1 /*
2 * Copyright (c) 2023, 2024, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2013, 2022, Red Hat, Inc. All rights reserved.
4 * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
5 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
6 *
7 * This code is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License version 2 only, as
9 * published by the Free Software Foundation.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 *
25 */
26
27 #include "precompiled.hpp"
28 #include "memory/allocation.hpp"
29 #include "memory/universe.hpp"
30
31 #include "gc/shared/classUnloadingContext.hpp"
32 #include "gc/shared/fullGCForwarding.hpp"
33 #include "gc/shared/gcArguments.hpp"
34 #include "gc/shared/gcTimer.hpp"
35 #include "gc/shared/gcTraceTime.inline.hpp"
36 #include "gc/shared/locationPrinter.inline.hpp"
37 #include "gc/shared/memAllocator.hpp"
38 #include "gc/shared/plab.hpp"
39 #include "gc/shared/tlab_globals.hpp"
40
41 #include "gc/shenandoah/heuristics/shenandoahOldHeuristics.hpp"
42 #include "gc/shenandoah/heuristics/shenandoahYoungHeuristics.hpp"
43 #include "gc/shenandoah/shenandoahAllocRequest.hpp"
44 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
45 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
46 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
47 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
48 #include "gc/shenandoah/shenandoahConcurrentMark.hpp"
49 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
50 #include "gc/shenandoah/shenandoahControlThread.hpp"
51 #include "gc/shenandoah/shenandoahFreeSet.hpp"
52 #include "gc/shenandoah/shenandoahGenerationalEvacuationTask.hpp"
53 #include "gc/shenandoah/shenandoahGenerationalHeap.hpp"
54 #include "gc/shenandoah/shenandoahGlobalGeneration.hpp"
55 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
56 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
57 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
58 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
59 #include "gc/shenandoah/shenandoahInitLogger.hpp"
60 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
61 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
62 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
63 #include "gc/shenandoah/shenandoahOldGeneration.hpp"
64 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
65 #include "gc/shenandoah/shenandoahPadding.hpp"
66 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
67 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
68 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
69 #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp"
70 #include "gc/shenandoah/shenandoahSTWMark.hpp"
71 #include "gc/shenandoah/shenandoahUtils.hpp"
72 #include "gc/shenandoah/shenandoahVerifier.hpp"
73 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
74 #include "gc/shenandoah/shenandoahVMOperations.hpp"
75 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
76 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
77 #include "gc/shenandoah/shenandoahYoungGeneration.hpp"
78 #include "gc/shenandoah/mode/shenandoahGenerationalMode.hpp"
79 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
80 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp"
81 #include "utilities/globalDefinitions.hpp"
82
83 #if INCLUDE_JFR
84 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
85 #endif
86
87 #include "cds/archiveHeapWriter.hpp"
88 #include "classfile/systemDictionary.hpp"
89 #include "code/codeCache.hpp"
90 #include "memory/classLoaderMetaspace.hpp"
91 #include "memory/metaspaceUtils.hpp"
92 #include "nmt/mallocTracker.hpp"
93 #include "nmt/memTracker.hpp"
94 #include "oops/compressedOops.inline.hpp"
95 #include "prims/jvmtiTagMap.hpp"
96 #include "runtime/atomic.hpp"
97 #include "runtime/globals.hpp"
98 #include "runtime/interfaceSupport.inline.hpp"
99 #include "runtime/java.hpp"
100 #include "runtime/orderAccess.hpp"
101 #include "runtime/safepointMechanism.hpp"
102 #include "runtime/stackWatermarkSet.hpp"
103 #include "runtime/vmThread.hpp"
104 #include "utilities/events.hpp"
105 #include "utilities/powerOfTwo.hpp"
106
107 class ShenandoahPretouchHeapTask : public WorkerTask {
108 private:
109 ShenandoahRegionIterator _regions;
110 const size_t _page_size;
111 public:
112 ShenandoahPretouchHeapTask(size_t page_size) :
113 WorkerTask("Shenandoah Pretouch Heap"),
114 _page_size(page_size) {}
115
116 virtual void work(uint worker_id) {
117 ShenandoahHeapRegion* r = _regions.next();
118 while (r != nullptr) {
119 if (r->is_committed()) {
120 os::pretouch_memory(r->bottom(), r->end(), _page_size);
121 }
122 r = _regions.next();
123 }
124 }
125 };
126
127 class ShenandoahPretouchBitmapTask : public WorkerTask {
128 private:
129 ShenandoahRegionIterator _regions;
130 char* _bitmap_base;
131 const size_t _bitmap_size;
132 const size_t _page_size;
133 public:
134 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
135 WorkerTask("Shenandoah Pretouch Bitmap"),
136 _bitmap_base(bitmap_base),
137 _bitmap_size(bitmap_size),
138 _page_size(page_size) {}
139
140 virtual void work(uint worker_id) {
141 ShenandoahHeapRegion* r = _regions.next();
142 while (r != nullptr) {
143 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
144 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
145 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
146
147 if (r->is_committed()) {
148 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
149 }
150
151 r = _regions.next();
152 }
153 }
154 };
155
156 jint ShenandoahHeap::initialize() {
157 //
158 // Figure out heap sizing
159 //
160
161 size_t init_byte_size = InitialHeapSize;
162 size_t min_byte_size = MinHeapSize;
163 size_t max_byte_size = MaxHeapSize;
164 size_t heap_alignment = HeapAlignment;
165
166 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
167
168 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
169 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
170
171 _num_regions = ShenandoahHeapRegion::region_count();
172 assert(_num_regions == (max_byte_size / reg_size_bytes),
173 "Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT,
174 _num_regions, max_byte_size, reg_size_bytes);
175
176 size_t num_committed_regions = init_byte_size / reg_size_bytes;
177 num_committed_regions = MIN2(num_committed_regions, _num_regions);
178 assert(num_committed_regions <= _num_regions, "sanity");
179 _initial_size = num_committed_regions * reg_size_bytes;
180
181 size_t num_min_regions = min_byte_size / reg_size_bytes;
182 num_min_regions = MIN2(num_min_regions, _num_regions);
183 assert(num_min_regions <= _num_regions, "sanity");
184 _minimum_size = num_min_regions * reg_size_bytes;
185
186 // Default to max heap size.
187 _soft_max_size = _num_regions * reg_size_bytes;
188
189 _committed = _initial_size;
190
191 size_t heap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
192 size_t bitmap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
193 size_t region_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
194
195 //
196 // Reserve and commit memory for heap
197 //
198
199 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
200 initialize_reserved_region(heap_rs);
201 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
202 _heap_region_special = heap_rs.special();
203
204 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
205 "Misaligned heap: " PTR_FORMAT, p2i(base()));
206 os::trace_page_sizes_for_requested_size("Heap",
207 max_byte_size, heap_alignment,
208 heap_rs.base(),
209 heap_rs.size(), heap_rs.page_size());
210
211 #if SHENANDOAH_OPTIMIZED_MARKTASK
212 // The optimized ShenandoahMarkTask takes some bits away from the full object bits.
213 // Fail if we ever attempt to address more than we can.
214 if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) {
215 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
216 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
217 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
218 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable());
219 vm_exit_during_initialization("Fatal Error", buf);
220 }
221 #endif
222
223 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
224 if (!_heap_region_special) {
225 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
226 "Cannot commit heap memory");
227 }
228
229 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this, _heap_region));
230
231 // Now we know the number of regions and heap sizes, initialize the heuristics.
232 initialize_heuristics();
233
234 assert(_heap_region.byte_size() == heap_rs.size(), "Need to know reserved size for card table");
235
236 //
237 // Worker threads must be initialized after the barrier is configured
238 //
239 _workers = new ShenandoahWorkerThreads("Shenandoah GC Threads", _max_workers);
240 if (_workers == nullptr) {
241 vm_exit_during_initialization("Failed necessary allocation.");
242 } else {
243 _workers->initialize_workers();
244 }
245
246 if (ParallelGCThreads > 1) {
247 _safepoint_workers = new ShenandoahWorkerThreads("Safepoint Cleanup Thread", ParallelGCThreads);
248 _safepoint_workers->initialize_workers();
249 }
250
251 //
252 // Reserve and commit memory for bitmap(s)
253 //
254
255 size_t bitmap_size_orig = ShenandoahMarkBitMap::compute_size(heap_rs.size());
256 _bitmap_size = align_up(bitmap_size_orig, bitmap_page_size);
257
258 size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor();
259
260 guarantee(bitmap_bytes_per_region != 0,
261 "Bitmap bytes per region should not be zero");
262 guarantee(is_power_of_2(bitmap_bytes_per_region),
263 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
264
265 if (bitmap_page_size > bitmap_bytes_per_region) {
266 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
267 _bitmap_bytes_per_slice = bitmap_page_size;
268 } else {
269 _bitmap_regions_per_slice = 1;
270 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
271 }
272
273 guarantee(_bitmap_regions_per_slice >= 1,
274 "Should have at least one region per slice: " SIZE_FORMAT,
275 _bitmap_regions_per_slice);
276
277 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
278 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
279 _bitmap_bytes_per_slice, bitmap_page_size);
280
281 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
282 os::trace_page_sizes_for_requested_size("Mark Bitmap",
283 bitmap_size_orig, bitmap_page_size,
284 bitmap.base(),
285 bitmap.size(), bitmap.page_size());
286 MemTracker::record_virtual_memory_tag(bitmap.base(), mtGC);
287 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
288 _bitmap_region_special = bitmap.special();
289
290 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
291 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
292 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
293 if (!_bitmap_region_special) {
294 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
295 "Cannot commit bitmap memory");
296 }
297
298 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
299
300 if (ShenandoahVerify) {
301 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
302 os::trace_page_sizes_for_requested_size("Verify Bitmap",
303 bitmap_size_orig, bitmap_page_size,
304 verify_bitmap.base(),
305 verify_bitmap.size(), verify_bitmap.page_size());
306 if (!verify_bitmap.special()) {
307 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
308 "Cannot commit verification bitmap memory");
309 }
310 MemTracker::record_virtual_memory_tag(verify_bitmap.base(), mtGC);
311 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
312 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
313 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
314 }
315
316 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
317 size_t aux_bitmap_page_size = bitmap_page_size;
318
319 ReservedSpace aux_bitmap(_bitmap_size, aux_bitmap_page_size);
320 os::trace_page_sizes_for_requested_size("Aux Bitmap",
321 bitmap_size_orig, aux_bitmap_page_size,
322 aux_bitmap.base(),
323 aux_bitmap.size(), aux_bitmap.page_size());
324 MemTracker::record_virtual_memory_tag(aux_bitmap.base(), mtGC);
325 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
326 _aux_bitmap_region_special = aux_bitmap.special();
327 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
328
329 //
330 // Create regions and region sets
331 //
332 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
333 size_t region_storage_size_orig = region_align * _num_regions;
334 size_t region_storage_size = align_up(region_storage_size_orig,
335 MAX2(region_page_size, os::vm_allocation_granularity()));
336
337 ReservedSpace region_storage(region_storage_size, region_page_size);
338 os::trace_page_sizes_for_requested_size("Region Storage",
339 region_storage_size_orig, region_page_size,
340 region_storage.base(),
341 region_storage.size(), region_storage.page_size());
342 MemTracker::record_virtual_memory_tag(region_storage.base(), mtGC);
343 if (!region_storage.special()) {
344 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false,
345 "Cannot commit region memory");
346 }
347
348 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks.
349 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there.
350 // If not successful, bite a bullet and allocate at whatever address.
351 {
352 const size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity());
353 const size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align);
354 const size_t cset_page_size = os::vm_page_size();
355
356 uintptr_t min = round_up_power_of_2(cset_align);
357 uintptr_t max = (1u << 30u);
358 ReservedSpace cset_rs;
359
360 for (uintptr_t addr = min; addr <= max; addr <<= 1u) {
361 char* req_addr = (char*)addr;
362 assert(is_aligned(req_addr, cset_align), "Should be aligned");
363 cset_rs = ReservedSpace(cset_size, cset_align, cset_page_size, req_addr);
364 if (cset_rs.is_reserved()) {
365 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr);
366 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
367 break;
368 }
369 }
370
371 if (_collection_set == nullptr) {
372 cset_rs = ReservedSpace(cset_size, cset_align, os::vm_page_size());
373 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
374 }
375 os::trace_page_sizes_for_requested_size("Collection Set",
376 cset_size, cset_page_size,
377 cset_rs.base(),
378 cset_rs.size(), cset_rs.page_size());
379 }
380
381 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
382 _affiliations = NEW_C_HEAP_ARRAY(uint8_t, _num_regions, mtGC);
383 _free_set = new ShenandoahFreeSet(this, _num_regions);
384
385 {
386 ShenandoahHeapLocker locker(lock());
387
388 for (size_t i = 0; i < _num_regions; i++) {
389 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
390 bool is_committed = i < num_committed_regions;
391 void* loc = region_storage.base() + i * region_align;
392
393 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
394 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
395
396 _marking_context->initialize_top_at_mark_start(r);
397 _regions[i] = r;
398 assert(!collection_set()->is_in(i), "New region should not be in collection set");
399
400 _affiliations[i] = ShenandoahAffiliation::FREE;
401 }
402
403 // Initialize to complete
404 _marking_context->mark_complete();
405 size_t young_cset_regions, old_cset_regions;
406
407 // We are initializing free set. We ignore cset region tallies.
408 size_t first_old, last_old, num_old;
409 _free_set->prepare_to_rebuild(young_cset_regions, old_cset_regions, first_old, last_old, num_old);
410 _free_set->finish_rebuild(young_cset_regions, old_cset_regions, num_old);
411 }
412
413 if (AlwaysPreTouch) {
414 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
415 // before initialize() below zeroes it with initializing thread. For any given region,
416 // we touch the region and the corresponding bitmaps from the same thread.
417 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
418
419 _pretouch_heap_page_size = heap_page_size;
420 _pretouch_bitmap_page_size = bitmap_page_size;
421
422 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
423 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
424
425 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size);
426 _workers->run_task(&bcl);
427
428 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size);
429 _workers->run_task(&hcl);
430 }
431
432 //
433 // Initialize the rest of GC subsystems
434 //
435
436 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC);
437 for (uint worker = 0; worker < _max_workers; worker++) {
438 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC);
439 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData));
440 }
441
442 // There should probably be Shenandoah-specific options for these,
443 // just as there are G1-specific options.
444 {
445 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
446 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
447 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
448 }
449
450 _monitoring_support = new ShenandoahMonitoringSupport(this);
451 _phase_timings = new ShenandoahPhaseTimings(max_workers());
452 ShenandoahCodeRoots::initialize();
453
454 if (ShenandoahPacing) {
455 _pacer = new ShenandoahPacer(this);
456 _pacer->setup_for_idle();
457 }
458
459 initialize_controller();
460
461 print_init_logger();
462
463 FullGCForwarding::initialize(_heap_region);
464
465 return JNI_OK;
466 }
467
468 void ShenandoahHeap::initialize_controller() {
469 _control_thread = new ShenandoahControlThread();
470 }
471
472 void ShenandoahHeap::print_init_logger() const {
473 ShenandoahInitLogger::print();
474 }
475
476 void ShenandoahHeap::initialize_mode() {
477 if (ShenandoahGCMode != nullptr) {
478 if (strcmp(ShenandoahGCMode, "satb") == 0) {
479 _gc_mode = new ShenandoahSATBMode();
480 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
481 _gc_mode = new ShenandoahPassiveMode();
482 } else if (strcmp(ShenandoahGCMode, "generational") == 0) {
483 _gc_mode = new ShenandoahGenerationalMode();
484 } else {
485 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
486 }
487 } else {
488 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option (null)");
489 }
490 _gc_mode->initialize_flags();
491 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
492 vm_exit_during_initialization(
493 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
494 _gc_mode->name()));
495 }
496 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
497 vm_exit_during_initialization(
498 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
499 _gc_mode->name()));
500 }
501 }
502
503 void ShenandoahHeap::initialize_heuristics() {
504 _global_generation = new ShenandoahGlobalGeneration(mode()->is_generational(), max_workers(), max_capacity(), max_capacity());
505 _global_generation->initialize_heuristics(mode());
506 }
507
508 #ifdef _MSC_VER
509 #pragma warning( push )
510 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
511 #endif
512
513 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
514 CollectedHeap(),
515 _gc_generation(nullptr),
516 _active_generation(nullptr),
517 _initial_size(0),
518 _committed(0),
519 _max_workers(MAX3(ConcGCThreads, ParallelGCThreads, 1U)),
520 _workers(nullptr),
521 _safepoint_workers(nullptr),
522 _heap_region_special(false),
523 _num_regions(0),
524 _regions(nullptr),
525 _affiliations(nullptr),
526 _gc_state_changed(false),
527 _gc_no_progress_count(0),
528 _cancel_requested_time(0),
529 _update_refs_iterator(this),
530 _global_generation(nullptr),
531 _control_thread(nullptr),
532 _young_generation(nullptr),
533 _old_generation(nullptr),
534 _shenandoah_policy(policy),
535 _gc_mode(nullptr),
536 _free_set(nullptr),
537 _pacer(nullptr),
538 _verifier(nullptr),
539 _phase_timings(nullptr),
540 _mmu_tracker(),
541 _monitoring_support(nullptr),
542 _memory_pool(nullptr),
543 _stw_memory_manager("Shenandoah Pauses"),
544 _cycle_memory_manager("Shenandoah Cycles"),
545 _gc_timer(new ConcurrentGCTimer()),
546 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
547 _marking_context(nullptr),
548 _bitmap_size(0),
549 _bitmap_regions_per_slice(0),
550 _bitmap_bytes_per_slice(0),
551 _bitmap_region_special(false),
552 _aux_bitmap_region_special(false),
553 _liveness_cache(nullptr),
554 _collection_set(nullptr)
555 {
556 // Initialize GC mode early, many subsequent initialization procedures depend on it
557 initialize_mode();
558 }
559
560 #ifdef _MSC_VER
561 #pragma warning( pop )
562 #endif
563
564 void ShenandoahHeap::print_on(outputStream* st) const {
565 st->print_cr("Shenandoah Heap");
566 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
567 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
568 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()),
569 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
570 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
571 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
572 num_regions(),
573 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
574 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
575
576 st->print("Status: ");
577 if (has_forwarded_objects()) st->print("has forwarded objects, ");
578 if (!mode()->is_generational()) {
579 if (is_concurrent_mark_in_progress()) st->print("marking,");
580 } else {
581 if (is_concurrent_old_mark_in_progress()) st->print("old marking, ");
582 if (is_concurrent_young_mark_in_progress()) st->print("young marking, ");
583 }
584 if (is_evacuation_in_progress()) st->print("evacuating, ");
585 if (is_update_refs_in_progress()) st->print("updating refs, ");
586 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
587 if (is_full_gc_in_progress()) st->print("full gc, ");
588 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
589 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, ");
590 if (is_concurrent_strong_root_in_progress() &&
591 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, ");
592
593 if (cancelled_gc()) {
594 st->print("cancelled");
595 } else {
596 st->print("not cancelled");
597 }
598 st->cr();
599
600 st->print_cr("Reserved region:");
601 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
602 p2i(reserved_region().start()),
603 p2i(reserved_region().end()));
604
605 ShenandoahCollectionSet* cset = collection_set();
606 st->print_cr("Collection set:");
607 if (cset != nullptr) {
608 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
609 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
610 } else {
611 st->print_cr(" (null)");
612 }
613
614 st->cr();
615 MetaspaceUtils::print_on(st);
616
617 if (Verbose) {
618 st->cr();
619 print_heap_regions_on(st);
620 }
621 }
622
623 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
624 public:
625 void do_thread(Thread* thread) {
626 assert(thread != nullptr, "Sanity");
627 assert(thread->is_Worker_thread(), "Only worker thread expected");
628 ShenandoahThreadLocalData::initialize_gclab(thread);
629 }
630 };
631
632 void ShenandoahHeap::post_initialize() {
633 CollectedHeap::post_initialize();
634 _mmu_tracker.initialize();
635
636 MutexLocker ml(Threads_lock);
637
638 ShenandoahInitWorkerGCLABClosure init_gclabs;
639 _workers->threads_do(&init_gclabs);
640
641 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
642 // Now, we will let WorkerThreads to initialize gclab when new worker is created.
643 _workers->set_initialize_gclab();
644 if (_safepoint_workers != nullptr) {
645 _safepoint_workers->threads_do(&init_gclabs);
646 _safepoint_workers->set_initialize_gclab();
647 }
648
649 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers();)
650 }
651
652 ShenandoahHeuristics* ShenandoahHeap::heuristics() {
653 return _global_generation->heuristics();
654 }
655
656 size_t ShenandoahHeap::used() const {
657 return global_generation()->used();
658 }
659
660 size_t ShenandoahHeap::committed() const {
661 return Atomic::load(&_committed);
662 }
663
664 void ShenandoahHeap::increase_committed(size_t bytes) {
665 shenandoah_assert_heaplocked_or_safepoint();
666 _committed += bytes;
667 }
668
669 void ShenandoahHeap::decrease_committed(size_t bytes) {
670 shenandoah_assert_heaplocked_or_safepoint();
671 _committed -= bytes;
672 }
673
674 // For tracking usage based on allocations, it should be the case that:
675 // * The sum of regions::used == heap::used
676 // * The sum of a generation's regions::used == generation::used
677 // * The sum of a generation's humongous regions::free == generation::humongous_waste
678 // These invariants are checked by the verifier on GC safepoints.
679 //
680 // Additional notes:
681 // * When a mutator's allocation request causes a region to be retired, the
682 // free memory left in that region is considered waste. It does not contribute
683 // to the usage, but it _does_ contribute to allocation rate.
684 // * The bottom of a PLAB must be aligned on card size. In some cases this will
685 // require padding in front of the PLAB (a filler object). Because this padding
686 // is included in the region's used memory we include the padding in the usage
687 // accounting as waste.
688 // * Mutator allocations are used to compute an allocation rate. They are also
689 // sent to the Pacer for those purposes.
690 // * There are three sources of waste:
691 // 1. The padding used to align a PLAB on card size
692 // 2. Region's free is less than minimum TLAB size and is retired
693 // 3. The unused portion of memory in the last region of a humongous object
694 void ShenandoahHeap::increase_used(const ShenandoahAllocRequest& req) {
695 size_t actual_bytes = req.actual_size() * HeapWordSize;
696 size_t wasted_bytes = req.waste() * HeapWordSize;
697 ShenandoahGeneration* generation = generation_for(req.affiliation());
698
699 if (req.is_gc_alloc()) {
700 assert(wasted_bytes == 0 || req.type() == ShenandoahAllocRequest::_alloc_plab, "Only PLABs have waste");
701 increase_used(generation, actual_bytes + wasted_bytes);
702 } else {
703 assert(req.is_mutator_alloc(), "Expected mutator alloc here");
704 // padding and actual size both count towards allocation counter
705 generation->increase_allocated(actual_bytes + wasted_bytes);
706
707 // only actual size counts toward usage for mutator allocations
708 increase_used(generation, actual_bytes);
709
710 // notify pacer of both actual size and waste
711 notify_mutator_alloc_words(req.actual_size(), req.waste());
712
713 if (wasted_bytes > 0 && ShenandoahHeapRegion::requires_humongous(req.actual_size())) {
714 increase_humongous_waste(generation,wasted_bytes);
715 }
716 }
717 }
718
719 void ShenandoahHeap::increase_humongous_waste(ShenandoahGeneration* generation, size_t bytes) {
720 generation->increase_humongous_waste(bytes);
721 if (!generation->is_global()) {
722 global_generation()->increase_humongous_waste(bytes);
723 }
724 }
725
726 void ShenandoahHeap::decrease_humongous_waste(ShenandoahGeneration* generation, size_t bytes) {
727 generation->decrease_humongous_waste(bytes);
728 if (!generation->is_global()) {
729 global_generation()->decrease_humongous_waste(bytes);
730 }
731 }
732
733 void ShenandoahHeap::increase_used(ShenandoahGeneration* generation, size_t bytes) {
734 generation->increase_used(bytes);
735 if (!generation->is_global()) {
736 global_generation()->increase_used(bytes);
737 }
738 }
739
740 void ShenandoahHeap::decrease_used(ShenandoahGeneration* generation, size_t bytes) {
741 generation->decrease_used(bytes);
742 if (!generation->is_global()) {
743 global_generation()->decrease_used(bytes);
744 }
745 }
746
747 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, size_t waste) {
748 if (ShenandoahPacing) {
749 control_thread()->pacing_notify_alloc(words);
750 if (waste > 0) {
751 pacer()->claim_for_alloc<true>(waste);
752 }
753 }
754 }
755
756 size_t ShenandoahHeap::capacity() const {
757 return committed();
758 }
759
760 size_t ShenandoahHeap::max_capacity() const {
761 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
762 }
763
764 size_t ShenandoahHeap::soft_max_capacity() const {
765 size_t v = Atomic::load(&_soft_max_size);
766 assert(min_capacity() <= v && v <= max_capacity(),
767 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
768 min_capacity(), v, max_capacity());
769 return v;
770 }
771
772 void ShenandoahHeap::set_soft_max_capacity(size_t v) {
773 assert(min_capacity() <= v && v <= max_capacity(),
774 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
775 min_capacity(), v, max_capacity());
776 Atomic::store(&_soft_max_size, v);
777 }
778
779 size_t ShenandoahHeap::min_capacity() const {
780 return _minimum_size;
781 }
782
783 size_t ShenandoahHeap::initial_capacity() const {
784 return _initial_size;
785 }
786
787 bool ShenandoahHeap::is_in(const void* p) const {
788 if (is_in_reserved(p)) {
789 if (is_full_gc_move_in_progress()) {
790 // Full GC move is running, we do not have a consistent region
791 // information yet. But we know the pointer is in heap.
792 return true;
793 }
794 // Now check if we point to a live section in active region.
795 ShenandoahHeapRegion* r = heap_region_containing(p);
796 return (r->is_active() && p < r->top());
797 } else {
798 return false;
799 }
800 }
801
802 void ShenandoahHeap::maybe_uncommit(double shrink_before, size_t shrink_until) {
803 assert (ShenandoahUncommit, "should be enabled");
804
805 // Determine if there is work to do. This avoids taking heap lock if there is
806 // no work available, avoids spamming logs with superfluous logging messages,
807 // and minimises the amount of work while locks are taken.
808
809 if (committed() <= shrink_until) return;
810
811 bool has_work = false;
812 for (size_t i = 0; i < num_regions(); i++) {
813 ShenandoahHeapRegion* r = get_region(i);
814 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
815 has_work = true;
816 break;
817 }
818 }
819
820 if (has_work) {
821 static const char* msg = "Concurrent uncommit";
822 ShenandoahConcurrentPhase gcPhase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */);
823 EventMark em("%s", msg);
824
825 op_uncommit(shrink_before, shrink_until);
826 }
827 }
828
829 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
830 assert (ShenandoahUncommit, "should be enabled");
831
832 // Application allocates from the beginning of the heap, and GC allocates at
833 // the end of it. It is more efficient to uncommit from the end, so that applications
834 // could enjoy the near committed regions. GC allocations are much less frequent,
835 // and therefore can accept the committing costs.
836
837 size_t count = 0;
838 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
839 ShenandoahHeapRegion* r = get_region(i - 1);
840 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
841 ShenandoahHeapLocker locker(lock());
842 if (r->is_empty_committed()) {
843 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) {
844 break;
845 }
846
847 r->make_uncommitted();
848 count++;
849 }
850 }
851 SpinPause(); // allow allocators to take the lock
852 }
853
854 if (count > 0) {
855 notify_heap_changed();
856 }
857 }
858
859 bool ShenandoahHeap::check_soft_max_changed() {
860 size_t new_soft_max = Atomic::load(&SoftMaxHeapSize);
861 size_t old_soft_max = soft_max_capacity();
862 if (new_soft_max != old_soft_max) {
863 new_soft_max = MAX2(min_capacity(), new_soft_max);
864 new_soft_max = MIN2(max_capacity(), new_soft_max);
865 if (new_soft_max != old_soft_max) {
866 log_info(gc)("Soft Max Heap Size: " SIZE_FORMAT "%s -> " SIZE_FORMAT "%s",
867 byte_size_in_proper_unit(old_soft_max), proper_unit_for_byte_size(old_soft_max),
868 byte_size_in_proper_unit(new_soft_max), proper_unit_for_byte_size(new_soft_max)
869 );
870 set_soft_max_capacity(new_soft_max);
871 return true;
872 }
873 }
874 return false;
875 }
876
877 void ShenandoahHeap::notify_heap_changed() {
878 // Update monitoring counters when we took a new region. This amortizes the
879 // update costs on slow path.
880 monitoring_support()->notify_heap_changed();
881 _heap_changed.set();
882 }
883
884 void ShenandoahHeap::set_forced_counters_update(bool value) {
885 monitoring_support()->set_forced_counters_update(value);
886 }
887
888 void ShenandoahHeap::handle_force_counters_update() {
889 monitoring_support()->handle_force_counters_update();
890 }
891
892 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
893 // New object should fit the GCLAB size
894 size_t min_size = MAX2(size, PLAB::min_size());
895
896 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
897 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
898
899 new_size = MIN2(new_size, PLAB::max_size());
900 new_size = MAX2(new_size, PLAB::min_size());
901
902 // Record new heuristic value even if we take any shortcut. This captures
903 // the case when moderately-sized objects always take a shortcut. At some point,
904 // heuristics should catch up with them.
905 log_debug(gc, free)("Set new GCLAB size: " SIZE_FORMAT, new_size);
906 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
907
908 if (new_size < size) {
909 // New size still does not fit the object. Fall back to shared allocation.
910 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
911 log_debug(gc, free)("New gclab size (" SIZE_FORMAT ") is too small for " SIZE_FORMAT, new_size, size);
912 return nullptr;
913 }
914
915 // Retire current GCLAB, and allocate a new one.
916 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
917 gclab->retire();
918
919 size_t actual_size = 0;
920 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
921 if (gclab_buf == nullptr) {
922 return nullptr;
923 }
924
925 assert (size <= actual_size, "allocation should fit");
926
927 // ...and clear or zap just allocated TLAB, if needed.
928 if (ZeroTLAB) {
929 Copy::zero_to_words(gclab_buf, actual_size);
930 } else if (ZapTLAB) {
931 // Skip mangling the space corresponding to the object header to
932 // ensure that the returned space is not considered parsable by
933 // any concurrent GC thread.
934 size_t hdr_size = oopDesc::header_size();
935 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
936 }
937 gclab->set_buf(gclab_buf, actual_size);
938 return gclab->allocate(size);
939 }
940
941 // Called from stubs in JIT code or interpreter
942 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
943 size_t requested_size,
944 size_t* actual_size) {
945 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
946 HeapWord* res = allocate_memory(req);
947 if (res != nullptr) {
948 *actual_size = req.actual_size();
949 } else {
950 *actual_size = 0;
951 }
952 return res;
953 }
954
955 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
956 size_t word_size,
957 size_t* actual_size) {
958 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
959 HeapWord* res = allocate_memory(req);
960 if (res != nullptr) {
961 *actual_size = req.actual_size();
962 } else {
963 *actual_size = 0;
964 }
965 return res;
966 }
967
968 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
969 intptr_t pacer_epoch = 0;
970 bool in_new_region = false;
971 HeapWord* result = nullptr;
972
973 if (req.is_mutator_alloc()) {
974 if (ShenandoahPacing) {
975 pacer()->pace_for_alloc(req.size());
976 pacer_epoch = pacer()->epoch();
977 }
978
979 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
980 result = allocate_memory_under_lock(req, in_new_region);
981 }
982
983 // Check that gc overhead is not exceeded.
984 //
985 // Shenandoah will grind along for quite a while allocating one
986 // object at a time using shared (non-tlab) allocations. This check
987 // is testing that the GC overhead limit has not been exceeded.
988 // This will notify the collector to start a cycle, but will raise
989 // an OOME to the mutator if the last Full GCs have not made progress.
990 // gc_no_progress_count is incremented following each degen or full GC that fails to achieve is_good_progress().
991 if (result == nullptr && !req.is_lab_alloc() && get_gc_no_progress_count() > ShenandoahNoProgressThreshold) {
992 control_thread()->handle_alloc_failure(req, false);
993 req.set_actual_size(0);
994 return nullptr;
995 }
996
997 if (result == nullptr) {
998 // Block until control thread reacted, then retry allocation.
999 //
1000 // It might happen that one of the threads requesting allocation would unblock
1001 // way later after GC happened, only to fail the second allocation, because
1002 // other threads have already depleted the free storage. In this case, a better
1003 // strategy is to try again, until at least one full GC has completed.
1004 //
1005 // Stop retrying and return nullptr to cause OOMError exception if our allocation failed even after:
1006 // a) We experienced a GC that had good progress, or
1007 // b) We experienced at least one Full GC (whether or not it had good progress)
1008
1009 size_t original_count = shenandoah_policy()->full_gc_count();
1010 while ((result == nullptr) && (original_count == shenandoah_policy()->full_gc_count())) {
1011 control_thread()->handle_alloc_failure(req, true);
1012 result = allocate_memory_under_lock(req, in_new_region);
1013 }
1014 if (result != nullptr) {
1015 // If our allocation request has been satisifed after it initially failed, we count this as good gc progress
1016 notify_gc_progress();
1017 }
1018 if (log_develop_is_enabled(Debug, gc, alloc)) {
1019 ResourceMark rm;
1020 log_debug(gc, alloc)("Thread: %s, Result: " PTR_FORMAT ", Request: %s, Size: " SIZE_FORMAT
1021 ", Original: " SIZE_FORMAT ", Latest: " SIZE_FORMAT,
1022 Thread::current()->name(), p2i(result), req.type_string(), req.size(),
1023 original_count, get_gc_no_progress_count());
1024 }
1025 }
1026 } else {
1027 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
1028 result = allocate_memory_under_lock(req, in_new_region);
1029 // Do not call handle_alloc_failure() here, because we cannot block.
1030 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
1031 }
1032
1033 if (in_new_region) {
1034 notify_heap_changed();
1035 }
1036
1037 if (result == nullptr) {
1038 req.set_actual_size(0);
1039 }
1040
1041 // This is called regardless of the outcome of the allocation to account
1042 // for any waste created by retiring regions with this request.
1043 increase_used(req);
1044
1045 if (result != nullptr) {
1046 size_t requested = req.size();
1047 size_t actual = req.actual_size();
1048
1049 assert (req.is_lab_alloc() || (requested == actual),
1050 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
1051 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
1052
1053 if (req.is_mutator_alloc()) {
1054 // If we requested more than we were granted, give the rest back to pacer.
1055 // This only matters if we are in the same pacing epoch: do not try to unpace
1056 // over the budget for the other phase.
1057 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
1058 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
1059 }
1060 }
1061 }
1062
1063 return result;
1064 }
1065
1066 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
1067 // If we are dealing with mutator allocation, then we may need to block for safepoint.
1068 // We cannot block for safepoint for GC allocations, because there is a high chance
1069 // we are already running at safepoint or from stack watermark machinery, and we cannot
1070 // block again.
1071 ShenandoahHeapLocker locker(lock(), req.is_mutator_alloc());
1072
1073 // Make sure the old generation has room for either evacuations or promotions before trying to allocate.
1074 if (req.is_old() && !old_generation()->can_allocate(req)) {
1075 return nullptr;
1076 }
1077
1078 // If TLAB request size is greater than available, allocate() will attempt to downsize request to fit within available
1079 // memory.
1080 HeapWord* result = _free_set->allocate(req, in_new_region);
1081
1082 // Record the plab configuration for this result and register the object.
1083 if (result != nullptr && req.is_old()) {
1084 old_generation()->configure_plab_for_current_thread(req);
1085 if (req.type() == ShenandoahAllocRequest::_alloc_shared_gc) {
1086 // Register the newly allocated object while we're holding the global lock since there's no synchronization
1087 // built in to the implementation of register_object(). There are potential races when multiple independent
1088 // threads are allocating objects, some of which might span the same card region. For example, consider
1089 // a card table's memory region within which three objects are being allocated by three different threads:
1090 //
1091 // objects being "concurrently" allocated:
1092 // [-----a------][-----b-----][--------------c------------------]
1093 // [---- card table memory range --------------]
1094 //
1095 // Before any objects are allocated, this card's memory range holds no objects. Note that allocation of object a
1096 // wants to set the starts-object, first-start, and last-start attributes of the preceding card region.
1097 // Allocation of object b wants to set the starts-object, first-start, and last-start attributes of this card region.
1098 // Allocation of object c also wants to set the starts-object, first-start, and last-start attributes of this
1099 // card region.
1100 //
1101 // The thread allocating b and the thread allocating c can "race" in various ways, resulting in confusion, such as
1102 // last-start representing object b while first-start represents object c. This is why we need to require all
1103 // register_object() invocations to be "mutually exclusive" with respect to each card's memory range.
1104 old_generation()->card_scan()->register_object(result);
1105 }
1106 }
1107
1108 return result;
1109 }
1110
1111 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
1112 bool* gc_overhead_limit_was_exceeded) {
1113 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
1114 return allocate_memory(req);
1115 }
1116
1117 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
1118 size_t size,
1119 Metaspace::MetadataType mdtype) {
1120 MetaWord* result;
1121
1122 // Inform metaspace OOM to GC heuristics if class unloading is possible.
1123 ShenandoahHeuristics* h = global_generation()->heuristics();
1124 if (h->can_unload_classes()) {
1125 h->record_metaspace_oom();
1126 }
1127
1128 // Expand and retry allocation
1129 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
1130 if (result != nullptr) {
1131 return result;
1132 }
1133
1134 // Start full GC
1135 collect(GCCause::_metadata_GC_clear_soft_refs);
1136
1137 // Retry allocation
1138 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
1139 if (result != nullptr) {
1140 return result;
1141 }
1142
1143 // Expand and retry allocation
1144 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
1145 if (result != nullptr) {
1146 return result;
1147 }
1148
1149 // Out of memory
1150 return nullptr;
1151 }
1152
1153 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
1154 private:
1155 ShenandoahHeap* const _heap;
1156 Thread* const _thread;
1157 public:
1158 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
1159 _heap(heap), _thread(Thread::current()) {}
1160
1161 void do_object(oop p) {
1162 shenandoah_assert_marked(nullptr, p);
1163 if (!p->is_forwarded()) {
1164 _heap->evacuate_object(p, _thread);
1165 }
1166 }
1167 };
1168
1169 class ShenandoahEvacuationTask : public WorkerTask {
1170 private:
1171 ShenandoahHeap* const _sh;
1172 ShenandoahCollectionSet* const _cs;
1173 bool _concurrent;
1174 public:
1175 ShenandoahEvacuationTask(ShenandoahHeap* sh,
1176 ShenandoahCollectionSet* cs,
1177 bool concurrent) :
1178 WorkerTask("Shenandoah Evacuation"),
1179 _sh(sh),
1180 _cs(cs),
1181 _concurrent(concurrent)
1182 {}
1183
1184 void work(uint worker_id) {
1185 if (_concurrent) {
1186 ShenandoahConcurrentWorkerSession worker_session(worker_id);
1187 ShenandoahSuspendibleThreadSetJoiner stsj;
1188 ShenandoahEvacOOMScope oom_evac_scope;
1189 do_work();
1190 } else {
1191 ShenandoahParallelWorkerSession worker_session(worker_id);
1192 ShenandoahEvacOOMScope oom_evac_scope;
1193 do_work();
1194 }
1195 }
1196
1197 private:
1198 void do_work() {
1199 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
1200 ShenandoahHeapRegion* r;
1201 while ((r =_cs->claim_next()) != nullptr) {
1202 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
1203 _sh->marked_object_iterate(r, &cl);
1204
1205 if (ShenandoahPacing) {
1206 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
1207 }
1208
1209 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
1210 break;
1211 }
1212 }
1213 }
1214 };
1215
1216 void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
1217 ShenandoahEvacuationTask task(this, _collection_set, concurrent);
1218 workers()->run_task(&task);
1219 }
1220
1221 oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) {
1222 assert(thread == Thread::current(), "Expected thread parameter to be current thread.");
1223 if (ShenandoahThreadLocalData::is_oom_during_evac(thread)) {
1224 // This thread went through the OOM during evac protocol. It is safe to return
1225 // the forward pointer. It must not attempt to evacuate any other objects.
1226 return ShenandoahBarrierSet::resolve_forwarded(p);
1227 }
1228
1229 assert(ShenandoahThreadLocalData::is_evac_allowed(thread), "must be enclosed in oom-evac scope");
1230
1231 ShenandoahHeapRegion* r = heap_region_containing(p);
1232 assert(!r->is_humongous(), "never evacuate humongous objects");
1233
1234 ShenandoahAffiliation target_gen = r->affiliation();
1235 return try_evacuate_object(p, thread, r, target_gen);
1236 }
1237
1238 oop ShenandoahHeap::try_evacuate_object(oop p, Thread* thread, ShenandoahHeapRegion* from_region,
1239 ShenandoahAffiliation target_gen) {
1240 assert(target_gen == YOUNG_GENERATION, "Only expect evacuations to young in this mode");
1241 assert(from_region->is_young(), "Only expect evacuations from young in this mode");
1242 bool alloc_from_lab = true;
1243 HeapWord* copy = nullptr;
1244 size_t size = ShenandoahForwarding::size(p);
1245
1246 #ifdef ASSERT
1247 if (ShenandoahOOMDuringEvacALot &&
1248 (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call
1249 copy = nullptr;
1250 } else {
1251 #endif
1252 if (UseTLAB) {
1253 copy = allocate_from_gclab(thread, size);
1254 }
1255 if (copy == nullptr) {
1256 // If we failed to allocate in LAB, we'll try a shared allocation.
1257 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size, target_gen);
1258 copy = allocate_memory(req);
1259 alloc_from_lab = false;
1260 }
1261 #ifdef ASSERT
1262 }
1263 #endif
1264
1265 if (copy == nullptr) {
1266 control_thread()->handle_alloc_failure_evac(size);
1267
1268 _oom_evac_handler.handle_out_of_memory_during_evacuation();
1269
1270 return ShenandoahBarrierSet::resolve_forwarded(p);
1271 }
1272
1273 // Copy the object:
1274 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(p), copy, size);
1275
1276 // Try to install the new forwarding pointer.
1277 oop copy_val = cast_to_oop(copy);
1278 oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val);
1279 if (result == copy_val) {
1280 // Successfully evacuated. Our copy is now the public one!
1281 ContinuationGCSupport::relativize_stack_chunk(copy_val);
1282 shenandoah_assert_correct(nullptr, copy_val);
1283 return copy_val;
1284 } else {
1285 // Failed to evacuate. We need to deal with the object that is left behind. Since this
1286 // new allocation is certainly after TAMS, it will be considered live in the next cycle.
1287 // But if it happens to contain references to evacuated regions, those references would
1288 // not get updated for this stale copy during this cycle, and we will crash while scanning
1289 // it the next cycle.
1290 if (alloc_from_lab) {
1291 // For LAB allocations, it is enough to rollback the allocation ptr. Either the next
1292 // object will overwrite this stale copy, or the filler object on LAB retirement will
1293 // do this.
1294 ShenandoahThreadLocalData::gclab(thread)->undo_allocation(copy, size);
1295 } else {
1296 // For non-LAB allocations, we have no way to retract the allocation, and
1297 // have to explicitly overwrite the copy with the filler object. With that overwrite,
1298 // we have to keep the fwdptr initialized and pointing to our (stale) copy.
1299 assert(size >= ShenandoahHeap::min_fill_size(), "previously allocated object known to be larger than min_size");
1300 fill_with_object(copy, size);
1301 shenandoah_assert_correct(nullptr, copy_val);
1302 // For non-LAB allocations, the object has already been registered
1303 }
1304 shenandoah_assert_correct(nullptr, result);
1305 return result;
1306 }
1307 }
1308
1309 void ShenandoahHeap::trash_cset_regions() {
1310 ShenandoahHeapLocker locker(lock());
1311
1312 ShenandoahCollectionSet* set = collection_set();
1313 ShenandoahHeapRegion* r;
1314 set->clear_current_index();
1315 while ((r = set->next()) != nullptr) {
1316 r->make_trash();
1317 }
1318 collection_set()->clear();
1319 }
1320
1321 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1322 st->print_cr("Heap Regions:");
1323 st->print_cr("Region state: EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HP=pinned humongous start");
1324 st->print_cr(" HC=humongous continuation, CS=collection set, TR=trash, P=pinned, CSP=pinned collection set");
1325 st->print_cr("BTE=bottom/top/end, TAMS=top-at-mark-start");
1326 st->print_cr("UWM=update watermark, U=used");
1327 st->print_cr("T=TLAB allocs, G=GCLAB allocs");
1328 st->print_cr("S=shared allocs, L=live data");
1329 st->print_cr("CP=critical pins");
1330
1331 for (size_t i = 0; i < num_regions(); i++) {
1332 get_region(i)->print_on(st);
1333 }
1334 }
1335
1336 size_t ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1337 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1338
1339 oop humongous_obj = cast_to_oop(start->bottom());
1340 size_t size = humongous_obj->size();
1341 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1342 size_t index = start->index() + required_regions - 1;
1343
1344 assert(!start->has_live(), "liveness must be zero");
1345
1346 for(size_t i = 0; i < required_regions; i++) {
1347 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1348 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1349 ShenandoahHeapRegion* region = get_region(index --);
1350
1351 assert(region->is_humongous(), "expect correct humongous start or continuation");
1352 assert(!region->is_cset(), "Humongous region should not be in collection set");
1353
1354 region->make_trash_immediate();
1355 }
1356 return required_regions;
1357 }
1358
1359 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1360 public:
1361 ShenandoahCheckCleanGCLABClosure() {}
1362 void do_thread(Thread* thread) {
1363 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1364 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1365 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
1366
1367 if (ShenandoahHeap::heap()->mode()->is_generational()) {
1368 PLAB* plab = ShenandoahThreadLocalData::plab(thread);
1369 assert(plab != nullptr, "PLAB should be initialized for %s", thread->name());
1370 assert(plab->words_remaining() == 0, "PLAB should not need retirement");
1371 }
1372 }
1373 };
1374
1375 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1376 private:
1377 bool const _resize;
1378 public:
1379 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1380 void do_thread(Thread* thread) {
1381 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1382 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1383 gclab->retire();
1384 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1385 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1386 }
1387
1388 if (ShenandoahHeap::heap()->mode()->is_generational()) {
1389 PLAB* plab = ShenandoahThreadLocalData::plab(thread);
1390 assert(plab != nullptr, "PLAB should be initialized for %s", thread->name());
1391
1392 // There are two reasons to retire all plabs between old-gen evacuation passes.
1393 // 1. We need to make the plab memory parsable by remembered-set scanning.
1394 // 2. We need to establish a trustworthy UpdateWaterMark value within each old-gen heap region
1395 ShenandoahGenerationalHeap::heap()->retire_plab(plab, thread);
1396 if (_resize && ShenandoahThreadLocalData::plab_size(thread) > 0) {
1397 ShenandoahThreadLocalData::set_plab_size(thread, 0);
1398 }
1399 }
1400 }
1401 };
1402
1403 void ShenandoahHeap::labs_make_parsable() {
1404 assert(UseTLAB, "Only call with UseTLAB");
1405
1406 ShenandoahRetireGCLABClosure cl(false);
1407
1408 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1409 ThreadLocalAllocBuffer& tlab = t->tlab();
1410 tlab.make_parsable();
1411 cl.do_thread(t);
1412 }
1413
1414 workers()->threads_do(&cl);
1415 }
1416
1417 void ShenandoahHeap::tlabs_retire(bool resize) {
1418 assert(UseTLAB, "Only call with UseTLAB");
1419 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1420
1421 ThreadLocalAllocStats stats;
1422
1423 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1424 ThreadLocalAllocBuffer& tlab = t->tlab();
1425 tlab.retire(&stats);
1426 if (resize) {
1427 tlab.resize();
1428 }
1429 }
1430
1431 stats.publish();
1432
1433 #ifdef ASSERT
1434 ShenandoahCheckCleanGCLABClosure cl;
1435 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1436 cl.do_thread(t);
1437 }
1438 workers()->threads_do(&cl);
1439 #endif
1440 }
1441
1442 void ShenandoahHeap::gclabs_retire(bool resize) {
1443 assert(UseTLAB, "Only call with UseTLAB");
1444 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1445
1446 ShenandoahRetireGCLABClosure cl(resize);
1447 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1448 cl.do_thread(t);
1449 }
1450 workers()->threads_do(&cl);
1451
1452 if (safepoint_workers() != nullptr) {
1453 safepoint_workers()->threads_do(&cl);
1454 }
1455 }
1456
1457 // Returns size in bytes
1458 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1459 // Return the max allowed size, and let the allocation path
1460 // figure out the safe size for current allocation.
1461 return ShenandoahHeapRegion::max_tlab_size_bytes();
1462 }
1463
1464 size_t ShenandoahHeap::max_tlab_size() const {
1465 // Returns size in words
1466 return ShenandoahHeapRegion::max_tlab_size_words();
1467 }
1468
1469 void ShenandoahHeap::collect(GCCause::Cause cause) {
1470 control_thread()->request_gc(cause);
1471 }
1472
1473 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1474 //assert(false, "Shouldn't need to do full collections");
1475 }
1476
1477 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1478 ShenandoahHeapRegion* r = heap_region_containing(addr);
1479 if (r != nullptr) {
1480 return r->block_start(addr);
1481 }
1482 return nullptr;
1483 }
1484
1485 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1486 ShenandoahHeapRegion* r = heap_region_containing(addr);
1487 return r->block_is_obj(addr);
1488 }
1489
1490 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1491 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1492 }
1493
1494 void ShenandoahHeap::prepare_for_verify() {
1495 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) {
1496 labs_make_parsable();
1497 }
1498 }
1499
1500 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1501 if (_shenandoah_policy->is_at_shutdown()) {
1502 return;
1503 }
1504
1505 if (_control_thread != nullptr) {
1506 tcl->do_thread(_control_thread);
1507 }
1508
1509 workers()->threads_do(tcl);
1510 if (_safepoint_workers != nullptr) {
1511 _safepoint_workers->threads_do(tcl);
1512 }
1513 }
1514
1515 void ShenandoahHeap::print_tracing_info() const {
1516 LogTarget(Info, gc, stats) lt;
1517 if (lt.is_enabled()) {
1518 ResourceMark rm;
1519 LogStream ls(lt);
1520
1521 phase_timings()->print_global_on(&ls);
1522
1523 ls.cr();
1524 ls.cr();
1525
1526 shenandoah_policy()->print_gc_stats(&ls);
1527
1528 ls.cr();
1529 ls.cr();
1530 }
1531 }
1532
1533 void ShenandoahHeap::set_gc_generation(ShenandoahGeneration* generation) {
1534 shenandoah_assert_control_or_vm_thread_at_safepoint();
1535 _gc_generation = generation;
1536 }
1537
1538 // Active generation may only be set by the VM thread at a safepoint.
1539 void ShenandoahHeap::set_active_generation() {
1540 assert(Thread::current()->is_VM_thread(), "Only the VM Thread");
1541 assert(SafepointSynchronize::is_at_safepoint(), "Only at a safepoint!");
1542 assert(_gc_generation != nullptr, "Will set _active_generation to nullptr");
1543 _active_generation = _gc_generation;
1544 }
1545
1546 void ShenandoahHeap::on_cycle_start(GCCause::Cause cause, ShenandoahGeneration* generation) {
1547 shenandoah_policy()->record_collection_cause(cause);
1548
1549 assert(gc_cause() == GCCause::_no_gc, "Over-writing cause");
1550 assert(_gc_generation == nullptr, "Over-writing _gc_generation");
1551
1552 set_gc_cause(cause);
1553 set_gc_generation(generation);
1554
1555 generation->heuristics()->record_cycle_start();
1556 }
1557
1558 void ShenandoahHeap::on_cycle_end(ShenandoahGeneration* generation) {
1559 assert(gc_cause() != GCCause::_no_gc, "cause wasn't set");
1560 assert(_gc_generation != nullptr, "_gc_generation wasn't set");
1561
1562 generation->heuristics()->record_cycle_end();
1563 if (mode()->is_generational() && generation->is_global()) {
1564 // If we just completed a GLOBAL GC, claim credit for completion of young-gen and old-gen GC as well
1565 young_generation()->heuristics()->record_cycle_end();
1566 old_generation()->heuristics()->record_cycle_end();
1567 }
1568
1569 set_gc_generation(nullptr);
1570 set_gc_cause(GCCause::_no_gc);
1571 }
1572
1573 void ShenandoahHeap::verify(VerifyOption vo) {
1574 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1575 if (ShenandoahVerify) {
1576 verifier()->verify_generic(vo);
1577 } else {
1578 // TODO: Consider allocating verification bitmaps on demand,
1579 // and turn this on unconditionally.
1580 }
1581 }
1582 }
1583 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1584 return _free_set->capacity();
1585 }
1586
1587 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1588 private:
1589 MarkBitMap* _bitmap;
1590 ShenandoahScanObjectStack* _oop_stack;
1591 ShenandoahHeap* const _heap;
1592 ShenandoahMarkingContext* const _marking_context;
1593
1594 template <class T>
1595 void do_oop_work(T* p) {
1596 T o = RawAccess<>::oop_load(p);
1597 if (!CompressedOops::is_null(o)) {
1598 oop obj = CompressedOops::decode_not_null(o);
1599 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1600 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1601 return;
1602 }
1603 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
1604
1605 assert(oopDesc::is_oop(obj), "must be a valid oop");
1606 if (!_bitmap->is_marked(obj)) {
1607 _bitmap->mark(obj);
1608 _oop_stack->push(obj);
1609 }
1610 }
1611 }
1612 public:
1613 ObjectIterateScanRootClosure(MarkBitMap* bitmap, ShenandoahScanObjectStack* oop_stack) :
1614 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1615 _marking_context(_heap->marking_context()) {}
1616 void do_oop(oop* p) { do_oop_work(p); }
1617 void do_oop(narrowOop* p) { do_oop_work(p); }
1618 };
1619
1620 /*
1621 * This is public API, used in preparation of object_iterate().
1622 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1623 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1624 * control, we call SH::tlabs_retire, SH::gclabs_retire.
1625 */
1626 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1627 // No-op.
1628 }
1629
1630 /*
1631 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1632 *
1633 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1634 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1635 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1636 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1637 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1638 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1639 * wiped the bitmap in preparation for next marking).
1640 *
1641 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1642 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1643 * is allowed to report dead objects, but is not required to do so.
1644 */
1645 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1646 // Reset bitmap
1647 if (!prepare_aux_bitmap_for_iteration())
1648 return;
1649
1650 ShenandoahScanObjectStack oop_stack;
1651 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1652 // Seed the stack with root scan
1653 scan_roots_for_iteration(&oop_stack, &oops);
1654
1655 // Work through the oop stack to traverse heap
1656 while (! oop_stack.is_empty()) {
1657 oop obj = oop_stack.pop();
1658 assert(oopDesc::is_oop(obj), "must be a valid oop");
1659 cl->do_object(obj);
1660 obj->oop_iterate(&oops);
1661 }
1662
1663 assert(oop_stack.is_empty(), "should be empty");
1664 // Reclaim bitmap
1665 reclaim_aux_bitmap_for_iteration();
1666 }
1667
1668 bool ShenandoahHeap::prepare_aux_bitmap_for_iteration() {
1669 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1670
1671 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1672 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1673 return false;
1674 }
1675 // Reset bitmap
1676 _aux_bit_map.clear();
1677 return true;
1678 }
1679
1680 void ShenandoahHeap::scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops) {
1681 // Process GC roots according to current GC cycle
1682 // This populates the work stack with initial objects
1683 // It is important to relinquish the associated locks before diving
1684 // into heap dumper
1685 uint n_workers = safepoint_workers() != nullptr ? safepoint_workers()->active_workers() : 1;
1686 ShenandoahHeapIterationRootScanner rp(n_workers);
1687 rp.roots_do(oops);
1688 }
1689
1690 void ShenandoahHeap::reclaim_aux_bitmap_for_iteration() {
1691 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1692 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1693 }
1694 }
1695
1696 // Closure for parallelly iterate objects
1697 class ShenandoahObjectIterateParScanClosure : public BasicOopIterateClosure {
1698 private:
1699 MarkBitMap* _bitmap;
1700 ShenandoahObjToScanQueue* _queue;
1701 ShenandoahHeap* const _heap;
1702 ShenandoahMarkingContext* const _marking_context;
1703
1704 template <class T>
1705 void do_oop_work(T* p) {
1706 T o = RawAccess<>::oop_load(p);
1707 if (!CompressedOops::is_null(o)) {
1708 oop obj = CompressedOops::decode_not_null(o);
1709 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1710 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1711 return;
1712 }
1713 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
1714
1715 assert(oopDesc::is_oop(obj), "Must be a valid oop");
1716 if (_bitmap->par_mark(obj)) {
1717 _queue->push(ShenandoahMarkTask(obj));
1718 }
1719 }
1720 }
1721 public:
1722 ShenandoahObjectIterateParScanClosure(MarkBitMap* bitmap, ShenandoahObjToScanQueue* q) :
1723 _bitmap(bitmap), _queue(q), _heap(ShenandoahHeap::heap()),
1724 _marking_context(_heap->marking_context()) {}
1725 void do_oop(oop* p) { do_oop_work(p); }
1726 void do_oop(narrowOop* p) { do_oop_work(p); }
1727 };
1728
1729 // Object iterator for parallel heap iteraion.
1730 // The root scanning phase happenes in construction as a preparation of
1731 // parallel marking queues.
1732 // Every worker processes it's own marking queue. work-stealing is used
1733 // to balance workload.
1734 class ShenandoahParallelObjectIterator : public ParallelObjectIteratorImpl {
1735 private:
1736 uint _num_workers;
1737 bool _init_ready;
1738 MarkBitMap* _aux_bit_map;
1739 ShenandoahHeap* _heap;
1740 ShenandoahScanObjectStack _roots_stack; // global roots stack
1741 ShenandoahObjToScanQueueSet* _task_queues;
1742 public:
1743 ShenandoahParallelObjectIterator(uint num_workers, MarkBitMap* bitmap) :
1744 _num_workers(num_workers),
1745 _init_ready(false),
1746 _aux_bit_map(bitmap),
1747 _heap(ShenandoahHeap::heap()) {
1748 // Initialize bitmap
1749 _init_ready = _heap->prepare_aux_bitmap_for_iteration();
1750 if (!_init_ready) {
1751 return;
1752 }
1753
1754 ObjectIterateScanRootClosure oops(_aux_bit_map, &_roots_stack);
1755 _heap->scan_roots_for_iteration(&_roots_stack, &oops);
1756
1757 _init_ready = prepare_worker_queues();
1758 }
1759
1760 ~ShenandoahParallelObjectIterator() {
1761 // Reclaim bitmap
1762 _heap->reclaim_aux_bitmap_for_iteration();
1763 // Reclaim queue for workers
1764 if (_task_queues!= nullptr) {
1765 for (uint i = 0; i < _num_workers; ++i) {
1766 ShenandoahObjToScanQueue* q = _task_queues->queue(i);
1767 if (q != nullptr) {
1768 delete q;
1769 _task_queues->register_queue(i, nullptr);
1770 }
1771 }
1772 delete _task_queues;
1773 _task_queues = nullptr;
1774 }
1775 }
1776
1777 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
1778 if (_init_ready) {
1779 object_iterate_parallel(cl, worker_id, _task_queues);
1780 }
1781 }
1782
1783 private:
1784 // Divide global root_stack into worker queues
1785 bool prepare_worker_queues() {
1786 _task_queues = new ShenandoahObjToScanQueueSet((int) _num_workers);
1787 // Initialize queues for every workers
1788 for (uint i = 0; i < _num_workers; ++i) {
1789 ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue();
1790 _task_queues->register_queue(i, task_queue);
1791 }
1792 // Divide roots among the workers. Assume that object referencing distribution
1793 // is related with root kind, use round-robin to make every worker have same chance
1794 // to process every kind of roots
1795 size_t roots_num = _roots_stack.size();
1796 if (roots_num == 0) {
1797 // No work to do
1798 return false;
1799 }
1800
1801 for (uint j = 0; j < roots_num; j++) {
1802 uint stack_id = j % _num_workers;
1803 oop obj = _roots_stack.pop();
1804 _task_queues->queue(stack_id)->push(ShenandoahMarkTask(obj));
1805 }
1806 return true;
1807 }
1808
1809 void object_iterate_parallel(ObjectClosure* cl,
1810 uint worker_id,
1811 ShenandoahObjToScanQueueSet* queue_set) {
1812 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1813 assert(queue_set != nullptr, "task queue must not be null");
1814
1815 ShenandoahObjToScanQueue* q = queue_set->queue(worker_id);
1816 assert(q != nullptr, "object iterate queue must not be null");
1817
1818 ShenandoahMarkTask t;
1819 ShenandoahObjectIterateParScanClosure oops(_aux_bit_map, q);
1820
1821 // Work through the queue to traverse heap.
1822 // Steal when there is no task in queue.
1823 while (q->pop(t) || queue_set->steal(worker_id, t)) {
1824 oop obj = t.obj();
1825 assert(oopDesc::is_oop(obj), "must be a valid oop");
1826 cl->do_object(obj);
1827 obj->oop_iterate(&oops);
1828 }
1829 assert(q->is_empty(), "should be empty");
1830 }
1831 };
1832
1833 ParallelObjectIteratorImpl* ShenandoahHeap::parallel_object_iterator(uint workers) {
1834 return new ShenandoahParallelObjectIterator(workers, &_aux_bit_map);
1835 }
1836
1837 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1838 void ShenandoahHeap::keep_alive(oop obj) {
1839 if (is_concurrent_mark_in_progress() && (obj != nullptr)) {
1840 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1841 }
1842 }
1843
1844 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1845 for (size_t i = 0; i < num_regions(); i++) {
1846 ShenandoahHeapRegion* current = get_region(i);
1847 blk->heap_region_do(current);
1848 }
1849 }
1850
1851 class ShenandoahParallelHeapRegionTask : public WorkerTask {
1852 private:
1853 ShenandoahHeap* const _heap;
1854 ShenandoahHeapRegionClosure* const _blk;
1855 size_t const _stride;
1856
1857 shenandoah_padding(0);
1858 volatile size_t _index;
1859 shenandoah_padding(1);
1860
1861 public:
1862 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk, size_t stride) :
1863 WorkerTask("Shenandoah Parallel Region Operation"),
1864 _heap(ShenandoahHeap::heap()), _blk(blk), _stride(stride), _index(0) {}
1865
1866 void work(uint worker_id) {
1867 ShenandoahParallelWorkerSession worker_session(worker_id);
1868 size_t stride = _stride;
1869
1870 size_t max = _heap->num_regions();
1871 while (Atomic::load(&_index) < max) {
1872 size_t cur = Atomic::fetch_then_add(&_index, stride, memory_order_relaxed);
1873 size_t start = cur;
1874 size_t end = MIN2(cur + stride, max);
1875 if (start >= max) break;
1876
1877 for (size_t i = cur; i < end; i++) {
1878 ShenandoahHeapRegion* current = _heap->get_region(i);
1879 _blk->heap_region_do(current);
1880 }
1881 }
1882 }
1883 };
1884
1885 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1886 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1887 const uint active_workers = workers()->active_workers();
1888 const size_t n_regions = num_regions();
1889 size_t stride = ShenandoahParallelRegionStride;
1890 if (stride == 0 && active_workers > 1) {
1891 // Automatically derive the stride to balance the work between threads
1892 // evenly. Do not try to split work if below the reasonable threshold.
1893 constexpr size_t threshold = 4096;
1894 stride = n_regions <= threshold ?
1895 threshold :
1896 (n_regions + active_workers - 1) / active_workers;
1897 }
1898
1899 if (n_regions > stride && active_workers > 1) {
1900 ShenandoahParallelHeapRegionTask task(blk, stride);
1901 workers()->run_task(&task);
1902 } else {
1903 heap_region_iterate(blk);
1904 }
1905 }
1906
1907 class ShenandoahRendezvousClosure : public HandshakeClosure {
1908 public:
1909 inline ShenandoahRendezvousClosure(const char* name) : HandshakeClosure(name) {}
1910 inline void do_thread(Thread* thread) {}
1911 };
1912
1913 void ShenandoahHeap::rendezvous_threads(const char* name) {
1914 ShenandoahRendezvousClosure cl(name);
1915 Handshake::execute(&cl);
1916 }
1917
1918 void ShenandoahHeap::recycle_trash() {
1919 free_set()->recycle_trash();
1920 }
1921
1922 void ShenandoahHeap::do_class_unloading() {
1923 _unloader.unload();
1924 if (mode()->is_generational()) {
1925 old_generation()->set_parsable(false);
1926 }
1927 }
1928
1929 void ShenandoahHeap::stw_weak_refs(bool full_gc) {
1930 // Weak refs processing
1931 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs
1932 : ShenandoahPhaseTimings::degen_gc_weakrefs;
1933 ShenandoahTimingsTracker t(phase);
1934 ShenandoahGCWorkerPhase worker_phase(phase);
1935 shenandoah_assert_generations_reconciled();
1936 gc_generation()->ref_processor()->process_references(phase, workers(), false /* concurrent */);
1937 }
1938
1939 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
1940 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
1941
1942 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to
1943 // make them parsable for update code to work correctly. Plus, we can compute new sizes
1944 // for future GCLABs here.
1945 if (UseTLAB) {
1946 ShenandoahGCPhase phase(concurrent ?
1947 ShenandoahPhaseTimings::init_update_refs_manage_gclabs :
1948 ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs);
1949 gclabs_retire(ResizeTLAB);
1950 }
1951
1952 _update_refs_iterator.reset();
1953 }
1954
1955 void ShenandoahHeap::propagate_gc_state_to_java_threads() {
1956 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint");
1957 if (_gc_state_changed) {
1958 _gc_state_changed = false;
1959 char state = gc_state();
1960 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1961 ShenandoahThreadLocalData::set_gc_state(t, state);
1962 }
1963 }
1964 }
1965
1966 void ShenandoahHeap::set_gc_state(uint mask, bool value) {
1967 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint");
1968 _gc_state.set_cond(mask, value);
1969 _gc_state_changed = true;
1970 // Check that if concurrent weak root is set then active_gen isn't null
1971 assert(!is_concurrent_weak_root_in_progress() || active_generation() != nullptr, "Error");
1972 shenandoah_assert_generations_reconciled();
1973 }
1974
1975 void ShenandoahHeap::set_concurrent_young_mark_in_progress(bool in_progress) {
1976 uint mask;
1977 assert(!has_forwarded_objects(), "Young marking is not concurrent with evacuation");
1978 if (!in_progress && is_concurrent_old_mark_in_progress()) {
1979 assert(mode()->is_generational(), "Only generational GC has old marking");
1980 assert(_gc_state.is_set(MARKING), "concurrent_old_marking_in_progress implies MARKING");
1981 // If old-marking is in progress when we turn off YOUNG_MARKING, leave MARKING (and OLD_MARKING) on
1982 mask = YOUNG_MARKING;
1983 } else {
1984 mask = MARKING | YOUNG_MARKING;
1985 }
1986 set_gc_state(mask, in_progress);
1987 manage_satb_barrier(in_progress);
1988 }
1989
1990 void ShenandoahHeap::set_concurrent_old_mark_in_progress(bool in_progress) {
1991 #ifdef ASSERT
1992 // has_forwarded_objects() iff UPDATEREFS or EVACUATION
1993 bool has_forwarded = has_forwarded_objects();
1994 bool updating_or_evacuating = _gc_state.is_set(UPDATEREFS | EVACUATION);
1995 bool evacuating = _gc_state.is_set(EVACUATION);
1996 assert ((has_forwarded == updating_or_evacuating) || (evacuating && !has_forwarded && collection_set()->is_empty()),
1997 "Updating or evacuating iff has forwarded objects, or if evacuation phase is promoting in place without forwarding");
1998 #endif
1999 if (!in_progress && is_concurrent_young_mark_in_progress()) {
2000 // If young-marking is in progress when we turn off OLD_MARKING, leave MARKING (and YOUNG_MARKING) on
2001 assert(_gc_state.is_set(MARKING), "concurrent_young_marking_in_progress implies MARKING");
2002 set_gc_state(OLD_MARKING, in_progress);
2003 } else {
2004 set_gc_state(MARKING | OLD_MARKING, in_progress);
2005 }
2006 manage_satb_barrier(in_progress);
2007 }
2008
2009 bool ShenandoahHeap::is_prepare_for_old_mark_in_progress() const {
2010 return old_generation()->is_preparing_for_mark();
2011 }
2012
2013 void ShenandoahHeap::manage_satb_barrier(bool active) {
2014 if (is_concurrent_mark_in_progress()) {
2015 // Ignore request to deactivate barrier while concurrent mark is in progress.
2016 // Do not attempt to re-activate the barrier if it is already active.
2017 if (active && !ShenandoahBarrierSet::satb_mark_queue_set().is_active()) {
2018 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(active, !active);
2019 }
2020 } else {
2021 // No concurrent marking is in progress so honor request to deactivate,
2022 // but only if the barrier is already active.
2023 if (!active && ShenandoahBarrierSet::satb_mark_queue_set().is_active()) {
2024 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(active, !active);
2025 }
2026 }
2027 }
2028
2029 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
2030 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
2031 set_gc_state(EVACUATION, in_progress);
2032 }
2033
2034 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
2035 if (in_progress) {
2036 _concurrent_strong_root_in_progress.set();
2037 } else {
2038 _concurrent_strong_root_in_progress.unset();
2039 }
2040 }
2041
2042 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) {
2043 set_gc_state(WEAK_ROOTS, cond);
2044 }
2045
2046 GCTracer* ShenandoahHeap::tracer() {
2047 return shenandoah_policy()->tracer();
2048 }
2049
2050 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
2051 return _free_set->used();
2052 }
2053
2054 bool ShenandoahHeap::try_cancel_gc() {
2055 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
2056 return prev == CANCELLABLE;
2057 }
2058
2059 void ShenandoahHeap::cancel_concurrent_mark() {
2060 if (mode()->is_generational()) {
2061 young_generation()->cancel_marking();
2062 old_generation()->cancel_marking();
2063 }
2064
2065 global_generation()->cancel_marking();
2066
2067 ShenandoahBarrierSet::satb_mark_queue_set().abandon_partial_marking();
2068 }
2069
2070 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
2071 if (try_cancel_gc()) {
2072 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
2073 log_info(gc)("%s", msg.buffer());
2074 Events::log(Thread::current(), "%s", msg.buffer());
2075 _cancel_requested_time = os::elapsedTime();
2076 }
2077 }
2078
2079 uint ShenandoahHeap::max_workers() {
2080 return _max_workers;
2081 }
2082
2083 void ShenandoahHeap::stop() {
2084 // The shutdown sequence should be able to terminate when GC is running.
2085
2086 // Step 0. Notify policy to disable event recording and prevent visiting gc threads during shutdown
2087 _shenandoah_policy->record_shutdown();
2088
2089 // Step 1. Notify control thread that we are in shutdown.
2090 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
2091 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
2092 control_thread()->prepare_for_graceful_shutdown();
2093
2094 // Step 2. Notify GC workers that we are cancelling GC.
2095 cancel_gc(GCCause::_shenandoah_stop_vm);
2096
2097 // Step 3. Wait until GC worker exits normally.
2098 control_thread()->stop();
2099 }
2100
2101 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
2102 if (!unload_classes()) return;
2103 ClassUnloadingContext ctx(_workers->active_workers(),
2104 true /* unregister_nmethods_during_purge */,
2105 false /* lock_nmethod_free_separately */);
2106
2107 // Unload classes and purge SystemDictionary.
2108 {
2109 ShenandoahPhaseTimings::Phase phase = full_gc ?
2110 ShenandoahPhaseTimings::full_gc_purge_class_unload :
2111 ShenandoahPhaseTimings::degen_gc_purge_class_unload;
2112 ShenandoahIsAliveSelector is_alive;
2113 {
2114 CodeCache::UnlinkingScope scope(is_alive.is_alive_closure());
2115 ShenandoahGCPhase gc_phase(phase);
2116 ShenandoahGCWorkerPhase worker_phase(phase);
2117 bool unloading_occurred = SystemDictionary::do_unloading(gc_timer());
2118
2119 uint num_workers = _workers->active_workers();
2120 ShenandoahClassUnloadingTask unlink_task(phase, num_workers, unloading_occurred);
2121 _workers->run_task(&unlink_task);
2122 }
2123 // Release unloaded nmethods's memory.
2124 ClassUnloadingContext::context()->purge_and_free_nmethods();
2125 }
2126
2127 {
2128 ShenandoahGCPhase phase(full_gc ?
2129 ShenandoahPhaseTimings::full_gc_purge_cldg :
2130 ShenandoahPhaseTimings::degen_gc_purge_cldg);
2131 ClassLoaderDataGraph::purge(true /* at_safepoint */);
2132 }
2133 // Resize and verify metaspace
2134 MetaspaceGC::compute_new_size();
2135 DEBUG_ONLY(MetaspaceUtils::verify();)
2136 }
2137
2138 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
2139 // so they should not have forwarded oops.
2140 // However, we do need to "null" dead oops in the roots, if can not be done
2141 // in concurrent cycles.
2142 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
2143 uint num_workers = _workers->active_workers();
2144 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
2145 ShenandoahPhaseTimings::full_gc_purge_weak_par :
2146 ShenandoahPhaseTimings::degen_gc_purge_weak_par;
2147 ShenandoahGCPhase phase(timing_phase);
2148 ShenandoahGCWorkerPhase worker_phase(timing_phase);
2149 // Cleanup weak roots
2150 if (has_forwarded_objects()) {
2151 ShenandoahForwardedIsAliveClosure is_alive;
2152 ShenandoahNonConcUpdateRefsClosure keep_alive;
2153 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahNonConcUpdateRefsClosure>
2154 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers);
2155 _workers->run_task(&cleaning_task);
2156 } else {
2157 ShenandoahIsAliveClosure is_alive;
2158 #ifdef ASSERT
2159 ShenandoahAssertNotForwardedClosure verify_cl;
2160 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
2161 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers);
2162 #else
2163 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
2164 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers);
2165 #endif
2166 _workers->run_task(&cleaning_task);
2167 }
2168 }
2169
2170 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
2171 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2172 assert(is_stw_gc_in_progress(), "Only for Degenerated and Full GC");
2173 ShenandoahGCPhase phase(full_gc ?
2174 ShenandoahPhaseTimings::full_gc_purge :
2175 ShenandoahPhaseTimings::degen_gc_purge);
2176 stw_weak_refs(full_gc);
2177 stw_process_weak_roots(full_gc);
2178 stw_unload_classes(full_gc);
2179 }
2180
2181 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2182 set_gc_state(HAS_FORWARDED, cond);
2183 }
2184
2185 void ShenandoahHeap::set_unload_classes(bool uc) {
2186 _unload_classes.set_cond(uc);
2187 }
2188
2189 bool ShenandoahHeap::unload_classes() const {
2190 return _unload_classes.is_set();
2191 }
2192
2193 address ShenandoahHeap::in_cset_fast_test_addr() {
2194 ShenandoahHeap* heap = ShenandoahHeap::heap();
2195 assert(heap->collection_set() != nullptr, "Sanity");
2196 return (address) heap->collection_set()->biased_map_address();
2197 }
2198
2199 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2200 if (mode()->is_generational()) {
2201 young_generation()->reset_bytes_allocated_since_gc_start();
2202 old_generation()->reset_bytes_allocated_since_gc_start();
2203 }
2204
2205 global_generation()->reset_bytes_allocated_since_gc_start();
2206 }
2207
2208 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2209 _degenerated_gc_in_progress.set_cond(in_progress);
2210 }
2211
2212 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2213 _full_gc_in_progress.set_cond(in_progress);
2214 }
2215
2216 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2217 assert (is_full_gc_in_progress(), "should be");
2218 _full_gc_move_in_progress.set_cond(in_progress);
2219 }
2220
2221 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2222 set_gc_state(UPDATEREFS, in_progress);
2223 }
2224
2225 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2226 ShenandoahCodeRoots::register_nmethod(nm);
2227 }
2228
2229 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2230 ShenandoahCodeRoots::unregister_nmethod(nm);
2231 }
2232
2233 void ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2234 heap_region_containing(o)->record_pin();
2235 }
2236
2237 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2238 ShenandoahHeapRegion* r = heap_region_containing(o);
2239 assert(r != nullptr, "Sanity");
2240 assert(r->pin_count() > 0, "Region " SIZE_FORMAT " should have non-zero pins", r->index());
2241 r->record_unpin();
2242 }
2243
2244 void ShenandoahHeap::sync_pinned_region_status() {
2245 ShenandoahHeapLocker locker(lock());
2246
2247 for (size_t i = 0; i < num_regions(); i++) {
2248 ShenandoahHeapRegion *r = get_region(i);
2249 if (r->is_active()) {
2250 if (r->is_pinned()) {
2251 if (r->pin_count() == 0) {
2252 r->make_unpinned();
2253 }
2254 } else {
2255 if (r->pin_count() > 0) {
2256 r->make_pinned();
2257 }
2258 }
2259 }
2260 }
2261
2262 assert_pinned_region_status();
2263 }
2264
2265 #ifdef ASSERT
2266 void ShenandoahHeap::assert_pinned_region_status() {
2267 for (size_t i = 0; i < num_regions(); i++) {
2268 ShenandoahHeapRegion* r = get_region(i);
2269 shenandoah_assert_generations_reconciled();
2270 if (gc_generation()->contains(r)) {
2271 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2272 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2273 }
2274 }
2275 }
2276 #endif
2277
2278 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
2279 return _gc_timer;
2280 }
2281
2282 void ShenandoahHeap::prepare_concurrent_roots() {
2283 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2284 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
2285 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
2286 set_concurrent_weak_root_in_progress(true);
2287 if (unload_classes()) {
2288 _unloader.prepare();
2289 }
2290 }
2291
2292 void ShenandoahHeap::finish_concurrent_roots() {
2293 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2294 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
2295 if (unload_classes()) {
2296 _unloader.finish();
2297 }
2298 }
2299
2300 #ifdef ASSERT
2301 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2302 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2303
2304 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2305 // Use ParallelGCThreads inside safepoints
2306 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads (%u) within safepoint, not %u",
2307 ParallelGCThreads, nworkers);
2308 } else {
2309 // Use ConcGCThreads outside safepoints
2310 assert(nworkers == ConcGCThreads, "Use ConcGCThreads (%u) outside safepoints, %u",
2311 ConcGCThreads, nworkers);
2312 }
2313 }
2314 #endif
2315
2316 ShenandoahVerifier* ShenandoahHeap::verifier() {
2317 guarantee(ShenandoahVerify, "Should be enabled");
2318 assert (_verifier != nullptr, "sanity");
2319 return _verifier;
2320 }
2321
2322 template<bool CONCURRENT>
2323 class ShenandoahUpdateHeapRefsTask : public WorkerTask {
2324 private:
2325 ShenandoahHeap* _heap;
2326 ShenandoahRegionIterator* _regions;
2327 public:
2328 explicit ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) :
2329 WorkerTask("Shenandoah Update References"),
2330 _heap(ShenandoahHeap::heap()),
2331 _regions(regions) {
2332 }
2333
2334 void work(uint worker_id) {
2335 if (CONCURRENT) {
2336 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2337 ShenandoahSuspendibleThreadSetJoiner stsj;
2338 do_work<ShenandoahConcUpdateRefsClosure>(worker_id);
2339 } else {
2340 ShenandoahParallelWorkerSession worker_session(worker_id);
2341 do_work<ShenandoahNonConcUpdateRefsClosure>(worker_id);
2342 }
2343 }
2344
2345 private:
2346 template<class T>
2347 void do_work(uint worker_id) {
2348 if (CONCURRENT && (worker_id == 0)) {
2349 // We ask the first worker to replenish the Mutator free set by moving regions previously reserved to hold the
2350 // results of evacuation. These reserves are no longer necessary because evacuation has completed.
2351 size_t cset_regions = _heap->collection_set()->count();
2352
2353 // Now that evacuation is done, we can reassign any regions that had been reserved to hold the results of evacuation
2354 // to the mutator free set. At the end of GC, we will have cset_regions newly evacuated fully empty regions from
2355 // which we will be able to replenish the Collector free set and the OldCollector free set in preparation for the
2356 // next GC cycle.
2357 _heap->free_set()->move_regions_from_collector_to_mutator(cset_regions);
2358 }
2359 // If !CONCURRENT, there's no value in expanding Mutator free set
2360 T cl;
2361 ShenandoahHeapRegion* r = _regions->next();
2362 while (r != nullptr) {
2363 HeapWord* update_watermark = r->get_update_watermark();
2364 assert (update_watermark >= r->bottom(), "sanity");
2365 if (r->is_active() && !r->is_cset()) {
2366 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2367 if (ShenandoahPacing) {
2368 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2369 }
2370 }
2371 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
2372 return;
2373 }
2374 r = _regions->next();
2375 }
2376 }
2377 };
2378
2379 void ShenandoahHeap::update_heap_references(bool concurrent) {
2380 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2381
2382 if (concurrent) {
2383 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator);
2384 workers()->run_task(&task);
2385 } else {
2386 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator);
2387 workers()->run_task(&task);
2388 }
2389 }
2390
2391 ShenandoahSynchronizePinnedRegionStates::ShenandoahSynchronizePinnedRegionStates() : _lock(ShenandoahHeap::heap()->lock()) { }
2392
2393 void ShenandoahSynchronizePinnedRegionStates::heap_region_do(ShenandoahHeapRegion* r) {
2394 // Drop "pinned" state from regions that no longer have a pinned count. Put
2395 // regions with a pinned count into the "pinned" state.
2396 if (r->is_active()) {
2397 if (r->is_pinned()) {
2398 if (r->pin_count() == 0) {
2399 ShenandoahHeapLocker locker(_lock);
2400 r->make_unpinned();
2401 }
2402 } else {
2403 if (r->pin_count() > 0) {
2404 ShenandoahHeapLocker locker(_lock);
2405 r->make_pinned();
2406 }
2407 }
2408 }
2409 }
2410
2411 void ShenandoahHeap::update_heap_region_states(bool concurrent) {
2412 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2413 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2414
2415 {
2416 ShenandoahGCPhase phase(concurrent ?
2417 ShenandoahPhaseTimings::final_update_refs_update_region_states :
2418 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states);
2419
2420 final_update_refs_update_region_states();
2421
2422 assert_pinned_region_status();
2423 }
2424
2425 {
2426 ShenandoahGCPhase phase(concurrent ?
2427 ShenandoahPhaseTimings::final_update_refs_trash_cset :
2428 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset);
2429 trash_cset_regions();
2430 }
2431 }
2432
2433 void ShenandoahHeap::final_update_refs_update_region_states() {
2434 ShenandoahSynchronizePinnedRegionStates cl;
2435 parallel_heap_region_iterate(&cl);
2436 }
2437
2438 void ShenandoahHeap::rebuild_free_set(bool concurrent) {
2439 ShenandoahGCPhase phase(concurrent ?
2440 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
2441 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
2442 ShenandoahHeapLocker locker(lock());
2443 size_t young_cset_regions, old_cset_regions;
2444 size_t first_old_region, last_old_region, old_region_count;
2445 _free_set->prepare_to_rebuild(young_cset_regions, old_cset_regions, first_old_region, last_old_region, old_region_count);
2446 // If there are no old regions, first_old_region will be greater than last_old_region
2447 assert((first_old_region > last_old_region) ||
2448 ((last_old_region + 1 - first_old_region >= old_region_count) &&
2449 get_region(first_old_region)->is_old() && get_region(last_old_region)->is_old()),
2450 "sanity: old_region_count: " SIZE_FORMAT ", first_old_region: " SIZE_FORMAT ", last_old_region: " SIZE_FORMAT,
2451 old_region_count, first_old_region, last_old_region);
2452
2453 if (mode()->is_generational()) {
2454 #ifdef ASSERT
2455 if (ShenandoahVerify) {
2456 verifier()->verify_before_rebuilding_free_set();
2457 }
2458 #endif
2459
2460 // The computation of bytes_of_allocation_runway_before_gc_trigger is quite conservative so consider all of this
2461 // available for transfer to old. Note that transfer of humongous regions does not impact available.
2462 ShenandoahGenerationalHeap* gen_heap = ShenandoahGenerationalHeap::heap();
2463 size_t allocation_runway = gen_heap->young_generation()->heuristics()->bytes_of_allocation_runway_before_gc_trigger(young_cset_regions);
2464 gen_heap->compute_old_generation_balance(allocation_runway, old_cset_regions);
2465
2466 // Total old_available may have been expanded to hold anticipated promotions. We trigger if the fragmented available
2467 // memory represents more than 16 regions worth of data. Note that fragmentation may increase when we promote regular
2468 // regions in place when many of these regular regions have an abundant amount of available memory within them. Fragmentation
2469 // will decrease as promote-by-copy consumes the available memory within these partially consumed regions.
2470 //
2471 // We consider old-gen to have excessive fragmentation if more than 12.5% of old-gen is free memory that resides
2472 // within partially consumed regions of memory.
2473 }
2474 // Rebuild free set based on adjusted generation sizes.
2475 _free_set->finish_rebuild(young_cset_regions, old_cset_regions, old_region_count);
2476
2477 if (mode()->is_generational()) {
2478 ShenandoahGenerationalHeap* gen_heap = ShenandoahGenerationalHeap::heap();
2479 ShenandoahOldGeneration* old_gen = gen_heap->old_generation();
2480 old_gen->heuristics()->evaluate_triggers(first_old_region, last_old_region, old_region_count, num_regions());
2481 }
2482 }
2483
2484 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2485 print_on(st);
2486 st->cr();
2487 print_heap_regions_on(st);
2488 }
2489
2490 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2491 size_t slice = r->index() / _bitmap_regions_per_slice;
2492
2493 size_t regions_from = _bitmap_regions_per_slice * slice;
2494 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2495 for (size_t g = regions_from; g < regions_to; g++) {
2496 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2497 if (skip_self && g == r->index()) continue;
2498 if (get_region(g)->is_committed()) {
2499 return true;
2500 }
2501 }
2502 return false;
2503 }
2504
2505 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2506 shenandoah_assert_heaplocked();
2507
2508 // Bitmaps in special regions do not need commits
2509 if (_bitmap_region_special) {
2510 return true;
2511 }
2512
2513 if (is_bitmap_slice_committed(r, true)) {
2514 // Some other region from the group is already committed, meaning the bitmap
2515 // slice is already committed, we exit right away.
2516 return true;
2517 }
2518
2519 // Commit the bitmap slice:
2520 size_t slice = r->index() / _bitmap_regions_per_slice;
2521 size_t off = _bitmap_bytes_per_slice * slice;
2522 size_t len = _bitmap_bytes_per_slice;
2523 char* start = (char*) _bitmap_region.start() + off;
2524
2525 if (!os::commit_memory(start, len, false)) {
2526 return false;
2527 }
2528
2529 if (AlwaysPreTouch) {
2530 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size);
2531 }
2532
2533 return true;
2534 }
2535
2536 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2537 shenandoah_assert_heaplocked();
2538
2539 // Bitmaps in special regions do not need uncommits
2540 if (_bitmap_region_special) {
2541 return true;
2542 }
2543
2544 if (is_bitmap_slice_committed(r, true)) {
2545 // Some other region from the group is still committed, meaning the bitmap
2546 // slice is should stay committed, exit right away.
2547 return true;
2548 }
2549
2550 // Uncommit the bitmap slice:
2551 size_t slice = r->index() / _bitmap_regions_per_slice;
2552 size_t off = _bitmap_bytes_per_slice * slice;
2553 size_t len = _bitmap_bytes_per_slice;
2554 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2555 return false;
2556 }
2557 return true;
2558 }
2559
2560 void ShenandoahHeap::safepoint_synchronize_begin() {
2561 StackWatermarkSet::safepoint_synchronize_begin();
2562 SuspendibleThreadSet::synchronize();
2563 }
2564
2565 void ShenandoahHeap::safepoint_synchronize_end() {
2566 SuspendibleThreadSet::desynchronize();
2567 }
2568
2569 void ShenandoahHeap::try_inject_alloc_failure() {
2570 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2571 _inject_alloc_failure.set();
2572 os::naked_short_sleep(1);
2573 if (cancelled_gc()) {
2574 log_info(gc)("Allocation failure was successfully injected");
2575 }
2576 }
2577 }
2578
2579 bool ShenandoahHeap::should_inject_alloc_failure() {
2580 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2581 }
2582
2583 void ShenandoahHeap::initialize_serviceability() {
2584 _memory_pool = new ShenandoahMemoryPool(this);
2585 _cycle_memory_manager.add_pool(_memory_pool);
2586 _stw_memory_manager.add_pool(_memory_pool);
2587 }
2588
2589 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2590 GrowableArray<GCMemoryManager*> memory_managers(2);
2591 memory_managers.append(&_cycle_memory_manager);
2592 memory_managers.append(&_stw_memory_manager);
2593 return memory_managers;
2594 }
2595
2596 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2597 GrowableArray<MemoryPool*> memory_pools(1);
2598 memory_pools.append(_memory_pool);
2599 return memory_pools;
2600 }
2601
2602 MemoryUsage ShenandoahHeap::memory_usage() {
2603 return MemoryUsage(_initial_size, used(), committed(), max_capacity());
2604 }
2605
2606 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2607 _heap(ShenandoahHeap::heap()),
2608 _index(0) {}
2609
2610 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2611 _heap(heap),
2612 _index(0) {}
2613
2614 void ShenandoahRegionIterator::reset() {
2615 _index = 0;
2616 }
2617
2618 bool ShenandoahRegionIterator::has_next() const {
2619 return _index < _heap->num_regions();
2620 }
2621
2622 char ShenandoahHeap::gc_state() const {
2623 return _gc_state.raw_value();
2624 }
2625
2626 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2627 #ifdef ASSERT
2628 assert(_liveness_cache != nullptr, "sanity");
2629 assert(worker_id < _max_workers, "sanity");
2630 for (uint i = 0; i < num_regions(); i++) {
2631 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2632 }
2633 #endif
2634 return _liveness_cache[worker_id];
2635 }
2636
2637 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2638 assert(worker_id < _max_workers, "sanity");
2639 assert(_liveness_cache != nullptr, "sanity");
2640 ShenandoahLiveData* ld = _liveness_cache[worker_id];
2641 for (uint i = 0; i < num_regions(); i++) {
2642 ShenandoahLiveData live = ld[i];
2643 if (live > 0) {
2644 ShenandoahHeapRegion* r = get_region(i);
2645 r->increase_live_data_gc_words(live);
2646 ld[i] = 0;
2647 }
2648 }
2649 }
2650
2651 bool ShenandoahHeap::requires_barriers(stackChunkOop obj) const {
2652 if (is_idle()) return false;
2653
2654 // Objects allocated after marking start are implicitly alive, don't need any barriers during
2655 // marking phase.
2656 if (is_concurrent_mark_in_progress() &&
2657 !marking_context()->allocated_after_mark_start(obj)) {
2658 return true;
2659 }
2660
2661 // Can not guarantee obj is deeply good.
2662 if (has_forwarded_objects()) {
2663 return true;
2664 }
2665
2666 return false;
2667 }
2668
2669 HeapWord* ShenandoahHeap::allocate_loaded_archive_space(size_t size) {
2670 #if INCLUDE_CDS_JAVA_HEAP
2671 // CDS wants a continuous memory range to load a bunch of objects.
2672 // This effectively bypasses normal allocation paths, and requires
2673 // a bit of massaging to unbreak GC invariants.
2674
2675 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
2676
2677 // Easy case: a single regular region, no further adjustments needed.
2678 if (!ShenandoahHeapRegion::requires_humongous(size)) {
2679 return allocate_memory(req);
2680 }
2681
2682 // Hard case: the requested size would cause a humongous allocation.
2683 // We need to make sure it looks like regular allocation to the rest of GC.
2684
2685 // CDS code would guarantee no objects straddle multiple regions, as long as
2686 // regions are as large as MIN_GC_REGION_ALIGNMENT. It is impractical at this
2687 // point to deal with case when Shenandoah runs with smaller regions.
2688 // TODO: This check can be dropped once MIN_GC_REGION_ALIGNMENT agrees more with Shenandoah.
2689 if (ShenandoahHeapRegion::region_size_bytes() < ArchiveHeapWriter::MIN_GC_REGION_ALIGNMENT) {
2690 return nullptr;
2691 }
2692
2693 HeapWord* mem = allocate_memory(req);
2694 size_t start_idx = heap_region_index_containing(mem);
2695 size_t num_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
2696
2697 // Flip humongous -> regular.
2698 {
2699 ShenandoahHeapLocker locker(lock(), false);
2700 for (size_t c = start_idx; c < start_idx + num_regions; c++) {
2701 get_region(c)->make_regular_bypass();
2702 }
2703 }
2704
2705 return mem;
2706 #else
2707 assert(false, "Archive heap loader should not be available, should not be here");
2708 return nullptr;
2709 #endif // INCLUDE_CDS_JAVA_HEAP
2710 }
2711
2712 void ShenandoahHeap::complete_loaded_archive_space(MemRegion archive_space) {
2713 // Nothing to do here, except checking that heap looks fine.
2714 #ifdef ASSERT
2715 HeapWord* start = archive_space.start();
2716 HeapWord* end = archive_space.end();
2717
2718 // No unclaimed space between the objects.
2719 // Objects are properly allocated in correct regions.
2720 HeapWord* cur = start;
2721 while (cur < end) {
2722 oop oop = cast_to_oop(cur);
2723 shenandoah_assert_in_correct_region(nullptr, oop);
2724 cur += oop->size();
2725 }
2726
2727 // No unclaimed tail at the end of archive space.
2728 assert(cur == end,
2729 "Archive space should be fully used: " PTR_FORMAT " " PTR_FORMAT,
2730 p2i(cur), p2i(end));
2731
2732 // Region bounds are good.
2733 ShenandoahHeapRegion* begin_reg = heap_region_containing(start);
2734 ShenandoahHeapRegion* end_reg = heap_region_containing(end);
2735 assert(begin_reg->is_regular(), "Must be");
2736 assert(end_reg->is_regular(), "Must be");
2737 assert(begin_reg->bottom() == start,
2738 "Must agree: archive-space-start: " PTR_FORMAT ", begin-region-bottom: " PTR_FORMAT,
2739 p2i(start), p2i(begin_reg->bottom()));
2740 assert(end_reg->top() == end,
2741 "Must agree: archive-space-end: " PTR_FORMAT ", end-region-top: " PTR_FORMAT,
2742 p2i(end), p2i(end_reg->top()));
2743 #endif
2744 }
2745
2746 ShenandoahGeneration* ShenandoahHeap::generation_for(ShenandoahAffiliation affiliation) const {
2747 if (!mode()->is_generational()) {
2748 return global_generation();
2749 } else if (affiliation == YOUNG_GENERATION) {
2750 return young_generation();
2751 } else if (affiliation == OLD_GENERATION) {
2752 return old_generation();
2753 }
2754
2755 ShouldNotReachHere();
2756 return nullptr;
2757 }
2758
2759 void ShenandoahHeap::log_heap_status(const char* msg) const {
2760 if (mode()->is_generational()) {
2761 young_generation()->log_status(msg);
2762 old_generation()->log_status(msg);
2763 } else {
2764 global_generation()->log_status(msg);
2765 }
2766 }
2767