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/slidingForwarding.hpp"
36 #include "gc/shared/tlab_globals.hpp"
37
38 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
39 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
40 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
41 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
42 #include "gc/shenandoah/shenandoahConcurrentMark.hpp"
43 #include "gc/shenandoah/shenandoahControlThread.hpp"
44 #include "gc/shenandoah/shenandoahFreeSet.hpp"
45 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
46 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
47 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
48 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
49 #include "gc/shenandoah/shenandoahInitLogger.hpp"
50 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
51 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
52 #include "gc/shenandoah/shenandoahMetrics.hpp"
53 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
54 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
55 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
56 #include "gc/shenandoah/shenandoahPadding.hpp"
57 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
58 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
59 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
60 #include "gc/shenandoah/shenandoahStringDedup.hpp"
61 #include "gc/shenandoah/shenandoahSTWMark.hpp"
62 #include "gc/shenandoah/shenandoahUtils.hpp"
63 #include "gc/shenandoah/shenandoahVerifier.hpp"
64 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
65 #include "gc/shenandoah/shenandoahVMOperations.hpp"
66 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
67 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
68 #include "gc/shenandoah/mode/shenandoahIUMode.hpp"
69 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
70 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp"
71 #if INCLUDE_JFR
72 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
73 #endif
74
75 #include "classfile/systemDictionary.hpp"
76 #include "memory/classLoaderMetaspace.hpp"
77 #include "memory/metaspaceUtils.hpp"
78 #include "oops/compressedOops.inline.hpp"
79 #include "prims/jvmtiTagMap.hpp"
80 #include "runtime/atomic.hpp"
81 #include "runtime/globals.hpp"
82 #include "runtime/interfaceSupport.inline.hpp"
83 #include "runtime/java.hpp"
84 #include "runtime/orderAccess.hpp"
85 #include "runtime/safepointMechanism.hpp"
86 #include "runtime/vmThread.hpp"
87 #include "services/mallocTracker.hpp"
88 #include "services/memTracker.hpp"
89 #include "utilities/events.hpp"
90 #include "utilities/powerOfTwo.hpp"
91
92 class ShenandoahPretouchHeapTask : public WorkerTask {
93 private:
94 ShenandoahRegionIterator _regions;
95 const size_t _page_size;
96 public:
97 ShenandoahPretouchHeapTask(size_t page_size) :
98 WorkerTask("Shenandoah Pretouch Heap"),
99 _page_size(page_size) {}
100
101 virtual void work(uint worker_id) {
102 ShenandoahHeapRegion* r = _regions.next();
103 while (r != NULL) {
104 if (r->is_committed()) {
105 os::pretouch_memory(r->bottom(), r->end(), _page_size);
106 }
107 r = _regions.next();
108 }
109 }
110 };
111
112 class ShenandoahPretouchBitmapTask : public WorkerTask {
113 private:
114 ShenandoahRegionIterator _regions;
115 char* _bitmap_base;
116 const size_t _bitmap_size;
117 const size_t _page_size;
118 public:
119 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
120 WorkerTask("Shenandoah Pretouch Bitmap"),
121 _bitmap_base(bitmap_base),
122 _bitmap_size(bitmap_size),
123 _page_size(page_size) {}
124
125 virtual void work(uint worker_id) {
126 ShenandoahHeapRegion* r = _regions.next();
127 while (r != NULL) {
128 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
129 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
130 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
131
132 if (r->is_committed()) {
133 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
134 }
135
136 r = _regions.next();
137 }
138 }
139 };
140
141 jint ShenandoahHeap::initialize() {
142 //
143 // Figure out heap sizing
144 //
145
146 size_t init_byte_size = InitialHeapSize;
147 size_t min_byte_size = MinHeapSize;
148 size_t max_byte_size = MaxHeapSize;
149 size_t heap_alignment = HeapAlignment;
150
151 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
152
153 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
154 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
155
156 _num_regions = ShenandoahHeapRegion::region_count();
157 assert(_num_regions == (max_byte_size / reg_size_bytes),
158 "Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT,
159 _num_regions, max_byte_size, reg_size_bytes);
160
161 // Now we know the number of regions, initialize the heuristics.
162 initialize_heuristics();
163
164 size_t num_committed_regions = init_byte_size / reg_size_bytes;
165 num_committed_regions = MIN2(num_committed_regions, _num_regions);
166 assert(num_committed_regions <= _num_regions, "sanity");
167 _initial_size = num_committed_regions * reg_size_bytes;
168
169 size_t num_min_regions = min_byte_size / reg_size_bytes;
170 num_min_regions = MIN2(num_min_regions, _num_regions);
171 assert(num_min_regions <= _num_regions, "sanity");
172 _minimum_size = num_min_regions * reg_size_bytes;
173
174 // Default to max heap size.
175 _soft_max_size = _num_regions * reg_size_bytes;
176
177 _committed = _initial_size;
178
179 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
180 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
181 size_t region_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
182
183 //
184 // Reserve and commit memory for heap
185 //
186
187 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
188 initialize_reserved_region(heap_rs);
189 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
190 _heap_region_special = heap_rs.special();
191
192 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
193 "Misaligned heap: " PTR_FORMAT, p2i(base()));
194
195 _forwarding = new SlidingForwarding(_heap_region, ShenandoahHeapRegion::region_size_words_shift());
196
197 #if SHENANDOAH_OPTIMIZED_MARKTASK
198 // The optimized ShenandoahMarkTask takes some bits away from the full object bits.
199 // Fail if we ever attempt to address more than we can.
200 if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) {
201 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
202 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
203 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
204 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable());
205 vm_exit_during_initialization("Fatal Error", buf);
206 }
207 #endif
208
209 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
210 if (!_heap_region_special) {
211 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
212 "Cannot commit heap memory");
213 }
214
215 //
216 // Reserve and commit memory for bitmap(s)
217 //
218
219 _bitmap_size = ShenandoahMarkBitMap::compute_size(heap_rs.size());
220 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
221
222 size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor();
223
224 guarantee(bitmap_bytes_per_region != 0,
225 "Bitmap bytes per region should not be zero");
226 guarantee(is_power_of_2(bitmap_bytes_per_region),
227 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
228
229 if (bitmap_page_size > bitmap_bytes_per_region) {
230 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
231 _bitmap_bytes_per_slice = bitmap_page_size;
232 } else {
233 _bitmap_regions_per_slice = 1;
234 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
235 }
236
237 guarantee(_bitmap_regions_per_slice >= 1,
238 "Should have at least one region per slice: " SIZE_FORMAT,
239 _bitmap_regions_per_slice);
240
241 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
242 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
243 _bitmap_bytes_per_slice, bitmap_page_size);
244
245 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
246 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
247 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
248 _bitmap_region_special = bitmap.special();
249
250 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
251 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
252 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
253 if (!_bitmap_region_special) {
254 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
255 "Cannot commit bitmap memory");
256 }
257
258 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions, _max_workers);
259
260 if (ShenandoahVerify) {
261 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
262 if (!verify_bitmap.special()) {
263 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
264 "Cannot commit verification bitmap memory");
265 }
266 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
267 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
268 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
269 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
270 }
271
272 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
273 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
274 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
275 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
276 _aux_bitmap_region_special = aux_bitmap.special();
277 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
278
279 //
280 // Create regions and region sets
281 //
282 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
283 size_t region_storage_size = align_up(region_align * _num_regions, region_page_size);
284 region_storage_size = align_up(region_storage_size, os::vm_allocation_granularity());
285
286 ReservedSpace region_storage(region_storage_size, region_page_size);
287 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC);
288 if (!region_storage.special()) {
289 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false,
290 "Cannot commit region memory");
291 }
292
293 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks.
294 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there.
295 // If not successful, bite a bullet and allocate at whatever address.
296 {
297 size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity());
298 size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align);
299
300 uintptr_t min = round_up_power_of_2(cset_align);
301 uintptr_t max = (1u << 30u);
302
303 for (uintptr_t addr = min; addr <= max; addr <<= 1u) {
304 char* req_addr = (char*)addr;
305 assert(is_aligned(req_addr, cset_align), "Should be aligned");
306 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size(), req_addr);
307 if (cset_rs.is_reserved()) {
308 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr);
309 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
310 break;
311 }
312 }
313
314 if (_collection_set == NULL) {
315 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size());
316 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
317 }
318 }
319
320 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
321 _free_set = new ShenandoahFreeSet(this, _num_regions);
322
323 {
324 ShenandoahHeapLocker locker(lock());
325
326 for (size_t i = 0; i < _num_regions; i++) {
327 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
328 bool is_committed = i < num_committed_regions;
329 void* loc = region_storage.base() + i * region_align;
330
331 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
332 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
333
334 _marking_context->initialize_top_at_mark_start(r);
335 _regions[i] = r;
336 assert(!collection_set()->is_in(i), "New region should not be in collection set");
337 }
338
339 // Initialize to complete
340 _marking_context->mark_complete();
341
342 _free_set->rebuild();
343 }
344
345 if (AlwaysPreTouch) {
346 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
347 // before initialize() below zeroes it with initializing thread. For any given region,
348 // we touch the region and the corresponding bitmaps from the same thread.
349 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
350
351 _pretouch_heap_page_size = heap_page_size;
352 _pretouch_bitmap_page_size = bitmap_page_size;
353
354 #ifdef LINUX
355 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
356 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
357 // them into huge one. Therefore, we need to pretouch with smaller pages.
358 if (UseTransparentHugePages) {
359 _pretouch_heap_page_size = (size_t)os::vm_page_size();
360 _pretouch_bitmap_page_size = (size_t)os::vm_page_size();
361 }
362 #endif
363
364 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
365 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
366
367 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size);
368 _workers->run_task(&bcl);
369
370 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size);
371 _workers->run_task(&hcl);
372 }
373
374 //
375 // Initialize the rest of GC subsystems
376 //
377
378 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC);
379 for (uint worker = 0; worker < _max_workers; worker++) {
380 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC);
381 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData));
382 }
383
384 // There should probably be Shenandoah-specific options for these,
385 // just as there are G1-specific options.
386 {
387 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
388 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
389 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
390 }
391
392 _monitoring_support = new ShenandoahMonitoringSupport(this);
393 _phase_timings = new ShenandoahPhaseTimings(max_workers());
394 ShenandoahCodeRoots::initialize();
395
396 if (ShenandoahPacing) {
397 _pacer = new ShenandoahPacer(this);
398 _pacer->setup_for_idle();
399 } else {
400 _pacer = NULL;
401 }
402
403 _control_thread = new ShenandoahControlThread();
404
405 ShenandoahInitLogger::print();
406
407 return JNI_OK;
408 }
409
410 void ShenandoahHeap::initialize_mode() {
411 if (ShenandoahGCMode != NULL) {
412 if (strcmp(ShenandoahGCMode, "satb") == 0) {
413 _gc_mode = new ShenandoahSATBMode();
414 } else if (strcmp(ShenandoahGCMode, "iu") == 0) {
415 _gc_mode = new ShenandoahIUMode();
416 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
417 _gc_mode = new ShenandoahPassiveMode();
418 } else {
419 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
420 }
421 } else {
422 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option (null)");
423 }
424 _gc_mode->initialize_flags();
425 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
426 vm_exit_during_initialization(
427 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
428 _gc_mode->name()));
429 }
430 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
431 vm_exit_during_initialization(
432 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
433 _gc_mode->name()));
434 }
435 }
436
437 void ShenandoahHeap::initialize_heuristics() {
438 assert(_gc_mode != NULL, "Must be initialized");
439 _heuristics = _gc_mode->initialize_heuristics();
440
441 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
442 vm_exit_during_initialization(
443 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
444 _heuristics->name()));
445 }
446 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
447 vm_exit_during_initialization(
448 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
449 _heuristics->name()));
450 }
451 }
452
453 #ifdef _MSC_VER
454 #pragma warning( push )
455 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
456 #endif
457
458 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
459 CollectedHeap(),
460 _initial_size(0),
461 _used(0),
462 _committed(0),
463 _bytes_allocated_since_gc_start(0),
464 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
465 _workers(NULL),
466 _safepoint_workers(NULL),
467 _heap_region_special(false),
468 _num_regions(0),
469 _regions(NULL),
470 _update_refs_iterator(this),
471 _control_thread(NULL),
472 _shenandoah_policy(policy),
473 _gc_mode(NULL),
474 _heuristics(NULL),
475 _free_set(NULL),
476 _pacer(NULL),
477 _verifier(NULL),
478 _phase_timings(NULL),
479 _monitoring_support(NULL),
480 _memory_pool(NULL),
481 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
482 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
483 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
484 _soft_ref_policy(),
485 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
486 _ref_processor(new ShenandoahReferenceProcessor(MAX2(_max_workers, 1U))),
487 _marking_context(NULL),
488 _bitmap_size(0),
489 _bitmap_regions_per_slice(0),
490 _bitmap_bytes_per_slice(0),
491 _bitmap_region_special(false),
492 _aux_bitmap_region_special(false),
493 _liveness_cache(NULL),
494 _collection_set(NULL)
495 {
496 // Initialize GC mode early, so we can adjust barrier support
497 initialize_mode();
498 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
499
500 _max_workers = MAX2(_max_workers, 1U);
501 _workers = new ShenandoahWorkerThreads("Shenandoah GC Threads", _max_workers);
502 if (_workers == 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 ShenandoahWorkerThreads("Safepoint Cleanup Thread",
510 ParallelGCThreads);
511 _safepoint_workers->initialize_workers();
512 }
513 }
514
515 #ifdef _MSC_VER
516 #pragma warning( pop )
517 #endif
518
519 class ShenandoahResetBitmapTask : public WorkerTask {
520 private:
521 ShenandoahRegionIterator _regions;
522
523 public:
524 ShenandoahResetBitmapTask() :
525 WorkerTask("Shenandoah Reset Bitmap") {}
526
527 void work(uint worker_id) {
528 ShenandoahHeapRegion* region = _regions.next();
529 ShenandoahHeap* heap = ShenandoahHeap::heap();
530 ShenandoahMarkingContext* const ctx = heap->marking_context();
531 while (region != NULL) {
532 if (heap->is_bitmap_slice_committed(region)) {
533 ctx->clear_bitmap(region);
534 }
535 region = _regions.next();
536 }
537 }
538 };
539
540 void ShenandoahHeap::reset_mark_bitmap() {
541 assert_gc_workers(_workers->active_workers());
542 mark_incomplete_marking_context();
543
544 ShenandoahResetBitmapTask task;
545 _workers->run_task(&task);
546 }
547
548 void ShenandoahHeap::print_on(outputStream* st) const {
549 st->print_cr("Shenandoah Heap");
550 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
551 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
552 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()),
553 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
554 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
555 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
556 num_regions(),
557 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
558 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
559
560 st->print("Status: ");
561 if (has_forwarded_objects()) st->print("has forwarded objects, ");
562 if (is_concurrent_mark_in_progress()) st->print("marking, ");
563 if (is_evacuation_in_progress()) st->print("evacuating, ");
564 if (is_update_refs_in_progress()) st->print("updating refs, ");
565 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
566 if (is_full_gc_in_progress()) st->print("full gc, ");
567 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
568 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, ");
569 if (is_concurrent_strong_root_in_progress() &&
570 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, ");
571
572 if (cancelled_gc()) {
573 st->print("cancelled");
574 } else {
575 st->print("not cancelled");
576 }
577 st->cr();
578
579 st->print_cr("Reserved region:");
580 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
581 p2i(reserved_region().start()),
582 p2i(reserved_region().end()));
583
584 ShenandoahCollectionSet* cset = collection_set();
585 st->print_cr("Collection set:");
586 if (cset != NULL) {
587 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
588 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
589 } else {
590 st->print_cr(" (NULL)");
591 }
592
593 st->cr();
594 MetaspaceUtils::print_on(st);
595
596 if (Verbose) {
597 print_heap_regions_on(st);
598 }
599 }
600
601 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
602 public:
603 void do_thread(Thread* thread) {
604 assert(thread != NULL, "Sanity");
605 assert(thread->is_Worker_thread(), "Only worker thread expected");
606 ShenandoahThreadLocalData::initialize_gclab(thread);
607 }
608 };
609
610 void ShenandoahHeap::post_initialize() {
611 CollectedHeap::post_initialize();
612 MutexLocker ml(Threads_lock);
613
614 ShenandoahInitWorkerGCLABClosure init_gclabs;
615 _workers->threads_do(&init_gclabs);
616
617 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
618 // Now, we will let WorkerThreads to initialize gclab when new worker is created.
619 _workers->set_initialize_gclab();
620 if (_safepoint_workers != NULL) {
621 _safepoint_workers->threads_do(&init_gclabs);
622 _safepoint_workers->set_initialize_gclab();
623 }
624
625 _heuristics->initialize();
626
627 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
628 }
629
630 size_t ShenandoahHeap::used() const {
631 return Atomic::load(&_used);
632 }
633
634 size_t ShenandoahHeap::committed() const {
635 return Atomic::load(&_committed);
636 }
637
638 void ShenandoahHeap::increase_committed(size_t bytes) {
639 shenandoah_assert_heaplocked_or_safepoint();
640 _committed += bytes;
641 }
642
643 void ShenandoahHeap::decrease_committed(size_t bytes) {
644 shenandoah_assert_heaplocked_or_safepoint();
645 _committed -= bytes;
646 }
647
648 void ShenandoahHeap::increase_used(size_t bytes) {
649 Atomic::add(&_used, bytes, memory_order_relaxed);
650 }
651
652 void ShenandoahHeap::set_used(size_t bytes) {
653 Atomic::store(&_used, bytes);
654 }
655
656 void ShenandoahHeap::decrease_used(size_t bytes) {
657 assert(used() >= bytes, "never decrease heap size by more than we've left");
658 Atomic::sub(&_used, bytes, memory_order_relaxed);
659 }
660
661 void ShenandoahHeap::increase_allocated(size_t bytes) {
662 Atomic::add(&_bytes_allocated_since_gc_start, bytes, memory_order_relaxed);
663 }
664
665 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
666 size_t bytes = words * HeapWordSize;
667 if (!waste) {
668 increase_used(bytes);
669 }
670 increase_allocated(bytes);
671 if (ShenandoahPacing) {
672 control_thread()->pacing_notify_alloc(words);
673 if (waste) {
674 pacer()->claim_for_alloc(words, true);
675 }
676 }
677 }
678
679 size_t ShenandoahHeap::capacity() const {
680 return committed();
681 }
682
683 size_t ShenandoahHeap::max_capacity() const {
684 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
685 }
686
687 size_t ShenandoahHeap::soft_max_capacity() const {
688 size_t v = Atomic::load(&_soft_max_size);
689 assert(min_capacity() <= v && v <= max_capacity(),
690 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
691 min_capacity(), v, max_capacity());
692 return v;
693 }
694
695 void ShenandoahHeap::set_soft_max_capacity(size_t v) {
696 assert(min_capacity() <= v && v <= max_capacity(),
697 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
698 min_capacity(), v, max_capacity());
699 Atomic::store(&_soft_max_size, v);
700 }
701
702 size_t ShenandoahHeap::min_capacity() const {
703 return _minimum_size;
704 }
705
706 size_t ShenandoahHeap::initial_capacity() const {
707 return _initial_size;
708 }
709
710 bool ShenandoahHeap::is_in(const void* p) const {
711 HeapWord* heap_base = (HeapWord*) base();
712 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
713 return p >= heap_base && p < last_region_end;
714 }
715
716 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
717 assert (ShenandoahUncommit, "should be enabled");
718
719 // Application allocates from the beginning of the heap, and GC allocates at
720 // the end of it. It is more efficient to uncommit from the end, so that applications
721 // could enjoy the near committed regions. GC allocations are much less frequent,
722 // and therefore can accept the committing costs.
723
724 size_t count = 0;
725 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
726 ShenandoahHeapRegion* r = get_region(i - 1);
727 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
728 ShenandoahHeapLocker locker(lock());
729 if (r->is_empty_committed()) {
730 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) {
731 break;
732 }
733
734 r->make_uncommitted();
735 count++;
736 }
737 }
738 SpinPause(); // allow allocators to take the lock
739 }
740
741 if (count > 0) {
742 control_thread()->notify_heap_changed();
743 }
744 }
745
746 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
747 // New object should fit the GCLAB size
748 size_t min_size = MAX2(size, PLAB::min_size());
749
750 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
751 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
752 new_size = MIN2(new_size, PLAB::max_size());
753 new_size = MAX2(new_size, PLAB::min_size());
754
755 // Record new heuristic value even if we take any shortcut. This captures
756 // the case when moderately-sized objects always take a shortcut. At some point,
757 // heuristics should catch up with them.
758 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
759
760 if (new_size < size) {
761 // New size still does not fit the object. Fall back to shared allocation.
762 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
763 return NULL;
764 }
765
766 // Retire current GCLAB, and allocate a new one.
767 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
768 gclab->retire();
769
770 size_t actual_size = 0;
771 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
772 if (gclab_buf == NULL) {
773 return NULL;
774 }
775
776 assert (size <= actual_size, "allocation should fit");
777
778 if (ZeroTLAB) {
779 // ..and clear it.
780 Copy::zero_to_words(gclab_buf, actual_size);
781 } else {
782 // ...and zap just allocated object.
783 #ifdef ASSERT
784 // Skip mangling the space corresponding to the object header to
785 // ensure that the returned space is not considered parsable by
786 // any concurrent GC thread.
787 size_t hdr_size = oopDesc::header_size();
788 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
789 #endif // ASSERT
790 }
791 gclab->set_buf(gclab_buf, actual_size);
792 return gclab->allocate(size);
793 }
794
795 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
796 size_t requested_size,
797 size_t* actual_size) {
798 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
799 HeapWord* res = allocate_memory(req);
800 if (res != NULL) {
801 *actual_size = req.actual_size();
802 } else {
803 *actual_size = 0;
804 }
805 return res;
806 }
807
808 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
809 size_t word_size,
810 size_t* actual_size) {
811 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
812 HeapWord* res = allocate_memory(req);
813 if (res != NULL) {
814 *actual_size = req.actual_size();
815 } else {
816 *actual_size = 0;
817 }
818 return res;
819 }
820
821 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
822 intptr_t pacer_epoch = 0;
823 bool in_new_region = false;
824 HeapWord* result = NULL;
825
826 if (req.is_mutator_alloc()) {
827 if (ShenandoahPacing) {
828 pacer()->pace_for_alloc(req.size());
829 pacer_epoch = pacer()->epoch();
830 }
831
832 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
833 result = allocate_memory_under_lock(req, in_new_region);
834 }
835
836 // Allocation failed, block until control thread reacted, then retry allocation.
837 //
838 // It might happen that one of the threads requesting allocation would unblock
839 // way later after GC happened, only to fail the second allocation, because
840 // other threads have already depleted the free storage. In this case, a better
841 // strategy is to try again, as long as GC makes progress.
842 //
843 // Then, we need to make sure the allocation was retried after at least one
844 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
845
846 size_t tries = 0;
847
848 while (result == NULL && _progress_last_gc.is_set()) {
849 tries++;
850 control_thread()->handle_alloc_failure(req);
851 result = allocate_memory_under_lock(req, in_new_region);
852 }
853
854 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
855 tries++;
856 control_thread()->handle_alloc_failure(req);
857 result = allocate_memory_under_lock(req, in_new_region);
858 }
859
860 } else {
861 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
862 result = allocate_memory_under_lock(req, in_new_region);
863 // Do not call handle_alloc_failure() here, because we cannot block.
864 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
865 }
866
867 if (in_new_region) {
868 control_thread()->notify_heap_changed();
869 }
870
871 if (result != NULL) {
872 size_t requested = req.size();
873 size_t actual = req.actual_size();
874
875 assert (req.is_lab_alloc() || (requested == actual),
876 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
877 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
878
879 if (req.is_mutator_alloc()) {
880 notify_mutator_alloc_words(actual, false);
881
882 // If we requested more than we were granted, give the rest back to pacer.
883 // This only matters if we are in the same pacing epoch: do not try to unpace
884 // over the budget for the other phase.
885 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
886 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
887 }
888 } else {
889 increase_used(actual*HeapWordSize);
890 }
891 }
892
893 return result;
894 }
895
896 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
897 ShenandoahHeapLocker locker(lock());
898 return _free_set->allocate(req, in_new_region);
899 }
900
901 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
902 bool* gc_overhead_limit_was_exceeded) {
903 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
904 return allocate_memory(req);
905 }
906
907 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
908 size_t size,
909 Metaspace::MetadataType mdtype) {
910 MetaWord* result;
911
912 // Inform metaspace OOM to GC heuristics if class unloading is possible.
913 if (heuristics()->can_unload_classes()) {
914 ShenandoahHeuristics* h = heuristics();
915 h->record_metaspace_oom();
916 }
917
918 // Expand and retry allocation
919 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
920 if (result != NULL) {
921 return result;
922 }
923
924 // Start full GC
925 collect(GCCause::_metadata_GC_clear_soft_refs);
926
927 // Retry allocation
928 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
929 if (result != NULL) {
930 return result;
931 }
932
933 // Expand and retry allocation
934 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
935 if (result != NULL) {
936 return result;
937 }
938
939 // Out of memory
940 return NULL;
941 }
942
943 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
944 private:
945 ShenandoahHeap* const _heap;
946 Thread* const _thread;
947 public:
948 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
949 _heap(heap), _thread(Thread::current()) {}
950
951 void do_object(oop p) {
952 shenandoah_assert_marked(NULL, p);
953 if (!ShenandoahForwarding::is_forwarded(p)) {
954 _heap->evacuate_object(p, _thread);
955 }
956 }
957 };
958
959 class ShenandoahEvacuationTask : public WorkerTask {
960 private:
961 ShenandoahHeap* const _sh;
962 ShenandoahCollectionSet* const _cs;
963 bool _concurrent;
964 public:
965 ShenandoahEvacuationTask(ShenandoahHeap* sh,
966 ShenandoahCollectionSet* cs,
967 bool concurrent) :
968 WorkerTask("Shenandoah Evacuation"),
969 _sh(sh),
970 _cs(cs),
971 _concurrent(concurrent)
972 {}
973
974 void work(uint worker_id) {
975 if (_concurrent) {
976 ShenandoahConcurrentWorkerSession worker_session(worker_id);
977 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
978 ShenandoahEvacOOMScope oom_evac_scope;
979 do_work();
980 } else {
981 ShenandoahParallelWorkerSession worker_session(worker_id);
982 ShenandoahEvacOOMScope oom_evac_scope;
983 do_work();
984 }
985 }
986
987 private:
988 void do_work() {
989 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
990 ShenandoahHeapRegion* r;
991 while ((r =_cs->claim_next()) != NULL) {
992 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
993 _sh->marked_object_iterate(r, &cl);
994
995 if (ShenandoahPacing) {
996 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
997 }
998
999 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
1000 break;
1001 }
1002 }
1003 }
1004 };
1005
1006 void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
1007 ShenandoahEvacuationTask task(this, _collection_set, concurrent);
1008 workers()->run_task(&task);
1009 }
1010
1011 void ShenandoahHeap::trash_cset_regions() {
1012 ShenandoahHeapLocker locker(lock());
1013
1014 ShenandoahCollectionSet* set = collection_set();
1015 ShenandoahHeapRegion* r;
1016 set->clear_current_index();
1017 while ((r = set->next()) != NULL) {
1018 r->make_trash();
1019 }
1020 collection_set()->clear();
1021 }
1022
1023 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1024 st->print_cr("Heap Regions:");
1025 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
1026 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
1027 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark");
1028 st->print_cr("SN=alloc sequence number");
1029
1030 for (size_t i = 0; i < num_regions(); i++) {
1031 get_region(i)->print_on(st);
1032 }
1033 }
1034
1035 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1036 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1037
1038 oop humongous_obj = cast_to_oop(start->bottom());
1039 size_t size = humongous_obj->size();
1040 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1041 size_t index = start->index() + required_regions - 1;
1042
1043 assert(!start->has_live(), "liveness must be zero");
1044
1045 for(size_t i = 0; i < required_regions; i++) {
1046 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1047 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1048 ShenandoahHeapRegion* region = get_region(index --);
1049
1050 assert(region->is_humongous(), "expect correct humongous start or continuation");
1051 assert(!region->is_cset(), "Humongous region should not be in collection set");
1052
1053 region->make_trash_immediate();
1054 }
1055 }
1056
1057 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1058 public:
1059 ShenandoahCheckCleanGCLABClosure() {}
1060 void do_thread(Thread* thread) {
1061 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1062 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1063 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
1064 }
1065 };
1066
1067 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1068 private:
1069 bool const _resize;
1070 public:
1071 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1072 void do_thread(Thread* thread) {
1073 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1074 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1075 gclab->retire();
1076 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1077 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1078 }
1079 }
1080 };
1081
1082 void ShenandoahHeap::labs_make_parsable() {
1083 assert(UseTLAB, "Only call with UseTLAB");
1084
1085 ShenandoahRetireGCLABClosure cl(false);
1086
1087 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1088 ThreadLocalAllocBuffer& tlab = t->tlab();
1089 tlab.make_parsable();
1090 cl.do_thread(t);
1091 }
1092
1093 workers()->threads_do(&cl);
1094 }
1095
1096 void ShenandoahHeap::tlabs_retire(bool resize) {
1097 assert(UseTLAB, "Only call with UseTLAB");
1098 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1099
1100 ThreadLocalAllocStats stats;
1101
1102 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1103 ThreadLocalAllocBuffer& tlab = t->tlab();
1104 tlab.retire(&stats);
1105 if (resize) {
1106 tlab.resize();
1107 }
1108 }
1109
1110 stats.publish();
1111
1112 #ifdef ASSERT
1113 ShenandoahCheckCleanGCLABClosure cl;
1114 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1115 cl.do_thread(t);
1116 }
1117 workers()->threads_do(&cl);
1118 #endif
1119 }
1120
1121 void ShenandoahHeap::gclabs_retire(bool resize) {
1122 assert(UseTLAB, "Only call with UseTLAB");
1123 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1124
1125 ShenandoahRetireGCLABClosure cl(resize);
1126 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1127 cl.do_thread(t);
1128 }
1129 workers()->threads_do(&cl);
1130
1131 if (safepoint_workers() != NULL) {
1132 safepoint_workers()->threads_do(&cl);
1133 }
1134 }
1135
1136 // Returns size in bytes
1137 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1138 if (ShenandoahElasticTLAB) {
1139 // With Elastic TLABs, return the max allowed size, and let the allocation path
1140 // figure out the safe size for current allocation.
1141 return ShenandoahHeapRegion::max_tlab_size_bytes();
1142 } else {
1143 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1144 }
1145 }
1146
1147 size_t ShenandoahHeap::max_tlab_size() const {
1148 // Returns size in words
1149 return ShenandoahHeapRegion::max_tlab_size_words();
1150 }
1151
1152 void ShenandoahHeap::collect(GCCause::Cause cause) {
1153 control_thread()->request_gc(cause);
1154 }
1155
1156 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1157 //assert(false, "Shouldn't need to do full collections");
1158 }
1159
1160 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1161 ShenandoahHeapRegion* r = heap_region_containing(addr);
1162 if (r != NULL) {
1163 return r->block_start(addr);
1164 }
1165 return NULL;
1166 }
1167
1168 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1169 ShenandoahHeapRegion* r = heap_region_containing(addr);
1170 return r->block_is_obj(addr);
1171 }
1172
1173 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1174 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1175 }
1176
1177 void ShenandoahHeap::prepare_for_verify() {
1178 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) {
1179 labs_make_parsable();
1180 }
1181 }
1182
1183 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1184 workers()->threads_do(tcl);
1185 if (_safepoint_workers != NULL) {
1186 _safepoint_workers->threads_do(tcl);
1187 }
1188 if (ShenandoahStringDedup::is_enabled()) {
1189 ShenandoahStringDedup::threads_do(tcl);
1190 }
1191 }
1192
1193 void ShenandoahHeap::print_tracing_info() const {
1194 LogTarget(Info, gc, stats) lt;
1195 if (lt.is_enabled()) {
1196 ResourceMark rm;
1197 LogStream ls(lt);
1198
1199 phase_timings()->print_global_on(&ls);
1200
1201 ls.cr();
1202 ls.cr();
1203
1204 shenandoah_policy()->print_gc_stats(&ls);
1205
1206 ls.cr();
1207 ls.cr();
1208 }
1209 }
1210
1211 void ShenandoahHeap::verify(VerifyOption vo) {
1212 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1213 if (ShenandoahVerify) {
1214 verifier()->verify_generic(vo);
1215 } else {
1216 // TODO: Consider allocating verification bitmaps on demand,
1217 // and turn this on unconditionally.
1218 }
1219 }
1220 }
1221 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1222 return _free_set->capacity();
1223 }
1224
1225 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1226 private:
1227 MarkBitMap* _bitmap;
1228 ShenandoahScanObjectStack* _oop_stack;
1229 ShenandoahHeap* const _heap;
1230 ShenandoahMarkingContext* const _marking_context;
1231
1232 template <class T>
1233 void do_oop_work(T* p) {
1234 T o = RawAccess<>::oop_load(p);
1235 if (!CompressedOops::is_null(o)) {
1236 oop obj = CompressedOops::decode_not_null(o);
1237 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1238 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1239 return;
1240 }
1241
1242 // We must not expose from-space oops to the rest of runtime, or else it
1243 // will call klass() on it, which might fail because of unexpected header.
1244 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
1245
1246 assert(oopDesc::is_oop(obj), "must be a valid oop");
1247 if (!_bitmap->is_marked(obj)) {
1248 _bitmap->mark(obj);
1249 _oop_stack->push(obj);
1250 }
1251 }
1252 }
1253 public:
1254 ObjectIterateScanRootClosure(MarkBitMap* bitmap, ShenandoahScanObjectStack* oop_stack) :
1255 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1256 _marking_context(_heap->marking_context()) {}
1257 void do_oop(oop* p) { do_oop_work(p); }
1258 void do_oop(narrowOop* p) { do_oop_work(p); }
1259 };
1260
1261 /*
1262 * This is public API, used in preparation of object_iterate().
1263 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1264 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1265 * control, we call SH::tlabs_retire, SH::gclabs_retire.
1266 */
1267 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1268 // No-op.
1269 }
1270
1271 /*
1272 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1273 *
1274 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1275 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1276 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1277 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1278 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1279 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1280 * wiped the bitmap in preparation for next marking).
1281 *
1282 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1283 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1284 * is allowed to report dead objects, but is not required to do so.
1285 */
1286 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1287 // Reset bitmap
1288 if (!prepare_aux_bitmap_for_iteration())
1289 return;
1290
1291 ShenandoahScanObjectStack oop_stack;
1292 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1293 // Seed the stack with root scan
1294 scan_roots_for_iteration(&oop_stack, &oops);
1295
1296 // Work through the oop stack to traverse heap
1297 while (! oop_stack.is_empty()) {
1298 oop obj = oop_stack.pop();
1299 assert(oopDesc::is_oop(obj), "must be a valid oop");
1300 shenandoah_assert_not_in_cset_except(NULL, obj, cancelled_gc());
1301 cl->do_object(obj);
1302 obj->oop_iterate(&oops);
1303 }
1304
1305 assert(oop_stack.is_empty(), "should be empty");
1306 // Reclaim bitmap
1307 reclaim_aux_bitmap_for_iteration();
1308 }
1309
1310 bool ShenandoahHeap::prepare_aux_bitmap_for_iteration() {
1311 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1312
1313 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1314 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1315 return false;
1316 }
1317 // Reset bitmap
1318 _aux_bit_map.clear();
1319 return true;
1320 }
1321
1322 void ShenandoahHeap::scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops) {
1323 // Process GC roots according to current GC cycle
1324 // This populates the work stack with initial objects
1325 // It is important to relinquish the associated locks before diving
1326 // into heap dumper
1327 uint n_workers = safepoint_workers() != NULL ? safepoint_workers()->active_workers() : 1;
1328 ShenandoahHeapIterationRootScanner rp(n_workers);
1329 rp.roots_do(oops);
1330 }
1331
1332 void ShenandoahHeap::reclaim_aux_bitmap_for_iteration() {
1333 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1334 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1335 }
1336 }
1337
1338 // Closure for parallelly iterate objects
1339 class ShenandoahObjectIterateParScanClosure : public BasicOopIterateClosure {
1340 private:
1341 MarkBitMap* _bitmap;
1342 ShenandoahObjToScanQueue* _queue;
1343 ShenandoahHeap* const _heap;
1344 ShenandoahMarkingContext* const _marking_context;
1345
1346 template <class T>
1347 void do_oop_work(T* p) {
1348 T o = RawAccess<>::oop_load(p);
1349 if (!CompressedOops::is_null(o)) {
1350 oop obj = CompressedOops::decode_not_null(o);
1351 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1352 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1353 return;
1354 }
1355 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1356
1357 assert(oopDesc::is_oop(obj), "Must be a valid oop");
1358 if (_bitmap->par_mark(obj)) {
1359 _queue->push(ShenandoahMarkTask(obj));
1360 }
1361 }
1362 }
1363 public:
1364 ShenandoahObjectIterateParScanClosure(MarkBitMap* bitmap, ShenandoahObjToScanQueue* q) :
1365 _bitmap(bitmap), _queue(q), _heap(ShenandoahHeap::heap()),
1366 _marking_context(_heap->marking_context()) {}
1367 void do_oop(oop* p) { do_oop_work(p); }
1368 void do_oop(narrowOop* p) { do_oop_work(p); }
1369 };
1370
1371 // Object iterator for parallel heap iteraion.
1372 // The root scanning phase happenes in construction as a preparation of
1373 // parallel marking queues.
1374 // Every worker processes it's own marking queue. work-stealing is used
1375 // to balance workload.
1376 class ShenandoahParallelObjectIterator : public ParallelObjectIteratorImpl {
1377 private:
1378 uint _num_workers;
1379 bool _init_ready;
1380 MarkBitMap* _aux_bit_map;
1381 ShenandoahHeap* _heap;
1382 ShenandoahScanObjectStack _roots_stack; // global roots stack
1383 ShenandoahObjToScanQueueSet* _task_queues;
1384 public:
1385 ShenandoahParallelObjectIterator(uint num_workers, MarkBitMap* bitmap) :
1386 _num_workers(num_workers),
1387 _init_ready(false),
1388 _aux_bit_map(bitmap),
1389 _heap(ShenandoahHeap::heap()) {
1390 // Initialize bitmap
1391 _init_ready = _heap->prepare_aux_bitmap_for_iteration();
1392 if (!_init_ready) {
1393 return;
1394 }
1395
1396 ObjectIterateScanRootClosure oops(_aux_bit_map, &_roots_stack);
1397 _heap->scan_roots_for_iteration(&_roots_stack, &oops);
1398
1399 _init_ready = prepare_worker_queues();
1400 }
1401
1402 ~ShenandoahParallelObjectIterator() {
1403 // Reclaim bitmap
1404 _heap->reclaim_aux_bitmap_for_iteration();
1405 // Reclaim queue for workers
1406 if (_task_queues!= NULL) {
1407 for (uint i = 0; i < _num_workers; ++i) {
1408 ShenandoahObjToScanQueue* q = _task_queues->queue(i);
1409 if (q != NULL) {
1410 delete q;
1411 _task_queues->register_queue(i, NULL);
1412 }
1413 }
1414 delete _task_queues;
1415 _task_queues = NULL;
1416 }
1417 }
1418
1419 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
1420 if (_init_ready) {
1421 object_iterate_parallel(cl, worker_id, _task_queues);
1422 }
1423 }
1424
1425 private:
1426 // Divide global root_stack into worker queues
1427 bool prepare_worker_queues() {
1428 _task_queues = new ShenandoahObjToScanQueueSet((int) _num_workers);
1429 // Initialize queues for every workers
1430 for (uint i = 0; i < _num_workers; ++i) {
1431 ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue();
1432 _task_queues->register_queue(i, task_queue);
1433 }
1434 // Divide roots among the workers. Assume that object referencing distribution
1435 // is related with root kind, use round-robin to make every worker have same chance
1436 // to process every kind of roots
1437 size_t roots_num = _roots_stack.size();
1438 if (roots_num == 0) {
1439 // No work to do
1440 return false;
1441 }
1442
1443 for (uint j = 0; j < roots_num; j++) {
1444 uint stack_id = j % _num_workers;
1445 oop obj = _roots_stack.pop();
1446 _task_queues->queue(stack_id)->push(ShenandoahMarkTask(obj));
1447 }
1448 return true;
1449 }
1450
1451 void object_iterate_parallel(ObjectClosure* cl,
1452 uint worker_id,
1453 ShenandoahObjToScanQueueSet* queue_set) {
1454 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1455 assert(queue_set != NULL, "task queue must not be NULL");
1456
1457 ShenandoahObjToScanQueue* q = queue_set->queue(worker_id);
1458 assert(q != NULL, "object iterate queue must not be NULL");
1459
1460 ShenandoahMarkTask t;
1461 ShenandoahObjectIterateParScanClosure oops(_aux_bit_map, q);
1462
1463 // Work through the queue to traverse heap.
1464 // Steal when there is no task in queue.
1465 while (q->pop(t) || queue_set->steal(worker_id, t)) {
1466 oop obj = t.obj();
1467 assert(oopDesc::is_oop(obj), "must be a valid oop");
1468 cl->do_object(obj);
1469 obj->oop_iterate(&oops);
1470 }
1471 assert(q->is_empty(), "should be empty");
1472 }
1473 };
1474
1475 ParallelObjectIteratorImpl* ShenandoahHeap::parallel_object_iterator(uint workers) {
1476 return new ShenandoahParallelObjectIterator(workers, &_aux_bit_map);
1477 }
1478
1479 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1480 void ShenandoahHeap::keep_alive(oop obj) {
1481 if (is_concurrent_mark_in_progress() && (obj != NULL)) {
1482 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1483 }
1484 }
1485
1486 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1487 for (size_t i = 0; i < num_regions(); i++) {
1488 ShenandoahHeapRegion* current = get_region(i);
1489 blk->heap_region_do(current);
1490 }
1491 }
1492
1493 class ShenandoahParallelHeapRegionTask : public WorkerTask {
1494 private:
1495 ShenandoahHeap* const _heap;
1496 ShenandoahHeapRegionClosure* const _blk;
1497
1498 shenandoah_padding(0);
1499 volatile size_t _index;
1500 shenandoah_padding(1);
1501
1502 public:
1503 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1504 WorkerTask("Shenandoah Parallel Region Operation"),
1505 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1506
1507 void work(uint worker_id) {
1508 ShenandoahParallelWorkerSession worker_session(worker_id);
1509 size_t stride = ShenandoahParallelRegionStride;
1510
1511 size_t max = _heap->num_regions();
1512 while (Atomic::load(&_index) < max) {
1513 size_t cur = Atomic::fetch_and_add(&_index, stride, memory_order_relaxed);
1514 size_t start = cur;
1515 size_t end = MIN2(cur + stride, max);
1516 if (start >= max) break;
1517
1518 for (size_t i = cur; i < end; i++) {
1519 ShenandoahHeapRegion* current = _heap->get_region(i);
1520 _blk->heap_region_do(current);
1521 }
1522 }
1523 }
1524 };
1525
1526 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1527 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1528 if (num_regions() > ShenandoahParallelRegionStride) {
1529 ShenandoahParallelHeapRegionTask task(blk);
1530 workers()->run_task(&task);
1531 } else {
1532 heap_region_iterate(blk);
1533 }
1534 }
1535
1536 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1537 private:
1538 ShenandoahMarkingContext* const _ctx;
1539 public:
1540 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1541
1542 void heap_region_do(ShenandoahHeapRegion* r) {
1543 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1544 if (r->is_active()) {
1545 // Check if region needs updating its TAMS. We have updated it already during concurrent
1546 // reset, so it is very likely we don't need to do another write here.
1547 if (_ctx->top_at_mark_start(r) != r->top()) {
1548 _ctx->capture_top_at_mark_start(r);
1549 }
1550 } else {
1551 assert(_ctx->top_at_mark_start(r) == r->top(),
1552 "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
1553 }
1554 }
1555
1556 bool is_thread_safe() { return true; }
1557 };
1558
1559 class ShenandoahRendezvousClosure : public HandshakeClosure {
1560 public:
1561 inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {}
1562 inline void do_thread(Thread* thread) {}
1563 };
1564
1565 void ShenandoahHeap::rendezvous_threads() {
1566 ShenandoahRendezvousClosure cl;
1567 Handshake::execute(&cl);
1568 }
1569
1570 void ShenandoahHeap::recycle_trash() {
1571 free_set()->recycle_trash();
1572 }
1573
1574 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1575 private:
1576 ShenandoahMarkingContext* const _ctx;
1577 public:
1578 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1579
1580 void heap_region_do(ShenandoahHeapRegion* r) {
1581 if (r->is_active()) {
1582 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1583 // anyway to capture any updates that happened since now.
1584 r->clear_live_data();
1585 _ctx->capture_top_at_mark_start(r);
1586 }
1587 }
1588
1589 bool is_thread_safe() { return true; }
1590 };
1591
1592 void ShenandoahHeap::prepare_gc() {
1593 reset_mark_bitmap();
1594
1595 ShenandoahResetUpdateRegionStateClosure cl;
1596 parallel_heap_region_iterate(&cl);
1597 }
1598
1599 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1600 private:
1601 ShenandoahMarkingContext* const _ctx;
1602 ShenandoahHeapLock* const _lock;
1603
1604 public:
1605 ShenandoahFinalMarkUpdateRegionStateClosure() :
1606 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1607
1608 void heap_region_do(ShenandoahHeapRegion* r) {
1609 if (r->is_active()) {
1610 // All allocations past TAMS are implicitly live, adjust the region data.
1611 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1612 HeapWord *tams = _ctx->top_at_mark_start(r);
1613 HeapWord *top = r->top();
1614 if (top > tams) {
1615 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1616 }
1617
1618 // We are about to select the collection set, make sure it knows about
1619 // current pinning status. Also, this allows trashing more regions that
1620 // now have their pinning status dropped.
1621 if (r->is_pinned()) {
1622 if (r->pin_count() == 0) {
1623 ShenandoahHeapLocker locker(_lock);
1624 r->make_unpinned();
1625 }
1626 } else {
1627 if (r->pin_count() > 0) {
1628 ShenandoahHeapLocker locker(_lock);
1629 r->make_pinned();
1630 }
1631 }
1632
1633 // Remember limit for updating refs. It's guaranteed that we get no
1634 // from-space-refs written from here on.
1635 r->set_update_watermark_at_safepoint(r->top());
1636 } else {
1637 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1638 assert(_ctx->top_at_mark_start(r) == r->top(),
1639 "Region " SIZE_FORMAT " should have correct TAMS", r->index());
1640 }
1641 }
1642
1643 bool is_thread_safe() { return true; }
1644 };
1645
1646 void ShenandoahHeap::prepare_regions_and_collection_set(bool concurrent) {
1647 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
1648 {
1649 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_region_states :
1650 ShenandoahPhaseTimings::degen_gc_final_update_region_states);
1651 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1652 parallel_heap_region_iterate(&cl);
1653
1654 assert_pinned_region_status();
1655 }
1656
1657 {
1658 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::choose_cset :
1659 ShenandoahPhaseTimings::degen_gc_choose_cset);
1660 ShenandoahHeapLocker locker(lock());
1661 _collection_set->clear();
1662 heuristics()->choose_collection_set(_collection_set);
1663 }
1664
1665 {
1666 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_rebuild_freeset :
1667 ShenandoahPhaseTimings::degen_gc_final_rebuild_freeset);
1668 ShenandoahHeapLocker locker(lock());
1669 _free_set->rebuild();
1670 }
1671 }
1672
1673 void ShenandoahHeap::do_class_unloading() {
1674 _unloader.unload();
1675 }
1676
1677 void ShenandoahHeap::stw_weak_refs(bool full_gc) {
1678 // Weak refs processing
1679 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs
1680 : ShenandoahPhaseTimings::degen_gc_weakrefs;
1681 ShenandoahTimingsTracker t(phase);
1682 ShenandoahGCWorkerPhase worker_phase(phase);
1683 ref_processor()->process_references(phase, workers(), false /* concurrent */);
1684 }
1685
1686 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
1687 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
1688
1689 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to
1690 // make them parsable for update code to work correctly. Plus, we can compute new sizes
1691 // for future GCLABs here.
1692 if (UseTLAB) {
1693 ShenandoahGCPhase phase(concurrent ?
1694 ShenandoahPhaseTimings::init_update_refs_manage_gclabs :
1695 ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs);
1696 gclabs_retire(ResizeTLAB);
1697 }
1698
1699 _update_refs_iterator.reset();
1700 }
1701
1702 void ShenandoahHeap::set_gc_state_all_threads(char state) {
1703 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1704 ShenandoahThreadLocalData::set_gc_state(t, state);
1705 }
1706 }
1707
1708 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1709 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1710 _gc_state.set_cond(mask, value);
1711 set_gc_state_all_threads(_gc_state.raw_value());
1712 }
1713
1714 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1715 assert(!has_forwarded_objects(), "Not expected before/after mark phase");
1716 set_gc_state_mask(MARKING, in_progress);
1717 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1718 }
1719
1720 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1721 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1722 set_gc_state_mask(EVACUATION, in_progress);
1723 }
1724
1725 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
1726 if (in_progress) {
1727 _concurrent_strong_root_in_progress.set();
1728 } else {
1729 _concurrent_strong_root_in_progress.unset();
1730 }
1731 }
1732
1733 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) {
1734 set_gc_state_mask(WEAK_ROOTS, cond);
1735 }
1736
1737 GCTracer* ShenandoahHeap::tracer() {
1738 return shenandoah_policy()->tracer();
1739 }
1740
1741 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1742 return _free_set->used();
1743 }
1744
1745 bool ShenandoahHeap::try_cancel_gc() {
1746 while (true) {
1747 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
1748 if (prev == CANCELLABLE) return true;
1749 else if (prev == CANCELLED) return false;
1750 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
1751 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
1752 Thread* thread = Thread::current();
1753 if (thread->is_Java_thread()) {
1754 // We need to provide a safepoint here, otherwise we might
1755 // spin forever if a SP is pending.
1756 ThreadBlockInVM sp(JavaThread::cast(thread));
1757 SpinPause();
1758 }
1759 }
1760 }
1761
1762 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1763 if (try_cancel_gc()) {
1764 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1765 log_info(gc)("%s", msg.buffer());
1766 Events::log(Thread::current(), "%s", msg.buffer());
1767 }
1768 }
1769
1770 uint ShenandoahHeap::max_workers() {
1771 return _max_workers;
1772 }
1773
1774 void ShenandoahHeap::stop() {
1775 // The shutdown sequence should be able to terminate when GC is running.
1776
1777 // Step 0. Notify policy to disable event recording.
1778 _shenandoah_policy->record_shutdown();
1779
1780 // Step 1. Notify control thread that we are in shutdown.
1781 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1782 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1783 control_thread()->prepare_for_graceful_shutdown();
1784
1785 // Step 2. Notify GC workers that we are cancelling GC.
1786 cancel_gc(GCCause::_shenandoah_stop_vm);
1787
1788 // Step 3. Wait until GC worker exits normally.
1789 control_thread()->stop();
1790 }
1791
1792 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
1793 if (!unload_classes()) return;
1794 // Unload classes and purge SystemDictionary.
1795 {
1796 ShenandoahPhaseTimings::Phase phase = full_gc ?
1797 ShenandoahPhaseTimings::full_gc_purge_class_unload :
1798 ShenandoahPhaseTimings::degen_gc_purge_class_unload;
1799 ShenandoahGCPhase gc_phase(phase);
1800 ShenandoahGCWorkerPhase worker_phase(phase);
1801 bool purged_class = SystemDictionary::do_unloading(gc_timer());
1802
1803 ShenandoahIsAliveSelector is_alive;
1804 uint num_workers = _workers->active_workers();
1805 ShenandoahClassUnloadingTask unlink_task(phase, is_alive.is_alive_closure(), num_workers, purged_class);
1806 _workers->run_task(&unlink_task);
1807 }
1808
1809 {
1810 ShenandoahGCPhase phase(full_gc ?
1811 ShenandoahPhaseTimings::full_gc_purge_cldg :
1812 ShenandoahPhaseTimings::degen_gc_purge_cldg);
1813 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
1814 }
1815 // Resize and verify metaspace
1816 MetaspaceGC::compute_new_size();
1817 DEBUG_ONLY(MetaspaceUtils::verify();)
1818 }
1819
1820 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
1821 // so they should not have forwarded oops.
1822 // However, we do need to "null" dead oops in the roots, if can not be done
1823 // in concurrent cycles.
1824 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
1825 uint num_workers = _workers->active_workers();
1826 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
1827 ShenandoahPhaseTimings::full_gc_purge_weak_par :
1828 ShenandoahPhaseTimings::degen_gc_purge_weak_par;
1829 ShenandoahGCPhase phase(timing_phase);
1830 ShenandoahGCWorkerPhase worker_phase(timing_phase);
1831 // Cleanup weak roots
1832 if (has_forwarded_objects()) {
1833 ShenandoahForwardedIsAliveClosure is_alive;
1834 ShenandoahUpdateRefsClosure keep_alive;
1835 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
1836 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers);
1837 _workers->run_task(&cleaning_task);
1838 } else {
1839 ShenandoahIsAliveClosure is_alive;
1840 #ifdef ASSERT
1841 ShenandoahAssertNotForwardedClosure verify_cl;
1842 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
1843 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers);
1844 #else
1845 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
1846 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers);
1847 #endif
1848 _workers->run_task(&cleaning_task);
1849 }
1850 }
1851
1852 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
1853 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1854 assert(is_stw_gc_in_progress(), "Only for Degenerated and Full GC");
1855 ShenandoahGCPhase phase(full_gc ?
1856 ShenandoahPhaseTimings::full_gc_purge :
1857 ShenandoahPhaseTimings::degen_gc_purge);
1858 stw_weak_refs(full_gc);
1859 stw_process_weak_roots(full_gc);
1860 stw_unload_classes(full_gc);
1861 }
1862
1863 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
1864 set_gc_state_mask(HAS_FORWARDED, cond);
1865 }
1866
1867 void ShenandoahHeap::set_unload_classes(bool uc) {
1868 _unload_classes.set_cond(uc);
1869 }
1870
1871 bool ShenandoahHeap::unload_classes() const {
1872 return _unload_classes.is_set();
1873 }
1874
1875 address ShenandoahHeap::in_cset_fast_test_addr() {
1876 ShenandoahHeap* heap = ShenandoahHeap::heap();
1877 assert(heap->collection_set() != NULL, "Sanity");
1878 return (address) heap->collection_set()->biased_map_address();
1879 }
1880
1881 address ShenandoahHeap::cancelled_gc_addr() {
1882 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
1883 }
1884
1885 address ShenandoahHeap::gc_state_addr() {
1886 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
1887 }
1888
1889 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
1890 return Atomic::load(&_bytes_allocated_since_gc_start);
1891 }
1892
1893 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
1894 Atomic::store(&_bytes_allocated_since_gc_start, (size_t)0);
1895 }
1896
1897 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
1898 _degenerated_gc_in_progress.set_cond(in_progress);
1899 }
1900
1901 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
1902 _full_gc_in_progress.set_cond(in_progress);
1903 }
1904
1905 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
1906 assert (is_full_gc_in_progress(), "should be");
1907 _full_gc_move_in_progress.set_cond(in_progress);
1908 }
1909
1910 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
1911 set_gc_state_mask(UPDATEREFS, in_progress);
1912 }
1913
1914 void ShenandoahHeap::register_nmethod(nmethod* nm) {
1915 ShenandoahCodeRoots::register_nmethod(nm);
1916 }
1917
1918 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
1919 ShenandoahCodeRoots::unregister_nmethod(nm);
1920 }
1921
1922 void ShenandoahHeap::flush_nmethod(nmethod* nm) {
1923 ShenandoahCodeRoots::flush_nmethod(nm);
1924 }
1925
1926 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
1927 heap_region_containing(o)->record_pin();
1928 return o;
1929 }
1930
1931 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
1932 ShenandoahHeapRegion* r = heap_region_containing(o);
1933 assert(r != NULL, "Sanity");
1934 assert(r->pin_count() > 0, "Region " SIZE_FORMAT " should have non-zero pins", r->index());
1935 r->record_unpin();
1936 }
1937
1938 void ShenandoahHeap::sync_pinned_region_status() {
1939 ShenandoahHeapLocker locker(lock());
1940
1941 for (size_t i = 0; i < num_regions(); i++) {
1942 ShenandoahHeapRegion *r = get_region(i);
1943 if (r->is_active()) {
1944 if (r->is_pinned()) {
1945 if (r->pin_count() == 0) {
1946 r->make_unpinned();
1947 }
1948 } else {
1949 if (r->pin_count() > 0) {
1950 r->make_pinned();
1951 }
1952 }
1953 }
1954 }
1955
1956 assert_pinned_region_status();
1957 }
1958
1959 #ifdef ASSERT
1960 void ShenandoahHeap::assert_pinned_region_status() {
1961 for (size_t i = 0; i < num_regions(); i++) {
1962 ShenandoahHeapRegion* r = get_region(i);
1963 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
1964 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
1965 }
1966 }
1967 #endif
1968
1969 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
1970 return _gc_timer;
1971 }
1972
1973 void ShenandoahHeap::prepare_concurrent_roots() {
1974 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1975 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1976 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
1977 set_concurrent_weak_root_in_progress(true);
1978 if (unload_classes()) {
1979 _unloader.prepare();
1980 }
1981 }
1982
1983 void ShenandoahHeap::finish_concurrent_roots() {
1984 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1985 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1986 if (unload_classes()) {
1987 _unloader.finish();
1988 }
1989 }
1990
1991 #ifdef ASSERT
1992 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
1993 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
1994
1995 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1996 if (UseDynamicNumberOfGCThreads) {
1997 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
1998 } else {
1999 // Use ParallelGCThreads inside safepoints
2000 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
2001 }
2002 } else {
2003 if (UseDynamicNumberOfGCThreads) {
2004 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2005 } else {
2006 // Use ConcGCThreads outside safepoints
2007 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2008 }
2009 }
2010 }
2011 #endif
2012
2013 ShenandoahVerifier* ShenandoahHeap::verifier() {
2014 guarantee(ShenandoahVerify, "Should be enabled");
2015 assert (_verifier != NULL, "sanity");
2016 return _verifier;
2017 }
2018
2019 template<bool CONCURRENT>
2020 class ShenandoahUpdateHeapRefsTask : public WorkerTask {
2021 private:
2022 ShenandoahHeap* _heap;
2023 ShenandoahRegionIterator* _regions;
2024 public:
2025 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) :
2026 WorkerTask("Shenandoah Update References"),
2027 _heap(ShenandoahHeap::heap()),
2028 _regions(regions) {
2029 }
2030
2031 void work(uint worker_id) {
2032 if (CONCURRENT) {
2033 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2034 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2035 do_work<ShenandoahConcUpdateRefsClosure>();
2036 } else {
2037 ShenandoahParallelWorkerSession worker_session(worker_id);
2038 do_work<ShenandoahSTWUpdateRefsClosure>();
2039 }
2040 }
2041
2042 private:
2043 template<class T>
2044 void do_work() {
2045 T cl;
2046 ShenandoahHeapRegion* r = _regions->next();
2047 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2048 while (r != NULL) {
2049 HeapWord* update_watermark = r->get_update_watermark();
2050 assert (update_watermark >= r->bottom(), "sanity");
2051 if (r->is_active() && !r->is_cset()) {
2052 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2053 }
2054 if (ShenandoahPacing) {
2055 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2056 }
2057 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
2058 return;
2059 }
2060 r = _regions->next();
2061 }
2062 }
2063 };
2064
2065 void ShenandoahHeap::update_heap_references(bool concurrent) {
2066 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2067
2068 if (concurrent) {
2069 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator);
2070 workers()->run_task(&task);
2071 } else {
2072 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator);
2073 workers()->run_task(&task);
2074 }
2075 }
2076
2077
2078 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2079 private:
2080 ShenandoahHeapLock* const _lock;
2081
2082 public:
2083 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2084
2085 void heap_region_do(ShenandoahHeapRegion* r) {
2086 // Drop unnecessary "pinned" state from regions that does not have CP marks
2087 // anymore, as this would allow trashing them.
2088
2089 if (r->is_active()) {
2090 if (r->is_pinned()) {
2091 if (r->pin_count() == 0) {
2092 ShenandoahHeapLocker locker(_lock);
2093 r->make_unpinned();
2094 }
2095 } else {
2096 if (r->pin_count() > 0) {
2097 ShenandoahHeapLocker locker(_lock);
2098 r->make_pinned();
2099 }
2100 }
2101 }
2102 }
2103
2104 bool is_thread_safe() { return true; }
2105 };
2106
2107 void ShenandoahHeap::update_heap_region_states(bool concurrent) {
2108 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2109 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2110
2111 {
2112 ShenandoahGCPhase phase(concurrent ?
2113 ShenandoahPhaseTimings::final_update_refs_update_region_states :
2114 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states);
2115 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2116 parallel_heap_region_iterate(&cl);
2117
2118 assert_pinned_region_status();
2119 }
2120
2121 {
2122 ShenandoahGCPhase phase(concurrent ?
2123 ShenandoahPhaseTimings::final_update_refs_trash_cset :
2124 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset);
2125 trash_cset_regions();
2126 }
2127 }
2128
2129 void ShenandoahHeap::rebuild_free_set(bool concurrent) {
2130 {
2131 ShenandoahGCPhase phase(concurrent ?
2132 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
2133 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
2134 ShenandoahHeapLocker locker(lock());
2135 _free_set->rebuild();
2136 }
2137 }
2138
2139 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2140 print_on(st);
2141 print_heap_regions_on(st);
2142 }
2143
2144 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2145 size_t slice = r->index() / _bitmap_regions_per_slice;
2146
2147 size_t regions_from = _bitmap_regions_per_slice * slice;
2148 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2149 for (size_t g = regions_from; g < regions_to; g++) {
2150 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2151 if (skip_self && g == r->index()) continue;
2152 if (get_region(g)->is_committed()) {
2153 return true;
2154 }
2155 }
2156 return false;
2157 }
2158
2159 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2160 shenandoah_assert_heaplocked();
2161
2162 // Bitmaps in special regions do not need commits
2163 if (_bitmap_region_special) {
2164 return true;
2165 }
2166
2167 if (is_bitmap_slice_committed(r, true)) {
2168 // Some other region from the group is already committed, meaning the bitmap
2169 // slice is already committed, we exit right away.
2170 return true;
2171 }
2172
2173 // Commit the bitmap slice:
2174 size_t slice = r->index() / _bitmap_regions_per_slice;
2175 size_t off = _bitmap_bytes_per_slice * slice;
2176 size_t len = _bitmap_bytes_per_slice;
2177 char* start = (char*) _bitmap_region.start() + off;
2178
2179 if (!os::commit_memory(start, len, false)) {
2180 return false;
2181 }
2182
2183 if (AlwaysPreTouch) {
2184 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size);
2185 }
2186
2187 return true;
2188 }
2189
2190 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2191 shenandoah_assert_heaplocked();
2192
2193 // Bitmaps in special regions do not need uncommits
2194 if (_bitmap_region_special) {
2195 return true;
2196 }
2197
2198 if (is_bitmap_slice_committed(r, true)) {
2199 // Some other region from the group is still committed, meaning the bitmap
2200 // slice is should stay committed, exit right away.
2201 return true;
2202 }
2203
2204 // Uncommit the bitmap slice:
2205 size_t slice = r->index() / _bitmap_regions_per_slice;
2206 size_t off = _bitmap_bytes_per_slice * slice;
2207 size_t len = _bitmap_bytes_per_slice;
2208 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2209 return false;
2210 }
2211 return true;
2212 }
2213
2214 void ShenandoahHeap::safepoint_synchronize_begin() {
2215 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2216 SuspendibleThreadSet::synchronize();
2217 }
2218 }
2219
2220 void ShenandoahHeap::safepoint_synchronize_end() {
2221 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2222 SuspendibleThreadSet::desynchronize();
2223 }
2224 }
2225
2226 void ShenandoahHeap::entry_uncommit(double shrink_before, size_t shrink_until) {
2227 static const char *msg = "Concurrent uncommit";
2228 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */);
2229 EventMark em("%s", msg);
2230
2231 op_uncommit(shrink_before, shrink_until);
2232 }
2233
2234 void ShenandoahHeap::try_inject_alloc_failure() {
2235 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2236 _inject_alloc_failure.set();
2237 os::naked_short_sleep(1);
2238 if (cancelled_gc()) {
2239 log_info(gc)("Allocation failure was successfully injected");
2240 }
2241 }
2242 }
2243
2244 bool ShenandoahHeap::should_inject_alloc_failure() {
2245 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2246 }
2247
2248 void ShenandoahHeap::initialize_serviceability() {
2249 _memory_pool = new ShenandoahMemoryPool(this);
2250 _cycle_memory_manager.add_pool(_memory_pool);
2251 _stw_memory_manager.add_pool(_memory_pool);
2252 }
2253
2254 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2255 GrowableArray<GCMemoryManager*> memory_managers(2);
2256 memory_managers.append(&_cycle_memory_manager);
2257 memory_managers.append(&_stw_memory_manager);
2258 return memory_managers;
2259 }
2260
2261 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2262 GrowableArray<MemoryPool*> memory_pools(1);
2263 memory_pools.append(_memory_pool);
2264 return memory_pools;
2265 }
2266
2267 MemoryUsage ShenandoahHeap::memory_usage() {
2268 return _memory_pool->get_memory_usage();
2269 }
2270
2271 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2272 _heap(ShenandoahHeap::heap()),
2273 _index(0) {}
2274
2275 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2276 _heap(heap),
2277 _index(0) {}
2278
2279 void ShenandoahRegionIterator::reset() {
2280 _index = 0;
2281 }
2282
2283 bool ShenandoahRegionIterator::has_next() const {
2284 return _index < _heap->num_regions();
2285 }
2286
2287 char ShenandoahHeap::gc_state() const {
2288 return _gc_state.raw_value();
2289 }
2290
2291 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2292 #ifdef ASSERT
2293 assert(_liveness_cache != NULL, "sanity");
2294 assert(worker_id < _max_workers, "sanity");
2295 for (uint i = 0; i < num_regions(); i++) {
2296 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2297 }
2298 #endif
2299 return _liveness_cache[worker_id];
2300 }
2301
2302 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2303 assert(worker_id < _max_workers, "sanity");
2304 assert(_liveness_cache != NULL, "sanity");
2305 ShenandoahLiveData* ld = _liveness_cache[worker_id];
2306 for (uint i = 0; i < num_regions(); i++) {
2307 ShenandoahLiveData live = ld[i];
2308 if (live > 0) {
2309 ShenandoahHeapRegion* r = get_region(i);
2310 r->increase_live_data_gc_words(live);
2311 ld[i] = 0;
2312 }
2313 }
2314 }