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