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 WorkerTask {
92 private:
93 ShenandoahRegionIterator _regions;
94 const size_t _page_size;
95 public:
96 ShenandoahPretouchHeapTask(size_t page_size) :
97 WorkerTask("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 WorkerTask {
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 WorkerTask("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 _control_thread(NULL),
469 _shenandoah_policy(policy),
470 _gc_mode(NULL),
471 _heuristics(NULL),
472 _free_set(NULL),
473 _pacer(NULL),
474 _verifier(NULL),
475 _phase_timings(NULL),
476 _monitoring_support(NULL),
477 _memory_pool(NULL),
478 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
479 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
480 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
481 _soft_ref_policy(),
482 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
483 _ref_processor(new ShenandoahReferenceProcessor(MAX2(_max_workers, 1U))),
484 _marking_context(NULL),
485 _bitmap_size(0),
486 _bitmap_regions_per_slice(0),
487 _bitmap_bytes_per_slice(0),
488 _bitmap_region_special(false),
489 _aux_bitmap_region_special(false),
490 _liveness_cache(NULL),
491 _collection_set(NULL)
492 {
493 // Initialize GC mode early, so we can adjust barrier support
494 initialize_mode();
495 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
496
497 _max_workers = MAX2(_max_workers, 1U);
498 _workers = new ShenandoahWorkerThreads("Shenandoah GC Threads", _max_workers);
499 if (_workers == NULL) {
500 vm_exit_during_initialization("Failed necessary allocation.");
501 } else {
502 _workers->initialize_workers();
503 }
504
505 if (ParallelGCThreads > 1) {
506 _safepoint_workers = new ShenandoahWorkerThreads("Safepoint Cleanup Thread",
507 ParallelGCThreads);
508 _safepoint_workers->initialize_workers();
509 }
510 }
511
512 #ifdef _MSC_VER
513 #pragma warning( pop )
514 #endif
515
516 class ShenandoahResetBitmapTask : public WorkerTask {
517 private:
518 ShenandoahRegionIterator _regions;
519
520 public:
521 ShenandoahResetBitmapTask() :
522 WorkerTask("Shenandoah Reset Bitmap") {}
523
524 void work(uint worker_id) {
525 ShenandoahHeapRegion* region = _regions.next();
526 ShenandoahHeap* heap = ShenandoahHeap::heap();
527 ShenandoahMarkingContext* const ctx = heap->marking_context();
528 while (region != NULL) {
529 if (heap->is_bitmap_slice_committed(region)) {
530 ctx->clear_bitmap(region);
531 }
532 region = _regions.next();
533 }
534 }
535 };
536
537 void ShenandoahHeap::reset_mark_bitmap() {
538 assert_gc_workers(_workers->active_workers());
539 mark_incomplete_marking_context();
540
541 ShenandoahResetBitmapTask task;
542 _workers->run_task(&task);
543 }
544
545 void ShenandoahHeap::print_on(outputStream* st) const {
546 st->print_cr("Shenandoah Heap");
547 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
548 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
549 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()),
550 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
551 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
552 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
553 num_regions(),
554 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
555 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
556
557 st->print("Status: ");
558 if (has_forwarded_objects()) st->print("has forwarded objects, ");
559 if (is_concurrent_mark_in_progress()) st->print("marking, ");
560 if (is_evacuation_in_progress()) st->print("evacuating, ");
561 if (is_update_refs_in_progress()) st->print("updating refs, ");
562 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
563 if (is_full_gc_in_progress()) st->print("full gc, ");
564 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
565 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, ");
566 if (is_concurrent_strong_root_in_progress() &&
567 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, ");
568
569 if (cancelled_gc()) {
570 st->print("cancelled");
571 } else {
572 st->print("not cancelled");
573 }
574 st->cr();
575
576 st->print_cr("Reserved region:");
577 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
578 p2i(reserved_region().start()),
579 p2i(reserved_region().end()));
580
581 ShenandoahCollectionSet* cset = collection_set();
582 st->print_cr("Collection set:");
583 if (cset != NULL) {
584 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
585 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
586 } else {
587 st->print_cr(" (NULL)");
588 }
589
590 st->cr();
591 MetaspaceUtils::print_on(st);
592
593 if (Verbose) {
594 print_heap_regions_on(st);
595 }
596 }
597
598 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
599 public:
600 void do_thread(Thread* thread) {
601 assert(thread != NULL, "Sanity");
602 assert(thread->is_Worker_thread(), "Only worker thread expected");
603 ShenandoahThreadLocalData::initialize_gclab(thread);
604 }
605 };
606
607 void ShenandoahHeap::post_initialize() {
608 CollectedHeap::post_initialize();
609 MutexLocker ml(Threads_lock);
610
611 ShenandoahInitWorkerGCLABClosure init_gclabs;
612 _workers->threads_do(&init_gclabs);
613
614 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
615 // Now, we will let WorkerThreads to initialize gclab when new worker is created.
616 _workers->set_initialize_gclab();
617 if (_safepoint_workers != NULL) {
618 _safepoint_workers->threads_do(&init_gclabs);
619 _safepoint_workers->set_initialize_gclab();
620 }
621
622 _heuristics->initialize();
623
624 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
625 }
626
627 size_t ShenandoahHeap::used() const {
628 return Atomic::load(&_used);
629 }
630
631 size_t ShenandoahHeap::committed() const {
632 return Atomic::load(&_committed);
633 }
634
635 void ShenandoahHeap::increase_committed(size_t bytes) {
636 shenandoah_assert_heaplocked_or_safepoint();
637 _committed += bytes;
638 }
639
640 void ShenandoahHeap::decrease_committed(size_t bytes) {
641 shenandoah_assert_heaplocked_or_safepoint();
642 _committed -= bytes;
643 }
644
645 void ShenandoahHeap::increase_used(size_t bytes) {
646 Atomic::add(&_used, bytes, memory_order_relaxed);
647 }
648
649 void ShenandoahHeap::set_used(size_t bytes) {
650 Atomic::store(&_used, bytes);
651 }
652
653 void ShenandoahHeap::decrease_used(size_t bytes) {
654 assert(used() >= bytes, "never decrease heap size by more than we've left");
655 Atomic::sub(&_used, bytes, memory_order_relaxed);
656 }
657
658 void ShenandoahHeap::increase_allocated(size_t bytes) {
659 Atomic::add(&_bytes_allocated_since_gc_start, bytes, memory_order_relaxed);
660 }
661
662 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
663 size_t bytes = words * HeapWordSize;
664 if (!waste) {
665 increase_used(bytes);
666 }
667 increase_allocated(bytes);
668 if (ShenandoahPacing) {
669 control_thread()->pacing_notify_alloc(words);
670 if (waste) {
671 pacer()->claim_for_alloc(words, true);
672 }
673 }
674 }
675
676 size_t ShenandoahHeap::capacity() const {
677 return committed();
678 }
679
680 size_t ShenandoahHeap::max_capacity() const {
681 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
682 }
683
684 size_t ShenandoahHeap::soft_max_capacity() const {
685 size_t v = Atomic::load(&_soft_max_size);
686 assert(min_capacity() <= v && v <= max_capacity(),
687 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
688 min_capacity(), v, max_capacity());
689 return v;
690 }
691
692 void ShenandoahHeap::set_soft_max_capacity(size_t v) {
693 assert(min_capacity() <= v && v <= max_capacity(),
694 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
695 min_capacity(), v, max_capacity());
696 Atomic::store(&_soft_max_size, v);
697 }
698
699 size_t ShenandoahHeap::min_capacity() const {
700 return _minimum_size;
701 }
702
703 size_t ShenandoahHeap::initial_capacity() const {
704 return _initial_size;
705 }
706
707 bool ShenandoahHeap::is_in(const void* p) const {
708 HeapWord* heap_base = (HeapWord*) base();
709 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
710 return p >= heap_base && p < last_region_end;
711 }
712
713 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
714 assert (ShenandoahUncommit, "should be enabled");
715
716 // Application allocates from the beginning of the heap, and GC allocates at
717 // the end of it. It is more efficient to uncommit from the end, so that applications
718 // could enjoy the near committed regions. GC allocations are much less frequent,
719 // and therefore can accept the committing costs.
720
721 size_t count = 0;
722 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
723 ShenandoahHeapRegion* r = get_region(i - 1);
724 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
725 ShenandoahHeapLocker locker(lock());
726 if (r->is_empty_committed()) {
727 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) {
728 break;
729 }
730
731 r->make_uncommitted();
732 count++;
733 }
734 }
735 SpinPause(); // allow allocators to take the lock
736 }
737
738 if (count > 0) {
739 control_thread()->notify_heap_changed();
740 }
741 }
742
743 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
744 // New object should fit the GCLAB size
745 size_t min_size = MAX2(size, PLAB::min_size());
746
747 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
748 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
749 new_size = MIN2(new_size, PLAB::max_size());
750 new_size = MAX2(new_size, PLAB::min_size());
751
752 // Record new heuristic value even if we take any shortcut. This captures
753 // the case when moderately-sized objects always take a shortcut. At some point,
754 // heuristics should catch up with them.
755 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
756
757 if (new_size < size) {
758 // New size still does not fit the object. Fall back to shared allocation.
759 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
760 return NULL;
761 }
762
763 // Retire current GCLAB, and allocate a new one.
764 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
765 gclab->retire();
766
767 size_t actual_size = 0;
768 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
769 if (gclab_buf == NULL) {
770 return NULL;
771 }
772
773 assert (size <= actual_size, "allocation should fit");
774
775 if (ZeroTLAB) {
776 // ..and clear it.
777 Copy::zero_to_words(gclab_buf, actual_size);
778 } else {
779 // ...and zap just allocated object.
780 #ifdef ASSERT
781 // Skip mangling the space corresponding to the object header to
782 // ensure that the returned space is not considered parsable by
783 // any concurrent GC thread.
784 size_t hdr_size = oopDesc::header_size();
785 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
786 #endif // ASSERT
787 }
788 gclab->set_buf(gclab_buf, actual_size);
789 return gclab->allocate(size);
790 }
791
792 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
793 size_t requested_size,
794 size_t* actual_size) {
795 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
796 HeapWord* res = allocate_memory(req);
797 if (res != NULL) {
798 *actual_size = req.actual_size();
799 } else {
800 *actual_size = 0;
801 }
802 return res;
803 }
804
805 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
806 size_t word_size,
807 size_t* actual_size) {
808 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
809 HeapWord* res = allocate_memory(req);
810 if (res != NULL) {
811 *actual_size = req.actual_size();
812 } else {
813 *actual_size = 0;
814 }
815 return res;
816 }
817
818 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
819 intptr_t pacer_epoch = 0;
820 bool in_new_region = false;
821 HeapWord* result = NULL;
822
823 if (req.is_mutator_alloc()) {
824 if (ShenandoahPacing) {
825 pacer()->pace_for_alloc(req.size());
826 pacer_epoch = pacer()->epoch();
827 }
828
829 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
830 result = allocate_memory_under_lock(req, in_new_region);
831 }
832
833 // Allocation failed, block until control thread reacted, then retry allocation.
834 //
835 // It might happen that one of the threads requesting allocation would unblock
836 // way later after GC happened, only to fail the second allocation, because
837 // other threads have already depleted the free storage. In this case, a better
838 // strategy is to try again, as long as GC makes progress.
839 //
840 // Then, we need to make sure the allocation was retried after at least one
841 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
842
843 size_t tries = 0;
844
845 while (result == NULL && _progress_last_gc.is_set()) {
846 tries++;
847 control_thread()->handle_alloc_failure(req);
848 result = allocate_memory_under_lock(req, in_new_region);
849 }
850
851 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
852 tries++;
853 control_thread()->handle_alloc_failure(req);
854 result = allocate_memory_under_lock(req, in_new_region);
855 }
856
857 } else {
858 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
859 result = allocate_memory_under_lock(req, in_new_region);
860 // Do not call handle_alloc_failure() here, because we cannot block.
861 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
862 }
863
864 if (in_new_region) {
865 control_thread()->notify_heap_changed();
866 }
867
868 if (result != NULL) {
869 size_t requested = req.size();
870 size_t actual = req.actual_size();
871
872 assert (req.is_lab_alloc() || (requested == actual),
873 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
874 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
875
876 if (req.is_mutator_alloc()) {
877 notify_mutator_alloc_words(actual, false);
878
879 // If we requested more than we were granted, give the rest back to pacer.
880 // This only matters if we are in the same pacing epoch: do not try to unpace
881 // over the budget for the other phase.
882 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
883 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
884 }
885 } else {
886 increase_used(actual*HeapWordSize);
887 }
888 }
889
890 return result;
891 }
892
893 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
894 ShenandoahHeapLocker locker(lock());
895 return _free_set->allocate(req, in_new_region);
896 }
897
898 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
899 bool* gc_overhead_limit_was_exceeded) {
900 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
901 return allocate_memory(req);
902 }
903
904 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
905 size_t size,
906 Metaspace::MetadataType mdtype) {
907 MetaWord* result;
908
909 // Inform metaspace OOM to GC heuristics if class unloading is possible.
910 if (heuristics()->can_unload_classes()) {
911 ShenandoahHeuristics* h = heuristics();
912 h->record_metaspace_oom();
913 }
914
915 // Expand and retry allocation
916 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
917 if (result != NULL) {
918 return result;
919 }
920
921 // Start full GC
922 collect(GCCause::_metadata_GC_clear_soft_refs);
923
924 // Retry allocation
925 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
926 if (result != NULL) {
927 return result;
928 }
929
930 // Expand and retry allocation
931 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
932 if (result != NULL) {
933 return result;
934 }
935
936 // Out of memory
937 return NULL;
938 }
939
940 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
941 private:
942 ShenandoahHeap* const _heap;
943 Thread* const _thread;
944 public:
945 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
946 _heap(heap), _thread(Thread::current()) {}
947
948 void do_object(oop p) {
949 shenandoah_assert_marked(NULL, p);
950 if (!p->is_forwarded()) {
951 _heap->evacuate_object(p, _thread);
952 }
953 }
954 };
955
956 class ShenandoahEvacuationTask : public WorkerTask {
957 private:
958 ShenandoahHeap* const _sh;
959 ShenandoahCollectionSet* const _cs;
960 bool _concurrent;
961 public:
962 ShenandoahEvacuationTask(ShenandoahHeap* sh,
963 ShenandoahCollectionSet* cs,
964 bool concurrent) :
965 WorkerTask("Shenandoah Evacuation"),
966 _sh(sh),
967 _cs(cs),
968 _concurrent(concurrent)
969 {}
970
971 void work(uint worker_id) {
972 if (_concurrent) {
973 ShenandoahConcurrentWorkerSession worker_session(worker_id);
974 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
975 ShenandoahEvacOOMScope oom_evac_scope;
976 do_work();
977 } else {
978 ShenandoahParallelWorkerSession worker_session(worker_id);
979 ShenandoahEvacOOMScope oom_evac_scope;
980 do_work();
981 }
982 }
983
984 private:
985 void do_work() {
986 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
987 ShenandoahHeapRegion* r;
988 while ((r =_cs->claim_next()) != NULL) {
989 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
990 _sh->marked_object_iterate(r, &cl);
991
992 if (ShenandoahPacing) {
993 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
994 }
995
996 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
997 break;
998 }
999 }
1000 }
1001 };
1002
1003 void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
1004 ShenandoahEvacuationTask task(this, _collection_set, concurrent);
1005 workers()->run_task(&task);
1006 }
1007
1008 void ShenandoahHeap::trash_cset_regions() {
1009 ShenandoahHeapLocker locker(lock());
1010
1011 ShenandoahCollectionSet* set = collection_set();
1012 ShenandoahHeapRegion* r;
1013 set->clear_current_index();
1014 while ((r = set->next()) != NULL) {
1015 r->make_trash();
1016 }
1017 collection_set()->clear();
1018 }
1019
1020 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1021 st->print_cr("Heap Regions:");
1022 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
1023 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
1024 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark");
1025 st->print_cr("SN=alloc sequence number");
1026
1027 for (size_t i = 0; i < num_regions(); i++) {
1028 get_region(i)->print_on(st);
1029 }
1030 }
1031
1032 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1033 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1034
1035 oop humongous_obj = cast_to_oop(start->bottom());
1036 size_t size = humongous_obj->size();
1037 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1038 size_t index = start->index() + required_regions - 1;
1039
1040 assert(!start->has_live(), "liveness must be zero");
1041
1042 for(size_t i = 0; i < required_regions; i++) {
1043 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1044 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1045 ShenandoahHeapRegion* region = get_region(index --);
1046
1047 assert(region->is_humongous(), "expect correct humongous start or continuation");
1048 assert(!region->is_cset(), "Humongous region should not be in collection set");
1049
1050 region->make_trash_immediate();
1051 }
1052 }
1053
1054 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1055 public:
1056 ShenandoahCheckCleanGCLABClosure() {}
1057 void do_thread(Thread* thread) {
1058 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1059 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1060 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
1061 }
1062 };
1063
1064 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1065 private:
1066 bool const _resize;
1067 public:
1068 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1069 void do_thread(Thread* thread) {
1070 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1071 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1072 gclab->retire();
1073 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1074 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1075 }
1076 }
1077 };
1078
1079 void ShenandoahHeap::labs_make_parsable() {
1080 assert(UseTLAB, "Only call with UseTLAB");
1081
1082 ShenandoahRetireGCLABClosure cl(false);
1083
1084 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1085 ThreadLocalAllocBuffer& tlab = t->tlab();
1086 tlab.make_parsable();
1087 cl.do_thread(t);
1088 }
1089
1090 workers()->threads_do(&cl);
1091 }
1092
1093 void ShenandoahHeap::tlabs_retire(bool resize) {
1094 assert(UseTLAB, "Only call with UseTLAB");
1095 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1096
1097 ThreadLocalAllocStats stats;
1098
1099 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1100 ThreadLocalAllocBuffer& tlab = t->tlab();
1101 tlab.retire(&stats);
1102 if (resize) {
1103 tlab.resize();
1104 }
1105 }
1106
1107 stats.publish();
1108
1109 #ifdef ASSERT
1110 ShenandoahCheckCleanGCLABClosure cl;
1111 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1112 cl.do_thread(t);
1113 }
1114 workers()->threads_do(&cl);
1115 #endif
1116 }
1117
1118 void ShenandoahHeap::gclabs_retire(bool resize) {
1119 assert(UseTLAB, "Only call with UseTLAB");
1120 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1121
1122 ShenandoahRetireGCLABClosure cl(resize);
1123 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1124 cl.do_thread(t);
1125 }
1126 workers()->threads_do(&cl);
1127
1128 if (safepoint_workers() != NULL) {
1129 safepoint_workers()->threads_do(&cl);
1130 }
1131 }
1132
1133 // Returns size in bytes
1134 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1135 if (ShenandoahElasticTLAB) {
1136 // With Elastic TLABs, return the max allowed size, and let the allocation path
1137 // figure out the safe size for current allocation.
1138 return ShenandoahHeapRegion::max_tlab_size_bytes();
1139 } else {
1140 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1141 }
1142 }
1143
1144 size_t ShenandoahHeap::max_tlab_size() const {
1145 // Returns size in words
1146 return ShenandoahHeapRegion::max_tlab_size_words();
1147 }
1148
1149 void ShenandoahHeap::collect(GCCause::Cause cause) {
1150 control_thread()->request_gc(cause);
1151 }
1152
1153 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1154 //assert(false, "Shouldn't need to do full collections");
1155 }
1156
1157 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1158 ShenandoahHeapRegion* r = heap_region_containing(addr);
1159 if (r != NULL) {
1160 return r->block_start(addr);
1161 }
1162 return NULL;
1163 }
1164
1165 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1166 ShenandoahHeapRegion* r = heap_region_containing(addr);
1167 return r->block_is_obj(addr);
1168 }
1169
1170 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1171 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1172 }
1173
1174 void ShenandoahHeap::prepare_for_verify() {
1175 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) {
1176 labs_make_parsable();
1177 }
1178 }
1179
1180 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1181 workers()->threads_do(tcl);
1182 if (_safepoint_workers != NULL) {
1183 _safepoint_workers->threads_do(tcl);
1184 }
1185 if (ShenandoahStringDedup::is_enabled()) {
1186 ShenandoahStringDedup::threads_do(tcl);
1187 }
1188 }
1189
1190 void ShenandoahHeap::print_tracing_info() const {
1191 LogTarget(Info, gc, stats) lt;
1192 if (lt.is_enabled()) {
1193 ResourceMark rm;
1194 LogStream ls(lt);
1195
1196 phase_timings()->print_global_on(&ls);
1197
1198 ls.cr();
1199 ls.cr();
1200
1201 shenandoah_policy()->print_gc_stats(&ls);
1202
1203 ls.cr();
1204 ls.cr();
1205 }
1206 }
1207
1208 void ShenandoahHeap::verify(VerifyOption vo) {
1209 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1210 if (ShenandoahVerify) {
1211 verifier()->verify_generic(vo);
1212 } else {
1213 // TODO: Consider allocating verification bitmaps on demand,
1214 // and turn this on unconditionally.
1215 }
1216 }
1217 }
1218 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1219 return _free_set->capacity();
1220 }
1221
1222 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1223 private:
1224 MarkBitMap* _bitmap;
1225 ShenandoahScanObjectStack* _oop_stack;
1226 ShenandoahHeap* const _heap;
1227 ShenandoahMarkingContext* const _marking_context;
1228
1229 template <class T>
1230 void do_oop_work(T* p) {
1231 T o = RawAccess<>::oop_load(p);
1232 if (!CompressedOops::is_null(o)) {
1233 oop obj = CompressedOops::decode_not_null(o);
1234 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1235 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1236 return;
1237 }
1238 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1239
1240 assert(oopDesc::is_oop(obj), "must be a valid oop");
1241 if (!_bitmap->is_marked(obj)) {
1242 _bitmap->mark(obj);
1243 _oop_stack->push(obj);
1244 }
1245 }
1246 }
1247 public:
1248 ObjectIterateScanRootClosure(MarkBitMap* bitmap, ShenandoahScanObjectStack* oop_stack) :
1249 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1250 _marking_context(_heap->marking_context()) {}
1251 void do_oop(oop* p) { do_oop_work(p); }
1252 void do_oop(narrowOop* p) { do_oop_work(p); }
1253 };
1254
1255 /*
1256 * This is public API, used in preparation of object_iterate().
1257 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1258 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1259 * control, we call SH::tlabs_retire, SH::gclabs_retire.
1260 */
1261 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1262 // No-op.
1263 }
1264
1265 /*
1266 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1267 *
1268 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1269 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1270 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1271 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1272 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1273 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1274 * wiped the bitmap in preparation for next marking).
1275 *
1276 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1277 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1278 * is allowed to report dead objects, but is not required to do so.
1279 */
1280 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1281 // Reset bitmap
1282 if (!prepare_aux_bitmap_for_iteration())
1283 return;
1284
1285 ShenandoahScanObjectStack oop_stack;
1286 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1287 // Seed the stack with root scan
1288 scan_roots_for_iteration(&oop_stack, &oops);
1289
1290 // Work through the oop stack to traverse heap
1291 while (! oop_stack.is_empty()) {
1292 oop obj = oop_stack.pop();
1293 assert(oopDesc::is_oop(obj), "must be a valid oop");
1294 cl->do_object(obj);
1295 obj->oop_iterate(&oops);
1296 }
1297
1298 assert(oop_stack.is_empty(), "should be empty");
1299 // Reclaim bitmap
1300 reclaim_aux_bitmap_for_iteration();
1301 }
1302
1303 bool ShenandoahHeap::prepare_aux_bitmap_for_iteration() {
1304 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1305
1306 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1307 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1308 return false;
1309 }
1310 // Reset bitmap
1311 _aux_bit_map.clear();
1312 return true;
1313 }
1314
1315 void ShenandoahHeap::scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops) {
1316 // Process GC roots according to current GC cycle
1317 // This populates the work stack with initial objects
1318 // It is important to relinquish the associated locks before diving
1319 // into heap dumper
1320 uint n_workers = safepoint_workers() != NULL ? safepoint_workers()->active_workers() : 1;
1321 ShenandoahHeapIterationRootScanner rp(n_workers);
1322 rp.roots_do(oops);
1323 }
1324
1325 void ShenandoahHeap::reclaim_aux_bitmap_for_iteration() {
1326 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1327 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1328 }
1329 }
1330
1331 // Closure for parallelly iterate objects
1332 class ShenandoahObjectIterateParScanClosure : public BasicOopIterateClosure {
1333 private:
1334 MarkBitMap* _bitmap;
1335 ShenandoahObjToScanQueue* _queue;
1336 ShenandoahHeap* const _heap;
1337 ShenandoahMarkingContext* const _marking_context;
1338
1339 template <class T>
1340 void do_oop_work(T* p) {
1341 T o = RawAccess<>::oop_load(p);
1342 if (!CompressedOops::is_null(o)) {
1343 oop obj = CompressedOops::decode_not_null(o);
1344 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1345 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1346 return;
1347 }
1348 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1349
1350 assert(oopDesc::is_oop(obj), "Must be a valid oop");
1351 if (_bitmap->par_mark(obj)) {
1352 _queue->push(ShenandoahMarkTask(obj));
1353 }
1354 }
1355 }
1356 public:
1357 ShenandoahObjectIterateParScanClosure(MarkBitMap* bitmap, ShenandoahObjToScanQueue* q) :
1358 _bitmap(bitmap), _queue(q), _heap(ShenandoahHeap::heap()),
1359 _marking_context(_heap->marking_context()) {}
1360 void do_oop(oop* p) { do_oop_work(p); }
1361 void do_oop(narrowOop* p) { do_oop_work(p); }
1362 };
1363
1364 // Object iterator for parallel heap iteraion.
1365 // The root scanning phase happenes in construction as a preparation of
1366 // parallel marking queues.
1367 // Every worker processes it's own marking queue. work-stealing is used
1368 // to balance workload.
1369 class ShenandoahParallelObjectIterator : public ParallelObjectIteratorImpl {
1370 private:
1371 uint _num_workers;
1372 bool _init_ready;
1373 MarkBitMap* _aux_bit_map;
1374 ShenandoahHeap* _heap;
1375 ShenandoahScanObjectStack _roots_stack; // global roots stack
1376 ShenandoahObjToScanQueueSet* _task_queues;
1377 public:
1378 ShenandoahParallelObjectIterator(uint num_workers, MarkBitMap* bitmap) :
1379 _num_workers(num_workers),
1380 _init_ready(false),
1381 _aux_bit_map(bitmap),
1382 _heap(ShenandoahHeap::heap()) {
1383 // Initialize bitmap
1384 _init_ready = _heap->prepare_aux_bitmap_for_iteration();
1385 if (!_init_ready) {
1386 return;
1387 }
1388
1389 ObjectIterateScanRootClosure oops(_aux_bit_map, &_roots_stack);
1390 _heap->scan_roots_for_iteration(&_roots_stack, &oops);
1391
1392 _init_ready = prepare_worker_queues();
1393 }
1394
1395 ~ShenandoahParallelObjectIterator() {
1396 // Reclaim bitmap
1397 _heap->reclaim_aux_bitmap_for_iteration();
1398 // Reclaim queue for workers
1399 if (_task_queues!= NULL) {
1400 for (uint i = 0; i < _num_workers; ++i) {
1401 ShenandoahObjToScanQueue* q = _task_queues->queue(i);
1402 if (q != NULL) {
1403 delete q;
1404 _task_queues->register_queue(i, NULL);
1405 }
1406 }
1407 delete _task_queues;
1408 _task_queues = NULL;
1409 }
1410 }
1411
1412 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
1413 if (_init_ready) {
1414 object_iterate_parallel(cl, worker_id, _task_queues);
1415 }
1416 }
1417
1418 private:
1419 // Divide global root_stack into worker queues
1420 bool prepare_worker_queues() {
1421 _task_queues = new ShenandoahObjToScanQueueSet((int) _num_workers);
1422 // Initialize queues for every workers
1423 for (uint i = 0; i < _num_workers; ++i) {
1424 ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue();
1425 _task_queues->register_queue(i, task_queue);
1426 }
1427 // Divide roots among the workers. Assume that object referencing distribution
1428 // is related with root kind, use round-robin to make every worker have same chance
1429 // to process every kind of roots
1430 size_t roots_num = _roots_stack.size();
1431 if (roots_num == 0) {
1432 // No work to do
1433 return false;
1434 }
1435
1436 for (uint j = 0; j < roots_num; j++) {
1437 uint stack_id = j % _num_workers;
1438 oop obj = _roots_stack.pop();
1439 _task_queues->queue(stack_id)->push(ShenandoahMarkTask(obj));
1440 }
1441 return true;
1442 }
1443
1444 void object_iterate_parallel(ObjectClosure* cl,
1445 uint worker_id,
1446 ShenandoahObjToScanQueueSet* queue_set) {
1447 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1448 assert(queue_set != NULL, "task queue must not be NULL");
1449
1450 ShenandoahObjToScanQueue* q = queue_set->queue(worker_id);
1451 assert(q != NULL, "object iterate queue must not be NULL");
1452
1453 ShenandoahMarkTask t;
1454 ShenandoahObjectIterateParScanClosure oops(_aux_bit_map, q);
1455
1456 // Work through the queue to traverse heap.
1457 // Steal when there is no task in queue.
1458 while (q->pop(t) || queue_set->steal(worker_id, t)) {
1459 oop obj = t.obj();
1460 assert(oopDesc::is_oop(obj), "must be a valid oop");
1461 cl->do_object(obj);
1462 obj->oop_iterate(&oops);
1463 }
1464 assert(q->is_empty(), "should be empty");
1465 }
1466 };
1467
1468 ParallelObjectIteratorImpl* ShenandoahHeap::parallel_object_iterator(uint workers) {
1469 return new ShenandoahParallelObjectIterator(workers, &_aux_bit_map);
1470 }
1471
1472 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1473 void ShenandoahHeap::keep_alive(oop obj) {
1474 if (is_concurrent_mark_in_progress() && (obj != NULL)) {
1475 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1476 }
1477 }
1478
1479 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1480 for (size_t i = 0; i < num_regions(); i++) {
1481 ShenandoahHeapRegion* current = get_region(i);
1482 blk->heap_region_do(current);
1483 }
1484 }
1485
1486 class ShenandoahParallelHeapRegionTask : public WorkerTask {
1487 private:
1488 ShenandoahHeap* const _heap;
1489 ShenandoahHeapRegionClosure* const _blk;
1490
1491 shenandoah_padding(0);
1492 volatile size_t _index;
1493 shenandoah_padding(1);
1494
1495 public:
1496 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1497 WorkerTask("Shenandoah Parallel Region Operation"),
1498 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1499
1500 void work(uint worker_id) {
1501 ShenandoahParallelWorkerSession worker_session(worker_id);
1502 size_t stride = ShenandoahParallelRegionStride;
1503
1504 size_t max = _heap->num_regions();
1505 while (Atomic::load(&_index) < max) {
1506 size_t cur = Atomic::fetch_and_add(&_index, stride, memory_order_relaxed);
1507 size_t start = cur;
1508 size_t end = MIN2(cur + stride, max);
1509 if (start >= max) break;
1510
1511 for (size_t i = cur; i < end; i++) {
1512 ShenandoahHeapRegion* current = _heap->get_region(i);
1513 _blk->heap_region_do(current);
1514 }
1515 }
1516 }
1517 };
1518
1519 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1520 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1521 if (num_regions() > ShenandoahParallelRegionStride) {
1522 ShenandoahParallelHeapRegionTask task(blk);
1523 workers()->run_task(&task);
1524 } else {
1525 heap_region_iterate(blk);
1526 }
1527 }
1528
1529 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1530 private:
1531 ShenandoahMarkingContext* const _ctx;
1532 public:
1533 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1534
1535 void heap_region_do(ShenandoahHeapRegion* r) {
1536 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1537 if (r->is_active()) {
1538 // Check if region needs updating its TAMS. We have updated it already during concurrent
1539 // reset, so it is very likely we don't need to do another write here.
1540 if (_ctx->top_at_mark_start(r) != r->top()) {
1541 _ctx->capture_top_at_mark_start(r);
1542 }
1543 } else {
1544 assert(_ctx->top_at_mark_start(r) == r->top(),
1545 "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
1546 }
1547 }
1548
1549 bool is_thread_safe() { return true; }
1550 };
1551
1552 class ShenandoahRendezvousClosure : public HandshakeClosure {
1553 public:
1554 inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {}
1555 inline void do_thread(Thread* thread) {}
1556 };
1557
1558 void ShenandoahHeap::rendezvous_threads() {
1559 ShenandoahRendezvousClosure cl;
1560 Handshake::execute(&cl);
1561 }
1562
1563 void ShenandoahHeap::recycle_trash() {
1564 free_set()->recycle_trash();
1565 }
1566
1567 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1568 private:
1569 ShenandoahMarkingContext* const _ctx;
1570 public:
1571 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1572
1573 void heap_region_do(ShenandoahHeapRegion* r) {
1574 if (r->is_active()) {
1575 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1576 // anyway to capture any updates that happened since now.
1577 r->clear_live_data();
1578 _ctx->capture_top_at_mark_start(r);
1579 }
1580 }
1581
1582 bool is_thread_safe() { return true; }
1583 };
1584
1585 void ShenandoahHeap::prepare_gc() {
1586 reset_mark_bitmap();
1587
1588 ShenandoahResetUpdateRegionStateClosure cl;
1589 parallel_heap_region_iterate(&cl);
1590 }
1591
1592 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1593 private:
1594 ShenandoahMarkingContext* const _ctx;
1595 ShenandoahHeapLock* const _lock;
1596
1597 public:
1598 ShenandoahFinalMarkUpdateRegionStateClosure() :
1599 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1600
1601 void heap_region_do(ShenandoahHeapRegion* r) {
1602 if (r->is_active()) {
1603 // All allocations past TAMS are implicitly live, adjust the region data.
1604 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1605 HeapWord *tams = _ctx->top_at_mark_start(r);
1606 HeapWord *top = r->top();
1607 if (top > tams) {
1608 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1609 }
1610
1611 // We are about to select the collection set, make sure it knows about
1612 // current pinning status. Also, this allows trashing more regions that
1613 // now have their pinning status dropped.
1614 if (r->is_pinned()) {
1615 if (r->pin_count() == 0) {
1616 ShenandoahHeapLocker locker(_lock);
1617 r->make_unpinned();
1618 }
1619 } else {
1620 if (r->pin_count() > 0) {
1621 ShenandoahHeapLocker locker(_lock);
1622 r->make_pinned();
1623 }
1624 }
1625
1626 // Remember limit for updating refs. It's guaranteed that we get no
1627 // from-space-refs written from here on.
1628 r->set_update_watermark_at_safepoint(r->top());
1629 } else {
1630 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1631 assert(_ctx->top_at_mark_start(r) == r->top(),
1632 "Region " SIZE_FORMAT " should have correct TAMS", r->index());
1633 }
1634 }
1635
1636 bool is_thread_safe() { return true; }
1637 };
1638
1639 void ShenandoahHeap::prepare_regions_and_collection_set(bool concurrent) {
1640 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
1641 {
1642 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_region_states :
1643 ShenandoahPhaseTimings::degen_gc_final_update_region_states);
1644 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1645 parallel_heap_region_iterate(&cl);
1646
1647 assert_pinned_region_status();
1648 }
1649
1650 {
1651 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::choose_cset :
1652 ShenandoahPhaseTimings::degen_gc_choose_cset);
1653 ShenandoahHeapLocker locker(lock());
1654 _collection_set->clear();
1655 heuristics()->choose_collection_set(_collection_set);
1656 }
1657
1658 {
1659 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_rebuild_freeset :
1660 ShenandoahPhaseTimings::degen_gc_final_rebuild_freeset);
1661 ShenandoahHeapLocker locker(lock());
1662 _free_set->rebuild();
1663 }
1664 }
1665
1666 void ShenandoahHeap::do_class_unloading() {
1667 _unloader.unload();
1668 }
1669
1670 void ShenandoahHeap::stw_weak_refs(bool full_gc) {
1671 // Weak refs processing
1672 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs
1673 : ShenandoahPhaseTimings::degen_gc_weakrefs;
1674 ShenandoahTimingsTracker t(phase);
1675 ShenandoahGCWorkerPhase worker_phase(phase);
1676 ref_processor()->process_references(phase, workers(), false /* concurrent */);
1677 }
1678
1679 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
1680 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
1681
1682 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to
1683 // make them parsable for update code to work correctly. Plus, we can compute new sizes
1684 // for future GCLABs here.
1685 if (UseTLAB) {
1686 ShenandoahGCPhase phase(concurrent ?
1687 ShenandoahPhaseTimings::init_update_refs_manage_gclabs :
1688 ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs);
1689 gclabs_retire(ResizeTLAB);
1690 }
1691
1692 _update_refs_iterator.reset();
1693 }
1694
1695 void ShenandoahHeap::set_gc_state_all_threads(char state) {
1696 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1697 ShenandoahThreadLocalData::set_gc_state(t, state);
1698 }
1699 }
1700
1701 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1702 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1703 _gc_state.set_cond(mask, value);
1704 set_gc_state_all_threads(_gc_state.raw_value());
1705 }
1706
1707 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1708 assert(!has_forwarded_objects(), "Not expected before/after mark phase");
1709 set_gc_state_mask(MARKING, in_progress);
1710 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1711 }
1712
1713 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1714 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1715 set_gc_state_mask(EVACUATION, in_progress);
1716 }
1717
1718 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
1719 if (in_progress) {
1720 _concurrent_strong_root_in_progress.set();
1721 } else {
1722 _concurrent_strong_root_in_progress.unset();
1723 }
1724 }
1725
1726 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) {
1727 set_gc_state_mask(WEAK_ROOTS, cond);
1728 }
1729
1730 GCTracer* ShenandoahHeap::tracer() {
1731 return shenandoah_policy()->tracer();
1732 }
1733
1734 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1735 return _free_set->used();
1736 }
1737
1738 bool ShenandoahHeap::try_cancel_gc() {
1739 while (true) {
1740 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
1741 if (prev == CANCELLABLE) return true;
1742 else if (prev == CANCELLED) return false;
1743 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
1744 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
1745 Thread* thread = Thread::current();
1746 if (thread->is_Java_thread()) {
1747 // We need to provide a safepoint here, otherwise we might
1748 // spin forever if a SP is pending.
1749 ThreadBlockInVM sp(JavaThread::cast(thread));
1750 SpinPause();
1751 }
1752 }
1753 }
1754
1755 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1756 if (try_cancel_gc()) {
1757 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1758 log_info(gc)("%s", msg.buffer());
1759 Events::log(Thread::current(), "%s", msg.buffer());
1760 }
1761 }
1762
1763 uint ShenandoahHeap::max_workers() {
1764 return _max_workers;
1765 }
1766
1767 void ShenandoahHeap::stop() {
1768 // The shutdown sequence should be able to terminate when GC is running.
1769
1770 // Step 0. Notify policy to disable event recording.
1771 _shenandoah_policy->record_shutdown();
1772
1773 // Step 1. Notify control thread that we are in shutdown.
1774 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1775 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1776 control_thread()->prepare_for_graceful_shutdown();
1777
1778 // Step 2. Notify GC workers that we are cancelling GC.
1779 cancel_gc(GCCause::_shenandoah_stop_vm);
1780
1781 // Step 3. Wait until GC worker exits normally.
1782 control_thread()->stop();
1783 }
1784
1785 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
1786 if (!unload_classes()) return;
1787 // Unload classes and purge SystemDictionary.
1788 {
1789 ShenandoahPhaseTimings::Phase phase = full_gc ?
1790 ShenandoahPhaseTimings::full_gc_purge_class_unload :
1791 ShenandoahPhaseTimings::degen_gc_purge_class_unload;
1792 ShenandoahGCPhase gc_phase(phase);
1793 ShenandoahGCWorkerPhase worker_phase(phase);
1794 bool purged_class = SystemDictionary::do_unloading(gc_timer());
1795
1796 ShenandoahIsAliveSelector is_alive;
1797 uint num_workers = _workers->active_workers();
1798 ShenandoahClassUnloadingTask unlink_task(phase, is_alive.is_alive_closure(), num_workers, purged_class);
1799 _workers->run_task(&unlink_task);
1800 }
1801
1802 {
1803 ShenandoahGCPhase phase(full_gc ?
1804 ShenandoahPhaseTimings::full_gc_purge_cldg :
1805 ShenandoahPhaseTimings::degen_gc_purge_cldg);
1806 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
1807 }
1808 // Resize and verify metaspace
1809 MetaspaceGC::compute_new_size();
1810 DEBUG_ONLY(MetaspaceUtils::verify();)
1811 }
1812
1813 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
1814 // so they should not have forwarded oops.
1815 // However, we do need to "null" dead oops in the roots, if can not be done
1816 // in concurrent cycles.
1817 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
1818 uint num_workers = _workers->active_workers();
1819 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
1820 ShenandoahPhaseTimings::full_gc_purge_weak_par :
1821 ShenandoahPhaseTimings::degen_gc_purge_weak_par;
1822 ShenandoahGCPhase phase(timing_phase);
1823 ShenandoahGCWorkerPhase worker_phase(timing_phase);
1824 // Cleanup weak roots
1825 if (has_forwarded_objects()) {
1826 ShenandoahForwardedIsAliveClosure is_alive;
1827 ShenandoahUpdateRefsClosure keep_alive;
1828 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
1829 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers);
1830 _workers->run_task(&cleaning_task);
1831 } else {
1832 ShenandoahIsAliveClosure is_alive;
1833 #ifdef ASSERT
1834 ShenandoahAssertNotForwardedClosure verify_cl;
1835 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
1836 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers);
1837 #else
1838 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
1839 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers);
1840 #endif
1841 _workers->run_task(&cleaning_task);
1842 }
1843 }
1844
1845 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
1846 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1847 assert(is_stw_gc_in_progress(), "Only for Degenerated and Full GC");
1848 ShenandoahGCPhase phase(full_gc ?
1849 ShenandoahPhaseTimings::full_gc_purge :
1850 ShenandoahPhaseTimings::degen_gc_purge);
1851 stw_weak_refs(full_gc);
1852 stw_process_weak_roots(full_gc);
1853 stw_unload_classes(full_gc);
1854 }
1855
1856 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
1857 set_gc_state_mask(HAS_FORWARDED, cond);
1858 }
1859
1860 void ShenandoahHeap::set_unload_classes(bool uc) {
1861 _unload_classes.set_cond(uc);
1862 }
1863
1864 bool ShenandoahHeap::unload_classes() const {
1865 return _unload_classes.is_set();
1866 }
1867
1868 address ShenandoahHeap::in_cset_fast_test_addr() {
1869 ShenandoahHeap* heap = ShenandoahHeap::heap();
1870 assert(heap->collection_set() != NULL, "Sanity");
1871 return (address) heap->collection_set()->biased_map_address();
1872 }
1873
1874 address ShenandoahHeap::cancelled_gc_addr() {
1875 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
1876 }
1877
1878 address ShenandoahHeap::gc_state_addr() {
1879 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
1880 }
1881
1882 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
1883 return Atomic::load(&_bytes_allocated_since_gc_start);
1884 }
1885
1886 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
1887 Atomic::store(&_bytes_allocated_since_gc_start, (size_t)0);
1888 }
1889
1890 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
1891 _degenerated_gc_in_progress.set_cond(in_progress);
1892 }
1893
1894 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
1895 _full_gc_in_progress.set_cond(in_progress);
1896 }
1897
1898 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
1899 assert (is_full_gc_in_progress(), "should be");
1900 _full_gc_move_in_progress.set_cond(in_progress);
1901 }
1902
1903 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
1904 set_gc_state_mask(UPDATEREFS, in_progress);
1905 }
1906
1907 void ShenandoahHeap::register_nmethod(nmethod* nm) {
1908 ShenandoahCodeRoots::register_nmethod(nm);
1909 }
1910
1911 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
1912 ShenandoahCodeRoots::unregister_nmethod(nm);
1913 }
1914
1915 void ShenandoahHeap::flush_nmethod(nmethod* nm) {
1916 ShenandoahCodeRoots::flush_nmethod(nm);
1917 }
1918
1919 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
1920 heap_region_containing(o)->record_pin();
1921 return o;
1922 }
1923
1924 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
1925 ShenandoahHeapRegion* r = heap_region_containing(o);
1926 assert(r != NULL, "Sanity");
1927 assert(r->pin_count() > 0, "Region " SIZE_FORMAT " should have non-zero pins", r->index());
1928 r->record_unpin();
1929 }
1930
1931 void ShenandoahHeap::sync_pinned_region_status() {
1932 ShenandoahHeapLocker locker(lock());
1933
1934 for (size_t i = 0; i < num_regions(); i++) {
1935 ShenandoahHeapRegion *r = get_region(i);
1936 if (r->is_active()) {
1937 if (r->is_pinned()) {
1938 if (r->pin_count() == 0) {
1939 r->make_unpinned();
1940 }
1941 } else {
1942 if (r->pin_count() > 0) {
1943 r->make_pinned();
1944 }
1945 }
1946 }
1947 }
1948
1949 assert_pinned_region_status();
1950 }
1951
1952 #ifdef ASSERT
1953 void ShenandoahHeap::assert_pinned_region_status() {
1954 for (size_t i = 0; i < num_regions(); i++) {
1955 ShenandoahHeapRegion* r = get_region(i);
1956 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
1957 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
1958 }
1959 }
1960 #endif
1961
1962 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
1963 return _gc_timer;
1964 }
1965
1966 void ShenandoahHeap::prepare_concurrent_roots() {
1967 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1968 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1969 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
1970 set_concurrent_weak_root_in_progress(true);
1971 if (unload_classes()) {
1972 _unloader.prepare();
1973 }
1974 }
1975
1976 void ShenandoahHeap::finish_concurrent_roots() {
1977 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1978 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1979 if (unload_classes()) {
1980 _unloader.finish();
1981 }
1982 }
1983
1984 #ifdef ASSERT
1985 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
1986 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
1987
1988 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1989 if (UseDynamicNumberOfGCThreads) {
1990 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
1991 } else {
1992 // Use ParallelGCThreads inside safepoints
1993 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
1994 }
1995 } else {
1996 if (UseDynamicNumberOfGCThreads) {
1997 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
1998 } else {
1999 // Use ConcGCThreads outside safepoints
2000 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2001 }
2002 }
2003 }
2004 #endif
2005
2006 ShenandoahVerifier* ShenandoahHeap::verifier() {
2007 guarantee(ShenandoahVerify, "Should be enabled");
2008 assert (_verifier != NULL, "sanity");
2009 return _verifier;
2010 }
2011
2012 template<bool CONCURRENT>
2013 class ShenandoahUpdateHeapRefsTask : public WorkerTask {
2014 private:
2015 ShenandoahHeap* _heap;
2016 ShenandoahRegionIterator* _regions;
2017 public:
2018 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) :
2019 WorkerTask("Shenandoah Update References"),
2020 _heap(ShenandoahHeap::heap()),
2021 _regions(regions) {
2022 }
2023
2024 void work(uint worker_id) {
2025 if (CONCURRENT) {
2026 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2027 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2028 do_work<ShenandoahConcUpdateRefsClosure>();
2029 } else {
2030 ShenandoahParallelWorkerSession worker_session(worker_id);
2031 do_work<ShenandoahSTWUpdateRefsClosure>();
2032 }
2033 }
2034
2035 private:
2036 template<class T>
2037 void do_work() {
2038 T cl;
2039 ShenandoahHeapRegion* r = _regions->next();
2040 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2041 while (r != NULL) {
2042 HeapWord* update_watermark = r->get_update_watermark();
2043 assert (update_watermark >= r->bottom(), "sanity");
2044 if (r->is_active() && !r->is_cset()) {
2045 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2046 }
2047 if (ShenandoahPacing) {
2048 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2049 }
2050 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
2051 return;
2052 }
2053 r = _regions->next();
2054 }
2055 }
2056 };
2057
2058 void ShenandoahHeap::update_heap_references(bool concurrent) {
2059 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2060
2061 if (concurrent) {
2062 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator);
2063 workers()->run_task(&task);
2064 } else {
2065 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator);
2066 workers()->run_task(&task);
2067 }
2068 }
2069
2070
2071 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2072 private:
2073 ShenandoahHeapLock* const _lock;
2074
2075 public:
2076 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2077
2078 void heap_region_do(ShenandoahHeapRegion* r) {
2079 // Drop unnecessary "pinned" state from regions that does not have CP marks
2080 // anymore, as this would allow trashing them.
2081
2082 if (r->is_active()) {
2083 if (r->is_pinned()) {
2084 if (r->pin_count() == 0) {
2085 ShenandoahHeapLocker locker(_lock);
2086 r->make_unpinned();
2087 }
2088 } else {
2089 if (r->pin_count() > 0) {
2090 ShenandoahHeapLocker locker(_lock);
2091 r->make_pinned();
2092 }
2093 }
2094 }
2095 }
2096
2097 bool is_thread_safe() { return true; }
2098 };
2099
2100 void ShenandoahHeap::update_heap_region_states(bool concurrent) {
2101 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2102 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2103
2104 {
2105 ShenandoahGCPhase phase(concurrent ?
2106 ShenandoahPhaseTimings::final_update_refs_update_region_states :
2107 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states);
2108 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2109 parallel_heap_region_iterate(&cl);
2110
2111 assert_pinned_region_status();
2112 }
2113
2114 {
2115 ShenandoahGCPhase phase(concurrent ?
2116 ShenandoahPhaseTimings::final_update_refs_trash_cset :
2117 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset);
2118 trash_cset_regions();
2119 }
2120 }
2121
2122 void ShenandoahHeap::rebuild_free_set(bool concurrent) {
2123 {
2124 ShenandoahGCPhase phase(concurrent ?
2125 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
2126 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
2127 ShenandoahHeapLocker locker(lock());
2128 _free_set->rebuild();
2129 }
2130 }
2131
2132 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2133 print_on(st);
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 }