1 /*
2 * Copyright (c) 2013, 2021, Red Hat, Inc. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "memory/allocation.hpp"
27 #include "memory/universe.hpp"
28
29 #include "gc/shared/gcArguments.hpp"
30 #include "gc/shared/gcTimer.hpp"
31 #include "gc/shared/gcTraceTime.inline.hpp"
32 #include "gc/shared/locationPrinter.inline.hpp"
33 #include "gc/shared/memAllocator.hpp"
34 #include "gc/shared/plab.hpp"
35 #include "gc/shared/tlab_globals.hpp"
36
37 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
38 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
39 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
40 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
41 #include "gc/shenandoah/shenandoahConcurrentMark.hpp"
42 #include "gc/shenandoah/shenandoahControlThread.hpp"
43 #include "gc/shenandoah/shenandoahFreeSet.hpp"
44 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
45 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
46 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
47 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
48 #include "gc/shenandoah/shenandoahInitLogger.hpp"
49 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
50 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
51 #include "gc/shenandoah/shenandoahMetrics.hpp"
52 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
53 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
54 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
55 #include "gc/shenandoah/shenandoahPadding.hpp"
56 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
57 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
58 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
59 #include "gc/shenandoah/shenandoahStringDedup.hpp"
60 #include "gc/shenandoah/shenandoahSTWMark.hpp"
61 #include "gc/shenandoah/shenandoahUtils.hpp"
62 #include "gc/shenandoah/shenandoahVerifier.hpp"
63 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
64 #include "gc/shenandoah/shenandoahVMOperations.hpp"
65 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
66 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
67 #include "gc/shenandoah/mode/shenandoahIUMode.hpp"
68 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
69 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp"
70 #if INCLUDE_JFR
71 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
72 #endif
73
74 #include "classfile/systemDictionary.hpp"
75 #include "memory/classLoaderMetaspace.hpp"
76 #include "memory/metaspaceUtils.hpp"
77 #include "oops/compressedOops.inline.hpp"
78 #include "prims/jvmtiTagMap.hpp"
79 #include "runtime/atomic.hpp"
80 #include "runtime/globals.hpp"
81 #include "runtime/interfaceSupport.inline.hpp"
82 #include "runtime/java.hpp"
83 #include "runtime/orderAccess.hpp"
84 #include "runtime/safepointMechanism.hpp"
85 #include "runtime/vmThread.hpp"
86 #include "services/mallocTracker.hpp"
87 #include "services/memTracker.hpp"
88 #include "utilities/events.hpp"
89 #include "utilities/powerOfTwo.hpp"
90
91 class ShenandoahPretouchHeapTask : public AbstractGangTask {
92 private:
93 ShenandoahRegionIterator _regions;
94 const size_t _page_size;
95 public:
96 ShenandoahPretouchHeapTask(size_t page_size) :
97 AbstractGangTask("Shenandoah Pretouch Heap"),
98 _page_size(page_size) {}
99
100 virtual void work(uint worker_id) {
101 ShenandoahHeapRegion* r = _regions.next();
102 while (r != NULL) {
103 if (r->is_committed()) {
104 os::pretouch_memory(r->bottom(), r->end(), _page_size);
105 }
106 r = _regions.next();
107 }
108 }
109 };
110
111 class ShenandoahPretouchBitmapTask : public AbstractGangTask {
112 private:
113 ShenandoahRegionIterator _regions;
114 char* _bitmap_base;
115 const size_t _bitmap_size;
116 const size_t _page_size;
117 public:
118 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
119 AbstractGangTask("Shenandoah Pretouch Bitmap"),
120 _bitmap_base(bitmap_base),
121 _bitmap_size(bitmap_size),
122 _page_size(page_size) {}
123
124 virtual void work(uint worker_id) {
125 ShenandoahHeapRegion* r = _regions.next();
126 while (r != NULL) {
127 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
128 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
129 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
130
131 if (r->is_committed()) {
132 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
133 }
134
135 r = _regions.next();
136 }
137 }
138 };
139
140 jint ShenandoahHeap::initialize() {
141 //
142 // Figure out heap sizing
143 //
144
145 size_t init_byte_size = InitialHeapSize;
146 size_t min_byte_size = MinHeapSize;
147 size_t max_byte_size = MaxHeapSize;
148 size_t heap_alignment = HeapAlignment;
149
150 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
151
152 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
153 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
154
155 _num_regions = ShenandoahHeapRegion::region_count();
156 assert(_num_regions == (max_byte_size / reg_size_bytes),
157 "Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT,
158 _num_regions, max_byte_size, reg_size_bytes);
159
160 // Now we know the number of regions, initialize the heuristics.
161 initialize_heuristics();
162
163 size_t num_committed_regions = init_byte_size / reg_size_bytes;
164 num_committed_regions = MIN2(num_committed_regions, _num_regions);
165 assert(num_committed_regions <= _num_regions, "sanity");
166 _initial_size = num_committed_regions * reg_size_bytes;
167
168 size_t num_min_regions = min_byte_size / reg_size_bytes;
169 num_min_regions = MIN2(num_min_regions, _num_regions);
170 assert(num_min_regions <= _num_regions, "sanity");
171 _minimum_size = num_min_regions * reg_size_bytes;
172
173 // Default to max heap size.
174 _soft_max_size = _num_regions * reg_size_bytes;
175
176 _committed = _initial_size;
177
178 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
179 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
180 size_t region_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
181
182 //
183 // Reserve and commit memory for heap
184 //
185
186 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
187 initialize_reserved_region(heap_rs);
188 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
189 _heap_region_special = heap_rs.special();
190
191 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
192 "Misaligned heap: " PTR_FORMAT, p2i(base()));
193
194 #if SHENANDOAH_OPTIMIZED_MARKTASK
195 // The optimized ShenandoahMarkTask takes some bits away from the full object bits.
196 // Fail if we ever attempt to address more than we can.
197 if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) {
198 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
199 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
200 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
201 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable());
202 vm_exit_during_initialization("Fatal Error", buf);
203 }
204 #endif
205
206 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
207 if (!_heap_region_special) {
208 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
209 "Cannot commit heap memory");
210 }
211
212 //
213 // Reserve and commit memory for bitmap(s)
214 //
215
216 _bitmap_size = ShenandoahMarkBitMap::compute_size(heap_rs.size());
217 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
218
219 size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor();
220
221 guarantee(bitmap_bytes_per_region != 0,
222 "Bitmap bytes per region should not be zero");
223 guarantee(is_power_of_2(bitmap_bytes_per_region),
224 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
225
226 if (bitmap_page_size > bitmap_bytes_per_region) {
227 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
228 _bitmap_bytes_per_slice = bitmap_page_size;
229 } else {
230 _bitmap_regions_per_slice = 1;
231 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
232 }
233
234 guarantee(_bitmap_regions_per_slice >= 1,
235 "Should have at least one region per slice: " SIZE_FORMAT,
236 _bitmap_regions_per_slice);
237
238 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
239 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
240 _bitmap_bytes_per_slice, bitmap_page_size);
241
242 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
243 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
244 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
245 _bitmap_region_special = bitmap.special();
246
247 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
248 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
249 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
250 if (!_bitmap_region_special) {
251 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
252 "Cannot commit bitmap memory");
253 }
254
255 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions, _max_workers);
256
257 if (ShenandoahVerify) {
258 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
259 if (!verify_bitmap.special()) {
260 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
261 "Cannot commit verification bitmap memory");
262 }
263 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
264 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
265 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
266 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
267 }
268
269 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
270 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
271 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
272 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
273 _aux_bitmap_region_special = aux_bitmap.special();
274 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
275
276 //
277 // Create regions and region sets
278 //
279 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
280 size_t region_storage_size = align_up(region_align * _num_regions, region_page_size);
281 region_storage_size = align_up(region_storage_size, os::vm_allocation_granularity());
282
283 ReservedSpace region_storage(region_storage_size, region_page_size);
284 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC);
285 if (!region_storage.special()) {
286 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false,
287 "Cannot commit region memory");
288 }
289
290 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks.
291 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there.
292 // If not successful, bite a bullet and allocate at whatever address.
293 {
294 size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity());
295 size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align);
296
297 uintptr_t min = round_up_power_of_2(cset_align);
298 uintptr_t max = (1u << 30u);
299
300 for (uintptr_t addr = min; addr <= max; addr <<= 1u) {
301 char* req_addr = (char*)addr;
302 assert(is_aligned(req_addr, cset_align), "Should be aligned");
303 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size(), req_addr);
304 if (cset_rs.is_reserved()) {
305 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr);
306 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
307 break;
308 }
309 }
310
311 if (_collection_set == NULL) {
312 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size());
313 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
314 }
315 }
316
317 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
318 _free_set = new ShenandoahFreeSet(this, _num_regions);
319
320 {
321 ShenandoahHeapLocker locker(lock());
322
323 for (size_t i = 0; i < _num_regions; i++) {
324 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
325 bool is_committed = i < num_committed_regions;
326 void* loc = region_storage.base() + i * region_align;
327
328 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
329 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
330
331 _marking_context->initialize_top_at_mark_start(r);
332 _regions[i] = r;
333 assert(!collection_set()->is_in(i), "New region should not be in collection set");
334 }
335
336 // Initialize to complete
337 _marking_context->mark_complete();
338
339 _free_set->rebuild();
340 }
341
342 if (AlwaysPreTouch) {
343 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
344 // before initialize() below zeroes it with initializing thread. For any given region,
345 // we touch the region and the corresponding bitmaps from the same thread.
346 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
347
348 _pretouch_heap_page_size = heap_page_size;
349 _pretouch_bitmap_page_size = bitmap_page_size;
350
351 #ifdef LINUX
352 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
353 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
354 // them into huge one. Therefore, we need to pretouch with smaller pages.
355 if (UseTransparentHugePages) {
356 _pretouch_heap_page_size = (size_t)os::vm_page_size();
357 _pretouch_bitmap_page_size = (size_t)os::vm_page_size();
358 }
359 #endif
360
361 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
362 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
363
364 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size);
365 _workers->run_task(&bcl);
366
367 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size);
368 _workers->run_task(&hcl);
369 }
370
371 //
372 // Initialize the rest of GC subsystems
373 //
374
375 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC);
376 for (uint worker = 0; worker < _max_workers; worker++) {
377 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC);
378 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData));
379 }
380
381 // There should probably be Shenandoah-specific options for these,
382 // just as there are G1-specific options.
383 {
384 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
385 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
386 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
387 }
388
389 _monitoring_support = new ShenandoahMonitoringSupport(this);
390 _phase_timings = new ShenandoahPhaseTimings(max_workers());
391 ShenandoahCodeRoots::initialize();
392
393 if (ShenandoahPacing) {
394 _pacer = new ShenandoahPacer(this);
395 _pacer->setup_for_idle();
396 } else {
397 _pacer = NULL;
398 }
399
400 _control_thread = new ShenandoahControlThread();
401
402 ShenandoahInitLogger::print();
403
404 return JNI_OK;
405 }
406
407 void ShenandoahHeap::initialize_mode() {
408 if (ShenandoahGCMode != NULL) {
409 if (strcmp(ShenandoahGCMode, "satb") == 0) {
410 _gc_mode = new ShenandoahSATBMode();
411 } else if (strcmp(ShenandoahGCMode, "iu") == 0) {
412 _gc_mode = new ShenandoahIUMode();
413 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
414 _gc_mode = new ShenandoahPassiveMode();
415 } else {
416 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
417 }
418 } else {
419 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option (null)");
420 }
421 _gc_mode->initialize_flags();
422 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
423 vm_exit_during_initialization(
424 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
425 _gc_mode->name()));
426 }
427 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
428 vm_exit_during_initialization(
429 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
430 _gc_mode->name()));
431 }
432 }
433
434 void ShenandoahHeap::initialize_heuristics() {
435 assert(_gc_mode != NULL, "Must be initialized");
436 _heuristics = _gc_mode->initialize_heuristics();
437
438 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
439 vm_exit_during_initialization(
440 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
441 _heuristics->name()));
442 }
443 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
444 vm_exit_during_initialization(
445 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
446 _heuristics->name()));
447 }
448 }
449
450 #ifdef _MSC_VER
451 #pragma warning( push )
452 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
453 #endif
454
455 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
456 CollectedHeap(),
457 _initial_size(0),
458 _used(0),
459 _committed(0),
460 _bytes_allocated_since_gc_start(0),
461 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
462 _workers(NULL),
463 _safepoint_workers(NULL),
464 _heap_region_special(false),
465 _num_regions(0),
466 _regions(NULL),
467 _update_refs_iterator(this),
468 _gc_state_changed(false),
469 _control_thread(NULL),
470 _shenandoah_policy(policy),
471 _gc_mode(NULL),
472 _heuristics(NULL),
473 _free_set(NULL),
474 _pacer(NULL),
475 _verifier(NULL),
476 _phase_timings(NULL),
477 _monitoring_support(NULL),
478 _memory_pool(NULL),
479 _stw_memory_manager("Shenandoah Pauses"),
480 _cycle_memory_manager("Shenandoah Cycles"),
481 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
482 _soft_ref_policy(),
483 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
484 _ref_processor(new ShenandoahReferenceProcessor(MAX2(_max_workers, 1U))),
485 _marking_context(NULL),
486 _bitmap_size(0),
487 _bitmap_regions_per_slice(0),
488 _bitmap_bytes_per_slice(0),
489 _bitmap_region_special(false),
490 _aux_bitmap_region_special(false),
491 _liveness_cache(NULL),
492 _collection_set(NULL)
493 {
494 // Initialize GC mode early, so we can adjust barrier support
495 initialize_mode();
496 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
497
498 _max_workers = MAX2(_max_workers, 1U);
499 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
500 /* are_GC_task_threads */ true,
501 /* are_ConcurrentGC_threads */ true);
502 if (_workers == NULL) {
503 vm_exit_during_initialization("Failed necessary allocation.");
504 } else {
505 _workers->initialize_workers();
506 }
507
508 if (ParallelGCThreads > 1) {
509 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
510 ParallelGCThreads,
511 /* are_GC_task_threads */ false,
512 /* are_ConcurrentGC_threads */ false);
513 _safepoint_workers->initialize_workers();
514 }
515 }
516
517 #ifdef _MSC_VER
518 #pragma warning( pop )
519 #endif
520
521 class ShenandoahResetBitmapTask : public AbstractGangTask {
522 private:
523 ShenandoahRegionIterator _regions;
524
525 public:
526 ShenandoahResetBitmapTask() :
527 AbstractGangTask("Shenandoah Reset Bitmap") {}
528
529 void work(uint worker_id) {
530 ShenandoahHeapRegion* region = _regions.next();
531 ShenandoahHeap* heap = ShenandoahHeap::heap();
532 ShenandoahMarkingContext* const ctx = heap->marking_context();
533 while (region != NULL) {
534 if (heap->is_bitmap_slice_committed(region)) {
535 ctx->clear_bitmap(region);
536 }
537 region = _regions.next();
538 }
539 }
540 };
541
542 void ShenandoahHeap::reset_mark_bitmap() {
543 assert_gc_workers(_workers->active_workers());
544 mark_incomplete_marking_context();
545
546 ShenandoahResetBitmapTask task;
547 _workers->run_task(&task);
548 }
549
550 void ShenandoahHeap::print_on(outputStream* st) const {
551 st->print_cr("Shenandoah Heap");
552 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
553 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
554 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()),
555 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
556 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
557 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
558 num_regions(),
559 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
560 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
561
562 st->print("Status: ");
563 if (has_forwarded_objects()) st->print("has forwarded objects, ");
564 if (is_concurrent_mark_in_progress()) st->print("marking, ");
565 if (is_evacuation_in_progress()) st->print("evacuating, ");
566 if (is_update_refs_in_progress()) st->print("updating refs, ");
567 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
568 if (is_full_gc_in_progress()) st->print("full gc, ");
569 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
570 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, ");
571 if (is_concurrent_strong_root_in_progress() &&
572 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, ");
573
574 if (cancelled_gc()) {
575 st->print("cancelled");
576 } else {
577 st->print("not cancelled");
578 }
579 st->cr();
580
581 st->print_cr("Reserved region:");
582 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
583 p2i(reserved_region().start()),
584 p2i(reserved_region().end()));
585
586 ShenandoahCollectionSet* cset = collection_set();
587 st->print_cr("Collection set:");
588 if (cset != NULL) {
589 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
590 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
591 } else {
592 st->print_cr(" (NULL)");
593 }
594
595 st->cr();
596 MetaspaceUtils::print_on(st);
597
598 if (Verbose) {
599 st->cr();
600 print_heap_regions_on(st);
601 }
602 }
603
604 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
605 public:
606 void do_thread(Thread* thread) {
607 assert(thread != NULL, "Sanity");
608 assert(thread->is_Worker_thread(), "Only worker thread expected");
609 ShenandoahThreadLocalData::initialize_gclab(thread);
610 }
611 };
612
613 void ShenandoahHeap::post_initialize() {
614 CollectedHeap::post_initialize();
615 MutexLocker ml(Threads_lock);
616
617 ShenandoahInitWorkerGCLABClosure init_gclabs;
618 _workers->threads_do(&init_gclabs);
619
620 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
621 // Now, we will let WorkGang to initialize gclab when new worker is created.
622 _workers->set_initialize_gclab();
623 if (_safepoint_workers != NULL) {
624 _safepoint_workers->threads_do(&init_gclabs);
625 _safepoint_workers->set_initialize_gclab();
626 }
627
628 _heuristics->initialize();
629
630 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
631 }
632
633 size_t ShenandoahHeap::used() const {
634 return Atomic::load(&_used);
635 }
636
637 size_t ShenandoahHeap::committed() const {
638 return Atomic::load(&_committed);
639 }
640
641 void ShenandoahHeap::increase_committed(size_t bytes) {
642 shenandoah_assert_heaplocked_or_safepoint();
643 _committed += bytes;
644 }
645
646 void ShenandoahHeap::decrease_committed(size_t bytes) {
647 shenandoah_assert_heaplocked_or_safepoint();
648 _committed -= bytes;
649 }
650
651 void ShenandoahHeap::increase_used(size_t bytes) {
652 Atomic::add(&_used, bytes, memory_order_relaxed);
653 }
654
655 void ShenandoahHeap::set_used(size_t bytes) {
656 Atomic::store(&_used, bytes);
657 }
658
659 void ShenandoahHeap::decrease_used(size_t bytes) {
660 assert(used() >= bytes, "never decrease heap size by more than we've left");
661 Atomic::sub(&_used, bytes, memory_order_relaxed);
662 }
663
664 void ShenandoahHeap::increase_allocated(size_t bytes) {
665 Atomic::add(&_bytes_allocated_since_gc_start, bytes, memory_order_relaxed);
666 }
667
668 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
669 size_t bytes = words * HeapWordSize;
670 if (!waste) {
671 increase_used(bytes);
672 }
673 increase_allocated(bytes);
674 if (ShenandoahPacing) {
675 control_thread()->pacing_notify_alloc(words);
676 if (waste) {
677 pacer()->claim_for_alloc(words, true);
678 }
679 }
680 }
681
682 size_t ShenandoahHeap::capacity() const {
683 return committed();
684 }
685
686 size_t ShenandoahHeap::max_capacity() const {
687 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
688 }
689
690 size_t ShenandoahHeap::soft_max_capacity() const {
691 size_t v = Atomic::load(&_soft_max_size);
692 assert(min_capacity() <= v && v <= max_capacity(),
693 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
694 min_capacity(), v, max_capacity());
695 return v;
696 }
697
698 void ShenandoahHeap::set_soft_max_capacity(size_t v) {
699 assert(min_capacity() <= v && v <= max_capacity(),
700 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
701 min_capacity(), v, max_capacity());
702 Atomic::store(&_soft_max_size, v);
703 }
704
705 size_t ShenandoahHeap::min_capacity() const {
706 return _minimum_size;
707 }
708
709 size_t ShenandoahHeap::initial_capacity() const {
710 return _initial_size;
711 }
712
713 bool ShenandoahHeap::is_in(const void* p) const {
714 HeapWord* heap_base = (HeapWord*) base();
715 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
716 return p >= heap_base && p < last_region_end;
717 }
718
719 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
720 assert (ShenandoahUncommit, "should be enabled");
721
722 // Application allocates from the beginning of the heap, and GC allocates at
723 // the end of it. It is more efficient to uncommit from the end, so that applications
724 // could enjoy the near committed regions. GC allocations are much less frequent,
725 // and therefore can accept the committing costs.
726
727 size_t count = 0;
728 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
729 ShenandoahHeapRegion* r = get_region(i - 1);
730 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
731 ShenandoahHeapLocker locker(lock());
732 if (r->is_empty_committed()) {
733 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) {
734 break;
735 }
736
737 r->make_uncommitted();
738 count++;
739 }
740 }
741 SpinPause(); // allow allocators to take the lock
742 }
743
744 if (count > 0) {
745 control_thread()->notify_heap_changed();
746 }
747 }
748
749 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
750 // New object should fit the GCLAB size
751 size_t min_size = MAX2(size, PLAB::min_size());
752
753 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
754 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
755 new_size = MIN2(new_size, PLAB::max_size());
756 new_size = MAX2(new_size, PLAB::min_size());
757
758 // Record new heuristic value even if we take any shortcut. This captures
759 // the case when moderately-sized objects always take a shortcut. At some point,
760 // heuristics should catch up with them.
761 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
762
763 if (new_size < size) {
764 // New size still does not fit the object. Fall back to shared allocation.
765 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
766 return NULL;
767 }
768
769 // Retire current GCLAB, and allocate a new one.
770 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
771 gclab->retire();
772
773 size_t actual_size = 0;
774 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
775 if (gclab_buf == NULL) {
776 return NULL;
777 }
778
779 assert (size <= actual_size, "allocation should fit");
780
781 if (ZeroTLAB) {
782 // ..and clear it.
783 Copy::zero_to_words(gclab_buf, actual_size);
784 } else {
785 // ...and zap just allocated object.
786 #ifdef ASSERT
787 // Skip mangling the space corresponding to the object header to
788 // ensure that the returned space is not considered parsable by
789 // any concurrent GC thread.
790 size_t hdr_size = oopDesc::header_size();
791 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
792 #endif // ASSERT
793 }
794 gclab->set_buf(gclab_buf, actual_size);
795 return gclab->allocate(size);
796 }
797
798 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
799 size_t requested_size,
800 size_t* actual_size) {
801 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
802 HeapWord* res = allocate_memory(req);
803 if (res != NULL) {
804 *actual_size = req.actual_size();
805 } else {
806 *actual_size = 0;
807 }
808 return res;
809 }
810
811 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
812 size_t word_size,
813 size_t* actual_size) {
814 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
815 HeapWord* res = allocate_memory(req);
816 if (res != NULL) {
817 *actual_size = req.actual_size();
818 } else {
819 *actual_size = 0;
820 }
821 return res;
822 }
823
824 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
825 intptr_t pacer_epoch = 0;
826 bool in_new_region = false;
827 HeapWord* result = NULL;
828
829 if (req.is_mutator_alloc()) {
830 if (ShenandoahPacing) {
831 pacer()->pace_for_alloc(req.size());
832 pacer_epoch = pacer()->epoch();
833 }
834
835 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
836 result = allocate_memory_under_lock(req, in_new_region);
837 }
838
839 // Allocation failed, block until control thread reacted, then retry allocation.
840 //
841 // It might happen that one of the threads requesting allocation would unblock
842 // way later after GC happened, only to fail the second allocation, because
843 // other threads have already depleted the free storage. In this case, a better
844 // strategy is to try again, as long as GC makes progress.
845 //
846 // Then, we need to make sure the allocation was retried after at least one
847 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
848
849 size_t tries = 0;
850
851 while (result == NULL && _progress_last_gc.is_set()) {
852 tries++;
853 control_thread()->handle_alloc_failure(req);
854 result = allocate_memory_under_lock(req, in_new_region);
855 }
856
857 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
858 tries++;
859 control_thread()->handle_alloc_failure(req);
860 result = allocate_memory_under_lock(req, in_new_region);
861 }
862
863 } else {
864 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
865 result = allocate_memory_under_lock(req, in_new_region);
866 // Do not call handle_alloc_failure() here, because we cannot block.
867 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
868 }
869
870 if (in_new_region) {
871 control_thread()->notify_heap_changed();
872 }
873
874 if (result != NULL) {
875 size_t requested = req.size();
876 size_t actual = req.actual_size();
877
878 assert (req.is_lab_alloc() || (requested == actual),
879 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
880 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
881
882 if (req.is_mutator_alloc()) {
883 notify_mutator_alloc_words(actual, false);
884
885 // If we requested more than we were granted, give the rest back to pacer.
886 // This only matters if we are in the same pacing epoch: do not try to unpace
887 // over the budget for the other phase.
888 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
889 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
890 }
891 } else {
892 increase_used(actual*HeapWordSize);
893 }
894 }
895
896 return result;
897 }
898
899 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
900 ShenandoahHeapLocker locker(lock());
901 return _free_set->allocate(req, in_new_region);
902 }
903
904 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
905 bool* gc_overhead_limit_was_exceeded) {
906 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
907 return allocate_memory(req);
908 }
909
910 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
911 size_t size,
912 Metaspace::MetadataType mdtype) {
913 MetaWord* result;
914
915 // Inform metaspace OOM to GC heuristics if class unloading is possible.
916 if (heuristics()->can_unload_classes()) {
917 ShenandoahHeuristics* h = heuristics();
918 h->record_metaspace_oom();
919 }
920
921 // Expand and retry allocation
922 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
923 if (result != NULL) {
924 return result;
925 }
926
927 // Start full GC
928 collect(GCCause::_metadata_GC_clear_soft_refs);
929
930 // Retry allocation
931 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
932 if (result != NULL) {
933 return result;
934 }
935
936 // Expand and retry allocation
937 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
938 if (result != NULL) {
939 return result;
940 }
941
942 // Out of memory
943 return NULL;
944 }
945
946 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
947 private:
948 ShenandoahHeap* const _heap;
949 Thread* const _thread;
950 public:
951 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
952 _heap(heap), _thread(Thread::current()) {}
953
954 void do_object(oop p) {
955 shenandoah_assert_marked(NULL, p);
956 if (!p->is_forwarded()) {
957 _heap->evacuate_object(p, _thread);
958 }
959 }
960 };
961
962 class ShenandoahEvacuationTask : public AbstractGangTask {
963 private:
964 ShenandoahHeap* const _sh;
965 ShenandoahCollectionSet* const _cs;
966 bool _concurrent;
967 public:
968 ShenandoahEvacuationTask(ShenandoahHeap* sh,
969 ShenandoahCollectionSet* cs,
970 bool concurrent) :
971 AbstractGangTask("Shenandoah Evacuation"),
972 _sh(sh),
973 _cs(cs),
974 _concurrent(concurrent)
975 {}
976
977 void work(uint worker_id) {
978 if (_concurrent) {
979 ShenandoahConcurrentWorkerSession worker_session(worker_id);
980 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
981 ShenandoahEvacOOMScope oom_evac_scope;
982 do_work();
983 } else {
984 ShenandoahParallelWorkerSession worker_session(worker_id);
985 ShenandoahEvacOOMScope oom_evac_scope;
986 do_work();
987 }
988 }
989
990 private:
991 void do_work() {
992 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
993 ShenandoahHeapRegion* r;
994 while ((r =_cs->claim_next()) != NULL) {
995 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
996 _sh->marked_object_iterate(r, &cl);
997
998 if (ShenandoahPacing) {
999 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
1000 }
1001
1002 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
1003 break;
1004 }
1005 }
1006 }
1007 };
1008
1009 void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
1010 ShenandoahEvacuationTask task(this, _collection_set, concurrent);
1011 workers()->run_task(&task);
1012 }
1013
1014 void ShenandoahHeap::trash_cset_regions() {
1015 ShenandoahHeapLocker locker(lock());
1016
1017 ShenandoahCollectionSet* set = collection_set();
1018 ShenandoahHeapRegion* r;
1019 set->clear_current_index();
1020 while ((r = set->next()) != NULL) {
1021 r->make_trash();
1022 }
1023 collection_set()->clear();
1024 }
1025
1026 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1027 st->print_cr("Heap Regions:");
1028 st->print_cr("Region state: EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HP=pinned humongous start");
1029 st->print_cr(" HC=humongous continuation, CS=collection set, TR=trash, P=pinned, CSP=pinned collection set");
1030 st->print_cr("BTE=bottom/top/end, TAMS=top-at-mark-start");
1031 st->print_cr("UWM=update watermark, U=used");
1032 st->print_cr("T=TLAB allocs, G=GCLAB allocs");
1033 st->print_cr("S=shared allocs, L=live data");
1034 st->print_cr("CP=critical pins");
1035
1036 for (size_t i = 0; i < num_regions(); i++) {
1037 get_region(i)->print_on(st);
1038 }
1039 }
1040
1041 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1042 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1043
1044 oop humongous_obj = cast_to_oop(start->bottom());
1045 size_t size = humongous_obj->size();
1046 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1047 size_t index = start->index() + required_regions - 1;
1048
1049 assert(!start->has_live(), "liveness must be zero");
1050
1051 for(size_t i = 0; i < required_regions; i++) {
1052 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1053 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1054 ShenandoahHeapRegion* region = get_region(index --);
1055
1056 assert(region->is_humongous(), "expect correct humongous start or continuation");
1057 assert(!region->is_cset(), "Humongous region should not be in collection set");
1058
1059 region->make_trash_immediate();
1060 }
1061 }
1062
1063 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1064 public:
1065 ShenandoahCheckCleanGCLABClosure() {}
1066 void do_thread(Thread* thread) {
1067 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1068 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1069 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
1070 }
1071 };
1072
1073 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1074 private:
1075 bool const _resize;
1076 public:
1077 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1078 void do_thread(Thread* thread) {
1079 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1080 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1081 gclab->retire();
1082 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1083 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1084 }
1085 }
1086 };
1087
1088 void ShenandoahHeap::labs_make_parsable() {
1089 assert(UseTLAB, "Only call with UseTLAB");
1090
1091 ShenandoahRetireGCLABClosure cl(false);
1092
1093 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1094 ThreadLocalAllocBuffer& tlab = t->tlab();
1095 tlab.make_parsable();
1096 cl.do_thread(t);
1097 }
1098
1099 workers()->threads_do(&cl);
1100 }
1101
1102 void ShenandoahHeap::tlabs_retire(bool resize) {
1103 assert(UseTLAB, "Only call with UseTLAB");
1104 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1105
1106 ThreadLocalAllocStats stats;
1107
1108 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1109 ThreadLocalAllocBuffer& tlab = t->tlab();
1110 tlab.retire(&stats);
1111 if (resize) {
1112 tlab.resize();
1113 }
1114 }
1115
1116 stats.publish();
1117
1118 #ifdef ASSERT
1119 ShenandoahCheckCleanGCLABClosure cl;
1120 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1121 cl.do_thread(t);
1122 }
1123 workers()->threads_do(&cl);
1124 #endif
1125 }
1126
1127 void ShenandoahHeap::gclabs_retire(bool resize) {
1128 assert(UseTLAB, "Only call with UseTLAB");
1129 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1130
1131 ShenandoahRetireGCLABClosure cl(resize);
1132 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1133 cl.do_thread(t);
1134 }
1135 workers()->threads_do(&cl);
1136
1137 if (safepoint_workers() != NULL) {
1138 safepoint_workers()->threads_do(&cl);
1139 }
1140 }
1141
1142 // Returns size in bytes
1143 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1144 if (ShenandoahElasticTLAB) {
1145 // With Elastic TLABs, return the max allowed size, and let the allocation path
1146 // figure out the safe size for current allocation.
1147 return ShenandoahHeapRegion::max_tlab_size_bytes();
1148 } else {
1149 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1150 }
1151 }
1152
1153 size_t ShenandoahHeap::max_tlab_size() const {
1154 // Returns size in words
1155 return ShenandoahHeapRegion::max_tlab_size_words();
1156 }
1157
1158 void ShenandoahHeap::collect(GCCause::Cause cause) {
1159 control_thread()->request_gc(cause);
1160 }
1161
1162 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1163 //assert(false, "Shouldn't need to do full collections");
1164 }
1165
1166 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1167 ShenandoahHeapRegion* r = heap_region_containing(addr);
1168 if (r != NULL) {
1169 return r->block_start(addr);
1170 }
1171 return NULL;
1172 }
1173
1174 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1175 ShenandoahHeapRegion* r = heap_region_containing(addr);
1176 return r->block_is_obj(addr);
1177 }
1178
1179 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1180 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1181 }
1182
1183 void ShenandoahHeap::prepare_for_verify() {
1184 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) {
1185 labs_make_parsable();
1186 }
1187 }
1188
1189 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1190 tcl->do_thread(_control_thread);
1191 workers()->threads_do(tcl);
1192 if (_safepoint_workers != NULL) {
1193 _safepoint_workers->threads_do(tcl);
1194 }
1195 if (ShenandoahStringDedup::is_enabled()) {
1196 ShenandoahStringDedup::threads_do(tcl);
1197 }
1198 }
1199
1200 void ShenandoahHeap::print_tracing_info() const {
1201 LogTarget(Info, gc, stats) lt;
1202 if (lt.is_enabled()) {
1203 ResourceMark rm;
1204 LogStream ls(lt);
1205
1206 phase_timings()->print_global_on(&ls);
1207
1208 ls.cr();
1209 ls.cr();
1210
1211 shenandoah_policy()->print_gc_stats(&ls);
1212
1213 ls.cr();
1214 ls.cr();
1215 }
1216 }
1217
1218 void ShenandoahHeap::verify(VerifyOption vo) {
1219 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1220 if (ShenandoahVerify) {
1221 verifier()->verify_generic(vo);
1222 } else {
1223 // TODO: Consider allocating verification bitmaps on demand,
1224 // and turn this on unconditionally.
1225 }
1226 }
1227 }
1228 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1229 return _free_set->capacity();
1230 }
1231
1232 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1233 private:
1234 MarkBitMap* _bitmap;
1235 ShenandoahScanObjectStack* _oop_stack;
1236 ShenandoahHeap* const _heap;
1237 ShenandoahMarkingContext* const _marking_context;
1238
1239 template <class T>
1240 void do_oop_work(T* p) {
1241 T o = RawAccess<>::oop_load(p);
1242 if (!CompressedOops::is_null(o)) {
1243 oop obj = CompressedOops::decode_not_null(o);
1244 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1245 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1246 return;
1247 }
1248 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
1249
1250 assert(oopDesc::is_oop(obj), "must be a valid oop");
1251 if (!_bitmap->is_marked(obj)) {
1252 _bitmap->mark(obj);
1253 _oop_stack->push(obj);
1254 }
1255 }
1256 }
1257 public:
1258 ObjectIterateScanRootClosure(MarkBitMap* bitmap, ShenandoahScanObjectStack* oop_stack) :
1259 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1260 _marking_context(_heap->marking_context()) {}
1261 void do_oop(oop* p) { do_oop_work(p); }
1262 void do_oop(narrowOop* p) { do_oop_work(p); }
1263 };
1264
1265 /*
1266 * This is public API, used in preparation of object_iterate().
1267 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1268 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1269 * control, we call SH::tlabs_retire, SH::gclabs_retire.
1270 */
1271 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1272 // No-op.
1273 }
1274
1275 /*
1276 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1277 *
1278 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1279 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1280 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1281 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1282 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1283 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1284 * wiped the bitmap in preparation for next marking).
1285 *
1286 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1287 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1288 * is allowed to report dead objects, but is not required to do so.
1289 */
1290 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1291 // Reset bitmap
1292 if (!prepare_aux_bitmap_for_iteration())
1293 return;
1294
1295 ShenandoahScanObjectStack oop_stack;
1296 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1297 // Seed the stack with root scan
1298 scan_roots_for_iteration(&oop_stack, &oops);
1299
1300 // Work through the oop stack to traverse heap
1301 while (! oop_stack.is_empty()) {
1302 oop obj = oop_stack.pop();
1303 assert(oopDesc::is_oop(obj), "must be a valid oop");
1304 cl->do_object(obj);
1305 obj->oop_iterate(&oops);
1306 }
1307
1308 assert(oop_stack.is_empty(), "should be empty");
1309 // Reclaim bitmap
1310 reclaim_aux_bitmap_for_iteration();
1311 }
1312
1313 bool ShenandoahHeap::prepare_aux_bitmap_for_iteration() {
1314 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1315
1316 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1317 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1318 return false;
1319 }
1320 // Reset bitmap
1321 _aux_bit_map.clear();
1322 return true;
1323 }
1324
1325 void ShenandoahHeap::scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops) {
1326 // Process GC roots according to current GC cycle
1327 // This populates the work stack with initial objects
1328 // It is important to relinquish the associated locks before diving
1329 // into heap dumper
1330 ShenandoahHeapIterationRootScanner rp;
1331 rp.roots_do(oops);
1332 }
1333
1334 void ShenandoahHeap::reclaim_aux_bitmap_for_iteration() {
1335 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1336 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1337 }
1338 }
1339
1340 // Closure for parallelly iterate objects
1341 class ShenandoahObjectIterateParScanClosure : public BasicOopIterateClosure {
1342 private:
1343 MarkBitMap* _bitmap;
1344 ShenandoahObjToScanQueue* _queue;
1345 ShenandoahHeap* const _heap;
1346 ShenandoahMarkingContext* const _marking_context;
1347
1348 template <class T>
1349 void do_oop_work(T* p) {
1350 T o = RawAccess<>::oop_load(p);
1351 if (!CompressedOops::is_null(o)) {
1352 oop obj = CompressedOops::decode_not_null(o);
1353 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1354 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1355 return;
1356 }
1357 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
1358
1359 assert(oopDesc::is_oop(obj), "Must be a valid oop");
1360 if (_bitmap->par_mark(obj)) {
1361 _queue->push(ShenandoahMarkTask(obj));
1362 }
1363 }
1364 }
1365 public:
1366 ShenandoahObjectIterateParScanClosure(MarkBitMap* bitmap, ShenandoahObjToScanQueue* q) :
1367 _bitmap(bitmap), _queue(q), _heap(ShenandoahHeap::heap()),
1368 _marking_context(_heap->marking_context()) {}
1369 void do_oop(oop* p) { do_oop_work(p); }
1370 void do_oop(narrowOop* p) { do_oop_work(p); }
1371 };
1372
1373 // Object iterator for parallel heap iteraion.
1374 // The root scanning phase happenes in construction as a preparation of
1375 // parallel marking queues.
1376 // Every worker processes it's own marking queue. work-stealing is used
1377 // to balance workload.
1378 class ShenandoahParallelObjectIterator : public ParallelObjectIteratorImpl {
1379 private:
1380 uint _num_workers;
1381 bool _init_ready;
1382 MarkBitMap* _aux_bit_map;
1383 ShenandoahHeap* _heap;
1384 ShenandoahScanObjectStack _roots_stack; // global roots stack
1385 ShenandoahObjToScanQueueSet* _task_queues;
1386 public:
1387 ShenandoahParallelObjectIterator(uint num_workers, MarkBitMap* bitmap) :
1388 _num_workers(num_workers),
1389 _init_ready(false),
1390 _aux_bit_map(bitmap),
1391 _heap(ShenandoahHeap::heap()) {
1392 // Initialize bitmap
1393 _init_ready = _heap->prepare_aux_bitmap_for_iteration();
1394 if (!_init_ready) {
1395 return;
1396 }
1397
1398 ObjectIterateScanRootClosure oops(_aux_bit_map, &_roots_stack);
1399 _heap->scan_roots_for_iteration(&_roots_stack, &oops);
1400
1401 _init_ready = prepare_worker_queues();
1402 }
1403
1404 ~ShenandoahParallelObjectIterator() {
1405 // Reclaim bitmap
1406 _heap->reclaim_aux_bitmap_for_iteration();
1407 // Reclaim queue for workers
1408 if (_task_queues!= NULL) {
1409 for (uint i = 0; i < _num_workers; ++i) {
1410 ShenandoahObjToScanQueue* q = _task_queues->queue(i);
1411 if (q != NULL) {
1412 delete q;
1413 _task_queues->register_queue(i, NULL);
1414 }
1415 }
1416 delete _task_queues;
1417 _task_queues = NULL;
1418 }
1419 }
1420
1421 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
1422 if (_init_ready) {
1423 object_iterate_parallel(cl, worker_id, _task_queues);
1424 }
1425 }
1426
1427 private:
1428 // Divide global root_stack into worker queues
1429 bool prepare_worker_queues() {
1430 _task_queues = new ShenandoahObjToScanQueueSet((int) _num_workers);
1431 // Initialize queues for every workers
1432 for (uint i = 0; i < _num_workers; ++i) {
1433 ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue();
1434 task_queue->initialize();
1435 _task_queues->register_queue(i, task_queue);
1436 }
1437 // Divide roots among the workers. Assume that object referencing distribution
1438 // is related with root kind, use round-robin to make every worker have same chance
1439 // to process every kind of roots
1440 size_t roots_num = _roots_stack.size();
1441 if (roots_num == 0) {
1442 // No work to do
1443 return false;
1444 }
1445
1446 for (uint j = 0; j < roots_num; j++) {
1447 uint stack_id = j % _num_workers;
1448 oop obj = _roots_stack.pop();
1449 _task_queues->queue(stack_id)->push(ShenandoahMarkTask(obj));
1450 }
1451 return true;
1452 }
1453
1454 void object_iterate_parallel(ObjectClosure* cl,
1455 uint worker_id,
1456 ShenandoahObjToScanQueueSet* queue_set) {
1457 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1458 assert(queue_set != NULL, "task queue must not be NULL");
1459
1460 ShenandoahObjToScanQueue* q = queue_set->queue(worker_id);
1461 assert(q != NULL, "object iterate queue must not be NULL");
1462
1463 ShenandoahMarkTask t;
1464 ShenandoahObjectIterateParScanClosure oops(_aux_bit_map, q);
1465
1466 // Work through the queue to traverse heap.
1467 // Steal when there is no task in queue.
1468 while (q->pop(t) || queue_set->steal(worker_id, t)) {
1469 oop obj = t.obj();
1470 assert(oopDesc::is_oop(obj), "must be a valid oop");
1471 cl->do_object(obj);
1472 obj->oop_iterate(&oops);
1473 }
1474 assert(q->is_empty(), "should be empty");
1475 }
1476 };
1477
1478 ParallelObjectIteratorImpl* ShenandoahHeap::parallel_object_iterator(uint workers) {
1479 return new ShenandoahParallelObjectIterator(workers, &_aux_bit_map);
1480 }
1481
1482 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1483 void ShenandoahHeap::keep_alive(oop obj) {
1484 if (is_concurrent_mark_in_progress() && (obj != NULL)) {
1485 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1486 }
1487 }
1488
1489 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1490 for (size_t i = 0; i < num_regions(); i++) {
1491 ShenandoahHeapRegion* current = get_region(i);
1492 blk->heap_region_do(current);
1493 }
1494 }
1495
1496 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1497 private:
1498 ShenandoahHeap* const _heap;
1499 ShenandoahHeapRegionClosure* const _blk;
1500
1501 shenandoah_padding(0);
1502 volatile size_t _index;
1503 shenandoah_padding(1);
1504
1505 public:
1506 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1507 AbstractGangTask("Shenandoah Parallel Region Operation"),
1508 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1509
1510 void work(uint worker_id) {
1511 ShenandoahParallelWorkerSession worker_session(worker_id);
1512 size_t stride = ShenandoahParallelRegionStride;
1513
1514 size_t max = _heap->num_regions();
1515 while (Atomic::load(&_index) < max) {
1516 size_t cur = Atomic::fetch_and_add(&_index, stride, memory_order_relaxed);
1517 size_t start = cur;
1518 size_t end = MIN2(cur + stride, max);
1519 if (start >= max) break;
1520
1521 for (size_t i = cur; i < end; i++) {
1522 ShenandoahHeapRegion* current = _heap->get_region(i);
1523 _blk->heap_region_do(current);
1524 }
1525 }
1526 }
1527 };
1528
1529 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1530 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1531 if (num_regions() > ShenandoahParallelRegionStride) {
1532 ShenandoahParallelHeapRegionTask task(blk);
1533 workers()->run_task(&task);
1534 } else {
1535 heap_region_iterate(blk);
1536 }
1537 }
1538
1539 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1540 private:
1541 ShenandoahMarkingContext* const _ctx;
1542 public:
1543 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1544
1545 void heap_region_do(ShenandoahHeapRegion* r) {
1546 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1547 if (r->is_active()) {
1548 // Check if region needs updating its TAMS. We have updated it already during concurrent
1549 // reset, so it is very likely we don't need to do another write here.
1550 if (_ctx->top_at_mark_start(r) != r->top()) {
1551 _ctx->capture_top_at_mark_start(r);
1552 }
1553 } else {
1554 assert(_ctx->top_at_mark_start(r) == r->top(),
1555 "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
1556 }
1557 }
1558
1559 bool is_thread_safe() { return true; }
1560 };
1561
1562 class ShenandoahRendezvousClosure : public HandshakeClosure {
1563 public:
1564 inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {}
1565 inline void do_thread(Thread* thread) {}
1566 };
1567
1568 void ShenandoahHeap::rendezvous_threads() {
1569 ShenandoahRendezvousClosure cl;
1570 Handshake::execute(&cl);
1571 }
1572
1573 void ShenandoahHeap::recycle_trash() {
1574 free_set()->recycle_trash();
1575 }
1576
1577 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1578 private:
1579 ShenandoahMarkingContext* const _ctx;
1580 public:
1581 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1582
1583 void heap_region_do(ShenandoahHeapRegion* r) {
1584 if (r->is_active()) {
1585 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1586 // anyway to capture any updates that happened since now.
1587 r->clear_live_data();
1588 _ctx->capture_top_at_mark_start(r);
1589 }
1590 }
1591
1592 bool is_thread_safe() { return true; }
1593 };
1594
1595 void ShenandoahHeap::prepare_gc() {
1596 reset_mark_bitmap();
1597
1598 ShenandoahResetUpdateRegionStateClosure cl;
1599 parallel_heap_region_iterate(&cl);
1600 }
1601
1602 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1603 private:
1604 ShenandoahMarkingContext* const _ctx;
1605 ShenandoahHeapLock* const _lock;
1606
1607 public:
1608 ShenandoahFinalMarkUpdateRegionStateClosure() :
1609 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1610
1611 void heap_region_do(ShenandoahHeapRegion* r) {
1612 if (r->is_active()) {
1613 // All allocations past TAMS are implicitly live, adjust the region data.
1614 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1615 HeapWord *tams = _ctx->top_at_mark_start(r);
1616 HeapWord *top = r->top();
1617 if (top > tams) {
1618 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1619 }
1620
1621 // We are about to select the collection set, make sure it knows about
1622 // current pinning status. Also, this allows trashing more regions that
1623 // now have their pinning status dropped.
1624 if (r->is_pinned()) {
1625 if (r->pin_count() == 0) {
1626 ShenandoahHeapLocker locker(_lock);
1627 r->make_unpinned();
1628 }
1629 } else {
1630 if (r->pin_count() > 0) {
1631 ShenandoahHeapLocker locker(_lock);
1632 r->make_pinned();
1633 }
1634 }
1635
1636 // Remember limit for updating refs. It's guaranteed that we get no
1637 // from-space-refs written from here on.
1638 r->set_update_watermark_at_safepoint(r->top());
1639 } else {
1640 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1641 assert(_ctx->top_at_mark_start(r) == r->top(),
1642 "Region " SIZE_FORMAT " should have correct TAMS", r->index());
1643 }
1644 }
1645
1646 bool is_thread_safe() { return true; }
1647 };
1648
1649 void ShenandoahHeap::prepare_regions_and_collection_set(bool concurrent) {
1650 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
1651 {
1652 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_region_states :
1653 ShenandoahPhaseTimings::degen_gc_final_update_region_states);
1654 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1655 parallel_heap_region_iterate(&cl);
1656
1657 assert_pinned_region_status();
1658 }
1659
1660 {
1661 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::choose_cset :
1662 ShenandoahPhaseTimings::degen_gc_choose_cset);
1663 ShenandoahHeapLocker locker(lock());
1664 _collection_set->clear();
1665 heuristics()->choose_collection_set(_collection_set);
1666 }
1667
1668 {
1669 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_rebuild_freeset :
1670 ShenandoahPhaseTimings::degen_gc_final_rebuild_freeset);
1671 ShenandoahHeapLocker locker(lock());
1672 _free_set->rebuild();
1673 }
1674 }
1675
1676 void ShenandoahHeap::do_class_unloading() {
1677 _unloader.unload();
1678 }
1679
1680 void ShenandoahHeap::stw_weak_refs(bool full_gc) {
1681 // Weak refs processing
1682 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs
1683 : ShenandoahPhaseTimings::degen_gc_weakrefs;
1684 ShenandoahTimingsTracker t(phase);
1685 ShenandoahGCWorkerPhase worker_phase(phase);
1686 ref_processor()->process_references(phase, workers(), false /* concurrent */);
1687 }
1688
1689 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
1690 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
1691
1692 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to
1693 // make them parsable for update code to work correctly. Plus, we can compute new sizes
1694 // for future GCLABs here.
1695 if (UseTLAB) {
1696 ShenandoahGCPhase phase(concurrent ?
1697 ShenandoahPhaseTimings::init_update_refs_manage_gclabs :
1698 ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs);
1699 gclabs_retire(ResizeTLAB);
1700 }
1701
1702 _update_refs_iterator.reset();
1703 }
1704
1705 void ShenandoahHeap::set_gc_state_all_threads() {
1706 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint");
1707 if (_gc_state_changed) {
1708 _gc_state_changed = false;
1709 char state = gc_state();
1710 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1711 ShenandoahThreadLocalData::set_gc_state(t, state);
1712 }
1713 }
1714 }
1715
1716 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1717 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint");
1718 _gc_state.set_cond(mask, value);
1719 _gc_state_changed = true;
1720 }
1721
1722 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1723 assert(!has_forwarded_objects(), "Not expected before/after mark phase");
1724 set_gc_state_mask(MARKING, in_progress);
1725 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1726 }
1727
1728 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1729 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1730 set_gc_state_mask(EVACUATION, in_progress);
1731 }
1732
1733 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
1734 if (in_progress) {
1735 _concurrent_strong_root_in_progress.set();
1736 } else {
1737 _concurrent_strong_root_in_progress.unset();
1738 }
1739 }
1740
1741 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) {
1742 set_gc_state_mask(WEAK_ROOTS, cond);
1743 }
1744
1745 GCTracer* ShenandoahHeap::tracer() {
1746 return shenandoah_policy()->tracer();
1747 }
1748
1749 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1750 return _free_set->used();
1751 }
1752
1753 bool ShenandoahHeap::try_cancel_gc() {
1754 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
1755 return prev == CANCELLABLE;
1756 }
1757
1758 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1759 if (try_cancel_gc()) {
1760 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1761 log_info(gc)("%s", msg.buffer());
1762 Events::log(Thread::current(), "%s", msg.buffer());
1763 }
1764 }
1765
1766 uint ShenandoahHeap::max_workers() {
1767 return _max_workers;
1768 }
1769
1770 void ShenandoahHeap::stop() {
1771 // The shutdown sequence should be able to terminate when GC is running.
1772
1773 // Step 0. Notify policy to disable event recording.
1774 _shenandoah_policy->record_shutdown();
1775
1776 // Step 1. Notify control thread that we are in shutdown.
1777 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1778 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1779 control_thread()->prepare_for_graceful_shutdown();
1780
1781 // Step 2. Notify GC workers that we are cancelling GC.
1782 cancel_gc(GCCause::_shenandoah_stop_vm);
1783
1784 // Step 3. Wait until GC worker exits normally.
1785 control_thread()->stop();
1786 }
1787
1788 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
1789 if (!unload_classes()) return;
1790 // Unload classes and purge SystemDictionary.
1791 {
1792 ShenandoahPhaseTimings::Phase phase = full_gc ?
1793 ShenandoahPhaseTimings::full_gc_purge_class_unload :
1794 ShenandoahPhaseTimings::degen_gc_purge_class_unload;
1795 ShenandoahGCPhase gc_phase(phase);
1796 ShenandoahGCWorkerPhase worker_phase(phase);
1797 bool purged_class = SystemDictionary::do_unloading(gc_timer());
1798
1799 ShenandoahIsAliveSelector is_alive;
1800 uint num_workers = _workers->active_workers();
1801 ShenandoahClassUnloadingTask unlink_task(phase, is_alive.is_alive_closure(), num_workers, purged_class);
1802 _workers->run_task(&unlink_task);
1803 }
1804
1805 {
1806 ShenandoahGCPhase phase(full_gc ?
1807 ShenandoahPhaseTimings::full_gc_purge_cldg :
1808 ShenandoahPhaseTimings::degen_gc_purge_cldg);
1809 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
1810 }
1811 // Resize and verify metaspace
1812 MetaspaceGC::compute_new_size();
1813 DEBUG_ONLY(MetaspaceUtils::verify();)
1814 }
1815
1816 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
1817 // so they should not have forwarded oops.
1818 // However, we do need to "null" dead oops in the roots, if can not be done
1819 // in concurrent cycles.
1820 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
1821 uint num_workers = _workers->active_workers();
1822 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
1823 ShenandoahPhaseTimings::full_gc_purge_weak_par :
1824 ShenandoahPhaseTimings::degen_gc_purge_weak_par;
1825 ShenandoahGCPhase phase(timing_phase);
1826 ShenandoahGCWorkerPhase worker_phase(timing_phase);
1827 // Cleanup weak roots
1828 if (has_forwarded_objects()) {
1829 ShenandoahForwardedIsAliveClosure is_alive;
1830 ShenandoahUpdateRefsClosure keep_alive;
1831 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
1832 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers);
1833 _workers->run_task(&cleaning_task);
1834 } else {
1835 ShenandoahIsAliveClosure is_alive;
1836 #ifdef ASSERT
1837 ShenandoahAssertNotForwardedClosure verify_cl;
1838 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
1839 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers);
1840 #else
1841 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
1842 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers);
1843 #endif
1844 _workers->run_task(&cleaning_task);
1845 }
1846 }
1847
1848 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
1849 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1850 assert(is_stw_gc_in_progress(), "Only for Degenerated and Full GC");
1851 ShenandoahGCPhase phase(full_gc ?
1852 ShenandoahPhaseTimings::full_gc_purge :
1853 ShenandoahPhaseTimings::degen_gc_purge);
1854 stw_weak_refs(full_gc);
1855 stw_process_weak_roots(full_gc);
1856 stw_unload_classes(full_gc);
1857 }
1858
1859 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
1860 set_gc_state_mask(HAS_FORWARDED, cond);
1861 }
1862
1863 void ShenandoahHeap::set_unload_classes(bool uc) {
1864 _unload_classes.set_cond(uc);
1865 }
1866
1867 bool ShenandoahHeap::unload_classes() const {
1868 return _unload_classes.is_set();
1869 }
1870
1871 address ShenandoahHeap::in_cset_fast_test_addr() {
1872 ShenandoahHeap* heap = ShenandoahHeap::heap();
1873 assert(heap->collection_set() != NULL, "Sanity");
1874 return (address) heap->collection_set()->biased_map_address();
1875 }
1876
1877 address ShenandoahHeap::cancelled_gc_addr() {
1878 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
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_mask(UPDATEREFS, in_progress);
1904 }
1905
1906 void ShenandoahHeap::register_nmethod(nmethod* nm) {
1907 ShenandoahCodeRoots::register_nmethod(nm);
1908 }
1909
1910 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
1911 ShenandoahCodeRoots::unregister_nmethod(nm);
1912 }
1913
1914 void ShenandoahHeap::flush_nmethod(nmethod* nm) {
1915 ShenandoahCodeRoots::flush_nmethod(nm);
1916 }
1917
1918 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
1919 heap_region_containing(o)->record_pin();
1920 return o;
1921 }
1922
1923 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
1924 ShenandoahHeapRegion* r = heap_region_containing(o);
1925 assert(r != NULL, "Sanity");
1926 assert(r->pin_count() > 0, "Region " SIZE_FORMAT " should have non-zero pins", r->index());
1927 r->record_unpin();
1928 }
1929
1930 void ShenandoahHeap::sync_pinned_region_status() {
1931 ShenandoahHeapLocker locker(lock());
1932
1933 for (size_t i = 0; i < num_regions(); i++) {
1934 ShenandoahHeapRegion *r = get_region(i);
1935 if (r->is_active()) {
1936 if (r->is_pinned()) {
1937 if (r->pin_count() == 0) {
1938 r->make_unpinned();
1939 }
1940 } else {
1941 if (r->pin_count() > 0) {
1942 r->make_pinned();
1943 }
1944 }
1945 }
1946 }
1947
1948 assert_pinned_region_status();
1949 }
1950
1951 #ifdef ASSERT
1952 void ShenandoahHeap::assert_pinned_region_status() {
1953 for (size_t i = 0; i < num_regions(); i++) {
1954 ShenandoahHeapRegion* r = get_region(i);
1955 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
1956 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
1957 }
1958 }
1959 #endif
1960
1961 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
1962 return _gc_timer;
1963 }
1964
1965 void ShenandoahHeap::prepare_concurrent_roots() {
1966 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1967 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1968 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
1969 set_concurrent_weak_root_in_progress(true);
1970 if (unload_classes()) {
1971 _unloader.prepare();
1972 }
1973 }
1974
1975 void ShenandoahHeap::finish_concurrent_roots() {
1976 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1977 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1978 if (unload_classes()) {
1979 _unloader.finish();
1980 }
1981 }
1982
1983 #ifdef ASSERT
1984 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
1985 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
1986
1987 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1988 if (UseDynamicNumberOfGCThreads) {
1989 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
1990 } else {
1991 // Use ParallelGCThreads inside safepoints
1992 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
1993 }
1994 } else {
1995 if (UseDynamicNumberOfGCThreads) {
1996 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
1997 } else {
1998 // Use ConcGCThreads outside safepoints
1999 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2000 }
2001 }
2002 }
2003 #endif
2004
2005 ShenandoahVerifier* ShenandoahHeap::verifier() {
2006 guarantee(ShenandoahVerify, "Should be enabled");
2007 assert (_verifier != NULL, "sanity");
2008 return _verifier;
2009 }
2010
2011 template<bool CONCURRENT>
2012 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2013 private:
2014 ShenandoahHeap* _heap;
2015 ShenandoahRegionIterator* _regions;
2016 public:
2017 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) :
2018 AbstractGangTask("Shenandoah Update References"),
2019 _heap(ShenandoahHeap::heap()),
2020 _regions(regions) {
2021 }
2022
2023 void work(uint worker_id) {
2024 if (CONCURRENT) {
2025 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2026 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2027 do_work<ShenandoahConcUpdateRefsClosure>();
2028 } else {
2029 ShenandoahParallelWorkerSession worker_session(worker_id);
2030 do_work<ShenandoahSTWUpdateRefsClosure>();
2031 }
2032 }
2033
2034 private:
2035 template<class T>
2036 void do_work() {
2037 T cl;
2038 ShenandoahHeapRegion* r = _regions->next();
2039 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2040 while (r != NULL) {
2041 HeapWord* update_watermark = r->get_update_watermark();
2042 assert (update_watermark >= r->bottom(), "sanity");
2043 if (r->is_active() && !r->is_cset()) {
2044 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2045 }
2046 if (ShenandoahPacing) {
2047 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2048 }
2049 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
2050 return;
2051 }
2052 r = _regions->next();
2053 }
2054 }
2055 };
2056
2057 void ShenandoahHeap::update_heap_references(bool concurrent) {
2058 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2059
2060 if (concurrent) {
2061 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator);
2062 workers()->run_task(&task);
2063 } else {
2064 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator);
2065 workers()->run_task(&task);
2066 }
2067 }
2068
2069
2070 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2071 private:
2072 ShenandoahHeapLock* const _lock;
2073
2074 public:
2075 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2076
2077 void heap_region_do(ShenandoahHeapRegion* r) {
2078 // Drop unnecessary "pinned" state from regions that does not have CP marks
2079 // anymore, as this would allow trashing them.
2080
2081 if (r->is_active()) {
2082 if (r->is_pinned()) {
2083 if (r->pin_count() == 0) {
2084 ShenandoahHeapLocker locker(_lock);
2085 r->make_unpinned();
2086 }
2087 } else {
2088 if (r->pin_count() > 0) {
2089 ShenandoahHeapLocker locker(_lock);
2090 r->make_pinned();
2091 }
2092 }
2093 }
2094 }
2095
2096 bool is_thread_safe() { return true; }
2097 };
2098
2099 void ShenandoahHeap::update_heap_region_states(bool concurrent) {
2100 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2101 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2102
2103 {
2104 ShenandoahGCPhase phase(concurrent ?
2105 ShenandoahPhaseTimings::final_update_refs_update_region_states :
2106 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states);
2107 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2108 parallel_heap_region_iterate(&cl);
2109
2110 assert_pinned_region_status();
2111 }
2112
2113 {
2114 ShenandoahGCPhase phase(concurrent ?
2115 ShenandoahPhaseTimings::final_update_refs_trash_cset :
2116 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset);
2117 trash_cset_regions();
2118 }
2119 }
2120
2121 void ShenandoahHeap::rebuild_free_set(bool concurrent) {
2122 {
2123 ShenandoahGCPhase phase(concurrent ?
2124 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
2125 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
2126 ShenandoahHeapLocker locker(lock());
2127 _free_set->rebuild();
2128 }
2129 }
2130
2131 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2132 print_on(st);
2133 st->cr();
2134 print_heap_regions_on(st);
2135 }
2136
2137 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2138 size_t slice = r->index() / _bitmap_regions_per_slice;
2139
2140 size_t regions_from = _bitmap_regions_per_slice * slice;
2141 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2142 for (size_t g = regions_from; g < regions_to; g++) {
2143 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2144 if (skip_self && g == r->index()) continue;
2145 if (get_region(g)->is_committed()) {
2146 return true;
2147 }
2148 }
2149 return false;
2150 }
2151
2152 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2153 shenandoah_assert_heaplocked();
2154
2155 // Bitmaps in special regions do not need commits
2156 if (_bitmap_region_special) {
2157 return true;
2158 }
2159
2160 if (is_bitmap_slice_committed(r, true)) {
2161 // Some other region from the group is already committed, meaning the bitmap
2162 // slice is already committed, we exit right away.
2163 return true;
2164 }
2165
2166 // Commit the bitmap slice:
2167 size_t slice = r->index() / _bitmap_regions_per_slice;
2168 size_t off = _bitmap_bytes_per_slice * slice;
2169 size_t len = _bitmap_bytes_per_slice;
2170 char* start = (char*) _bitmap_region.start() + off;
2171
2172 if (!os::commit_memory(start, len, false)) {
2173 return false;
2174 }
2175
2176 if (AlwaysPreTouch) {
2177 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size);
2178 }
2179
2180 return true;
2181 }
2182
2183 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2184 shenandoah_assert_heaplocked();
2185
2186 // Bitmaps in special regions do not need uncommits
2187 if (_bitmap_region_special) {
2188 return true;
2189 }
2190
2191 if (is_bitmap_slice_committed(r, true)) {
2192 // Some other region from the group is still committed, meaning the bitmap
2193 // slice is should stay committed, exit right away.
2194 return true;
2195 }
2196
2197 // Uncommit the bitmap slice:
2198 size_t slice = r->index() / _bitmap_regions_per_slice;
2199 size_t off = _bitmap_bytes_per_slice * slice;
2200 size_t len = _bitmap_bytes_per_slice;
2201 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2202 return false;
2203 }
2204 return true;
2205 }
2206
2207 void ShenandoahHeap::safepoint_synchronize_begin() {
2208 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2209 SuspendibleThreadSet::synchronize();
2210 }
2211 }
2212
2213 void ShenandoahHeap::safepoint_synchronize_end() {
2214 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2215 SuspendibleThreadSet::desynchronize();
2216 }
2217 }
2218
2219 void ShenandoahHeap::entry_uncommit(double shrink_before, size_t shrink_until) {
2220 static const char *msg = "Concurrent uncommit";
2221 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */);
2222 EventMark em("%s", msg);
2223
2224 op_uncommit(shrink_before, shrink_until);
2225 }
2226
2227 void ShenandoahHeap::try_inject_alloc_failure() {
2228 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2229 _inject_alloc_failure.set();
2230 os::naked_short_sleep(1);
2231 if (cancelled_gc()) {
2232 log_info(gc)("Allocation failure was successfully injected");
2233 }
2234 }
2235 }
2236
2237 bool ShenandoahHeap::should_inject_alloc_failure() {
2238 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2239 }
2240
2241 void ShenandoahHeap::initialize_serviceability() {
2242 _memory_pool = new ShenandoahMemoryPool(this);
2243 _cycle_memory_manager.add_pool(_memory_pool);
2244 _stw_memory_manager.add_pool(_memory_pool);
2245 }
2246
2247 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2248 GrowableArray<GCMemoryManager*> memory_managers(2);
2249 memory_managers.append(&_cycle_memory_manager);
2250 memory_managers.append(&_stw_memory_manager);
2251 return memory_managers;
2252 }
2253
2254 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2255 GrowableArray<MemoryPool*> memory_pools(1);
2256 memory_pools.append(_memory_pool);
2257 return memory_pools;
2258 }
2259
2260 MemoryUsage ShenandoahHeap::memory_usage() {
2261 return _memory_pool->get_memory_usage();
2262 }
2263
2264 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2265 _heap(ShenandoahHeap::heap()),
2266 _index(0) {}
2267
2268 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2269 _heap(heap),
2270 _index(0) {}
2271
2272 void ShenandoahRegionIterator::reset() {
2273 _index = 0;
2274 }
2275
2276 bool ShenandoahRegionIterator::has_next() const {
2277 return _index < _heap->num_regions();
2278 }
2279
2280 char ShenandoahHeap::gc_state() const {
2281 return _gc_state.raw_value();
2282 }
2283
2284 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2285 #ifdef ASSERT
2286 assert(_liveness_cache != NULL, "sanity");
2287 assert(worker_id < _max_workers, "sanity");
2288 for (uint i = 0; i < num_regions(); i++) {
2289 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2290 }
2291 #endif
2292 return _liveness_cache[worker_id];
2293 }
2294
2295 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2296 assert(worker_id < _max_workers, "sanity");
2297 assert(_liveness_cache != NULL, "sanity");
2298 ShenandoahLiveData* ld = _liveness_cache[worker_id];
2299 for (uint i = 0; i < num_regions(); i++) {
2300 ShenandoahLiveData live = ld[i];
2301 if (live > 0) {
2302 ShenandoahHeapRegion* r = get_region(i);
2303 r->increase_live_data_gc_words(live);
2304 ld[i] = 0;
2305 }
2306 }
2307 }