
1000 workers()->run_task(&task);
1001 }
1002
1003 void ShenandoahHeap::trash_cset_regions() {
1004 ShenandoahHeapLocker locker(lock());
1005
1006 ShenandoahCollectionSet* set = collection_set();
1007 ShenandoahHeapRegion* r;
1008 set->clear_current_index();
1009 while ((r = set->next()) != nullptr) {
1010 r->make_trash();
1011 }
1012 collection_set()->clear();
1013 }
1014
1015 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1016 st->print_cr("Heap Regions:");
1017 st->print_cr("Region state: EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HP=pinned humongous start");
1018 st->print_cr(" HC=humongous continuation, CS=collection set, TR=trash, P=pinned, CSP=pinned collection set");
1019 st->print_cr("BTE=bottom/top/end, TAMS=top-at-mark-start");
1020 st->print_cr("UWM=update watermark, U=used");
1021 st->print_cr("T=TLAB allocs, G=GCLAB allocs");
1022 st->print_cr("S=shared allocs, L=live data");
1023 st->print_cr("CP=critical pins");
1024
1025 for (size_t i = 0; i < num_regions(); i++) {
1026 get_region(i)->print_on(st);
1027 }
1028 }
1029
1030 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1031 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1032
1033 oop humongous_obj = cast_to_oop(start->bottom());
1034 size_t size = humongous_obj->size();
1035 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1036 size_t index = start->index() + required_regions - 1;
1037
1038 assert(!start->has_live(), "liveness must be zero");
1039
1040 for(size_t i = 0; i < required_regions; i++) {
1041 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1042 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1043 ShenandoahHeapRegion* region = get_region(index --);
1044
1045 assert(region->is_humongous(), "expect correct humongous start or continuation");
1046 assert(!region->is_cset(), "Humongous region should not be in collection set");
1047
1048 region->make_trash_immediate();
1049 }
1050 }
1051
1052 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1053 public:
1054 ShenandoahCheckCleanGCLABClosure() {}
1055 void do_thread(Thread* thread) {
1056 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1057 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1058 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
1059 }
1060 };
1061
1062 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1063 private:
1064 bool const _resize;
1065 public:
1066 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1067 void do_thread(Thread* thread) {
1068 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1069 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1070 gclab->retire();
1071 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1072 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1073 }
1074 }
1075 };
1076
1077 void ShenandoahHeap::labs_make_parsable() {
1078 assert(UseTLAB, "Only call with UseTLAB");
1079
1080 ShenandoahRetireGCLABClosure cl(false);
1081
1082 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1083 ThreadLocalAllocBuffer& tlab = t->tlab();
1084 tlab.make_parsable();
1085 cl.do_thread(t);
1086 }
1087
1088 workers()->threads_do(&cl);
1089 }
1090
1091 void ShenandoahHeap::tlabs_retire(bool resize) {
1092 assert(UseTLAB, "Only call with UseTLAB");
1093 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1123 }
1124 workers()->threads_do(&cl);
1125
1126 if (safepoint_workers() != nullptr) {
1127 safepoint_workers()->threads_do(&cl);
1128 }
1129 }
1130
1131 // Returns size in bytes
1132 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1133 // Return the max allowed size, and let the allocation path
1134 // figure out the safe size for current allocation.
1135 return ShenandoahHeapRegion::max_tlab_size_bytes();
1136 }
1137
1138 size_t ShenandoahHeap::max_tlab_size() const {
1139 // Returns size in words
1140 return ShenandoahHeapRegion::max_tlab_size_words();
1141 }
1142
1143 void ShenandoahHeap::collect(GCCause::Cause cause) {
1144 control_thread()->request_gc(cause);
1145 }
1146
1147 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1148 //assert(false, "Shouldn't need to do full collections");
1149 }
1150
1151 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1152 ShenandoahHeapRegion* r = heap_region_containing(addr);
1153 if (r != nullptr) {
1154 return r->block_start(addr);
1155 }
1156 return nullptr;
1157 }
1158
1159 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1160 ShenandoahHeapRegion* r = heap_region_containing(addr);
1161 return r->block_is_obj(addr);
1162 }
1163
1164 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1165 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1166 }
1167
1168 void ShenandoahHeap::prepare_for_verify() {
1169 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) {
1170 labs_make_parsable();
1171 }
1172 }
1173
1174 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1175 tcl->do_thread(_control_thread);
1176 workers()->threads_do(tcl);
1177 if (_safepoint_workers != nullptr) {
1178 _safepoint_workers->threads_do(tcl);
1179 }
1180 }
1181
1182 void ShenandoahHeap::print_tracing_info() const {
1183 LogTarget(Info, gc, stats) lt;
1184 if (lt.is_enabled()) {
1185 ResourceMark rm;
1186 LogStream ls(lt);
1187
1188 phase_timings()->print_global_on(&ls);
1189
1190 ls.cr();
1191 ls.cr();
1192
1193 shenandoah_policy()->print_gc_stats(&ls);
1194
1195 ls.cr();
1196 ls.cr();
1197 }
1198 }
1199
1200 void ShenandoahHeap::verify(VerifyOption vo) {
1201 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1202 if (ShenandoahVerify) {
1203 verifier()->verify_generic(vo);
1204 } else {
1205 // TODO: Consider allocating verification bitmaps on demand,
1206 // and turn this on unconditionally.
1207 }
1208 }
1209 }
1210 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1211 return _free_set->capacity();
1212 }
1213
1214 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1215 private:
1216 MarkBitMap* _bitmap;
1217 ShenandoahScanObjectStack* _oop_stack;
1218 ShenandoahHeap* const _heap;
1219 ShenandoahMarkingContext* const _marking_context;
1514 const uint active_workers = workers()->active_workers();
1515 const size_t n_regions = num_regions();
1516 size_t stride = ShenandoahParallelRegionStride;
1517 if (stride == 0 && active_workers > 1) {
1518 // Automatically derive the stride to balance the work between threads
1519 // evenly. Do not try to split work if below the reasonable threshold.
1520 constexpr size_t threshold = 4096;
1521 stride = n_regions <= threshold ?
1522 threshold :
1523 (n_regions + active_workers - 1) / active_workers;
1524 }
1525
1526 if (n_regions > stride && active_workers > 1) {
1527 ShenandoahParallelHeapRegionTask task(blk, stride);
1528 workers()->run_task(&task);
1529 } else {
1530 heap_region_iterate(blk);
1531 }
1532 }
1533
1534 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1535 private:
1536 ShenandoahMarkingContext* const _ctx;
1537 public:
1538 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1539
1540 void heap_region_do(ShenandoahHeapRegion* r) {
1541 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1542 if (r->is_active()) {
1543 // Check if region needs updating its TAMS. We have updated it already during concurrent
1544 // reset, so it is very likely we don't need to do another write here.
1545 if (_ctx->top_at_mark_start(r) != r->top()) {
1546 _ctx->capture_top_at_mark_start(r);
1547 }
1548 } else {
1549 assert(_ctx->top_at_mark_start(r) == r->top(),
1550 "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
1551 }
1552 }
1553
1554 bool is_thread_safe() { return true; }
1555 };
1556
1557 class ShenandoahRendezvousClosure : public HandshakeClosure {
1558 public:
1559 inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {}
1560 inline void do_thread(Thread* thread) {}
1561 };
1562
1563 void ShenandoahHeap::rendezvous_threads() {
1564 ShenandoahRendezvousClosure cl;
1565 Handshake::execute(&cl);
1566 }
1567
1568 void ShenandoahHeap::recycle_trash() {
1569 free_set()->recycle_trash();
1570 }
1571
1572 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1573 private:
1574 ShenandoahMarkingContext* const _ctx;
1575 public:
1576 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1577
1578 void heap_region_do(ShenandoahHeapRegion* r) {
1579 if (r->is_active()) {
1580 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1581 // anyway to capture any updates that happened since now.
1582 r->clear_live_data();
1583 _ctx->capture_top_at_mark_start(r);
1584 }
1585 }
1586
1587 bool is_thread_safe() { return true; }
1588 };
1589
1590 void ShenandoahHeap::prepare_gc() {
1591 reset_mark_bitmap();
1592
1593 ShenandoahResetUpdateRegionStateClosure cl;
1594 parallel_heap_region_iterate(&cl);
1595 }
1596
1597 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1598 private:
1599 ShenandoahMarkingContext* const _ctx;
1600 ShenandoahHeapLock* const _lock;
1601
1602 public:
1603 ShenandoahFinalMarkUpdateRegionStateClosure() :
1604 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1605
1606 void heap_region_do(ShenandoahHeapRegion* r) {
1607 if (r->is_active()) {
1608 // All allocations past TAMS are implicitly live, adjust the region data.
1609 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1610 HeapWord *tams = _ctx->top_at_mark_start(r);
1611 HeapWord *top = r->top();
1612 if (top > tams) {
1613 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1614 }
1615
1616 // We are about to select the collection set, make sure it knows about
1617 // current pinning status. Also, this allows trashing more regions that
1618 // now have their pinning status dropped.
1619 if (r->is_pinned()) {
1620 if (r->pin_count() == 0) {
1621 ShenandoahHeapLocker locker(_lock);
1622 r->make_unpinned();
1623 }
1624 } else {
1625 if (r->pin_count() > 0) {
1626 ShenandoahHeapLocker locker(_lock);
1627 r->make_pinned();
1628 }
1629 }
1630
1631 // Remember limit for updating refs. It's guaranteed that we get no
1632 // from-space-refs written from here on.
1633 r->set_update_watermark_at_safepoint(r->top());
1634 } else {
1635 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1636 assert(_ctx->top_at_mark_start(r) == r->top(),
1637 "Region " SIZE_FORMAT " should have correct TAMS", r->index());
1638 }
1639 }
1640
1641 bool is_thread_safe() { return true; }
1642 };
1643
1644 void ShenandoahHeap::prepare_regions_and_collection_set(bool concurrent) {
1645 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
1646 {
1647 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_region_states :
1648 ShenandoahPhaseTimings::degen_gc_final_update_region_states);
1649 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1650 parallel_heap_region_iterate(&cl);
1651
1652 assert_pinned_region_status();
1653 }
1654
1655 {
1656 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::choose_cset :
1657 ShenandoahPhaseTimings::degen_gc_choose_cset);
1658 ShenandoahHeapLocker locker(lock());
1659 _collection_set->clear();
1660 heuristics()->choose_collection_set(_collection_set);
1661 }
1662
1663 {
1664 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_rebuild_freeset :
1665 ShenandoahPhaseTimings::degen_gc_final_rebuild_freeset);
1666 ShenandoahHeapLocker locker(lock());
1667 _free_set->rebuild();
1668 }
1669 }
1670
1671 void ShenandoahHeap::do_class_unloading() {
1672 _unloader.unload();
1673 }
1674
1675 void ShenandoahHeap::stw_weak_refs(bool full_gc) {
1676 // Weak refs processing
1677 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs
1678 : ShenandoahPhaseTimings::degen_gc_weakrefs;
1679 ShenandoahTimingsTracker t(phase);
1680 ShenandoahGCWorkerPhase worker_phase(phase);
1681 ref_processor()->process_references(phase, workers(), false /* concurrent */);
1682 }
1683
1684 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
1685 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
1686
1687 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to
1688 // make them parsable for update code to work correctly. Plus, we can compute new sizes
1689 // for future GCLABs here.
1690 if (UseTLAB) {
1691 ShenandoahGCPhase phase(concurrent ?
1692 ShenandoahPhaseTimings::init_update_refs_manage_gclabs :
1693 ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs);
1694 gclabs_retire(ResizeTLAB);
1695 }
1696
1697 _update_refs_iterator.reset();
1698 }
1699
1700 void ShenandoahHeap::propagate_gc_state_to_java_threads() {
1701 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint");
1702 if (_gc_state_changed) {
1703 _gc_state_changed = false;
1704 char state = gc_state();
1705 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1706 ShenandoahThreadLocalData::set_gc_state(t, state);
1707 }
1708 }
1709 }
1710
1711 void ShenandoahHeap::set_gc_state(uint mask, bool value) {
1712 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint");
1713 _gc_state.set_cond(mask, value);
1714 _gc_state_changed = true;
1715 }
1716
1717 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1718 assert(!has_forwarded_objects(), "Not expected before/after mark phase");
1719 set_gc_state(MARKING, in_progress);
1720 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1721 }
1722
1723 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1724 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1725 set_gc_state(EVACUATION, in_progress);
1726 }
1727
1728 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
1729 if (in_progress) {
1730 _concurrent_strong_root_in_progress.set();
1731 } else {
1732 _concurrent_strong_root_in_progress.unset();
1733 }
1734 }
1735
1736 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) {
1737 set_gc_state(WEAK_ROOTS, cond);
1738 }
1739
1740 GCTracer* ShenandoahHeap::tracer() {
1741 return shenandoah_policy()->tracer();
1742 }
1743
1744 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1745 return _free_set->used();
1746 }
1747
1748 bool ShenandoahHeap::try_cancel_gc() {
1749 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
1750 return prev == CANCELLABLE;
1751 }
1752
1753 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1754 if (try_cancel_gc()) {
1755 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1756 log_info(gc)("%s", msg.buffer());
1757 Events::log(Thread::current(), "%s", msg.buffer());
1758 }
1759 }
1760
1761 uint ShenandoahHeap::max_workers() {
1762 return _max_workers;
1763 }
1764
1765 void ShenandoahHeap::stop() {
1766 // The shutdown sequence should be able to terminate when GC is running.
1767
1768 // Step 0. Notify policy to disable event recording.
1769 _shenandoah_policy->record_shutdown();
1770
1771 // Step 1. Notify control thread that we are in shutdown.
1772 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1773 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1774 control_thread()->prepare_for_graceful_shutdown();
1775
1776 // Step 2. Notify GC workers that we are cancelling GC.
1777 cancel_gc(GCCause::_shenandoah_stop_vm);
1778
1779 // Step 3. Wait until GC worker exits normally.
1780 control_thread()->stop();
1781 }
1782
1783 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
1784 if (!unload_classes()) return;
1785 ClassUnloadingContext ctx(_workers->active_workers(),
1786 true /* unregister_nmethods_during_purge */,
1787 false /* lock_codeblob_free_separately */);
1788
1789 // Unload classes and purge SystemDictionary.
1790 {
1861 }
1862
1863 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
1864 set_gc_state(HAS_FORWARDED, cond);
1865 }
1866
1867 void ShenandoahHeap::set_unload_classes(bool uc) {
1868 _unload_classes.set_cond(uc);
1869 }
1870
1871 bool ShenandoahHeap::unload_classes() const {
1872 return _unload_classes.is_set();
1873 }
1874
1875 address ShenandoahHeap::in_cset_fast_test_addr() {
1876 ShenandoahHeap* heap = ShenandoahHeap::heap();
1877 assert(heap->collection_set() != nullptr, "Sanity");
1878 return (address) heap->collection_set()->biased_map_address();
1879 }
1880
1881 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
1882 return Atomic::load(&_bytes_allocated_since_gc_start);
1883 }
1884
1885 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
1886 Atomic::store(&_bytes_allocated_since_gc_start, (size_t)0);
1887 }
1888
1889 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
1890 _degenerated_gc_in_progress.set_cond(in_progress);
1891 }
1892
1893 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
1894 _full_gc_in_progress.set_cond(in_progress);
1895 }
1896
1897 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
1898 assert (is_full_gc_in_progress(), "should be");
1899 _full_gc_move_in_progress.set_cond(in_progress);
1900 }
1901
1902 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
1903 set_gc_state(UPDATEREFS, in_progress);
1904 }
1905
1906 void ShenandoahHeap::register_nmethod(nmethod* nm) {
1930 if (r->is_active()) {
1931 if (r->is_pinned()) {
1932 if (r->pin_count() == 0) {
1933 r->make_unpinned();
1934 }
1935 } else {
1936 if (r->pin_count() > 0) {
1937 r->make_pinned();
1938 }
1939 }
1940 }
1941 }
1942
1943 assert_pinned_region_status();
1944 }
1945
1946 #ifdef ASSERT
1947 void ShenandoahHeap::assert_pinned_region_status() {
1948 for (size_t i = 0; i < num_regions(); i++) {
1949 ShenandoahHeapRegion* r = get_region(i);
1950 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
1951 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
1952 }
1953 }
1954 #endif
1955
1956 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
1957 return _gc_timer;
1958 }
1959
1960 void ShenandoahHeap::prepare_concurrent_roots() {
1961 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1962 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1963 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
1964 set_concurrent_weak_root_in_progress(true);
1965 if (unload_classes()) {
1966 _unloader.prepare();
1967 }
1968 }
1969
1970 void ShenandoahHeap::finish_concurrent_roots() {
1971 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1972 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1973 if (unload_classes()) {
1974 _unloader.finish();
1975 }
1976 }
1977
1978 #ifdef ASSERT
1979 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
1980 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
1981
1982 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1983 if (UseDynamicNumberOfGCThreads) {
1984 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
1985 } else {
1986 // Use ParallelGCThreads inside safepoints
1987 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
1988 }
1989 } else {
1990 if (UseDynamicNumberOfGCThreads) {
1991 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
1992 } else {
1993 // Use ConcGCThreads outside safepoints
1994 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
1995 }
1996 }
1997 }
1998 #endif
1999
2000 ShenandoahVerifier* ShenandoahHeap::verifier() {
2001 guarantee(ShenandoahVerify, "Should be enabled");
2002 assert (_verifier != nullptr, "sanity");
2003 return _verifier;
2004 }
2005
2006 template<bool CONCURRENT>
2007 class ShenandoahUpdateHeapRefsTask : public WorkerTask {
2008 private:
2009 ShenandoahHeap* _heap;
2010 ShenandoahRegionIterator* _regions;
2011 public:
2012 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) :
2013 WorkerTask("Shenandoah Update References"),
2014 _heap(ShenandoahHeap::heap()),
2015 _regions(regions) {
2016 }
2017
2018 void work(uint worker_id) {
2019 if (CONCURRENT) {
2020 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2021 ShenandoahSuspendibleThreadSetJoiner stsj;
2022 do_work<ShenandoahConcUpdateRefsClosure>();
2023 } else {
2024 ShenandoahParallelWorkerSession worker_session(worker_id);
2025 do_work<ShenandoahSTWUpdateRefsClosure>();
2026 }
2027 }
2028
2029 private:
2030 template<class T>
2031 void do_work() {
2032 T cl;
2033 ShenandoahHeapRegion* r = _regions->next();
2034 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2035 while (r != nullptr) {
2036 HeapWord* update_watermark = r->get_update_watermark();
2037 assert (update_watermark >= r->bottom(), "sanity");
2038 if (r->is_active() && !r->is_cset()) {
2039 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2040 }
2041 if (ShenandoahPacing) {
2042 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2043 }
2044 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
2045 return;
2046 }
2047 r = _regions->next();
2048 }
2049 }
2050 };
2051
2052 void ShenandoahHeap::update_heap_references(bool concurrent) {
2053 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2054
2055 if (concurrent) {
2056 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator);
2057 workers()->run_task(&task);
2058 } else {
2059 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator);
2060 workers()->run_task(&task);
2061 }
2062 }
2063
2064
2065 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2066 private:
2067 ShenandoahHeapLock* const _lock;
2068
2069 public:
2070 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2071
2072 void heap_region_do(ShenandoahHeapRegion* r) {
2073 // Drop unnecessary "pinned" state from regions that does not have CP marks
2074 // anymore, as this would allow trashing them.
2075
2076 if (r->is_active()) {
2077 if (r->is_pinned()) {
2078 if (r->pin_count() == 0) {
2079 ShenandoahHeapLocker locker(_lock);
2080 r->make_unpinned();
2081 }
2082 } else {
2083 if (r->pin_count() > 0) {
2084 ShenandoahHeapLocker locker(_lock);
2085 r->make_pinned();
2086 }
2087 }
2088 }
2089 }
2090
2091 bool is_thread_safe() { return true; }
2092 };
2093
2094 void ShenandoahHeap::update_heap_region_states(bool concurrent) {
2095 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2096 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2097
2098 {
2099 ShenandoahGCPhase phase(concurrent ?
2100 ShenandoahPhaseTimings::final_update_refs_update_region_states :
2101 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states);
2102 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2103 parallel_heap_region_iterate(&cl);
2104
2105 assert_pinned_region_status();
2106 }
2107
2108 {
2109 ShenandoahGCPhase phase(concurrent ?
2110 ShenandoahPhaseTimings::final_update_refs_trash_cset :
2111 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset);
2112 trash_cset_regions();
2113 }
2114 }
2115
2116 void ShenandoahHeap::rebuild_free_set(bool concurrent) {
2117 {
2118 ShenandoahGCPhase phase(concurrent ?
2119 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
2120 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
2121 ShenandoahHeapLocker locker(lock());
2122 _free_set->rebuild();
2123 }
2124 }
2125
2126 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2127 print_on(st);
2128 st->cr();
2129 print_heap_regions_on(st);
2130 }
2131
2132 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2133 size_t slice = r->index() / _bitmap_regions_per_slice;
2134
2135 size_t regions_from = _bitmap_regions_per_slice * slice;
2136 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2137 for (size_t g = regions_from; g < regions_to; g++) {
2138 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2139 if (skip_self && g == r->index()) continue;
2140 if (get_region(g)->is_committed()) {
2141 return true;
2142 }
2190 }
2191
2192 // Uncommit the bitmap slice:
2193 size_t slice = r->index() / _bitmap_regions_per_slice;
2194 size_t off = _bitmap_bytes_per_slice * slice;
2195 size_t len = _bitmap_bytes_per_slice;
2196 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2197 return false;
2198 }
2199 return true;
2200 }
2201
2202 void ShenandoahHeap::safepoint_synchronize_begin() {
2203 SuspendibleThreadSet::synchronize();
2204 }
2205
2206 void ShenandoahHeap::safepoint_synchronize_end() {
2207 SuspendibleThreadSet::desynchronize();
2208 }
2209
2210 void ShenandoahHeap::entry_uncommit(double shrink_before, size_t shrink_until) {
2211 static const char *msg = "Concurrent uncommit";
2212 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */);
2213 EventMark em("%s", msg);
2214
2215 op_uncommit(shrink_before, shrink_until);
2216 }
2217
2218 void ShenandoahHeap::try_inject_alloc_failure() {
2219 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2220 _inject_alloc_failure.set();
2221 os::naked_short_sleep(1);
2222 if (cancelled_gc()) {
2223 log_info(gc)("Allocation failure was successfully injected");
2224 }
2225 }
2226 }
2227
2228 bool ShenandoahHeap::should_inject_alloc_failure() {
2229 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2230 }
2231
2232 void ShenandoahHeap::initialize_serviceability() {
2233 _memory_pool = new ShenandoahMemoryPool(this);
2234 _cycle_memory_manager.add_pool(_memory_pool);
2235 _stw_memory_manager.add_pool(_memory_pool);
2236 }
2237
2238 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2239 GrowableArray<GCMemoryManager*> memory_managers(2);
2240 memory_managers.append(&_cycle_memory_manager);
2241 memory_managers.append(&_stw_memory_manager);
2242 return memory_managers;
2243 }
2244
2245 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2246 GrowableArray<MemoryPool*> memory_pools(1);
2247 memory_pools.append(_memory_pool);
2248 return memory_pools;
2249 }
2250
2251 MemoryUsage ShenandoahHeap::memory_usage() {
2252 return _memory_pool->get_memory_usage();
2253 }
2254
2255 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2256 _heap(ShenandoahHeap::heap()),
2257 _index(0) {}
2258
2259 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2260 _heap(heap),
2261 _index(0) {}
2262
2263 void ShenandoahRegionIterator::reset() {
2264 _index = 0;
2265 }
2266
2267 bool ShenandoahRegionIterator::has_next() const {
2268 return _index < _heap->num_regions();
2269 }
2270
2271 char ShenandoahHeap::gc_state() const {
2272 return _gc_state.raw_value();
2297 }
2298 }
2299
2300 bool ShenandoahHeap::requires_barriers(stackChunkOop obj) const {
2301 if (is_idle()) return false;
2302
2303 // Objects allocated after marking start are implicitly alive, don't need any barriers during
2304 // marking phase.
2305 if (is_concurrent_mark_in_progress() &&
2306 !marking_context()->allocated_after_mark_start(obj)) {
2307 return true;
2308 }
2309
2310 // Can not guarantee obj is deeply good.
2311 if (has_forwarded_objects()) {
2312 return true;
2313 }
2314
2315 return false;
2316 }
|
1 /*
2 * Copyright (c) 2023, 2024, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2013, 2022, Red Hat, Inc. All rights reserved.
4 * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
5 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
6 *
7 * This code is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License version 2 only, as
9 * published by the Free Software Foundation.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 *
25 */
26
27 #include "precompiled.hpp"
28 #include "memory/allocation.hpp"
29 #include "memory/universe.hpp"
30
31 #include "gc/shared/classUnloadingContext.hpp"
32 #include "gc/shared/gcArguments.hpp"
33 #include "gc/shared/gcTimer.hpp"
34 #include "gc/shared/gcTraceTime.inline.hpp"
35 #include "gc/shared/locationPrinter.inline.hpp"
36 #include "gc/shared/memAllocator.hpp"
37 #include "gc/shared/plab.hpp"
38 #include "gc/shared/tlab_globals.hpp"
39
40 #include "gc/shenandoah/heuristics/shenandoahOldHeuristics.hpp"
41 #include "gc/shenandoah/heuristics/shenandoahYoungHeuristics.hpp"
42 #include "gc/shenandoah/shenandoahAllocRequest.hpp"
43 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
44 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
45 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
46 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
47 #include "gc/shenandoah/shenandoahConcurrentMark.hpp"
48 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
49 #include "gc/shenandoah/shenandoahControlThread.hpp"
50 #include "gc/shenandoah/shenandoahFreeSet.hpp"
51 #include "gc/shenandoah/shenandoahGenerationalEvacuationTask.hpp"
52 #include "gc/shenandoah/shenandoahGenerationalHeap.hpp"
53 #include "gc/shenandoah/shenandoahGlobalGeneration.hpp"
54 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
55 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
56 #include "gc/shenandoah/shenandoahHeapRegionClosures.hpp"
57 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
58 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
59 #include "gc/shenandoah/shenandoahInitLogger.hpp"
60 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
61 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
62 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
63 #include "gc/shenandoah/shenandoahOldGeneration.hpp"
64 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
65 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
66 #include "gc/shenandoah/shenandoahPadding.hpp"
67 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
68 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
69 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
70 #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp"
71 #include "gc/shenandoah/shenandoahSTWMark.hpp"
72 #include "gc/shenandoah/shenandoahUtils.hpp"
73 #include "gc/shenandoah/shenandoahVerifier.hpp"
74 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
75 #include "gc/shenandoah/shenandoahVMOperations.hpp"
76 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
77 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
78 #include "gc/shenandoah/shenandoahYoungGeneration.hpp"
79 #include "gc/shenandoah/mode/shenandoahGenerationalMode.hpp"
80 #include "gc/shenandoah/mode/shenandoahIUMode.hpp"
81 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
82 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp"
83 #include "utilities/globalDefinitions.hpp"
84
85 #if INCLUDE_JFR
86 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
87 #endif
88
89 #include "classfile/systemDictionary.hpp"
90 #include "code/codeCache.hpp"
91 #include "memory/classLoaderMetaspace.hpp"
92 #include "memory/metaspaceUtils.hpp"
93 #include "oops/compressedOops.inline.hpp"
94 #include "prims/jvmtiTagMap.hpp"
95 #include "runtime/atomic.hpp"
96 #include "runtime/globals.hpp"
97 #include "runtime/interfaceSupport.inline.hpp"
98 #include "runtime/java.hpp"
99 #include "runtime/orderAccess.hpp"
100 #include "runtime/safepointMechanism.hpp"
101 #include "runtime/vmThread.hpp"
102 #include "services/mallocTracker.hpp"
103 #include "services/memTracker.hpp"
104 #include "utilities/events.hpp"
156 jint ShenandoahHeap::initialize() {
157 //
158 // Figure out heap sizing
159 //
160
161 size_t init_byte_size = InitialHeapSize;
162 size_t min_byte_size = MinHeapSize;
163 size_t max_byte_size = MaxHeapSize;
164 size_t heap_alignment = HeapAlignment;
165
166 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
167
168 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
169 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
170
171 _num_regions = ShenandoahHeapRegion::region_count();
172 assert(_num_regions == (max_byte_size / reg_size_bytes),
173 "Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT,
174 _num_regions, max_byte_size, reg_size_bytes);
175
176 size_t num_committed_regions = init_byte_size / reg_size_bytes;
177 num_committed_regions = MIN2(num_committed_regions, _num_regions);
178 assert(num_committed_regions <= _num_regions, "sanity");
179 _initial_size = num_committed_regions * reg_size_bytes;
180
181 size_t num_min_regions = min_byte_size / reg_size_bytes;
182 num_min_regions = MIN2(num_min_regions, _num_regions);
183 assert(num_min_regions <= _num_regions, "sanity");
184 _minimum_size = num_min_regions * reg_size_bytes;
185
186 // Default to max heap size.
187 _soft_max_size = _num_regions * reg_size_bytes;
188
189 _committed = _initial_size;
190
191 size_t heap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
192 size_t bitmap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
193 size_t region_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
194
195 //
196 // Reserve and commit memory for heap
197 //
198
199 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
200 initialize_reserved_region(heap_rs);
201 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
202 _heap_region_special = heap_rs.special();
203
204 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
205 "Misaligned heap: " PTR_FORMAT, p2i(base()));
206 os::trace_page_sizes_for_requested_size("Heap",
207 max_byte_size, heap_rs.page_size(), heap_alignment,
208 heap_rs.base(), heap_rs.size());
209
210 #if SHENANDOAH_OPTIMIZED_MARKTASK
211 // The optimized ShenandoahMarkTask takes some bits away from the full object bits.
212 // Fail if we ever attempt to address more than we can.
213 if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) {
214 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
215 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
216 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
217 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable());
218 vm_exit_during_initialization("Fatal Error", buf);
219 }
220 #endif
221
222 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
223 if (!_heap_region_special) {
224 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
225 "Cannot commit heap memory");
226 }
227
228 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this, _heap_region));
229
230 // Now we know the number of regions and heap sizes, initialize the heuristics.
231 initialize_heuristics();
232
233 assert(_heap_region.byte_size() == heap_rs.size(), "Need to know reserved size for card table");
234
235 //
236 // Worker threads must be initialized after the barrier is configured
237 //
238 _workers = new ShenandoahWorkerThreads("Shenandoah GC Threads", _max_workers);
239 if (_workers == nullptr) {
240 vm_exit_during_initialization("Failed necessary allocation.");
241 } else {
242 _workers->initialize_workers();
243 }
244
245 if (ParallelGCThreads > 1) {
246 _safepoint_workers = new ShenandoahWorkerThreads("Safepoint Cleanup Thread", ParallelGCThreads);
247 _safepoint_workers->initialize_workers();
248 }
249
250 //
251 // Reserve and commit memory for bitmap(s)
252 //
253
254 size_t bitmap_size_orig = ShenandoahMarkBitMap::compute_size(heap_rs.size());
255 _bitmap_size = align_up(bitmap_size_orig, bitmap_page_size);
256
257 size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor();
258
259 guarantee(bitmap_bytes_per_region != 0,
260 "Bitmap bytes per region should not be zero");
261 guarantee(is_power_of_2(bitmap_bytes_per_region),
262 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
263
264 if (bitmap_page_size > bitmap_bytes_per_region) {
265 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
266 _bitmap_bytes_per_slice = bitmap_page_size;
267 } else {
268 _bitmap_regions_per_slice = 1;
269 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
270 }
271
272 guarantee(_bitmap_regions_per_slice >= 1,
273 "Should have at least one region per slice: " SIZE_FORMAT,
274 _bitmap_regions_per_slice);
275
276 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
277 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
278 _bitmap_bytes_per_slice, bitmap_page_size);
279
280 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
281 os::trace_page_sizes_for_requested_size("Mark Bitmap",
282 bitmap_size_orig, bitmap.page_size(), bitmap_page_size,
283 bitmap.base(),
284 bitmap.size());
285 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
286 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
287 _bitmap_region_special = bitmap.special();
288
289 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
290 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
291 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
292 if (!_bitmap_region_special) {
293 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
294 "Cannot commit bitmap memory");
295 }
296
297 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
298
299 if (ShenandoahVerify) {
300 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
301 os::trace_page_sizes_for_requested_size("Verify Bitmap",
302 bitmap_size_orig, verify_bitmap.page_size(), bitmap_page_size,
303 verify_bitmap.base(),
304 verify_bitmap.size());
305 if (!verify_bitmap.special()) {
306 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
307 "Cannot commit verification bitmap memory");
308 }
309 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
310 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
311 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
312 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
313 }
314
315 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
316 size_t aux_bitmap_page_size = bitmap_page_size;
317
318 ReservedSpace aux_bitmap(_bitmap_size, aux_bitmap_page_size);
319 os::trace_page_sizes_for_requested_size("Aux Bitmap",
320 bitmap_size_orig, aux_bitmap.page_size(), aux_bitmap_page_size,
321 aux_bitmap.base(), aux_bitmap.size());
322 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
323 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
324 _aux_bitmap_region_special = aux_bitmap.special();
325 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
326
327 //
328 // Create regions and region sets
329 //
330 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
331 size_t region_storage_size_orig = region_align * _num_regions;
332 size_t region_storage_size = align_up(region_storage_size_orig,
333 MAX2(region_page_size, os::vm_allocation_granularity()));
334
335 ReservedSpace region_storage(region_storage_size, region_page_size);
336 os::trace_page_sizes_for_requested_size("Region Storage",
337 region_storage_size_orig, region_storage.page_size(), region_page_size,
338 region_storage.base(), region_storage.size());
339 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC);
340 if (!region_storage.special()) {
341 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false,
342 "Cannot commit region memory");
343 }
344
345 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks.
346 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there.
347 // If not successful, bite a bullet and allocate at whatever address.
348 {
349 const size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity());
350 const size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align);
351 const size_t cset_page_size = os::vm_page_size();
352
353 uintptr_t min = round_up_power_of_2(cset_align);
354 uintptr_t max = (1u << 30u);
355 ReservedSpace cset_rs;
356
357 for (uintptr_t addr = min; addr <= max; addr <<= 1u) {
358 char* req_addr = (char*)addr;
359 assert(is_aligned(req_addr, cset_align), "Should be aligned");
360 cset_rs = ReservedSpace(cset_size, cset_align, cset_page_size, req_addr);
361 if (cset_rs.is_reserved()) {
362 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr);
363 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
364 break;
365 }
366 }
367
368 if (_collection_set == nullptr) {
369 cset_rs = ReservedSpace(cset_size, cset_align, os::vm_page_size());
370 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
371 }
372 os::trace_page_sizes_for_requested_size("Collection Set",
373 cset_size, cset_rs.page_size(), cset_page_size,
374 cset_rs.base(),
375 cset_rs.size());
376 }
377
378 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
379 _affiliations = NEW_C_HEAP_ARRAY(uint8_t, _num_regions, mtGC);
380 _free_set = new ShenandoahFreeSet(this, _num_regions);
381
382 {
383 ShenandoahHeapLocker locker(lock());
384
385 for (size_t i = 0; i < _num_regions; i++) {
386 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
387 bool is_committed = i < num_committed_regions;
388 void* loc = region_storage.base() + i * region_align;
389
390 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
391 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
392
393 _marking_context->initialize_top_at_mark_start(r);
394 _regions[i] = r;
395 assert(!collection_set()->is_in(i), "New region should not be in collection set");
396
397 _affiliations[i] = ShenandoahAffiliation::FREE;
398 }
399
400 // Initialize to complete
401 _marking_context->mark_complete();
402 size_t young_cset_regions, old_cset_regions;
403
404 // We are initializing free set. We ignore cset region tallies.
405 size_t first_old, last_old, num_old;
406 _free_set->prepare_to_rebuild(young_cset_regions, old_cset_regions, first_old, last_old, num_old);
407 _free_set->finish_rebuild(young_cset_regions, old_cset_regions, num_old);
408 }
409
410 if (AlwaysPreTouch) {
411 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
412 // before initialize() below zeroes it with initializing thread. For any given region,
413 // we touch the region and the corresponding bitmaps from the same thread.
414 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
415
416 _pretouch_heap_page_size = heap_page_size;
417 _pretouch_bitmap_page_size = bitmap_page_size;
418
419 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
420 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
421
422 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size);
423 _workers->run_task(&bcl);
424
425 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size);
426 _workers->run_task(&hcl);
427 }
428
429 //
430 // Initialize the rest of GC subsystems
431 //
432
433 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC);
434 for (uint worker = 0; worker < _max_workers; worker++) {
435 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC);
436 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData));
437 }
438
439 // There should probably be Shenandoah-specific options for these,
440 // just as there are G1-specific options.
441 {
442 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
443 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
444 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
445 }
446
447 _monitoring_support = new ShenandoahMonitoringSupport(this);
448 _phase_timings = new ShenandoahPhaseTimings(max_workers());
449 ShenandoahCodeRoots::initialize();
450
451 if (ShenandoahPacing) {
452 _pacer = new ShenandoahPacer(this);
453 _pacer->setup_for_idle();
454 }
455
456 initialize_controller();
457
458 print_init_logger();
459
460 return JNI_OK;
461 }
462
463 void ShenandoahHeap::initialize_controller() {
464 _control_thread = new ShenandoahControlThread();
465 }
466
467 void ShenandoahHeap::print_init_logger() const {
468 ShenandoahInitLogger::print();
469 }
470
471 void ShenandoahHeap::initialize_mode() {
472 if (ShenandoahGCMode != nullptr) {
473 if (strcmp(ShenandoahGCMode, "satb") == 0) {
474 _gc_mode = new ShenandoahSATBMode();
475 } else if (strcmp(ShenandoahGCMode, "iu") == 0) {
476 _gc_mode = new ShenandoahIUMode();
477 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
478 _gc_mode = new ShenandoahPassiveMode();
479 } else if (strcmp(ShenandoahGCMode, "generational") == 0) {
480 _gc_mode = new ShenandoahGenerationalMode();
481 } else {
482 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
483 }
484 } else {
485 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option (null)");
486 }
487 _gc_mode->initialize_flags();
488 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
489 vm_exit_during_initialization(
490 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
491 _gc_mode->name()));
492 }
493 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
494 vm_exit_during_initialization(
495 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
496 _gc_mode->name()));
497 }
498 }
499
500 void ShenandoahHeap::initialize_heuristics() {
501 _global_generation = new ShenandoahGlobalGeneration(mode()->is_generational(), max_workers(), max_capacity(), max_capacity());
502 _global_generation->initialize_heuristics(mode());
503 }
504
505 #ifdef _MSC_VER
506 #pragma warning( push )
507 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
508 #endif
509
510 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
511 CollectedHeap(),
512 _gc_generation(nullptr),
513 _active_generation(nullptr),
514 _initial_size(0),
515 _committed(0),
516 _max_workers(MAX3(ConcGCThreads, ParallelGCThreads, 1U)),
517 _workers(nullptr),
518 _safepoint_workers(nullptr),
519 _heap_region_special(false),
520 _num_regions(0),
521 _regions(nullptr),
522 _affiliations(nullptr),
523 _gc_state_changed(false),
524 _gc_no_progress_count(0),
525 _cancel_requested_time(0),
526 _update_refs_iterator(this),
527 _global_generation(nullptr),
528 _control_thread(nullptr),
529 _young_generation(nullptr),
530 _old_generation(nullptr),
531 _shenandoah_policy(policy),
532 _gc_mode(nullptr),
533 _free_set(nullptr),
534 _pacer(nullptr),
535 _verifier(nullptr),
536 _phase_timings(nullptr),
537 _monitoring_support(nullptr),
538 _memory_pool(nullptr),
539 _stw_memory_manager("Shenandoah Pauses"),
540 _cycle_memory_manager("Shenandoah Cycles"),
541 _gc_timer(new ConcurrentGCTimer()),
542 _soft_ref_policy(),
543 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
544 _marking_context(nullptr),
545 _bitmap_size(0),
546 _bitmap_regions_per_slice(0),
547 _bitmap_bytes_per_slice(0),
548 _bitmap_region_special(false),
549 _aux_bitmap_region_special(false),
550 _liveness_cache(nullptr),
551 _collection_set(nullptr)
552 {
553 // Initialize GC mode early, many subsequent initialization procedures depend on it
554 initialize_mode();
555 }
556
557 #ifdef _MSC_VER
558 #pragma warning( pop )
559 #endif
560
561 void ShenandoahHeap::print_on(outputStream* st) const {
562 st->print_cr("Shenandoah Heap");
563 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
564 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
565 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()),
566 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
567 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
568 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
569 num_regions(),
570 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
571 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
572
573 st->print("Status: ");
574 if (has_forwarded_objects()) st->print("has forwarded objects, ");
575 if (!mode()->is_generational()) {
576 if (is_concurrent_mark_in_progress()) st->print("marking,");
577 } else {
578 if (is_concurrent_old_mark_in_progress()) st->print("old marking, ");
579 if (is_concurrent_young_mark_in_progress()) st->print("young marking, ");
580 }
581 if (is_evacuation_in_progress()) st->print("evacuating, ");
582 if (is_update_refs_in_progress()) st->print("updating refs, ");
583 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
584 if (is_full_gc_in_progress()) st->print("full gc, ");
585 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
586 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, ");
587 if (is_concurrent_strong_root_in_progress() &&
588 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, ");
589
590 if (cancelled_gc()) {
591 st->print("cancelled");
592 } else {
593 st->print("not cancelled");
594 }
595 st->cr();
596
597 st->print_cr("Reserved region:");
598 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
599 p2i(reserved_region().start()),
600 p2i(reserved_region().end()));
611 st->cr();
612 MetaspaceUtils::print_on(st);
613
614 if (Verbose) {
615 st->cr();
616 print_heap_regions_on(st);
617 }
618 }
619
620 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
621 public:
622 void do_thread(Thread* thread) {
623 assert(thread != nullptr, "Sanity");
624 assert(thread->is_Worker_thread(), "Only worker thread expected");
625 ShenandoahThreadLocalData::initialize_gclab(thread);
626 }
627 };
628
629 void ShenandoahHeap::post_initialize() {
630 CollectedHeap::post_initialize();
631
632 // Schedule periodic task to report on gc thread CPU utilization
633 _mmu_tracker.initialize();
634
635 MutexLocker ml(Threads_lock);
636
637 ShenandoahInitWorkerGCLABClosure init_gclabs;
638 _workers->threads_do(&init_gclabs);
639
640 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
641 // Now, we will let WorkerThreads to initialize gclab when new worker is created.
642 _workers->set_initialize_gclab();
643 if (_safepoint_workers != nullptr) {
644 _safepoint_workers->threads_do(&init_gclabs);
645 _safepoint_workers->set_initialize_gclab();
646 }
647
648 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
649 }
650
651 ShenandoahHeuristics* ShenandoahHeap::heuristics() {
652 return _global_generation->heuristics();
653 }
654
655 size_t ShenandoahHeap::used() const {
656 return global_generation()->used();
657 }
658
659 size_t ShenandoahHeap::committed() const {
660 return Atomic::load(&_committed);
661 }
662
663 void ShenandoahHeap::increase_committed(size_t bytes) {
664 shenandoah_assert_heaplocked_or_safepoint();
665 _committed += bytes;
666 }
667
668 void ShenandoahHeap::decrease_committed(size_t bytes) {
669 shenandoah_assert_heaplocked_or_safepoint();
670 _committed -= bytes;
671 }
672
673 // For tracking usage based on allocations, it should be the case that:
674 // * The sum of regions::used == heap::used
675 // * The sum of a generation's regions::used == generation::used
676 // * The sum of a generation's humongous regions::free == generation::humongous_waste
677 // These invariants are checked by the verifier on GC safepoints.
678 //
679 // Additional notes:
680 // * When a mutator's allocation request causes a region to be retired, the
681 // free memory left in that region is considered waste. It does not contribute
682 // to the usage, but it _does_ contribute to allocation rate.
683 // * The bottom of a PLAB must be aligned on card size. In some cases this will
684 // require padding in front of the PLAB (a filler object). Because this padding
685 // is included in the region's used memory we include the padding in the usage
686 // accounting as waste.
687 // * Mutator allocations are used to compute an allocation rate. They are also
688 // sent to the Pacer for those purposes.
689 // * There are three sources of waste:
690 // 1. The padding used to align a PLAB on card size
691 // 2. Region's free is less than minimum TLAB size and is retired
692 // 3. The unused portion of memory in the last region of a humongous object
693 void ShenandoahHeap::increase_used(const ShenandoahAllocRequest& req) {
694 size_t actual_bytes = req.actual_size() * HeapWordSize;
695 size_t wasted_bytes = req.waste() * HeapWordSize;
696 ShenandoahGeneration* generation = generation_for(req.affiliation());
697
698 if (req.is_gc_alloc()) {
699 assert(wasted_bytes == 0 || req.type() == ShenandoahAllocRequest::_alloc_plab, "Only PLABs have waste");
700 increase_used(generation, actual_bytes + wasted_bytes);
701 } else {
702 assert(req.is_mutator_alloc(), "Expected mutator alloc here");
703 // padding and actual size both count towards allocation counter
704 generation->increase_allocated(actual_bytes + wasted_bytes);
705
706 // only actual size counts toward usage for mutator allocations
707 increase_used(generation, actual_bytes);
708
709 // notify pacer of both actual size and waste
710 notify_mutator_alloc_words(req.actual_size(), req.waste());
711
712 if (wasted_bytes > 0 && ShenandoahHeapRegion::requires_humongous(req.actual_size())) {
713 increase_humongous_waste(generation,wasted_bytes);
714 }
715 }
716 }
717
718 void ShenandoahHeap::increase_humongous_waste(ShenandoahGeneration* generation, size_t bytes) {
719 generation->increase_humongous_waste(bytes);
720 if (!generation->is_global()) {
721 global_generation()->increase_humongous_waste(bytes);
722 }
723 }
724
725 void ShenandoahHeap::decrease_humongous_waste(ShenandoahGeneration* generation, size_t bytes) {
726 generation->decrease_humongous_waste(bytes);
727 if (!generation->is_global()) {
728 global_generation()->decrease_humongous_waste(bytes);
729 }
730 }
731
732 void ShenandoahHeap::increase_used(ShenandoahGeneration* generation, size_t bytes) {
733 generation->increase_used(bytes);
734 if (!generation->is_global()) {
735 global_generation()->increase_used(bytes);
736 }
737 }
738
739 void ShenandoahHeap::decrease_used(ShenandoahGeneration* generation, size_t bytes) {
740 generation->decrease_used(bytes);
741 if (!generation->is_global()) {
742 global_generation()->decrease_used(bytes);
743 }
744 }
745
746 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, size_t waste) {
747 if (ShenandoahPacing) {
748 control_thread()->pacing_notify_alloc(words);
749 if (waste > 0) {
750 pacer()->claim_for_alloc<true>(waste);
751 }
752 }
753 }
754
755 size_t ShenandoahHeap::capacity() const {
756 return committed();
757 }
758
759 size_t ShenandoahHeap::max_capacity() const {
760 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
761 }
762
763 size_t ShenandoahHeap::soft_max_capacity() const {
764 size_t v = Atomic::load(&_soft_max_size);
765 assert(min_capacity() <= v && v <= max_capacity(),
766 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
767 min_capacity(), v, max_capacity());
768 return v;
769 }
770
771 void ShenandoahHeap::set_soft_max_capacity(size_t v) {
772 assert(min_capacity() <= v && v <= max_capacity(),
773 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
774 min_capacity(), v, max_capacity());
775 Atomic::store(&_soft_max_size, v);
776 }
777
778 size_t ShenandoahHeap::min_capacity() const {
779 return _minimum_size;
780 }
781
782 size_t ShenandoahHeap::initial_capacity() const {
783 return _initial_size;
784 }
785
786 void ShenandoahHeap::maybe_uncommit(double shrink_before, size_t shrink_until) {
787 assert (ShenandoahUncommit, "should be enabled");
788
789 // Determine if there is work to do. This avoids taking heap lock if there is
790 // no work available, avoids spamming logs with superfluous logging messages,
791 // and minimises the amount of work while locks are taken.
792
793 if (committed() <= shrink_until) return;
794
795 bool has_work = false;
796 for (size_t i = 0; i < num_regions(); i++) {
797 ShenandoahHeapRegion* r = get_region(i);
798 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
799 has_work = true;
800 break;
801 }
802 }
803
804 if (has_work) {
805 static const char* msg = "Concurrent uncommit";
806 ShenandoahConcurrentPhase gcPhase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */);
807 EventMark em("%s", msg);
808
809 op_uncommit(shrink_before, shrink_until);
810 }
811 }
812
813 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
814 assert (ShenandoahUncommit, "should be enabled");
815
816 // Application allocates from the beginning of the heap, and GC allocates at
817 // the end of it. It is more efficient to uncommit from the end, so that applications
818 // could enjoy the near committed regions. GC allocations are much less frequent,
819 // and therefore can accept the committing costs.
820
821 size_t count = 0;
822 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
823 ShenandoahHeapRegion* r = get_region(i - 1);
824 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
825 ShenandoahHeapLocker locker(lock());
826 if (r->is_empty_committed()) {
827 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) {
828 break;
829 }
830
831 r->make_uncommitted();
832 count++;
833 }
834 }
835 SpinPause(); // allow allocators to take the lock
836 }
837
838 if (count > 0) {
839 notify_heap_changed();
840 }
841 }
842
843 bool ShenandoahHeap::check_soft_max_changed() {
844 size_t new_soft_max = Atomic::load(&SoftMaxHeapSize);
845 size_t old_soft_max = soft_max_capacity();
846 if (new_soft_max != old_soft_max) {
847 new_soft_max = MAX2(min_capacity(), new_soft_max);
848 new_soft_max = MIN2(max_capacity(), new_soft_max);
849 if (new_soft_max != old_soft_max) {
850 log_info(gc)("Soft Max Heap Size: " SIZE_FORMAT "%s -> " SIZE_FORMAT "%s",
851 byte_size_in_proper_unit(old_soft_max), proper_unit_for_byte_size(old_soft_max),
852 byte_size_in_proper_unit(new_soft_max), proper_unit_for_byte_size(new_soft_max)
853 );
854 set_soft_max_capacity(new_soft_max);
855 return true;
856 }
857 }
858 return false;
859 }
860
861 void ShenandoahHeap::notify_heap_changed() {
862 // Update monitoring counters when we took a new region. This amortizes the
863 // update costs on slow path.
864 monitoring_support()->notify_heap_changed();
865 _heap_changed.try_set();
866 }
867
868 void ShenandoahHeap::set_forced_counters_update(bool value) {
869 monitoring_support()->set_forced_counters_update(value);
870 }
871
872 void ShenandoahHeap::handle_force_counters_update() {
873 monitoring_support()->handle_force_counters_update();
874 }
875
876 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
877 // New object should fit the GCLAB size
878 size_t min_size = MAX2(size, PLAB::min_size());
879
880 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
881 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
882
883 new_size = MIN2(new_size, PLAB::max_size());
884 new_size = MAX2(new_size, PLAB::min_size());
885
886 // Record new heuristic value even if we take any shortcut. This captures
887 // the case when moderately-sized objects always take a shortcut. At some point,
888 // heuristics should catch up with them.
889 log_debug(gc, free)("Set new GCLAB size: " SIZE_FORMAT, new_size);
890 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
891
892 if (new_size < size) {
893 // New size still does not fit the object. Fall back to shared allocation.
894 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
895 log_debug(gc, free)("New gclab size (" SIZE_FORMAT ") is too small for " SIZE_FORMAT, new_size, size);
896 return nullptr;
897 }
898
899 // Retire current GCLAB, and allocate a new one.
900 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
901 gclab->retire();
902
903 size_t actual_size = 0;
904 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
905 if (gclab_buf == nullptr) {
906 return nullptr;
907 }
908
909 assert (size <= actual_size, "allocation should fit");
910
911 // ...and clear or zap just allocated TLAB, if needed.
912 if (ZeroTLAB) {
913 Copy::zero_to_words(gclab_buf, actual_size);
914 } else if (ZapTLAB) {
915 // Skip mangling the space corresponding to the object header to
916 // ensure that the returned space is not considered parsable by
917 // any concurrent GC thread.
918 size_t hdr_size = oopDesc::header_size();
919 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
920 }
921 gclab->set_buf(gclab_buf, actual_size);
922 return gclab->allocate(size);
923 }
924
925 // Called from stubs in JIT code or interpreter
926 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
927 size_t requested_size,
928 size_t* actual_size) {
929 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
930 HeapWord* res = allocate_memory(req);
931 if (res != nullptr) {
932 *actual_size = req.actual_size();
933 } else {
934 *actual_size = 0;
935 }
936 return res;
937 }
938
939 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
940 size_t word_size,
941 size_t* actual_size) {
942 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
943 HeapWord* res = allocate_memory(req);
944 if (res != nullptr) {
945 *actual_size = req.actual_size();
947 *actual_size = 0;
948 }
949 return res;
950 }
951
952 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
953 intptr_t pacer_epoch = 0;
954 bool in_new_region = false;
955 HeapWord* result = nullptr;
956
957 if (req.is_mutator_alloc()) {
958 if (ShenandoahPacing) {
959 pacer()->pace_for_alloc(req.size());
960 pacer_epoch = pacer()->epoch();
961 }
962
963 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
964 result = allocate_memory_under_lock(req, in_new_region);
965 }
966
967 // Check that gc overhead is not exceeded.
968 //
969 // Shenandoah will grind along for quite a while allocating one
970 // object at a time using shared (non-tlab) allocations. This check
971 // is testing that the GC overhead limit has not been exceeded.
972 // This will notify the collector to start a cycle, but will raise
973 // an OOME to the mutator if the last Full GCs have not made progress.
974 // gc_no_progress_count is incremented following each degen or full GC that fails to achieve is_good_progress().
975 if ((result == nullptr) && !req.is_lab_alloc() && (get_gc_no_progress_count() > ShenandoahNoProgressThreshold)) {
976 control_thread()->handle_alloc_failure(req, false);
977 req.set_actual_size(0);
978 return nullptr;
979 }
980
981 if (result == nullptr) {
982 // Block until control thread reacted, then retry allocation.
983 //
984 // It might happen that one of the threads requesting allocation would unblock
985 // way later after GC happened, only to fail the second allocation, because
986 // other threads have already depleted the free storage. In this case, a better
987 // strategy is to try again, until at least one full GC has completed.
988 //
989 // Stop retrying and return nullptr to cause OOMError exception if our allocation failed even after:
990 // a) We experienced a GC that had good progress, or
991 // b) We experienced at least one Full GC (whether or not it had good progress)
992
993 size_t original_count = shenandoah_policy()->full_gc_count();
994 while ((result == nullptr) && (original_count == shenandoah_policy()->full_gc_count())) {
995 control_thread()->handle_alloc_failure(req, true);
996 result = allocate_memory_under_lock(req, in_new_region);
997 }
998 if (result != nullptr) {
999 // If our allocation request has been satisifed after it initially failed, we count this as good gc progress
1000 notify_gc_progress();
1001 }
1002 if (log_develop_is_enabled(Debug, gc, alloc)) {
1003 ResourceMark rm;
1004 log_debug(gc, alloc)("Thread: %s, Result: " PTR_FORMAT ", Request: %s, Size: " SIZE_FORMAT
1005 ", Original: " SIZE_FORMAT ", Latest: " SIZE_FORMAT,
1006 Thread::current()->name(), p2i(result), req.type_string(), req.size(),
1007 original_count, get_gc_no_progress_count());
1008 }
1009 }
1010 } else {
1011 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
1012 result = allocate_memory_under_lock(req, in_new_region);
1013 // Do not call handle_alloc_failure() here, because we cannot block.
1014 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
1015 }
1016
1017 if (in_new_region) {
1018 notify_heap_changed();
1019 }
1020
1021 if (result == nullptr) {
1022 req.set_actual_size(0);
1023 }
1024
1025 // This is called regardless of the outcome of the allocation to account
1026 // for any waste created by retiring regions with this request.
1027 increase_used(req);
1028
1029 if (result != nullptr) {
1030 size_t requested = req.size();
1031 size_t actual = req.actual_size();
1032
1033 assert (req.is_lab_alloc() || (requested == actual),
1034 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
1035 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
1036
1037 if (req.is_mutator_alloc()) {
1038 // If we requested more than we were granted, give the rest back to pacer.
1039 // This only matters if we are in the same pacing epoch: do not try to unpace
1040 // over the budget for the other phase.
1041 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
1042 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
1043 }
1044 }
1045 }
1046
1047 return result;
1048 }
1049
1050 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
1051 // If we are dealing with mutator allocation, then we may need to block for safepoint.
1052 // We cannot block for safepoint for GC allocations, because there is a high chance
1053 // we are already running at safepoint or from stack watermark machinery, and we cannot
1054 // block again.
1055 ShenandoahHeapLocker locker(lock(), req.is_mutator_alloc());
1056
1057 // Make sure the old generation has room for either evacuations or promotions before trying to allocate.
1058 if (req.is_old() && !old_generation()->can_allocate(req)) {
1059 return nullptr;
1060 }
1061
1062 // If TLAB request size is greater than available, allocate() will attempt to downsize request to fit within available
1063 // memory.
1064 HeapWord* result = _free_set->allocate(req, in_new_region);
1065
1066 // Record the plab configuration for this result and register the object.
1067 if (result != nullptr && req.is_old()) {
1068 old_generation()->configure_plab_for_current_thread(req);
1069 if (req.type() == ShenandoahAllocRequest::_alloc_shared_gc) {
1070 // Register the newly allocated object while we're holding the global lock since there's no synchronization
1071 // built in to the implementation of register_object(). There are potential races when multiple independent
1072 // threads are allocating objects, some of which might span the same card region. For example, consider
1073 // a card table's memory region within which three objects are being allocated by three different threads:
1074 //
1075 // objects being "concurrently" allocated:
1076 // [-----a------][-----b-----][--------------c------------------]
1077 // [---- card table memory range --------------]
1078 //
1079 // Before any objects are allocated, this card's memory range holds no objects. Note that allocation of object a
1080 // wants to set the starts-object, first-start, and last-start attributes of the preceding card region.
1081 // Allocation of object b wants to set the starts-object, first-start, and last-start attributes of this card region.
1082 // Allocation of object c also wants to set the starts-object, first-start, and last-start attributes of this
1083 // card region.
1084 //
1085 // The thread allocating b and the thread allocating c can "race" in various ways, resulting in confusion, such as
1086 // last-start representing object b while first-start represents object c. This is why we need to require all
1087 // register_object() invocations to be "mutually exclusive" with respect to each card's memory range.
1088 old_generation()->card_scan()->register_object(result);
1089 }
1090 }
1091
1092 return result;
1093 }
1094
1095 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
1096 bool* gc_overhead_limit_was_exceeded) {
1097 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
1098 return allocate_memory(req);
1099 }
1100
1101 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
1102 size_t size,
1103 Metaspace::MetadataType mdtype) {
1104 MetaWord* result;
1105
1106 // Inform metaspace OOM to GC heuristics if class unloading is possible.
1107 ShenandoahHeuristics* h = global_generation()->heuristics();
1108 if (h->can_unload_classes()) {
1109 h->record_metaspace_oom();
1110 }
1111
1112 // Expand and retry allocation
1113 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
1114 if (result != nullptr) {
1115 return result;
1116 }
1117
1118 // Start full GC
1119 collect(GCCause::_metadata_GC_clear_soft_refs);
1120
1121 // Retry allocation
1122 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
1123 if (result != nullptr) {
1124 return result;
1125 }
1126
1127 // Expand and retry allocation
1128 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
1185 while ((r =_cs->claim_next()) != nullptr) {
1186 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
1187 _sh->marked_object_iterate(r, &cl);
1188
1189 if (ShenandoahPacing) {
1190 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
1191 }
1192
1193 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
1194 break;
1195 }
1196 }
1197 }
1198 };
1199
1200 void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
1201 ShenandoahEvacuationTask task(this, _collection_set, concurrent);
1202 workers()->run_task(&task);
1203 }
1204
1205 oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) {
1206 assert(thread == Thread::current(), "Expected thread parameter to be current thread.");
1207 if (ShenandoahThreadLocalData::is_oom_during_evac(thread)) {
1208 // This thread went through the OOM during evac protocol. It is safe to return
1209 // the forward pointer. It must not attempt to evacuate any other objects.
1210 return ShenandoahBarrierSet::resolve_forwarded(p);
1211 }
1212
1213 assert(ShenandoahThreadLocalData::is_evac_allowed(thread), "must be enclosed in oom-evac scope");
1214
1215 ShenandoahHeapRegion* r = heap_region_containing(p);
1216 assert(!r->is_humongous(), "never evacuate humongous objects");
1217
1218 ShenandoahAffiliation target_gen = r->affiliation();
1219 return try_evacuate_object(p, thread, r, target_gen);
1220 }
1221
1222 oop ShenandoahHeap::try_evacuate_object(oop p, Thread* thread, ShenandoahHeapRegion* from_region,
1223 ShenandoahAffiliation target_gen) {
1224 assert(target_gen == YOUNG_GENERATION, "Only expect evacuations to young in this mode");
1225 assert(from_region->is_young(), "Only expect evacuations from young in this mode");
1226 bool alloc_from_lab = true;
1227 HeapWord* copy = nullptr;
1228 size_t size = p->size();
1229
1230 #ifdef ASSERT
1231 if (ShenandoahOOMDuringEvacALot &&
1232 (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call
1233 copy = nullptr;
1234 } else {
1235 #endif
1236 if (UseTLAB) {
1237 copy = allocate_from_gclab(thread, size);
1238 }
1239 if (copy == nullptr) {
1240 // If we failed to allocate in LAB, we'll try a shared allocation.
1241 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size, target_gen);
1242 copy = allocate_memory(req);
1243 alloc_from_lab = false;
1244 }
1245 #ifdef ASSERT
1246 }
1247 #endif
1248
1249 if (copy == nullptr) {
1250 control_thread()->handle_alloc_failure_evac(size);
1251
1252 _oom_evac_handler.handle_out_of_memory_during_evacuation();
1253
1254 return ShenandoahBarrierSet::resolve_forwarded(p);
1255 }
1256
1257 // Copy the object:
1258 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(p), copy, size);
1259
1260 // Try to install the new forwarding pointer.
1261 oop copy_val = cast_to_oop(copy);
1262 oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val);
1263 if (result == copy_val) {
1264 // Successfully evacuated. Our copy is now the public one!
1265 ContinuationGCSupport::relativize_stack_chunk(copy_val);
1266 shenandoah_assert_correct(nullptr, copy_val);
1267 return copy_val;
1268 } else {
1269 // Failed to evacuate. We need to deal with the object that is left behind. Since this
1270 // new allocation is certainly after TAMS, it will be considered live in the next cycle.
1271 // But if it happens to contain references to evacuated regions, those references would
1272 // not get updated for this stale copy during this cycle, and we will crash while scanning
1273 // it the next cycle.
1274 if (alloc_from_lab) {
1275 // For LAB allocations, it is enough to rollback the allocation ptr. Either the next
1276 // object will overwrite this stale copy, or the filler object on LAB retirement will
1277 // do this.
1278 ShenandoahThreadLocalData::gclab(thread)->undo_allocation(copy, size);
1279 } else {
1280 // For non-LAB allocations, we have no way to retract the allocation, and
1281 // have to explicitly overwrite the copy with the filler object. With that overwrite,
1282 // we have to keep the fwdptr initialized and pointing to our (stale) copy.
1283 assert(size >= ShenandoahHeap::min_fill_size(), "previously allocated object known to be larger than min_size");
1284 fill_with_object(copy, size);
1285 shenandoah_assert_correct(nullptr, copy_val);
1286 // For non-LAB allocations, the object has already been registered
1287 }
1288 shenandoah_assert_correct(nullptr, result);
1289 return result;
1290 }
1291 }
1292
1293 void ShenandoahHeap::trash_cset_regions() {
1294 ShenandoahHeapLocker locker(lock());
1295
1296 ShenandoahCollectionSet* set = collection_set();
1297 ShenandoahHeapRegion* r;
1298 set->clear_current_index();
1299 while ((r = set->next()) != nullptr) {
1300 r->make_trash();
1301 }
1302 collection_set()->clear();
1303 }
1304
1305 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1306 st->print_cr("Heap Regions:");
1307 st->print_cr("Region state: EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HP=pinned humongous start");
1308 st->print_cr(" HC=humongous continuation, CS=collection set, TR=trash, P=pinned, CSP=pinned collection set");
1309 st->print_cr("BTE=bottom/top/end, TAMS=top-at-mark-start");
1310 st->print_cr("UWM=update watermark, U=used");
1311 st->print_cr("T=TLAB allocs, G=GCLAB allocs");
1312 st->print_cr("S=shared allocs, L=live data");
1313 st->print_cr("CP=critical pins");
1314
1315 for (size_t i = 0; i < num_regions(); i++) {
1316 get_region(i)->print_on(st);
1317 }
1318 }
1319
1320 size_t ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1321 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1322
1323 oop humongous_obj = cast_to_oop(start->bottom());
1324 size_t size = humongous_obj->size();
1325 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1326 size_t index = start->index() + required_regions - 1;
1327
1328 assert(!start->has_live(), "liveness must be zero");
1329
1330 for(size_t i = 0; i < required_regions; i++) {
1331 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1332 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1333 ShenandoahHeapRegion* region = get_region(index --);
1334
1335 assert(region->is_humongous(), "expect correct humongous start or continuation");
1336 assert(!region->is_cset(), "Humongous region should not be in collection set");
1337
1338 region->make_trash_immediate();
1339 }
1340 return required_regions;
1341 }
1342
1343 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1344 public:
1345 ShenandoahCheckCleanGCLABClosure() {}
1346 void do_thread(Thread* thread) {
1347 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1348 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1349 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
1350
1351 if (ShenandoahHeap::heap()->mode()->is_generational()) {
1352 PLAB* plab = ShenandoahThreadLocalData::plab(thread);
1353 assert(plab != nullptr, "PLAB should be initialized for %s", thread->name());
1354 assert(plab->words_remaining() == 0, "PLAB should not need retirement");
1355 }
1356 }
1357 };
1358
1359 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1360 private:
1361 bool const _resize;
1362 public:
1363 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1364 void do_thread(Thread* thread) {
1365 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1366 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1367 gclab->retire();
1368 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1369 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1370 }
1371
1372 if (ShenandoahHeap::heap()->mode()->is_generational()) {
1373 PLAB* plab = ShenandoahThreadLocalData::plab(thread);
1374 assert(plab != nullptr, "PLAB should be initialized for %s", thread->name());
1375
1376 // There are two reasons to retire all plabs between old-gen evacuation passes.
1377 // 1. We need to make the plab memory parsable by remembered-set scanning.
1378 // 2. We need to establish a trustworthy UpdateWaterMark value within each old-gen heap region
1379 ShenandoahGenerationalHeap::heap()->retire_plab(plab, thread);
1380 if (_resize && ShenandoahThreadLocalData::plab_size(thread) > 0) {
1381 ShenandoahThreadLocalData::set_plab_size(thread, 0);
1382 }
1383 }
1384 }
1385 };
1386
1387 void ShenandoahHeap::labs_make_parsable() {
1388 assert(UseTLAB, "Only call with UseTLAB");
1389
1390 ShenandoahRetireGCLABClosure cl(false);
1391
1392 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1393 ThreadLocalAllocBuffer& tlab = t->tlab();
1394 tlab.make_parsable();
1395 cl.do_thread(t);
1396 }
1397
1398 workers()->threads_do(&cl);
1399 }
1400
1401 void ShenandoahHeap::tlabs_retire(bool resize) {
1402 assert(UseTLAB, "Only call with UseTLAB");
1403 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1433 }
1434 workers()->threads_do(&cl);
1435
1436 if (safepoint_workers() != nullptr) {
1437 safepoint_workers()->threads_do(&cl);
1438 }
1439 }
1440
1441 // Returns size in bytes
1442 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1443 // Return the max allowed size, and let the allocation path
1444 // figure out the safe size for current allocation.
1445 return ShenandoahHeapRegion::max_tlab_size_bytes();
1446 }
1447
1448 size_t ShenandoahHeap::max_tlab_size() const {
1449 // Returns size in words
1450 return ShenandoahHeapRegion::max_tlab_size_words();
1451 }
1452
1453 void ShenandoahHeap::collect_as_vm_thread(GCCause::Cause cause) {
1454 // These requests are ignored because we can't easily have Shenandoah jump into
1455 // a synchronous (degenerated or full) cycle while it is in the middle of a concurrent
1456 // cycle. We _could_ cancel the concurrent cycle and then try to run a cycle directly
1457 // on the VM thread, but this would confuse the control thread mightily and doesn't
1458 // seem worth the trouble. Instead, we will have the caller thread run (and wait for) a
1459 // concurrent cycle in the prologue of the heap inspect/dump operation. This is how
1460 // other concurrent collectors in the JVM handle this scenario as well.
1461 assert(Thread::current()->is_VM_thread(), "Should be the VM thread");
1462 guarantee(cause == GCCause::_heap_dump || cause == GCCause::_heap_inspection, "Invalid cause");
1463 }
1464
1465 void ShenandoahHeap::collect(GCCause::Cause cause) {
1466 control_thread()->request_gc(cause);
1467 }
1468
1469 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1470 //assert(false, "Shouldn't need to do full collections");
1471 }
1472
1473 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1474 ShenandoahHeapRegion* r = heap_region_containing(addr);
1475 if (r != nullptr) {
1476 return r->block_start(addr);
1477 }
1478 return nullptr;
1479 }
1480
1481 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1482 ShenandoahHeapRegion* r = heap_region_containing(addr);
1483 return r->block_is_obj(addr);
1484 }
1485
1486 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1487 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1488 }
1489
1490 void ShenandoahHeap::prepare_for_verify() {
1491 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) {
1492 labs_make_parsable();
1493 }
1494 }
1495
1496 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1497 if (_shenandoah_policy->is_at_shutdown()) {
1498 return;
1499 }
1500
1501 if (_control_thread != nullptr) {
1502 tcl->do_thread(_control_thread);
1503 }
1504
1505 workers()->threads_do(tcl);
1506 if (_safepoint_workers != nullptr) {
1507 _safepoint_workers->threads_do(tcl);
1508 }
1509 }
1510
1511 void ShenandoahHeap::print_tracing_info() const {
1512 LogTarget(Info, gc, stats) lt;
1513 if (lt.is_enabled()) {
1514 ResourceMark rm;
1515 LogStream ls(lt);
1516
1517 phase_timings()->print_global_on(&ls);
1518
1519 ls.cr();
1520 ls.cr();
1521
1522 shenandoah_policy()->print_gc_stats(&ls);
1523
1524 ls.cr();
1525 ls.cr();
1526 }
1527 }
1528
1529 void ShenandoahHeap::set_gc_generation(ShenandoahGeneration* generation) {
1530 shenandoah_assert_control_or_vm_thread_at_safepoint();
1531 _gc_generation = generation;
1532 }
1533
1534 // Active generation may only be set by the VM thread at a safepoint.
1535 void ShenandoahHeap::set_active_generation() {
1536 assert(Thread::current()->is_VM_thread(), "Only the VM Thread");
1537 assert(SafepointSynchronize::is_at_safepoint(), "Only at a safepoint!");
1538 assert(_gc_generation != nullptr, "Will set _active_generation to nullptr");
1539 _active_generation = _gc_generation;
1540 }
1541
1542 void ShenandoahHeap::on_cycle_start(GCCause::Cause cause, ShenandoahGeneration* generation) {
1543 shenandoah_policy()->record_collection_cause(cause);
1544
1545 const GCCause::Cause current = gc_cause();
1546 assert(current == GCCause::_no_gc, "Over-writing cause: %s, with: %s",
1547 GCCause::to_string(current), GCCause::to_string(cause));
1548 assert(_gc_generation == nullptr, "Over-writing _gc_generation");
1549
1550 set_gc_cause(cause);
1551 set_gc_generation(generation);
1552
1553 generation->heuristics()->record_cycle_start();
1554 }
1555
1556 void ShenandoahHeap::on_cycle_end(ShenandoahGeneration* generation) {
1557 assert(gc_cause() != GCCause::_no_gc, "cause wasn't set");
1558 assert(_gc_generation != nullptr, "_gc_generation wasn't set");
1559
1560 generation->heuristics()->record_cycle_end();
1561 if (mode()->is_generational() && generation->is_global()) {
1562 // If we just completed a GLOBAL GC, claim credit for completion of young-gen and old-gen GC as well
1563 young_generation()->heuristics()->record_cycle_end();
1564 old_generation()->heuristics()->record_cycle_end();
1565 }
1566
1567 set_gc_generation(nullptr);
1568 set_gc_cause(GCCause::_no_gc);
1569 }
1570
1571 void ShenandoahHeap::verify(VerifyOption vo) {
1572 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1573 if (ShenandoahVerify) {
1574 verifier()->verify_generic(vo);
1575 } else {
1576 // TODO: Consider allocating verification bitmaps on demand,
1577 // and turn this on unconditionally.
1578 }
1579 }
1580 }
1581 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1582 return _free_set->capacity();
1583 }
1584
1585 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1586 private:
1587 MarkBitMap* _bitmap;
1588 ShenandoahScanObjectStack* _oop_stack;
1589 ShenandoahHeap* const _heap;
1590 ShenandoahMarkingContext* const _marking_context;
1885 const uint active_workers = workers()->active_workers();
1886 const size_t n_regions = num_regions();
1887 size_t stride = ShenandoahParallelRegionStride;
1888 if (stride == 0 && active_workers > 1) {
1889 // Automatically derive the stride to balance the work between threads
1890 // evenly. Do not try to split work if below the reasonable threshold.
1891 constexpr size_t threshold = 4096;
1892 stride = n_regions <= threshold ?
1893 threshold :
1894 (n_regions + active_workers - 1) / active_workers;
1895 }
1896
1897 if (n_regions > stride && active_workers > 1) {
1898 ShenandoahParallelHeapRegionTask task(blk, stride);
1899 workers()->run_task(&task);
1900 } else {
1901 heap_region_iterate(blk);
1902 }
1903 }
1904
1905 class ShenandoahRendezvousClosure : public HandshakeClosure {
1906 public:
1907 inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {}
1908 inline void do_thread(Thread* thread) {}
1909 };
1910
1911 void ShenandoahHeap::rendezvous_threads() {
1912 ShenandoahRendezvousClosure cl;
1913 Handshake::execute(&cl);
1914 }
1915
1916 void ShenandoahHeap::recycle_trash() {
1917 free_set()->recycle_trash();
1918 }
1919
1920 void ShenandoahHeap::do_class_unloading() {
1921 _unloader.unload();
1922 if (mode()->is_generational()) {
1923 old_generation()->set_parsable(false);
1924 }
1925 }
1926
1927 void ShenandoahHeap::stw_weak_refs(bool full_gc) {
1928 // Weak refs processing
1929 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs
1930 : ShenandoahPhaseTimings::degen_gc_weakrefs;
1931 ShenandoahTimingsTracker t(phase);
1932 ShenandoahGCWorkerPhase worker_phase(phase);
1933 shenandoah_assert_generations_reconciled();
1934 gc_generation()->ref_processor()->process_references(phase, workers(), false /* concurrent */);
1935 }
1936
1937 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
1938 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
1939
1940 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to
1941 // make them parsable for update code to work correctly. Plus, we can compute new sizes
1942 // for future GCLABs here.
1943 if (UseTLAB) {
1944 ShenandoahGCPhase phase(concurrent ?
1945 ShenandoahPhaseTimings::init_update_refs_manage_gclabs :
1946 ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs);
1947 gclabs_retire(ResizeTLAB);
1948 }
1949
1950 _update_refs_iterator.reset();
1951 }
1952
1953 void ShenandoahHeap::propagate_gc_state_to_java_threads() {
1954 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint");
1955 if (_gc_state_changed) {
1956 _gc_state_changed = false;
1957 char state = gc_state();
1958 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1959 ShenandoahThreadLocalData::set_gc_state(t, state);
1960 }
1961 }
1962 }
1963
1964 void ShenandoahHeap::set_gc_state(uint mask, bool value) {
1965 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint");
1966 _gc_state.set_cond(mask, value);
1967 _gc_state_changed = true;
1968 }
1969
1970 void ShenandoahHeap::set_concurrent_young_mark_in_progress(bool in_progress) {
1971 uint mask;
1972 assert(!has_forwarded_objects(), "Young marking is not concurrent with evacuation");
1973 if (!in_progress && is_concurrent_old_mark_in_progress()) {
1974 assert(mode()->is_generational(), "Only generational GC has old marking");
1975 assert(_gc_state.is_set(MARKING), "concurrent_old_marking_in_progress implies MARKING");
1976 // If old-marking is in progress when we turn off YOUNG_MARKING, leave MARKING (and OLD_MARKING) on
1977 mask = YOUNG_MARKING;
1978 } else {
1979 mask = MARKING | YOUNG_MARKING;
1980 }
1981 set_gc_state(mask, in_progress);
1982 manage_satb_barrier(in_progress);
1983 }
1984
1985 void ShenandoahHeap::set_concurrent_old_mark_in_progress(bool in_progress) {
1986 #ifdef ASSERT
1987 // has_forwarded_objects() iff UPDATEREFS or EVACUATION
1988 bool has_forwarded = has_forwarded_objects();
1989 bool updating_or_evacuating = _gc_state.is_set(UPDATEREFS | EVACUATION);
1990 bool evacuating = _gc_state.is_set(EVACUATION);
1991 assert ((has_forwarded == updating_or_evacuating) || (evacuating && !has_forwarded && collection_set()->is_empty()),
1992 "Updating or evacuating iff has forwarded objects, or if evacuation phase is promoting in place without forwarding");
1993 #endif
1994 if (!in_progress && is_concurrent_young_mark_in_progress()) {
1995 // If young-marking is in progress when we turn off OLD_MARKING, leave MARKING (and YOUNG_MARKING) on
1996 assert(_gc_state.is_set(MARKING), "concurrent_young_marking_in_progress implies MARKING");
1997 set_gc_state(OLD_MARKING, in_progress);
1998 } else {
1999 set_gc_state(MARKING | OLD_MARKING, in_progress);
2000 }
2001 manage_satb_barrier(in_progress);
2002 }
2003
2004 bool ShenandoahHeap::is_prepare_for_old_mark_in_progress() const {
2005 return old_generation()->is_preparing_for_mark();
2006 }
2007
2008 void ShenandoahHeap::manage_satb_barrier(bool active) {
2009 if (is_concurrent_mark_in_progress()) {
2010 // Ignore request to deactivate barrier while concurrent mark is in progress.
2011 // Do not attempt to re-activate the barrier if it is already active.
2012 if (active && !ShenandoahBarrierSet::satb_mark_queue_set().is_active()) {
2013 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(active, !active);
2014 }
2015 } else {
2016 // No concurrent marking is in progress so honor request to deactivate,
2017 // but only if the barrier is already active.
2018 if (!active && ShenandoahBarrierSet::satb_mark_queue_set().is_active()) {
2019 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(active, !active);
2020 }
2021 }
2022 }
2023
2024 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
2025 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
2026 set_gc_state(EVACUATION, in_progress);
2027 }
2028
2029 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
2030 if (in_progress) {
2031 _concurrent_strong_root_in_progress.set();
2032 } else {
2033 _concurrent_strong_root_in_progress.unset();
2034 }
2035 }
2036
2037 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) {
2038 set_gc_state(WEAK_ROOTS, cond);
2039 }
2040
2041 GCTracer* ShenandoahHeap::tracer() {
2042 return shenandoah_policy()->tracer();
2043 }
2044
2045 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
2046 return _free_set->used();
2047 }
2048
2049 bool ShenandoahHeap::try_cancel_gc() {
2050 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
2051 return prev == CANCELLABLE;
2052 }
2053
2054 void ShenandoahHeap::cancel_concurrent_mark() {
2055 if (mode()->is_generational()) {
2056 young_generation()->cancel_marking();
2057 old_generation()->cancel_marking();
2058 }
2059
2060 global_generation()->cancel_marking();
2061
2062 ShenandoahBarrierSet::satb_mark_queue_set().abandon_partial_marking();
2063 }
2064
2065 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
2066 if (try_cancel_gc()) {
2067 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
2068 log_info(gc)("%s", msg.buffer());
2069 Events::log(Thread::current(), "%s", msg.buffer());
2070 _cancel_requested_time = os::elapsedTime();
2071 }
2072 }
2073
2074 uint ShenandoahHeap::max_workers() {
2075 return _max_workers;
2076 }
2077
2078 void ShenandoahHeap::stop() {
2079 // The shutdown sequence should be able to terminate when GC is running.
2080
2081 // Step 0. Notify policy to disable event recording.
2082 _shenandoah_policy->record_shutdown();
2083
2084 // Step 0a. Stop reporting on gc thread cpu utilization
2085 mmu_tracker()->stop();
2086
2087 // Step 1. Notify control thread that we are in shutdown.
2088 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
2089 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
2090 control_thread()->prepare_for_graceful_shutdown();
2091
2092 // Step 2. Notify GC workers that we are cancelling GC.
2093 cancel_gc(GCCause::_shenandoah_stop_vm);
2094
2095 // Step 3. Wait until GC worker exits normally.
2096 control_thread()->stop();
2097 }
2098
2099 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
2100 if (!unload_classes()) return;
2101 ClassUnloadingContext ctx(_workers->active_workers(),
2102 true /* unregister_nmethods_during_purge */,
2103 false /* lock_codeblob_free_separately */);
2104
2105 // Unload classes and purge SystemDictionary.
2106 {
2177 }
2178
2179 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2180 set_gc_state(HAS_FORWARDED, cond);
2181 }
2182
2183 void ShenandoahHeap::set_unload_classes(bool uc) {
2184 _unload_classes.set_cond(uc);
2185 }
2186
2187 bool ShenandoahHeap::unload_classes() const {
2188 return _unload_classes.is_set();
2189 }
2190
2191 address ShenandoahHeap::in_cset_fast_test_addr() {
2192 ShenandoahHeap* heap = ShenandoahHeap::heap();
2193 assert(heap->collection_set() != nullptr, "Sanity");
2194 return (address) heap->collection_set()->biased_map_address();
2195 }
2196
2197 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2198 if (mode()->is_generational()) {
2199 young_generation()->reset_bytes_allocated_since_gc_start();
2200 old_generation()->reset_bytes_allocated_since_gc_start();
2201 }
2202
2203 global_generation()->reset_bytes_allocated_since_gc_start();
2204 }
2205
2206 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2207 _degenerated_gc_in_progress.set_cond(in_progress);
2208 }
2209
2210 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2211 _full_gc_in_progress.set_cond(in_progress);
2212 }
2213
2214 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2215 assert (is_full_gc_in_progress(), "should be");
2216 _full_gc_move_in_progress.set_cond(in_progress);
2217 }
2218
2219 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2220 set_gc_state(UPDATEREFS, in_progress);
2221 }
2222
2223 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2247 if (r->is_active()) {
2248 if (r->is_pinned()) {
2249 if (r->pin_count() == 0) {
2250 r->make_unpinned();
2251 }
2252 } else {
2253 if (r->pin_count() > 0) {
2254 r->make_pinned();
2255 }
2256 }
2257 }
2258 }
2259
2260 assert_pinned_region_status();
2261 }
2262
2263 #ifdef ASSERT
2264 void ShenandoahHeap::assert_pinned_region_status() {
2265 for (size_t i = 0; i < num_regions(); i++) {
2266 ShenandoahHeapRegion* r = get_region(i);
2267 shenandoah_assert_generations_reconciled();
2268 if (gc_generation()->contains(r)) {
2269 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2270 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2271 }
2272 }
2273 }
2274 #endif
2275
2276 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
2277 return _gc_timer;
2278 }
2279
2280 void ShenandoahHeap::prepare_concurrent_roots() {
2281 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2282 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
2283 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
2284 set_concurrent_weak_root_in_progress(true);
2285 if (unload_classes()) {
2286 _unloader.prepare();
2287 }
2288 }
2289
2290 void ShenandoahHeap::finish_concurrent_roots() {
2291 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2292 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
2293 if (unload_classes()) {
2294 _unloader.finish();
2295 }
2296 }
2297
2298 #ifdef ASSERT
2299 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2300 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2301
2302 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2303 // Use ParallelGCThreads inside safepoints
2304 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads (%u) within safepoint, not %u",
2305 ParallelGCThreads, nworkers);
2306 } else {
2307 // Use ConcGCThreads outside safepoints
2308 assert(nworkers == ConcGCThreads, "Use ConcGCThreads (%u) outside safepoints, %u",
2309 ConcGCThreads, nworkers);
2310 }
2311 }
2312 #endif
2313
2314 ShenandoahVerifier* ShenandoahHeap::verifier() {
2315 guarantee(ShenandoahVerify, "Should be enabled");
2316 assert (_verifier != nullptr, "sanity");
2317 return _verifier;
2318 }
2319
2320 template<bool CONCURRENT>
2321 class ShenandoahUpdateHeapRefsTask : public WorkerTask {
2322 private:
2323 ShenandoahHeap* _heap;
2324 ShenandoahRegionIterator* _regions;
2325 public:
2326 explicit ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) :
2327 WorkerTask("Shenandoah Update References"),
2328 _heap(ShenandoahHeap::heap()),
2329 _regions(regions) {
2330 }
2331
2332 void work(uint worker_id) {
2333 if (CONCURRENT) {
2334 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2335 ShenandoahSuspendibleThreadSetJoiner stsj;
2336 do_work<ShenandoahConcUpdateRefsClosure>(worker_id);
2337 } else {
2338 ShenandoahParallelWorkerSession worker_session(worker_id);
2339 do_work<ShenandoahSTWUpdateRefsClosure>(worker_id);
2340 }
2341 }
2342
2343 private:
2344 template<class T>
2345 void do_work(uint worker_id) {
2346 if (CONCURRENT && (worker_id == 0)) {
2347 // We ask the first worker to replenish the Mutator free set by moving regions previously reserved to hold the
2348 // results of evacuation. These reserves are no longer necessary because evacuation has completed.
2349 size_t cset_regions = _heap->collection_set()->count();
2350
2351 // Now that evacuation is done, we can reassign any regions that had been reserved to hold the results of evacuation
2352 // to the mutator free set. At the end of GC, we will have cset_regions newly evacuated fully empty regions from
2353 // which we will be able to replenish the Collector free set and the OldCollector free set in preparation for the
2354 // next GC cycle.
2355 _heap->free_set()->move_regions_from_collector_to_mutator(cset_regions);
2356 }
2357 // If !CONCURRENT, there's no value in expanding Mutator free set
2358 T cl;
2359 ShenandoahHeapRegion* r = _regions->next();
2360 while (r != nullptr) {
2361 HeapWord* update_watermark = r->get_update_watermark();
2362 assert (update_watermark >= r->bottom(), "sanity");
2363 if (r->is_active() && !r->is_cset()) {
2364 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2365 if (ShenandoahPacing) {
2366 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2367 }
2368 }
2369 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
2370 return;
2371 }
2372 r = _regions->next();
2373 }
2374 }
2375 };
2376
2377 void ShenandoahHeap::update_heap_references(bool concurrent) {
2378 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2379
2380 if (concurrent) {
2381 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator);
2382 workers()->run_task(&task);
2383 } else {
2384 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator);
2385 workers()->run_task(&task);
2386 }
2387 }
2388
2389 void ShenandoahHeap::update_heap_region_states(bool concurrent) {
2390 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2391 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2392
2393 {
2394 ShenandoahGCPhase phase(concurrent ?
2395 ShenandoahPhaseTimings::final_update_refs_update_region_states :
2396 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states);
2397
2398 final_update_refs_update_region_states();
2399
2400 assert_pinned_region_status();
2401 }
2402
2403 {
2404 ShenandoahGCPhase phase(concurrent ?
2405 ShenandoahPhaseTimings::final_update_refs_trash_cset :
2406 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset);
2407 trash_cset_regions();
2408 }
2409 }
2410
2411 void ShenandoahHeap::final_update_refs_update_region_states() {
2412 ShenandoahSynchronizePinnedRegionStates cl;
2413 parallel_heap_region_iterate(&cl);
2414 }
2415
2416 void ShenandoahHeap::rebuild_free_set(bool concurrent) {
2417 ShenandoahGCPhase phase(concurrent ?
2418 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
2419 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
2420 ShenandoahHeapLocker locker(lock());
2421 size_t young_cset_regions, old_cset_regions;
2422 size_t first_old_region, last_old_region, old_region_count;
2423 _free_set->prepare_to_rebuild(young_cset_regions, old_cset_regions, first_old_region, last_old_region, old_region_count);
2424 // If there are no old regions, first_old_region will be greater than last_old_region
2425 assert((first_old_region > last_old_region) ||
2426 ((last_old_region + 1 - first_old_region >= old_region_count) &&
2427 get_region(first_old_region)->is_old() && get_region(last_old_region)->is_old()),
2428 "sanity: old_region_count: " SIZE_FORMAT ", first_old_region: " SIZE_FORMAT ", last_old_region: " SIZE_FORMAT,
2429 old_region_count, first_old_region, last_old_region);
2430
2431 if (mode()->is_generational()) {
2432 #ifdef ASSERT
2433 if (ShenandoahVerify) {
2434 verifier()->verify_before_rebuilding_free_set();
2435 }
2436 #endif
2437
2438 // The computation of bytes_of_allocation_runway_before_gc_trigger is quite conservative so consider all of this
2439 // available for transfer to old. Note that transfer of humongous regions does not impact available.
2440 ShenandoahGenerationalHeap* gen_heap = ShenandoahGenerationalHeap::heap();
2441 size_t allocation_runway = gen_heap->young_generation()->heuristics()->bytes_of_allocation_runway_before_gc_trigger(young_cset_regions);
2442 gen_heap->compute_old_generation_balance(allocation_runway, old_cset_regions);
2443
2444 // Total old_available may have been expanded to hold anticipated promotions. We trigger if the fragmented available
2445 // memory represents more than 16 regions worth of data. Note that fragmentation may increase when we promote regular
2446 // regions in place when many of these regular regions have an abundant amount of available memory within them. Fragmentation
2447 // will decrease as promote-by-copy consumes the available memory within these partially consumed regions.
2448 //
2449 // We consider old-gen to have excessive fragmentation if more than 12.5% of old-gen is free memory that resides
2450 // within partially consumed regions of memory.
2451 }
2452 // Rebuild free set based on adjusted generation sizes.
2453 _free_set->finish_rebuild(young_cset_regions, old_cset_regions, old_region_count);
2454
2455 if (mode()->is_generational()) {
2456 ShenandoahGenerationalHeap* gen_heap = ShenandoahGenerationalHeap::heap();
2457 ShenandoahOldGeneration* old_gen = gen_heap->old_generation();
2458 old_gen->heuristics()->evaluate_triggers(first_old_region, last_old_region, old_region_count, num_regions());
2459 }
2460 }
2461
2462 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2463 print_on(st);
2464 st->cr();
2465 print_heap_regions_on(st);
2466 }
2467
2468 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2469 size_t slice = r->index() / _bitmap_regions_per_slice;
2470
2471 size_t regions_from = _bitmap_regions_per_slice * slice;
2472 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2473 for (size_t g = regions_from; g < regions_to; g++) {
2474 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2475 if (skip_self && g == r->index()) continue;
2476 if (get_region(g)->is_committed()) {
2477 return true;
2478 }
2526 }
2527
2528 // Uncommit the bitmap slice:
2529 size_t slice = r->index() / _bitmap_regions_per_slice;
2530 size_t off = _bitmap_bytes_per_slice * slice;
2531 size_t len = _bitmap_bytes_per_slice;
2532 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2533 return false;
2534 }
2535 return true;
2536 }
2537
2538 void ShenandoahHeap::safepoint_synchronize_begin() {
2539 SuspendibleThreadSet::synchronize();
2540 }
2541
2542 void ShenandoahHeap::safepoint_synchronize_end() {
2543 SuspendibleThreadSet::desynchronize();
2544 }
2545
2546 void ShenandoahHeap::try_inject_alloc_failure() {
2547 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2548 _inject_alloc_failure.set();
2549 os::naked_short_sleep(1);
2550 if (cancelled_gc()) {
2551 log_info(gc)("Allocation failure was successfully injected");
2552 }
2553 }
2554 }
2555
2556 bool ShenandoahHeap::should_inject_alloc_failure() {
2557 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2558 }
2559
2560 void ShenandoahHeap::initialize_serviceability() {
2561 _memory_pool = new ShenandoahMemoryPool(this);
2562 _cycle_memory_manager.add_pool(_memory_pool);
2563 _stw_memory_manager.add_pool(_memory_pool);
2564 }
2565
2566 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2567 GrowableArray<GCMemoryManager*> memory_managers(2);
2568 memory_managers.append(&_cycle_memory_manager);
2569 memory_managers.append(&_stw_memory_manager);
2570 return memory_managers;
2571 }
2572
2573 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2574 GrowableArray<MemoryPool*> memory_pools(1);
2575 memory_pools.append(_memory_pool);
2576 return memory_pools;
2577 }
2578
2579 MemoryUsage ShenandoahHeap::memory_usage() {
2580 return MemoryUsage(_initial_size, used(), committed(), max_capacity());
2581 }
2582
2583 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2584 _heap(ShenandoahHeap::heap()),
2585 _index(0) {}
2586
2587 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2588 _heap(heap),
2589 _index(0) {}
2590
2591 void ShenandoahRegionIterator::reset() {
2592 _index = 0;
2593 }
2594
2595 bool ShenandoahRegionIterator::has_next() const {
2596 return _index < _heap->num_regions();
2597 }
2598
2599 char ShenandoahHeap::gc_state() const {
2600 return _gc_state.raw_value();
2625 }
2626 }
2627
2628 bool ShenandoahHeap::requires_barriers(stackChunkOop obj) const {
2629 if (is_idle()) return false;
2630
2631 // Objects allocated after marking start are implicitly alive, don't need any barriers during
2632 // marking phase.
2633 if (is_concurrent_mark_in_progress() &&
2634 !marking_context()->allocated_after_mark_start(obj)) {
2635 return true;
2636 }
2637
2638 // Can not guarantee obj is deeply good.
2639 if (has_forwarded_objects()) {
2640 return true;
2641 }
2642
2643 return false;
2644 }
2645
2646 ShenandoahGeneration* ShenandoahHeap::generation_for(ShenandoahAffiliation affiliation) const {
2647 if (!mode()->is_generational()) {
2648 return global_generation();
2649 } else if (affiliation == YOUNG_GENERATION) {
2650 return young_generation();
2651 } else if (affiliation == OLD_GENERATION) {
2652 return old_generation();
2653 }
2654
2655 ShouldNotReachHere();
2656 return nullptr;
2657 }
2658
2659 void ShenandoahHeap::log_heap_status(const char* msg) const {
2660 if (mode()->is_generational()) {
2661 young_generation()->log_status(msg);
2662 old_generation()->log_status(msg);
2663 } else {
2664 global_generation()->log_status(msg);
2665 }
2666 }
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