1 /*
2 * Copyright (c) 2013, 2020, Red Hat, Inc. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "memory/allocation.hpp"
27 #include "memory/universe.hpp"
28
29 #include "gc/shared/gcArguments.hpp"
30 #include "gc/shared/gcTimer.hpp"
31 #include "gc/shared/gcTraceTime.inline.hpp"
32 #include "gc/shared/locationPrinter.inline.hpp"
33 #include "gc/shared/memAllocator.hpp"
34 #include "gc/shared/oopStorageSet.hpp"
35 #include "gc/shared/plab.hpp"
36
37 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
38 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
39 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
40 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
41 #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp"
42 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
43 #include "gc/shenandoah/shenandoahControlThread.hpp"
44 #include "gc/shenandoah/shenandoahFreeSet.hpp"
45 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
46 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
47 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
48 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
49 #include "gc/shenandoah/shenandoahInitLogger.hpp"
50 #include "gc/shenandoah/shenandoahMarkCompact.hpp"
51 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
52 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
53 #include "gc/shenandoah/shenandoahMetrics.hpp"
54 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
55 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
56 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
57 #include "gc/shenandoah/shenandoahPadding.hpp"
58 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
59 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
60 #include "gc/shenandoah/shenandoahStringDedup.hpp"
61 #include "gc/shenandoah/shenandoahTaskqueue.hpp"
62 #include "gc/shenandoah/shenandoahUtils.hpp"
63 #include "gc/shenandoah/shenandoahVerifier.hpp"
64 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
65 #include "gc/shenandoah/shenandoahVMOperations.hpp"
66 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
67 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
68 #include "gc/shenandoah/mode/shenandoahIUMode.hpp"
69 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
70 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp"
71 #if INCLUDE_JFR
72 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
73 #endif
74
75 #include "memory/metaspace.hpp"
76 #include "oops/compressedOops.inline.hpp"
77 #include "runtime/atomic.hpp"
78 #include "runtime/globals.hpp"
79 #include "runtime/interfaceSupport.inline.hpp"
80 #include "runtime/orderAccess.hpp"
81 #include "runtime/safepointMechanism.hpp"
82 #include "runtime/vmThread.hpp"
83 #include "services/mallocTracker.hpp"
84 #include "utilities/powerOfTwo.hpp"
85
86 #ifdef ASSERT
87 template <class T>
88 void ShenandoahAssertToSpaceClosure::do_oop_work(T* p) {
89 T o = RawAccess<>::oop_load(p);
90 if (! CompressedOops::is_null(o)) {
91 oop obj = CompressedOops::decode_not_null(o);
92 shenandoah_assert_not_forwarded(p, obj);
93 }
94 }
95
96 void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_work(p); }
97 void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_work(p); }
98 #endif
99
100 class ShenandoahPretouchHeapTask : public AbstractGangTask {
101 private:
102 ShenandoahRegionIterator _regions;
103 const size_t _page_size;
104 public:
105 ShenandoahPretouchHeapTask(size_t page_size) :
106 AbstractGangTask("Shenandoah Pretouch Heap"),
107 _page_size(page_size) {}
108
109 virtual void work(uint worker_id) {
110 ShenandoahHeapRegion* r = _regions.next();
111 while (r != NULL) {
112 if (r->is_committed()) {
113 os::pretouch_memory(r->bottom(), r->end(), _page_size);
114 }
115 r = _regions.next();
116 }
117 }
118 };
119
120 class ShenandoahPretouchBitmapTask : public AbstractGangTask {
121 private:
122 ShenandoahRegionIterator _regions;
123 char* _bitmap_base;
124 const size_t _bitmap_size;
125 const size_t _page_size;
126 public:
127 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
128 AbstractGangTask("Shenandoah Pretouch Bitmap"),
129 _bitmap_base(bitmap_base),
130 _bitmap_size(bitmap_size),
131 _page_size(page_size) {}
132
133 virtual void work(uint worker_id) {
134 ShenandoahHeapRegion* r = _regions.next();
135 while (r != NULL) {
136 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
137 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
138 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
139
140 if (r->is_committed()) {
141 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
142 }
143
144 r = _regions.next();
145 }
146 }
147 };
148
149 jint ShenandoahHeap::initialize() {
150 //
151 // Figure out heap sizing
152 //
153
154 size_t init_byte_size = InitialHeapSize;
155 size_t min_byte_size = MinHeapSize;
156 size_t max_byte_size = MaxHeapSize;
157 size_t heap_alignment = HeapAlignment;
158
159 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
160
161 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
162 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
163
164 _num_regions = ShenandoahHeapRegion::region_count();
165
166 // Now we know the number of regions, initialize the heuristics.
167 initialize_heuristics();
168
169 size_t num_committed_regions = init_byte_size / reg_size_bytes;
170 num_committed_regions = MIN2(num_committed_regions, _num_regions);
171 assert(num_committed_regions <= _num_regions, "sanity");
172 _initial_size = num_committed_regions * reg_size_bytes;
173
174 size_t num_min_regions = min_byte_size / reg_size_bytes;
175 num_min_regions = MIN2(num_min_regions, _num_regions);
176 assert(num_min_regions <= _num_regions, "sanity");
177 _minimum_size = num_min_regions * reg_size_bytes;
178
179 _committed = _initial_size;
180
181 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
182 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
183 size_t region_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
184
185 //
186 // Reserve and commit memory for heap
187 //
188
189 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
190 initialize_reserved_region(heap_rs);
191 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
192 _heap_region_special = heap_rs.special();
193
194 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
195 "Misaligned heap: " PTR_FORMAT, p2i(base()));
196
197 #if SHENANDOAH_OPTIMIZED_OBJTASK
198 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits.
199 // Fail if we ever attempt to address more than we can.
200 if ((uintptr_t)heap_rs.end() >= ObjArrayChunkedTask::max_addressable()) {
201 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
202 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
203 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
204 p2i(heap_rs.base()), p2i(heap_rs.end()), ObjArrayChunkedTask::max_addressable());
205 vm_exit_during_initialization("Fatal Error", buf);
206 }
207 #endif
208
209 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
210 if (!_heap_region_special) {
211 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
212 "Cannot commit heap memory");
213 }
214
215 //
216 // Reserve and commit memory for bitmap(s)
217 //
218
219 _bitmap_size = MarkBitMap::compute_size(heap_rs.size());
220 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
221
222 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor();
223
224 guarantee(bitmap_bytes_per_region != 0,
225 "Bitmap bytes per region should not be zero");
226 guarantee(is_power_of_2(bitmap_bytes_per_region),
227 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
228
229 if (bitmap_page_size > bitmap_bytes_per_region) {
230 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
231 _bitmap_bytes_per_slice = bitmap_page_size;
232 } else {
233 _bitmap_regions_per_slice = 1;
234 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
235 }
236
237 guarantee(_bitmap_regions_per_slice >= 1,
238 "Should have at least one region per slice: " SIZE_FORMAT,
239 _bitmap_regions_per_slice);
240
241 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
242 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
243 _bitmap_bytes_per_slice, bitmap_page_size);
244
245 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
246 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
247 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
248 _bitmap_region_special = bitmap.special();
249
250 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
251 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
252 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
253 if (!_bitmap_region_special) {
254 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
255 "Cannot commit bitmap memory");
256 }
257
258 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
259
260 if (ShenandoahVerify) {
261 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
262 if (!verify_bitmap.special()) {
263 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
264 "Cannot commit verification bitmap memory");
265 }
266 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
267 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
268 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
269 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
270 }
271
272 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
273 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
274 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
275 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
276 _aux_bitmap_region_special = aux_bitmap.special();
277 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
278
279 //
280 // Create regions and region sets
281 //
282 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
283 size_t region_storage_size = align_up(region_align * _num_regions, region_page_size);
284 region_storage_size = align_up(region_storage_size, os::vm_allocation_granularity());
285
286 ReservedSpace region_storage(region_storage_size, region_page_size);
287 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC);
288 if (!region_storage.special()) {
289 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false,
290 "Cannot commit region memory");
291 }
292
293 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks.
294 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there.
295 // If not successful, bite a bullet and allocate at whatever address.
296 {
297 size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity());
298 size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align);
299
300 uintptr_t min = round_up_power_of_2(cset_align);
301 uintptr_t max = (1u << 30u);
302
303 for (uintptr_t addr = min; addr <= max; addr <<= 1u) {
304 char* req_addr = (char*)addr;
305 assert(is_aligned(req_addr, cset_align), "Should be aligned");
306 ReservedSpace cset_rs(cset_size, cset_align, false, req_addr);
307 if (cset_rs.is_reserved()) {
308 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr);
309 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
310 break;
311 }
312 }
313
314 if (_collection_set == NULL) {
315 ReservedSpace cset_rs(cset_size, cset_align, false);
316 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
317 }
318 }
319
320 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
321 _free_set = new ShenandoahFreeSet(this, _num_regions);
322
323 {
324 ShenandoahHeapLocker locker(lock());
325
326 for (size_t i = 0; i < _num_regions; i++) {
327 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
328 bool is_committed = i < num_committed_regions;
329 void* loc = region_storage.base() + i * region_align;
330
331 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
332 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
333
334 _marking_context->initialize_top_at_mark_start(r);
335 _regions[i] = r;
336 assert(!collection_set()->is_in(i), "New region should not be in collection set");
337 }
338
339 // Initialize to complete
340 _marking_context->mark_complete();
341
342 _free_set->rebuild();
343 }
344
345 if (AlwaysPreTouch) {
346 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
347 // before initialize() below zeroes it with initializing thread. For any given region,
348 // we touch the region and the corresponding bitmaps from the same thread.
349 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
350
351 _pretouch_heap_page_size = heap_page_size;
352 _pretouch_bitmap_page_size = bitmap_page_size;
353
354 #ifdef LINUX
355 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
356 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
357 // them into huge one. Therefore, we need to pretouch with smaller pages.
358 if (UseTransparentHugePages) {
359 _pretouch_heap_page_size = (size_t)os::vm_page_size();
360 _pretouch_bitmap_page_size = (size_t)os::vm_page_size();
361 }
362 #endif
363
364 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
365 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
366
367 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size);
368 _workers->run_task(&bcl);
369
370 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size);
371 _workers->run_task(&hcl);
372 }
373
374 //
375 // Initialize the rest of GC subsystems
376 //
377
378 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC);
379 for (uint worker = 0; worker < _max_workers; worker++) {
380 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC);
381 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData));
382 }
383
384 // There should probably be Shenandoah-specific options for these,
385 // just as there are G1-specific options.
386 {
387 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
388 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
389 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
390 }
391
392 _monitoring_support = new ShenandoahMonitoringSupport(this);
393 _phase_timings = new ShenandoahPhaseTimings(max_workers());
394 ShenandoahStringDedup::initialize();
395 ShenandoahCodeRoots::initialize();
396
397 if (ShenandoahPacing) {
398 _pacer = new ShenandoahPacer(this);
399 _pacer->setup_for_idle();
400 } else {
401 _pacer = NULL;
402 }
403
404 _control_thread = new ShenandoahControlThread();
405
406 _ref_proc_mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
407 _ref_proc_mt_discovery = _max_workers > 1;
408
409 ShenandoahInitLogger::print();
410
411 return JNI_OK;
412 }
413
414 void ShenandoahHeap::initialize_heuristics() {
415 if (ShenandoahGCMode != NULL) {
416 if (strcmp(ShenandoahGCMode, "satb") == 0) {
417 _gc_mode = new ShenandoahSATBMode();
418 } else if (strcmp(ShenandoahGCMode, "iu") == 0) {
419 _gc_mode = new ShenandoahIUMode();
420 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
421 _gc_mode = new ShenandoahPassiveMode();
422 } else {
423 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
424 }
425 } else {
426 ShouldNotReachHere();
427 }
428 _gc_mode->initialize_flags();
429 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
430 vm_exit_during_initialization(
431 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
432 _gc_mode->name()));
433 }
434 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
435 vm_exit_during_initialization(
436 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
437 _gc_mode->name()));
438 }
439
440 _heuristics = _gc_mode->initialize_heuristics();
441
442 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
443 vm_exit_during_initialization(
444 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
445 _heuristics->name()));
446 }
447 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
448 vm_exit_during_initialization(
449 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
450 _heuristics->name()));
451 }
452 }
453
454 #ifdef _MSC_VER
455 #pragma warning( push )
456 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
457 #endif
458
459 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
460 CollectedHeap(),
461 _initial_size(0),
462 _used(0),
463 _committed(0),
464 _bytes_allocated_since_gc_start(0),
465 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
466 _workers(NULL),
467 _safepoint_workers(NULL),
468 _heap_region_special(false),
469 _num_regions(0),
470 _regions(NULL),
471 _update_refs_iterator(this),
472 _control_thread(NULL),
473 _shenandoah_policy(policy),
474 _heuristics(NULL),
475 _free_set(NULL),
476 _scm(new ShenandoahConcurrentMark()),
477 _full_gc(new ShenandoahMarkCompact()),
478 _pacer(NULL),
479 _verifier(NULL),
480 _phase_timings(NULL),
481 _monitoring_support(NULL),
482 _memory_pool(NULL),
483 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
484 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
485 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
486 _soft_ref_policy(),
487 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
488 _ref_processor(NULL),
489 _marking_context(NULL),
490 _bitmap_size(0),
491 _bitmap_regions_per_slice(0),
492 _bitmap_bytes_per_slice(0),
493 _bitmap_region_special(false),
494 _aux_bitmap_region_special(false),
495 _liveness_cache(NULL),
496 _collection_set(NULL)
497 {
498 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
499
500 _max_workers = MAX2(_max_workers, 1U);
501 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
502 /* are_GC_task_threads */ true,
503 /* are_ConcurrentGC_threads */ true);
504 if (_workers == NULL) {
505 vm_exit_during_initialization("Failed necessary allocation.");
506 } else {
507 _workers->initialize_workers();
508 }
509
510 if (ParallelGCThreads > 1) {
511 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
512 ParallelGCThreads,
513 /* are_GC_task_threads */ false,
514 /* are_ConcurrentGC_threads */ false);
515 _safepoint_workers->initialize_workers();
516 }
517 }
518
519 #ifdef _MSC_VER
520 #pragma warning( pop )
521 #endif
522
523 class ShenandoahResetBitmapTask : public AbstractGangTask {
524 private:
525 ShenandoahRegionIterator _regions;
526
527 public:
528 ShenandoahResetBitmapTask() :
529 AbstractGangTask("Parallel Reset Bitmap Task") {}
530
531 void work(uint worker_id) {
532 ShenandoahHeapRegion* region = _regions.next();
533 ShenandoahHeap* heap = ShenandoahHeap::heap();
534 ShenandoahMarkingContext* const ctx = heap->marking_context();
535 while (region != NULL) {
536 if (heap->is_bitmap_slice_committed(region)) {
537 ctx->clear_bitmap(region);
538 }
539 region = _regions.next();
540 }
541 }
542 };
543
544 void ShenandoahHeap::reset_mark_bitmap() {
545 assert_gc_workers(_workers->active_workers());
546 mark_incomplete_marking_context();
547
548 ShenandoahResetBitmapTask task;
549 _workers->run_task(&task);
550 }
551
552 void ShenandoahHeap::print_on(outputStream* st) const {
553 st->print_cr("Shenandoah Heap");
554 st->print_cr(" " SIZE_FORMAT "%s total, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
555 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
556 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
557 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
558 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
559 num_regions(),
560 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
561 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
562
563 st->print("Status: ");
564 if (has_forwarded_objects()) st->print("has forwarded objects, ");
565 if (is_concurrent_mark_in_progress()) st->print("marking, ");
566 if (is_evacuation_in_progress()) st->print("evacuating, ");
567 if (is_update_refs_in_progress()) st->print("updating refs, ");
568 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
569 if (is_full_gc_in_progress()) st->print("full gc, ");
570 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
571 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, ");
572 if (is_concurrent_strong_root_in_progress() &&
573 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, ");
574
575 if (cancelled_gc()) {
576 st->print("cancelled");
577 } else {
578 st->print("not cancelled");
579 }
580 st->cr();
581
582 st->print_cr("Reserved region:");
583 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
584 p2i(reserved_region().start()),
585 p2i(reserved_region().end()));
586
587 ShenandoahCollectionSet* cset = collection_set();
588 st->print_cr("Collection set:");
589 if (cset != NULL) {
590 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
591 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
592 } else {
593 st->print_cr(" (NULL)");
594 }
595
596 st->cr();
597 MetaspaceUtils::print_on(st);
598
599 if (Verbose) {
600 print_heap_regions_on(st);
601 }
602 }
603
604 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
605 public:
606 void do_thread(Thread* thread) {
607 assert(thread != NULL, "Sanity");
608 assert(thread->is_Worker_thread(), "Only worker thread expected");
609 ShenandoahThreadLocalData::initialize_gclab(thread);
610 }
611 };
612
613 void ShenandoahHeap::post_initialize() {
614 CollectedHeap::post_initialize();
615 MutexLocker ml(Threads_lock);
616
617 ShenandoahInitWorkerGCLABClosure init_gclabs;
618 _workers->threads_do(&init_gclabs);
619
620 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
621 // Now, we will let WorkGang to initialize gclab when new worker is created.
622 _workers->set_initialize_gclab();
623
624 _scm->initialize(_max_workers);
625 _full_gc->initialize(_gc_timer);
626
627 ref_processing_init();
628
629 _heuristics->initialize();
630
631 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
632 }
633
634 size_t ShenandoahHeap::used() const {
635 return Atomic::load_acquire(&_used);
636 }
637
638 size_t ShenandoahHeap::committed() const {
639 OrderAccess::acquire();
640 return _committed;
641 }
642
643 void ShenandoahHeap::increase_committed(size_t bytes) {
644 shenandoah_assert_heaplocked_or_safepoint();
645 _committed += bytes;
646 }
647
648 void ShenandoahHeap::decrease_committed(size_t bytes) {
649 shenandoah_assert_heaplocked_or_safepoint();
650 _committed -= bytes;
651 }
652
653 void ShenandoahHeap::increase_used(size_t bytes) {
654 Atomic::add(&_used, bytes);
655 }
656
657 void ShenandoahHeap::set_used(size_t bytes) {
658 Atomic::release_store_fence(&_used, bytes);
659 }
660
661 void ShenandoahHeap::decrease_used(size_t bytes) {
662 assert(used() >= bytes, "never decrease heap size by more than we've left");
663 Atomic::sub(&_used, bytes);
664 }
665
666 void ShenandoahHeap::increase_allocated(size_t bytes) {
667 Atomic::add(&_bytes_allocated_since_gc_start, bytes);
668 }
669
670 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
671 size_t bytes = words * HeapWordSize;
672 if (!waste) {
673 increase_used(bytes);
674 }
675 increase_allocated(bytes);
676 if (ShenandoahPacing) {
677 control_thread()->pacing_notify_alloc(words);
678 if (waste) {
679 pacer()->claim_for_alloc(words, true);
680 }
681 }
682 }
683
684 size_t ShenandoahHeap::capacity() const {
685 return committed();
686 }
687
688 size_t ShenandoahHeap::max_capacity() const {
689 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
690 }
691
692 size_t ShenandoahHeap::min_capacity() const {
693 return _minimum_size;
694 }
695
696 size_t ShenandoahHeap::initial_capacity() const {
697 return _initial_size;
698 }
699
700 bool ShenandoahHeap::is_in(const void* p) const {
701 HeapWord* heap_base = (HeapWord*) base();
702 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
703 return p >= heap_base && p < last_region_end;
704 }
705
706 void ShenandoahHeap::op_uncommit(double shrink_before) {
707 assert (ShenandoahUncommit, "should be enabled");
708
709 // Application allocates from the beginning of the heap, and GC allocates at
710 // the end of it. It is more efficient to uncommit from the end, so that applications
711 // could enjoy the near committed regions. GC allocations are much less frequent,
712 // and therefore can accept the committing costs.
713
714 size_t count = 0;
715 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
716 ShenandoahHeapRegion* r = get_region(i - 1);
717 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
718 ShenandoahHeapLocker locker(lock());
719 if (r->is_empty_committed()) {
720 // Do not uncommit below minimal capacity
721 if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) {
722 break;
723 }
724
725 r->make_uncommitted();
726 count++;
727 }
728 }
729 SpinPause(); // allow allocators to take the lock
730 }
731
732 if (count > 0) {
733 control_thread()->notify_heap_changed();
734 }
735 }
736
737 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
738 // New object should fit the GCLAB size
739 size_t min_size = MAX2(size, PLAB::min_size());
740
741 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
742 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
743 new_size = MIN2(new_size, PLAB::max_size());
744 new_size = MAX2(new_size, PLAB::min_size());
745
746 // Record new heuristic value even if we take any shortcut. This captures
747 // the case when moderately-sized objects always take a shortcut. At some point,
748 // heuristics should catch up with them.
749 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
750
751 if (new_size < size) {
752 // New size still does not fit the object. Fall back to shared allocation.
753 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
754 return NULL;
755 }
756
757 // Retire current GCLAB, and allocate a new one.
758 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
759 gclab->retire();
760
761 size_t actual_size = 0;
762 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
763 if (gclab_buf == NULL) {
764 return NULL;
765 }
766
767 assert (size <= actual_size, "allocation should fit");
768
769 if (ZeroTLAB) {
770 // ..and clear it.
771 Copy::zero_to_words(gclab_buf, actual_size);
772 } else {
773 // ...and zap just allocated object.
774 #ifdef ASSERT
775 // Skip mangling the space corresponding to the object header to
776 // ensure that the returned space is not considered parsable by
777 // any concurrent GC thread.
778 size_t hdr_size = oopDesc::header_size();
779 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
780 #endif // ASSERT
781 }
782 gclab->set_buf(gclab_buf, actual_size);
783 return gclab->allocate(size);
784 }
785
786 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
787 size_t requested_size,
788 size_t* actual_size) {
789 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
790 HeapWord* res = allocate_memory(req);
791 if (res != NULL) {
792 *actual_size = req.actual_size();
793 } else {
794 *actual_size = 0;
795 }
796 return res;
797 }
798
799 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
800 size_t word_size,
801 size_t* actual_size) {
802 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
803 HeapWord* res = allocate_memory(req);
804 if (res != NULL) {
805 *actual_size = req.actual_size();
806 } else {
807 *actual_size = 0;
808 }
809 return res;
810 }
811
812 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
813 intptr_t pacer_epoch = 0;
814 bool in_new_region = false;
815 HeapWord* result = NULL;
816
817 if (req.is_mutator_alloc()) {
818 if (ShenandoahPacing) {
819 pacer()->pace_for_alloc(req.size());
820 pacer_epoch = pacer()->epoch();
821 }
822
823 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
824 result = allocate_memory_under_lock(req, in_new_region);
825 }
826
827 // Allocation failed, block until control thread reacted, then retry allocation.
828 //
829 // It might happen that one of the threads requesting allocation would unblock
830 // way later after GC happened, only to fail the second allocation, because
831 // other threads have already depleted the free storage. In this case, a better
832 // strategy is to try again, as long as GC makes progress.
833 //
834 // Then, we need to make sure the allocation was retried after at least one
835 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
836
837 size_t tries = 0;
838
839 while (result == NULL && _progress_last_gc.is_set()) {
840 tries++;
841 control_thread()->handle_alloc_failure(req);
842 result = allocate_memory_under_lock(req, in_new_region);
843 }
844
845 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
846 tries++;
847 control_thread()->handle_alloc_failure(req);
848 result = allocate_memory_under_lock(req, in_new_region);
849 }
850
851 } else {
852 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
853 result = allocate_memory_under_lock(req, in_new_region);
854 // Do not call handle_alloc_failure() here, because we cannot block.
855 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
856 }
857
858 if (in_new_region) {
859 control_thread()->notify_heap_changed();
860 }
861
862 if (result != NULL) {
863 size_t requested = req.size();
864 size_t actual = req.actual_size();
865
866 assert (req.is_lab_alloc() || (requested == actual),
867 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
868 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
869
870 if (req.is_mutator_alloc()) {
871 notify_mutator_alloc_words(actual, false);
872
873 // If we requested more than we were granted, give the rest back to pacer.
874 // This only matters if we are in the same pacing epoch: do not try to unpace
875 // over the budget for the other phase.
876 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
877 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
878 }
879 } else {
880 increase_used(actual*HeapWordSize);
881 }
882 }
883
884 return result;
885 }
886
887 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
888 ShenandoahHeapLocker locker(lock());
889 return _free_set->allocate(req, in_new_region);
890 }
891
892 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
893 bool* gc_overhead_limit_was_exceeded) {
894 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
895 return allocate_memory(req);
896 }
897
898 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
899 size_t size,
900 Metaspace::MetadataType mdtype) {
901 MetaWord* result;
902
903 // Inform metaspace OOM to GC heuristics if class unloading is possible.
904 if (heuristics()->can_unload_classes()) {
905 ShenandoahHeuristics* h = heuristics();
906 h->record_metaspace_oom();
907 }
908
909 // Expand and retry allocation
910 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
911 if (result != NULL) {
912 return result;
913 }
914
915 // Start full GC
916 collect(GCCause::_metadata_GC_clear_soft_refs);
917
918 // Retry allocation
919 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
920 if (result != NULL) {
921 return result;
922 }
923
924 // Expand and retry allocation
925 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
926 if (result != NULL) {
927 return result;
928 }
929
930 // Out of memory
931 return NULL;
932 }
933
934 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
935 private:
936 ShenandoahHeap* const _heap;
937 Thread* const _thread;
938 public:
939 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
940 _heap(heap), _thread(Thread::current()) {}
941
942 void do_object(oop p) {
943 shenandoah_assert_marked(NULL, p);
944 if (!p->is_forwarded()) {
945 _heap->evacuate_object(p, _thread);
946 }
947 }
948 };
949
950 class ShenandoahEvacuationTask : public AbstractGangTask {
951 private:
952 ShenandoahHeap* const _sh;
953 ShenandoahCollectionSet* const _cs;
954 bool _concurrent;
955 public:
956 ShenandoahEvacuationTask(ShenandoahHeap* sh,
957 ShenandoahCollectionSet* cs,
958 bool concurrent) :
959 AbstractGangTask("Parallel Evacuation Task"),
960 _sh(sh),
961 _cs(cs),
962 _concurrent(concurrent)
963 {}
964
965 void work(uint worker_id) {
966 if (_concurrent) {
967 ShenandoahConcurrentWorkerSession worker_session(worker_id);
968 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
969 ShenandoahEvacOOMScope oom_evac_scope;
970 do_work();
971 } else {
972 ShenandoahParallelWorkerSession worker_session(worker_id);
973 ShenandoahEvacOOMScope oom_evac_scope;
974 do_work();
975 }
976 }
977
978 private:
979 void do_work() {
980 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
981 ShenandoahHeapRegion* r;
982 while ((r =_cs->claim_next()) != NULL) {
983 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
984 _sh->marked_object_iterate(r, &cl);
985
986 if (ShenandoahPacing) {
987 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
988 }
989
990 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
991 break;
992 }
993 }
994 }
995 };
996
997 void ShenandoahHeap::trash_cset_regions() {
998 ShenandoahHeapLocker locker(lock());
999
1000 ShenandoahCollectionSet* set = collection_set();
1001 ShenandoahHeapRegion* r;
1002 set->clear_current_index();
1003 while ((r = set->next()) != NULL) {
1004 r->make_trash();
1005 }
1006 collection_set()->clear();
1007 }
1008
1009 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1010 st->print_cr("Heap Regions:");
1011 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
1012 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
1013 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark");
1014 st->print_cr("SN=alloc sequence number");
1015
1016 for (size_t i = 0; i < num_regions(); i++) {
1017 get_region(i)->print_on(st);
1018 }
1019 }
1020
1021 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1022 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1023
1024 oop humongous_obj = oop(start->bottom());
1025 size_t size = humongous_obj->size();
1026 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1027 size_t index = start->index() + required_regions - 1;
1028
1029 assert(!start->has_live(), "liveness must be zero");
1030
1031 for(size_t i = 0; i < required_regions; i++) {
1032 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1033 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1034 ShenandoahHeapRegion* region = get_region(index --);
1035
1036 assert(region->is_humongous(), "expect correct humongous start or continuation");
1037 assert(!region->is_cset(), "Humongous region should not be in collection set");
1038
1039 region->make_trash_immediate();
1040 }
1041 }
1042
1043 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1044 public:
1045 ShenandoahCheckCleanGCLABClosure() {}
1046 void do_thread(Thread* thread) {
1047 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1048 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1049 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
1050 }
1051 };
1052
1053 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1054 private:
1055 bool const _resize;
1056 public:
1057 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1058 void do_thread(Thread* thread) {
1059 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1060 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1061 gclab->retire();
1062 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1063 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1064 }
1065 }
1066 };
1067
1068 void ShenandoahHeap::labs_make_parsable() {
1069 assert(UseTLAB, "Only call with UseTLAB");
1070
1071 ShenandoahRetireGCLABClosure cl(false);
1072
1073 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1074 ThreadLocalAllocBuffer& tlab = t->tlab();
1075 tlab.make_parsable();
1076 cl.do_thread(t);
1077 }
1078
1079 workers()->threads_do(&cl);
1080 }
1081
1082 void ShenandoahHeap::tlabs_retire(bool resize) {
1083 assert(UseTLAB, "Only call with UseTLAB");
1084 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1085
1086 ThreadLocalAllocStats stats;
1087
1088 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1089 ThreadLocalAllocBuffer& tlab = t->tlab();
1090 tlab.retire(&stats);
1091 if (resize) {
1092 tlab.resize();
1093 }
1094 }
1095
1096 stats.publish();
1097
1098 #ifdef ASSERT
1099 ShenandoahCheckCleanGCLABClosure cl;
1100 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1101 cl.do_thread(t);
1102 }
1103 workers()->threads_do(&cl);
1104 #endif
1105 }
1106
1107 void ShenandoahHeap::gclabs_retire(bool resize) {
1108 assert(UseTLAB, "Only call with UseTLAB");
1109 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1110
1111 ShenandoahRetireGCLABClosure cl(resize);
1112 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1113 cl.do_thread(t);
1114 }
1115 workers()->threads_do(&cl);
1116 }
1117
1118 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
1119 private:
1120 ShenandoahRootEvacuator* _rp;
1121
1122 public:
1123 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
1124 AbstractGangTask("Shenandoah evacuate and update roots"),
1125 _rp(rp) {}
1126
1127 void work(uint worker_id) {
1128 ShenandoahParallelWorkerSession worker_session(worker_id);
1129 ShenandoahEvacOOMScope oom_evac_scope;
1130 ShenandoahEvacuateUpdateRootsClosure<> cl;
1131 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
1132 _rp->roots_do(worker_id, &cl);
1133 }
1134 };
1135
1136 void ShenandoahHeap::evacuate_and_update_roots() {
1137 #if COMPILER2_OR_JVMCI
1138 DerivedPointerTable::clear();
1139 #endif
1140 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
1141 {
1142 // Include concurrent roots if current cycle can not process those roots concurrently
1143 ShenandoahRootEvacuator rp(workers()->active_workers(),
1144 ShenandoahPhaseTimings::init_evac,
1145 !ShenandoahConcurrentRoots::should_do_concurrent_roots(),
1146 !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
1147 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1148 workers()->run_task(&roots_task);
1149 }
1150
1151 #if COMPILER2_OR_JVMCI
1152 DerivedPointerTable::update_pointers();
1153 #endif
1154 }
1155
1156 // Returns size in bytes
1157 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1158 if (ShenandoahElasticTLAB) {
1159 // With Elastic TLABs, return the max allowed size, and let the allocation path
1160 // figure out the safe size for current allocation.
1161 return ShenandoahHeapRegion::max_tlab_size_bytes();
1162 } else {
1163 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1164 }
1165 }
1166
1167 size_t ShenandoahHeap::max_tlab_size() const {
1168 // Returns size in words
1169 return ShenandoahHeapRegion::max_tlab_size_words();
1170 }
1171
1172 void ShenandoahHeap::collect(GCCause::Cause cause) {
1173 control_thread()->request_gc(cause);
1174 }
1175
1176 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1177 //assert(false, "Shouldn't need to do full collections");
1178 }
1179
1180 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1181 ShenandoahHeapRegion* r = heap_region_containing(addr);
1182 if (r != NULL) {
1183 return r->block_start(addr);
1184 }
1185 return NULL;
1186 }
1187
1188 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1189 ShenandoahHeapRegion* r = heap_region_containing(addr);
1190 return r->block_is_obj(addr);
1191 }
1192
1193 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1194 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1195 }
1196
1197 jlong ShenandoahHeap::millis_since_last_gc() {
1198 double v = heuristics()->time_since_last_gc() * 1000;
1199 assert(0 <= v && v <= max_jlong, "value should fit: %f", v);
1200 return (jlong)v;
1201 }
1202
1203 void ShenandoahHeap::prepare_for_verify() {
1204 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) {
1205 labs_make_parsable();
1206 }
1207 }
1208
1209 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1210 workers()->threads_do(tcl);
1211 if (_safepoint_workers != NULL) {
1212 _safepoint_workers->threads_do(tcl);
1213 }
1214 if (ShenandoahStringDedup::is_enabled()) {
1215 ShenandoahStringDedup::threads_do(tcl);
1216 }
1217 }
1218
1219 void ShenandoahHeap::print_tracing_info() const {
1220 LogTarget(Info, gc, stats) lt;
1221 if (lt.is_enabled()) {
1222 ResourceMark rm;
1223 LogStream ls(lt);
1224
1225 phase_timings()->print_global_on(&ls);
1226
1227 ls.cr();
1228 ls.cr();
1229
1230 shenandoah_policy()->print_gc_stats(&ls);
1231
1232 ls.cr();
1233 ls.cr();
1234
1235 if (ShenandoahPacing) {
1236 pacer()->print_on(&ls);
1237 }
1238
1239 ls.cr();
1240 ls.cr();
1241 }
1242 }
1243
1244 void ShenandoahHeap::verify(VerifyOption vo) {
1245 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1246 if (ShenandoahVerify) {
1247 verifier()->verify_generic(vo);
1248 } else {
1249 // TODO: Consider allocating verification bitmaps on demand,
1250 // and turn this on unconditionally.
1251 }
1252 }
1253 }
1254 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1255 return _free_set->capacity();
1256 }
1257
1258 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1259 private:
1260 MarkBitMap* _bitmap;
1261 Stack<oop,mtGC>* _oop_stack;
1262 ShenandoahHeap* const _heap;
1263 ShenandoahMarkingContext* const _marking_context;
1264
1265 template <class T>
1266 void do_oop_work(T* p) {
1267 T o = RawAccess<>::oop_load(p);
1268 if (!CompressedOops::is_null(o)) {
1269 oop obj = CompressedOops::decode_not_null(o);
1270 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1271 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1272 return;
1273 }
1274 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1275
1276 assert(oopDesc::is_oop(obj), "must be a valid oop");
1277 if (!_bitmap->is_marked(obj)) {
1278 _bitmap->mark(obj);
1279 _oop_stack->push(obj);
1280 }
1281 }
1282 }
1283 public:
1284 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1285 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1286 _marking_context(_heap->marking_context()) {}
1287 void do_oop(oop* p) { do_oop_work(p); }
1288 void do_oop(narrowOop* p) { do_oop_work(p); }
1289 };
1290
1291 /*
1292 * This is public API, used in preparation of object_iterate().
1293 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1294 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1295 * control, we call SH::tlabs_retire, SH::gclabs_retire.
1296 */
1297 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1298 // No-op.
1299 }
1300
1301 /*
1302 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1303 *
1304 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1305 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1306 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1307 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1308 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1309 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1310 * wiped the bitmap in preparation for next marking).
1311 *
1312 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1313 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1314 * is allowed to report dead objects, but is not required to do so.
1315 */
1316 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1317 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1318 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1319 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1320 return;
1321 }
1322
1323 // Reset bitmap
1324 _aux_bit_map.clear();
1325
1326 Stack<oop,mtGC> oop_stack;
1327
1328 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1329
1330 {
1331 // First, we process GC roots according to current GC cycle.
1332 // This populates the work stack with initial objects.
1333 // It is important to relinquish the associated locks before diving
1334 // into heap dumper.
1335 ShenandoahHeapIterationRootScanner rp;
1336 rp.roots_do(&oops);
1337 }
1338
1339 // Work through the oop stack to traverse heap.
1340 while (! oop_stack.is_empty()) {
1341 oop obj = oop_stack.pop();
1342 assert(oopDesc::is_oop(obj), "must be a valid oop");
1343 cl->do_object(obj);
1344 obj->oop_iterate(&oops);
1345 }
1346
1347 assert(oop_stack.is_empty(), "should be empty");
1348
1349 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1350 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1351 }
1352 }
1353
1354 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1355 void ShenandoahHeap::keep_alive(oop obj) {
1356 if (is_concurrent_mark_in_progress()) {
1357 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1358 }
1359 }
1360
1361 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1362 for (size_t i = 0; i < num_regions(); i++) {
1363 ShenandoahHeapRegion* current = get_region(i);
1364 blk->heap_region_do(current);
1365 }
1366 }
1367
1368 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1369 private:
1370 ShenandoahHeap* const _heap;
1371 ShenandoahHeapRegionClosure* const _blk;
1372
1373 shenandoah_padding(0);
1374 volatile size_t _index;
1375 shenandoah_padding(1);
1376
1377 public:
1378 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1379 AbstractGangTask("Parallel Region Task"),
1380 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1381
1382 void work(uint worker_id) {
1383 ShenandoahParallelWorkerSession worker_session(worker_id);
1384 size_t stride = ShenandoahParallelRegionStride;
1385
1386 size_t max = _heap->num_regions();
1387 while (_index < max) {
1388 size_t cur = Atomic::fetch_and_add(&_index, stride);
1389 size_t start = cur;
1390 size_t end = MIN2(cur + stride, max);
1391 if (start >= max) break;
1392
1393 for (size_t i = cur; i < end; i++) {
1394 ShenandoahHeapRegion* current = _heap->get_region(i);
1395 _blk->heap_region_do(current);
1396 }
1397 }
1398 }
1399 };
1400
1401 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1402 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1403 if (num_regions() > ShenandoahParallelRegionStride) {
1404 ShenandoahParallelHeapRegionTask task(blk);
1405 workers()->run_task(&task);
1406 } else {
1407 heap_region_iterate(blk);
1408 }
1409 }
1410
1411 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1412 private:
1413 ShenandoahMarkingContext* const _ctx;
1414 public:
1415 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1416
1417 void heap_region_do(ShenandoahHeapRegion* r) {
1418 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1419 if (r->is_active()) {
1420 // Check if region needs updating its TAMS. We have updated it already during concurrent
1421 // reset, so it is very likely we don't need to do another write here.
1422 if (_ctx->top_at_mark_start(r) != r->top()) {
1423 _ctx->capture_top_at_mark_start(r);
1424 }
1425 } else {
1426 assert(_ctx->top_at_mark_start(r) == r->top(),
1427 "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
1428 }
1429 }
1430
1431 bool is_thread_safe() { return true; }
1432 };
1433
1434 void ShenandoahHeap::op_init_mark() {
1435 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1436 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1437
1438 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1439 assert(!marking_context()->is_complete(), "should not be complete");
1440 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1441
1442 if (ShenandoahVerify) {
1443 verifier()->verify_before_concmark();
1444 }
1445
1446 if (VerifyBeforeGC) {
1447 Universe::verify();
1448 }
1449
1450 set_concurrent_mark_in_progress(true);
1451
1452 // We need to reset all TLABs because they might be below the TAMS, and we need to mark
1453 // the objects in them. Do not let mutators allocate any new objects in their current TLABs.
1454 // It is also a good place to resize the TLAB sizes for future allocations.
1455 if (UseTLAB) {
1456 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_manage_tlabs);
1457 tlabs_retire(ResizeTLAB);
1458 }
1459
1460 {
1461 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_region_states);
1462 ShenandoahInitMarkUpdateRegionStateClosure cl;
1463 parallel_heap_region_iterate(&cl);
1464 }
1465
1466 // Make above changes visible to worker threads
1467 OrderAccess::fence();
1468
1469 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1470
1471 if (ShenandoahPacing) {
1472 pacer()->setup_for_mark();
1473 }
1474
1475 // Arm nmethods for concurrent marking. When a nmethod is about to be executed,
1476 // we need to make sure that all its metadata are marked. alternative is to remark
1477 // thread roots at final mark pause, but it can be potential latency killer.
1478 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1479 ShenandoahCodeRoots::arm_nmethods();
1480 }
1481 }
1482
1483 void ShenandoahHeap::op_mark() {
1484 concurrent_mark()->mark_from_roots();
1485 }
1486
1487 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1488 private:
1489 ShenandoahMarkingContext* const _ctx;
1490 ShenandoahHeapLock* const _lock;
1491
1492 public:
1493 ShenandoahFinalMarkUpdateRegionStateClosure() :
1494 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1495
1496 void heap_region_do(ShenandoahHeapRegion* r) {
1497 if (r->is_active()) {
1498 // All allocations past TAMS are implicitly live, adjust the region data.
1499 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1500 HeapWord *tams = _ctx->top_at_mark_start(r);
1501 HeapWord *top = r->top();
1502 if (top > tams) {
1503 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1504 }
1505
1506 // We are about to select the collection set, make sure it knows about
1507 // current pinning status. Also, this allows trashing more regions that
1508 // now have their pinning status dropped.
1509 if (r->is_pinned()) {
1510 if (r->pin_count() == 0) {
1511 ShenandoahHeapLocker locker(_lock);
1512 r->make_unpinned();
1513 }
1514 } else {
1515 if (r->pin_count() > 0) {
1516 ShenandoahHeapLocker locker(_lock);
1517 r->make_pinned();
1518 }
1519 }
1520
1521 // Remember limit for updating refs. It's guaranteed that we get no
1522 // from-space-refs written from here on.
1523 r->set_update_watermark_at_safepoint(r->top());
1524 } else {
1525 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1526 assert(_ctx->top_at_mark_start(r) == r->top(),
1527 "Region " SIZE_FORMAT " should have correct TAMS", r->index());
1528 }
1529 }
1530
1531 bool is_thread_safe() { return true; }
1532 };
1533
1534 void ShenandoahHeap::op_final_mark() {
1535 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1536 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1537
1538 // It is critical that we
1539 // evacuate roots right after finishing marking, so that we don't
1540 // get unmarked objects in the roots.
1541
1542 if (!cancelled_gc()) {
1543 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1544
1545 // Marking is completed, deactivate SATB barrier
1546 set_concurrent_mark_in_progress(false);
1547 mark_complete_marking_context();
1548
1549 parallel_cleaning(false /* full gc*/);
1550
1551 if (ShenandoahVerify) {
1552 verifier()->verify_roots_no_forwarded();
1553 }
1554
1555 {
1556 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_region_states);
1557 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1558 parallel_heap_region_iterate(&cl);
1559
1560 assert_pinned_region_status();
1561 }
1562
1563 // Retire the TLABs, which will force threads to reacquire their TLABs after the pause.
1564 // This is needed for two reasons. Strong one: new allocations would be with new freeset,
1565 // which would be outside the collection set, so no cset writes would happen there.
1566 // Weaker one: new allocations would happen past update watermark, and so less work would
1567 // be needed for reference updates (would update the large filler instead).
1568 if (UseTLAB) {
1569 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_manage_labs);
1570 tlabs_retire(false);
1571 }
1572
1573 {
1574 ShenandoahGCPhase phase(ShenandoahPhaseTimings::choose_cset);
1575 ShenandoahHeapLocker locker(lock());
1576 _collection_set->clear();
1577 heuristics()->choose_collection_set(_collection_set);
1578 }
1579
1580 {
1581 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_rebuild_freeset);
1582 ShenandoahHeapLocker locker(lock());
1583 _free_set->rebuild();
1584 }
1585
1586 if (!is_degenerated_gc_in_progress()) {
1587 prepare_concurrent_roots();
1588 prepare_concurrent_unloading();
1589 }
1590
1591 // If collection set has candidates, start evacuation.
1592 // Otherwise, bypass the rest of the cycle.
1593 if (!collection_set()->is_empty()) {
1594 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
1595
1596 if (ShenandoahVerify) {
1597 verifier()->verify_before_evacuation();
1598 }
1599
1600 set_evacuation_in_progress(true);
1601 // From here on, we need to update references.
1602 set_has_forwarded_objects(true);
1603
1604 if (!is_degenerated_gc_in_progress()) {
1605 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1606 ShenandoahCodeRoots::arm_nmethods();
1607 }
1608 evacuate_and_update_roots();
1609 }
1610
1611 if (ShenandoahPacing) {
1612 pacer()->setup_for_evac();
1613 }
1614
1615 if (ShenandoahVerify) {
1616 // If OOM while evacuating/updating of roots, there is no guarantee of their consistencies
1617 if (!cancelled_gc()) {
1618 ShenandoahRootVerifier::RootTypes types = ShenandoahRootVerifier::None;
1619 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1620 types = ShenandoahRootVerifier::combine(ShenandoahRootVerifier::JNIHandleRoots, ShenandoahRootVerifier::WeakRoots);
1621 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CLDGRoots);
1622 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::StringDedupRoots);
1623 }
1624
1625 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1626 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CodeRoots);
1627 }
1628 verifier()->verify_roots_no_forwarded_except(types);
1629 }
1630 verifier()->verify_during_evacuation();
1631 }
1632 } else {
1633 if (ShenandoahVerify) {
1634 verifier()->verify_after_concmark();
1635 }
1636
1637 if (VerifyAfterGC) {
1638 Universe::verify();
1639 }
1640 }
1641
1642 } else {
1643 // If this cycle was updating references, we need to keep the has_forwarded_objects
1644 // flag on, for subsequent phases to deal with it.
1645 concurrent_mark()->cancel();
1646 set_concurrent_mark_in_progress(false);
1647
1648 if (process_references()) {
1649 // Abandon reference processing right away: pre-cleaning must have failed.
1650 ReferenceProcessor *rp = ref_processor();
1651 rp->disable_discovery();
1652 rp->abandon_partial_discovery();
1653 rp->verify_no_references_recorded();
1654 }
1655 }
1656 }
1657
1658 void ShenandoahHeap::op_conc_evac() {
1659 ShenandoahEvacuationTask task(this, _collection_set, true);
1660 workers()->run_task(&task);
1661 }
1662
1663 void ShenandoahHeap::op_stw_evac() {
1664 ShenandoahEvacuationTask task(this, _collection_set, false);
1665 workers()->run_task(&task);
1666 }
1667
1668 void ShenandoahHeap::op_updaterefs() {
1669 update_heap_references(true);
1670 }
1671
1672 void ShenandoahHeap::op_cleanup_early() {
1673 free_set()->recycle_trash();
1674 }
1675
1676 void ShenandoahHeap::op_cleanup_complete() {
1677 free_set()->recycle_trash();
1678 }
1679
1680 class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask {
1681 private:
1682 ShenandoahVMRoots<true /*concurrent*/> _vm_roots;
1683 ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_roots;
1684
1685 public:
1686 ShenandoahConcurrentRootsEvacUpdateTask(ShenandoahPhaseTimings::Phase phase) :
1687 AbstractGangTask("Shenandoah Evacuate/Update Concurrent Strong Roots Task"),
1688 _vm_roots(phase),
1689 _cld_roots(phase, ShenandoahHeap::heap()->workers()->active_workers()) {}
1690
1691 void work(uint worker_id) {
1692 ShenandoahConcurrentWorkerSession worker_session(worker_id);
1693 ShenandoahEvacOOMScope oom;
1694 {
1695 // vm_roots and weak_roots are OopStorage backed roots, concurrent iteration
1696 // may race against OopStorage::release() calls.
1697 ShenandoahEvacUpdateOopStorageRootsClosure cl;
1698 _vm_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl, worker_id);
1699 }
1700
1701 {
1702 ShenandoahEvacuateUpdateRootsClosure<> cl;
1703 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
1704 _cld_roots.cld_do(&clds, worker_id);
1705 }
1706 }
1707 };
1708
1709 class ShenandoahEvacUpdateCleanupOopStorageRootsClosure : public BasicOopIterateClosure {
1710 private:
1711 ShenandoahHeap* const _heap;
1712 ShenandoahMarkingContext* const _mark_context;
1713 bool _evac_in_progress;
1714 Thread* const _thread;
1715 size_t _dead_counter;
1716
1717 public:
1718 ShenandoahEvacUpdateCleanupOopStorageRootsClosure();
1719 void do_oop(oop* p);
1720 void do_oop(narrowOop* p);
1721
1722 size_t dead_counter() const;
1723 void reset_dead_counter();
1724 };
1725
1726 ShenandoahEvacUpdateCleanupOopStorageRootsClosure::ShenandoahEvacUpdateCleanupOopStorageRootsClosure() :
1727 _heap(ShenandoahHeap::heap()),
1728 _mark_context(ShenandoahHeap::heap()->marking_context()),
1729 _evac_in_progress(ShenandoahHeap::heap()->is_evacuation_in_progress()),
1730 _thread(Thread::current()),
1731 _dead_counter(0) {
1732 }
1733
1734 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(oop* p) {
1735 const oop obj = RawAccess<>::oop_load(p);
1736 if (!CompressedOops::is_null(obj)) {
1737 if (!_mark_context->is_marked(obj)) {
1738 shenandoah_assert_correct(p, obj);
1739 oop old = Atomic::cmpxchg(p, obj, oop(NULL));
1740 if (obj == old) {
1741 _dead_counter ++;
1742 }
1743 } else if (_evac_in_progress && _heap->in_collection_set(obj)) {
1744 oop resolved = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1745 if (resolved == obj) {
1746 resolved = _heap->evacuate_object(obj, _thread);
1747 }
1748 Atomic::cmpxchg(p, obj, resolved);
1749 assert(_heap->cancelled_gc() ||
1750 _mark_context->is_marked(resolved) && !_heap->in_collection_set(resolved),
1751 "Sanity");
1752 }
1753 }
1754 }
1755
1756 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(narrowOop* p) {
1757 ShouldNotReachHere();
1758 }
1759
1760 size_t ShenandoahEvacUpdateCleanupOopStorageRootsClosure::dead_counter() const {
1761 return _dead_counter;
1762 }
1763
1764 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::reset_dead_counter() {
1765 _dead_counter = 0;
1766 }
1767
1768 class ShenandoahIsCLDAliveClosure : public CLDClosure {
1769 public:
1770 void do_cld(ClassLoaderData* cld) {
1771 cld->is_alive();
1772 }
1773 };
1774
1775 class ShenandoahIsNMethodAliveClosure: public NMethodClosure {
1776 public:
1777 void do_nmethod(nmethod* n) {
1778 n->is_unloading();
1779 }
1780 };
1781
1782 // This task not only evacuates/updates marked weak roots, but also "NULL"
1783 // dead weak roots.
1784 class ShenandoahConcurrentWeakRootsEvacUpdateTask : public AbstractGangTask {
1785 private:
1786 ShenandoahWeakRoot<true /*concurrent*/> _jni_roots;
1787 ShenandoahWeakRoot<true /*concurrent*/> _string_table_roots;
1788 ShenandoahWeakRoot<true /*concurrent*/> _resolved_method_table_roots;
1789 ShenandoahWeakRoot<true /*concurrent*/> _vm_roots;
1790
1791 // Roots related to concurrent class unloading
1792 ShenandoahClassLoaderDataRoots<true /* concurrent */, false /* single thread*/>
1793 _cld_roots;
1794 ShenandoahConcurrentNMethodIterator _nmethod_itr;
1795 ShenandoahConcurrentStringDedupRoots _dedup_roots;
1796 bool _concurrent_class_unloading;
1797
1798 public:
1799 ShenandoahConcurrentWeakRootsEvacUpdateTask(ShenandoahPhaseTimings::Phase phase) :
1800 AbstractGangTask("Shenandoah Concurrent Weak Root Task"),
1801 _jni_roots(OopStorageSet::jni_weak(), phase, ShenandoahPhaseTimings::JNIWeakRoots),
1802 _string_table_roots(OopStorageSet::string_table_weak(), phase, ShenandoahPhaseTimings::StringTableRoots),
1803 _resolved_method_table_roots(OopStorageSet::resolved_method_table_weak(), phase, ShenandoahPhaseTimings::ResolvedMethodTableRoots),
1804 _vm_roots(OopStorageSet::vm_weak(), phase, ShenandoahPhaseTimings::VMWeakRoots),
1805 _cld_roots(phase, ShenandoahHeap::heap()->workers()->active_workers()),
1806 _nmethod_itr(ShenandoahCodeRoots::table()),
1807 _dedup_roots(phase),
1808 _concurrent_class_unloading(ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1809 StringTable::reset_dead_counter();
1810 ResolvedMethodTable::reset_dead_counter();
1811 if (_concurrent_class_unloading) {
1812 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
1813 _nmethod_itr.nmethods_do_begin();
1814 }
1815 }
1816
1817 ~ShenandoahConcurrentWeakRootsEvacUpdateTask() {
1818 StringTable::finish_dead_counter();
1819 ResolvedMethodTable::finish_dead_counter();
1820 if (_concurrent_class_unloading) {
1821 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
1822 _nmethod_itr.nmethods_do_end();
1823 }
1824 }
1825
1826 void work(uint worker_id) {
1827 ShenandoahConcurrentWorkerSession worker_session(worker_id);
1828 {
1829 ShenandoahEvacOOMScope oom;
1830 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration
1831 // may race against OopStorage::release() calls.
1832 ShenandoahEvacUpdateCleanupOopStorageRootsClosure cl;
1833 _jni_roots.oops_do(&cl, worker_id);
1834 _vm_roots.oops_do(&cl, worker_id);
1835
1836 cl.reset_dead_counter();
1837 _string_table_roots.oops_do(&cl, worker_id);
1838 StringTable::inc_dead_counter(cl.dead_counter());
1839
1840 cl.reset_dead_counter();
1841 _resolved_method_table_roots.oops_do(&cl, worker_id);
1842 ResolvedMethodTable::inc_dead_counter(cl.dead_counter());
1843
1844 // String dedup weak roots
1845 ShenandoahForwardedIsAliveClosure is_alive;
1846 ShenandoahEvacuateUpdateRootsClosure<MO_RELEASE> keep_alive;
1847 _dedup_roots.oops_do(&is_alive, &keep_alive, worker_id);
1848 }
1849
1850 // If we are going to perform concurrent class unloading later on, we need to
1851 // cleanup the weak oops in CLD and determinate nmethod's unloading state, so that we
1852 // can cleanup immediate garbage sooner.
1853 if (_concurrent_class_unloading) {
1854 // Applies ShenandoahIsCLDAlive closure to CLDs, native barrier will either NULL the
1855 // CLD's holder or evacuate it.
1856 ShenandoahIsCLDAliveClosure is_cld_alive;
1857 _cld_roots.cld_do(&is_cld_alive, worker_id);
1858
1859 // Applies ShenandoahIsNMethodAliveClosure to registered nmethods.
1860 // The closure calls nmethod->is_unloading(). The is_unloading
1861 // state is cached, therefore, during concurrent class unloading phase,
1862 // we will not touch the metadata of unloading nmethods
1863 ShenandoahIsNMethodAliveClosure is_nmethod_alive;
1864 _nmethod_itr.nmethods_do(&is_nmethod_alive);
1865 }
1866 }
1867 };
1868
1869 void ShenandoahHeap::op_weak_roots() {
1870 if (is_concurrent_weak_root_in_progress()) {
1871 // Concurrent weak root processing
1872 {
1873 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_weak_roots_work);
1874 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_weak_roots_work);
1875 ShenandoahConcurrentWeakRootsEvacUpdateTask task(ShenandoahPhaseTimings::conc_weak_roots_work);
1876 workers()->run_task(&task);
1877 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1878 set_concurrent_weak_root_in_progress(false);
1879 }
1880 }
1881
1882 // Perform handshake to flush out dead oops
1883 {
1884 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_weak_roots_rendezvous);
1885 ShenandoahRendezvousClosure cl;
1886 Handshake::execute(&cl);
1887 }
1888 }
1889 }
1890
1891 void ShenandoahHeap::op_class_unloading() {
1892 assert (is_concurrent_weak_root_in_progress() &&
1893 ShenandoahConcurrentRoots::should_do_concurrent_class_unloading(),
1894 "Checked by caller");
1895 _unloader.unload();
1896 set_concurrent_weak_root_in_progress(false);
1897 }
1898
1899 void ShenandoahHeap::op_strong_roots() {
1900 assert(is_concurrent_strong_root_in_progress(), "Checked by caller");
1901 ShenandoahConcurrentRootsEvacUpdateTask task(ShenandoahPhaseTimings::conc_strong_roots);
1902 workers()->run_task(&task);
1903 set_concurrent_strong_root_in_progress(false);
1904 }
1905
1906 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1907 private:
1908 ShenandoahMarkingContext* const _ctx;
1909 public:
1910 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1911
1912 void heap_region_do(ShenandoahHeapRegion* r) {
1913 if (r->is_active()) {
1914 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1915 // anyway to capture any updates that happened since now.
1916 r->clear_live_data();
1917 _ctx->capture_top_at_mark_start(r);
1918 }
1919 }
1920
1921 bool is_thread_safe() { return true; }
1922 };
1923
1924 void ShenandoahHeap::op_reset() {
1925 if (ShenandoahPacing) {
1926 pacer()->setup_for_reset();
1927 }
1928 reset_mark_bitmap();
1929
1930 ShenandoahResetUpdateRegionStateClosure cl;
1931 parallel_heap_region_iterate(&cl);
1932 }
1933
1934 void ShenandoahHeap::op_preclean() {
1935 if (ShenandoahPacing) {
1936 pacer()->setup_for_preclean();
1937 }
1938 concurrent_mark()->preclean_weak_refs();
1939 }
1940
1941 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1942 ShenandoahMetricsSnapshot metrics;
1943 metrics.snap_before();
1944
1945 full_gc()->do_it(cause);
1946
1947 metrics.snap_after();
1948
1949 if (metrics.is_good_progress()) {
1950 _progress_last_gc.set();
1951 } else {
1952 // Nothing to do. Tell the allocation path that we have failed to make
1953 // progress, and it can finally fail.
1954 _progress_last_gc.unset();
1955 }
1956 }
1957
1958 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1959 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1960 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1961 // some phase, we have to upgrade the Degenerate GC to Full GC.
1962
1963 clear_cancelled_gc();
1964
1965 ShenandoahMetricsSnapshot metrics;
1966 metrics.snap_before();
1967
1968 switch (point) {
1969 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1970 // but enters it at different points, depending on which concurrent phase had
1971 // degenerated.
1972
1973 case _degenerated_outside_cycle:
1974 // We have degenerated from outside the cycle, which means something is bad with
1975 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1976 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1977 // we can do the most aggressive degen cycle, which includes processing references and
1978 // class unloading, unless those features are explicitly disabled.
1979 //
1980 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1981 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1982 set_process_references(heuristics()->can_process_references());
1983 set_unload_classes(heuristics()->can_unload_classes());
1984
1985 op_reset();
1986
1987 op_init_mark();
1988 if (cancelled_gc()) {
1989 op_degenerated_fail();
1990 return;
1991 }
1992
1993 case _degenerated_mark:
1994 op_final_mark();
1995 if (cancelled_gc()) {
1996 op_degenerated_fail();
1997 return;
1998 }
1999
2000 if (!has_forwarded_objects() && ShenandoahConcurrentRoots::can_do_concurrent_class_unloading()) {
2001 // Disarm nmethods that armed for concurrent mark. On normal cycle, it would
2002 // be disarmed while conc-roots phase is running.
2003 // TODO: Call op_conc_roots() here instead
2004 ShenandoahCodeRoots::disarm_nmethods();
2005 }
2006
2007 op_cleanup_early();
2008
2009 case _degenerated_evac:
2010 // If heuristics thinks we should do the cycle, this flag would be set,
2011 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
2012 if (is_evacuation_in_progress()) {
2013
2014 // Degeneration under oom-evac protocol might have left some objects in
2015 // collection set un-evacuated. Restart evacuation from the beginning to
2016 // capture all objects. For all the objects that are already evacuated,
2017 // it would be a simple check, which is supposed to be fast. This is also
2018 // safe to do even without degeneration, as CSet iterator is at beginning
2019 // in preparation for evacuation anyway.
2020 //
2021 // Before doing that, we need to make sure we never had any cset-pinned
2022 // regions. This may happen if allocation failure happened when evacuating
2023 // the about-to-be-pinned object, oom-evac protocol left the object in
2024 // the collection set, and then the pin reached the cset region. If we continue
2025 // the cycle here, we would trash the cset and alive objects in it. To avoid
2026 // it, we fail degeneration right away and slide into Full GC to recover.
2027
2028 {
2029 sync_pinned_region_status();
2030 collection_set()->clear_current_index();
2031
2032 ShenandoahHeapRegion* r;
2033 while ((r = collection_set()->next()) != NULL) {
2034 if (r->is_pinned()) {
2035 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
2036 op_degenerated_fail();
2037 return;
2038 }
2039 }
2040
2041 collection_set()->clear_current_index();
2042 }
2043
2044 op_stw_evac();
2045 if (cancelled_gc()) {
2046 op_degenerated_fail();
2047 return;
2048 }
2049 }
2050
2051 // If heuristics thinks we should do the cycle, this flag would be set,
2052 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
2053 if (has_forwarded_objects()) {
2054 op_init_updaterefs();
2055 if (cancelled_gc()) {
2056 op_degenerated_fail();
2057 return;
2058 }
2059 }
2060
2061 case _degenerated_updaterefs:
2062 if (has_forwarded_objects()) {
2063 op_final_updaterefs();
2064 if (cancelled_gc()) {
2065 op_degenerated_fail();
2066 return;
2067 }
2068 }
2069
2070 op_cleanup_complete();
2071 break;
2072
2073 default:
2074 ShouldNotReachHere();
2075 }
2076
2077 if (ShenandoahVerify) {
2078 verifier()->verify_after_degenerated();
2079 }
2080
2081 if (VerifyAfterGC) {
2082 Universe::verify();
2083 }
2084
2085 metrics.snap_after();
2086
2087 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
2088 // because that probably means the heap is overloaded and/or fragmented.
2089 if (!metrics.is_good_progress()) {
2090 _progress_last_gc.unset();
2091 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
2092 op_degenerated_futile();
2093 } else {
2094 _progress_last_gc.set();
2095 }
2096 }
2097
2098 void ShenandoahHeap::op_degenerated_fail() {
2099 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
2100 shenandoah_policy()->record_degenerated_upgrade_to_full();
2101 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
2102 }
2103
2104 void ShenandoahHeap::op_degenerated_futile() {
2105 shenandoah_policy()->record_degenerated_upgrade_to_full();
2106 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
2107 }
2108
2109 void ShenandoahHeap::force_satb_flush_all_threads() {
2110 if (!is_concurrent_mark_in_progress()) {
2111 // No need to flush SATBs
2112 return;
2113 }
2114
2115 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2116 ShenandoahThreadLocalData::set_force_satb_flush(t, true);
2117 }
2118 // The threads are not "acquiring" their thread-local data, but it does not
2119 // hurt to "release" the updates here anyway.
2120 OrderAccess::fence();
2121 }
2122
2123 void ShenandoahHeap::set_gc_state_all_threads(char state) {
2124 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2125 ShenandoahThreadLocalData::set_gc_state(t, state);
2126 }
2127 }
2128
2129 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
2130 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
2131 _gc_state.set_cond(mask, value);
2132 set_gc_state_all_threads(_gc_state.raw_value());
2133 }
2134
2135 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
2136 if (has_forwarded_objects()) {
2137 set_gc_state_mask(MARKING | UPDATEREFS, in_progress);
2138 } else {
2139 set_gc_state_mask(MARKING, in_progress);
2140 }
2141 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
2142 }
2143
2144 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
2145 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
2146 set_gc_state_mask(EVACUATION, in_progress);
2147 }
2148
2149 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
2150 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?");
2151 if (in_progress) {
2152 _concurrent_strong_root_in_progress.set();
2153 } else {
2154 _concurrent_strong_root_in_progress.unset();
2155 }
2156 }
2157
2158 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool in_progress) {
2159 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?");
2160 if (in_progress) {
2161 _concurrent_weak_root_in_progress.set();
2162 } else {
2163 _concurrent_weak_root_in_progress.unset();
2164 }
2165 }
2166
2167 void ShenandoahHeap::ref_processing_init() {
2168 assert(_max_workers > 0, "Sanity");
2169
2170 _ref_processor =
2171 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery
2172 _ref_proc_mt_processing, // MT processing
2173 _max_workers, // Degree of MT processing
2174 _ref_proc_mt_discovery, // MT discovery
2175 _max_workers, // Degree of MT discovery
2176 false, // Reference discovery is not atomic
2177 NULL, // No closure, should be installed before use
2178 true); // Scale worker threads
2179
2180 shenandoah_assert_rp_isalive_not_installed();
2181 }
2182
2183 GCTracer* ShenandoahHeap::tracer() {
2184 return shenandoah_policy()->tracer();
2185 }
2186
2187 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
2188 return _free_set->used();
2189 }
2190
2191 bool ShenandoahHeap::try_cancel_gc() {
2192 while (true) {
2193 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
2194 if (prev == CANCELLABLE) return true;
2195 else if (prev == CANCELLED) return false;
2196 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
2197 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
2198 if (Thread::current()->is_Java_thread()) {
2199 // We need to provide a safepoint here, otherwise we might
2200 // spin forever if a SP is pending.
2201 ThreadBlockInVM sp(JavaThread::current());
2202 SpinPause();
2203 }
2204 }
2205 }
2206
2207 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
2208 if (try_cancel_gc()) {
2209 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
2210 log_info(gc)("%s", msg.buffer());
2211 Events::log(Thread::current(), "%s", msg.buffer());
2212 }
2213 }
2214
2215 uint ShenandoahHeap::max_workers() {
2216 return _max_workers;
2217 }
2218
2219 void ShenandoahHeap::stop() {
2220 // The shutdown sequence should be able to terminate when GC is running.
2221
2222 // Step 0. Notify policy to disable event recording.
2223 _shenandoah_policy->record_shutdown();
2224
2225 // Step 1. Notify control thread that we are in shutdown.
2226 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
2227 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
2228 control_thread()->prepare_for_graceful_shutdown();
2229
2230 // Step 2. Notify GC workers that we are cancelling GC.
2231 cancel_gc(GCCause::_shenandoah_stop_vm);
2232
2233 // Step 3. Wait until GC worker exits normally.
2234 control_thread()->stop();
2235
2236 // Step 4. Stop String Dedup thread if it is active
2237 if (ShenandoahStringDedup::is_enabled()) {
2238 ShenandoahStringDedup::stop();
2239 }
2240 }
2241
2242 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
2243 if (!unload_classes()) return;
2244
2245 // Unload classes and purge SystemDictionary.
2246 {
2247 ShenandoahGCPhase phase(full_gc ?
2248 ShenandoahPhaseTimings::full_gc_purge_class_unload :
2249 ShenandoahPhaseTimings::purge_class_unload);
2250 bool purged_class = SystemDictionary::do_unloading(gc_timer());
2251
2252 ShenandoahIsAliveSelector is_alive;
2253 uint num_workers = _workers->active_workers();
2254 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class);
2255 _workers->run_task(&unlink_task);
2256 }
2257
2258 {
2259 ShenandoahGCPhase phase(full_gc ?
2260 ShenandoahPhaseTimings::full_gc_purge_cldg :
2261 ShenandoahPhaseTimings::purge_cldg);
2262 ClassLoaderDataGraph::purge();
2263 }
2264 // Resize and verify metaspace
2265 MetaspaceGC::compute_new_size();
2266 MetaspaceUtils::verify_metrics();
2267 }
2268
2269 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
2270 // so they should not have forwarded oops.
2271 // However, we do need to "null" dead oops in the roots, if can not be done
2272 // in concurrent cycles.
2273 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
2274 ShenandoahGCPhase root_phase(full_gc ?
2275 ShenandoahPhaseTimings::full_gc_purge :
2276 ShenandoahPhaseTimings::purge);
2277 uint num_workers = _workers->active_workers();
2278 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
2279 ShenandoahPhaseTimings::full_gc_purge_weak_par :
2280 ShenandoahPhaseTimings::purge_weak_par;
2281 ShenandoahGCPhase phase(timing_phase);
2282 ShenandoahGCWorkerPhase worker_phase(timing_phase);
2283
2284 // Cleanup weak roots
2285 if (has_forwarded_objects()) {
2286 ShenandoahForwardedIsAliveClosure is_alive;
2287 ShenandoahUpdateRefsClosure keep_alive;
2288 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
2289 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2290 _workers->run_task(&cleaning_task);
2291 } else {
2292 ShenandoahIsAliveClosure is_alive;
2293 #ifdef ASSERT
2294 ShenandoahAssertNotForwardedClosure verify_cl;
2295 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
2296 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2297 #else
2298 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
2299 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2300 #endif
2301 _workers->run_task(&cleaning_task);
2302 }
2303 }
2304
2305 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
2306 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2307 stw_process_weak_roots(full_gc);
2308 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2309 stw_unload_classes(full_gc);
2310 }
2311 }
2312
2313 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2314 set_gc_state_mask(HAS_FORWARDED, cond);
2315 }
2316
2317 void ShenandoahHeap::set_process_references(bool pr) {
2318 _process_references.set_cond(pr);
2319 }
2320
2321 void ShenandoahHeap::set_unload_classes(bool uc) {
2322 _unload_classes.set_cond(uc);
2323 }
2324
2325 bool ShenandoahHeap::process_references() const {
2326 return _process_references.is_set();
2327 }
2328
2329 bool ShenandoahHeap::unload_classes() const {
2330 return _unload_classes.is_set();
2331 }
2332
2333 address ShenandoahHeap::in_cset_fast_test_addr() {
2334 ShenandoahHeap* heap = ShenandoahHeap::heap();
2335 assert(heap->collection_set() != NULL, "Sanity");
2336 return (address) heap->collection_set()->biased_map_address();
2337 }
2338
2339 address ShenandoahHeap::cancelled_gc_addr() {
2340 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
2341 }
2342
2343 address ShenandoahHeap::gc_state_addr() {
2344 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
2345 }
2346
2347 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
2348 return Atomic::load_acquire(&_bytes_allocated_since_gc_start);
2349 }
2350
2351 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2352 Atomic::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
2353 }
2354
2355 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2356 _degenerated_gc_in_progress.set_cond(in_progress);
2357 }
2358
2359 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2360 _full_gc_in_progress.set_cond(in_progress);
2361 }
2362
2363 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2364 assert (is_full_gc_in_progress(), "should be");
2365 _full_gc_move_in_progress.set_cond(in_progress);
2366 }
2367
2368 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2369 set_gc_state_mask(UPDATEREFS, in_progress);
2370 }
2371
2372 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2373 ShenandoahCodeRoots::register_nmethod(nm);
2374 }
2375
2376 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2377 ShenandoahCodeRoots::unregister_nmethod(nm);
2378 }
2379
2380 void ShenandoahHeap::flush_nmethod(nmethod* nm) {
2381 ShenandoahCodeRoots::flush_nmethod(nm);
2382 }
2383
2384 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2385 heap_region_containing(o)->record_pin();
2386 return o;
2387 }
2388
2389 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2390 heap_region_containing(o)->record_unpin();
2391 }
2392
2393 void ShenandoahHeap::sync_pinned_region_status() {
2394 ShenandoahHeapLocker locker(lock());
2395
2396 for (size_t i = 0; i < num_regions(); i++) {
2397 ShenandoahHeapRegion *r = get_region(i);
2398 if (r->is_active()) {
2399 if (r->is_pinned()) {
2400 if (r->pin_count() == 0) {
2401 r->make_unpinned();
2402 }
2403 } else {
2404 if (r->pin_count() > 0) {
2405 r->make_pinned();
2406 }
2407 }
2408 }
2409 }
2410
2411 assert_pinned_region_status();
2412 }
2413
2414 #ifdef ASSERT
2415 void ShenandoahHeap::assert_pinned_region_status() {
2416 for (size_t i = 0; i < num_regions(); i++) {
2417 ShenandoahHeapRegion* r = get_region(i);
2418 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2419 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2420 }
2421 }
2422 #endif
2423
2424 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
2425 return _gc_timer;
2426 }
2427
2428 void ShenandoahHeap::prepare_concurrent_roots() {
2429 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2430 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
2431 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
2432 set_concurrent_weak_root_in_progress(true);
2433 }
2434 }
2435
2436 void ShenandoahHeap::prepare_concurrent_unloading() {
2437 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2438 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2439 _unloader.prepare();
2440 }
2441 }
2442
2443 void ShenandoahHeap::finish_concurrent_unloading() {
2444 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2445 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2446 _unloader.finish();
2447 }
2448 }
2449
2450 #ifdef ASSERT
2451 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2452 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2453
2454 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2455 if (UseDynamicNumberOfGCThreads) {
2456 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2457 } else {
2458 // Use ParallelGCThreads inside safepoints
2459 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
2460 }
2461 } else {
2462 if (UseDynamicNumberOfGCThreads) {
2463 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2464 } else {
2465 // Use ConcGCThreads outside safepoints
2466 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2467 }
2468 }
2469 }
2470 #endif
2471
2472 ShenandoahVerifier* ShenandoahHeap::verifier() {
2473 guarantee(ShenandoahVerify, "Should be enabled");
2474 assert (_verifier != NULL, "sanity");
2475 return _verifier;
2476 }
2477
2478 template<class T>
2479 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2480 private:
2481 T cl;
2482 ShenandoahHeap* _heap;
2483 ShenandoahRegionIterator* _regions;
2484 bool _concurrent;
2485 public:
2486 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2487 AbstractGangTask("Concurrent Update References Task"),
2488 cl(T()),
2489 _heap(ShenandoahHeap::heap()),
2490 _regions(regions),
2491 _concurrent(concurrent) {
2492 }
2493
2494 void work(uint worker_id) {
2495 if (_concurrent) {
2496 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2497 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2498 do_work();
2499 } else {
2500 ShenandoahParallelWorkerSession worker_session(worker_id);
2501 do_work();
2502 }
2503 }
2504
2505 private:
2506 void do_work() {
2507 ShenandoahHeapRegion* r = _regions->next();
2508 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2509 while (r != NULL) {
2510 HeapWord* update_watermark = r->get_update_watermark();
2511 assert (update_watermark >= r->bottom(), "sanity");
2512 if (r->is_active() && !r->is_cset()) {
2513 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2514 }
2515 if (ShenandoahPacing) {
2516 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2517 }
2518 if (_heap->check_cancelled_gc_and_yield(_concurrent)) {
2519 return;
2520 }
2521 r = _regions->next();
2522 }
2523 }
2524 };
2525
2526 void ShenandoahHeap::update_heap_references(bool concurrent) {
2527 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent);
2528 workers()->run_task(&task);
2529 }
2530
2531 void ShenandoahHeap::op_init_updaterefs() {
2532 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2533
2534 set_evacuation_in_progress(false);
2535
2536 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to
2537 // make them parsable for update code to work correctly. Plus, we can compute new sizes
2538 // for future GCLABs here.
2539 if (UseTLAB) {
2540 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_manage_gclabs);
2541 gclabs_retire(ResizeTLAB);
2542 }
2543
2544 if (ShenandoahVerify) {
2545 if (!is_degenerated_gc_in_progress()) {
2546 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2547 }
2548 verifier()->verify_before_updaterefs();
2549 }
2550
2551 set_update_refs_in_progress(true);
2552
2553 _update_refs_iterator.reset();
2554
2555 if (ShenandoahPacing) {
2556 pacer()->setup_for_updaterefs();
2557 }
2558 }
2559
2560 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2561 private:
2562 ShenandoahHeapLock* const _lock;
2563
2564 public:
2565 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2566
2567 void heap_region_do(ShenandoahHeapRegion* r) {
2568 // Drop unnecessary "pinned" state from regions that does not have CP marks
2569 // anymore, as this would allow trashing them.
2570
2571 if (r->is_active()) {
2572 if (r->is_pinned()) {
2573 if (r->pin_count() == 0) {
2574 ShenandoahHeapLocker locker(_lock);
2575 r->make_unpinned();
2576 }
2577 } else {
2578 if (r->pin_count() > 0) {
2579 ShenandoahHeapLocker locker(_lock);
2580 r->make_pinned();
2581 }
2582 }
2583 }
2584 }
2585
2586 bool is_thread_safe() { return true; }
2587 };
2588
2589 void ShenandoahHeap::op_final_updaterefs() {
2590 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2591
2592 finish_concurrent_unloading();
2593
2594 // Check if there is left-over work, and finish it
2595 if (_update_refs_iterator.has_next()) {
2596 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
2597
2598 // Finish updating references where we left off.
2599 clear_cancelled_gc();
2600 update_heap_references(false);
2601 }
2602
2603 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2604 // everything. On degenerated paths, cancelled gc would not be set anyway.
2605 if (cancelled_gc()) {
2606 clear_cancelled_gc();
2607 }
2608 assert(!cancelled_gc(), "Should have been done right before");
2609
2610 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
2611 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2612 }
2613
2614 if (is_degenerated_gc_in_progress()) {
2615 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
2616 } else {
2617 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
2618 }
2619
2620 // Has to be done before cset is clear
2621 if (ShenandoahVerify) {
2622 verifier()->verify_roots_in_to_space();
2623 }
2624
2625 {
2626 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_update_region_states);
2627 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2628 parallel_heap_region_iterate(&cl);
2629
2630 assert_pinned_region_status();
2631 }
2632
2633 {
2634 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
2635 trash_cset_regions();
2636 }
2637
2638 set_has_forwarded_objects(false);
2639 set_update_refs_in_progress(false);
2640
2641 if (ShenandoahVerify) {
2642 verifier()->verify_after_updaterefs();
2643 }
2644
2645 if (VerifyAfterGC) {
2646 Universe::verify();
2647 }
2648
2649 {
2650 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_rebuild_freeset);
2651 ShenandoahHeapLocker locker(lock());
2652 _free_set->rebuild();
2653 }
2654 }
2655
2656 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2657 print_on(st);
2658 print_heap_regions_on(st);
2659 }
2660
2661 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2662 size_t slice = r->index() / _bitmap_regions_per_slice;
2663
2664 size_t regions_from = _bitmap_regions_per_slice * slice;
2665 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2666 for (size_t g = regions_from; g < regions_to; g++) {
2667 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2668 if (skip_self && g == r->index()) continue;
2669 if (get_region(g)->is_committed()) {
2670 return true;
2671 }
2672 }
2673 return false;
2674 }
2675
2676 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2677 shenandoah_assert_heaplocked();
2678
2679 // Bitmaps in special regions do not need commits
2680 if (_bitmap_region_special) {
2681 return true;
2682 }
2683
2684 if (is_bitmap_slice_committed(r, true)) {
2685 // Some other region from the group is already committed, meaning the bitmap
2686 // slice is already committed, we exit right away.
2687 return true;
2688 }
2689
2690 // Commit the bitmap slice:
2691 size_t slice = r->index() / _bitmap_regions_per_slice;
2692 size_t off = _bitmap_bytes_per_slice * slice;
2693 size_t len = _bitmap_bytes_per_slice;
2694 char* start = (char*) _bitmap_region.start() + off;
2695
2696 if (!os::commit_memory(start, len, false)) {
2697 return false;
2698 }
2699
2700 if (AlwaysPreTouch) {
2701 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size);
2702 }
2703
2704 return true;
2705 }
2706
2707 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2708 shenandoah_assert_heaplocked();
2709
2710 // Bitmaps in special regions do not need uncommits
2711 if (_bitmap_region_special) {
2712 return true;
2713 }
2714
2715 if (is_bitmap_slice_committed(r, true)) {
2716 // Some other region from the group is still committed, meaning the bitmap
2717 // slice is should stay committed, exit right away.
2718 return true;
2719 }
2720
2721 // Uncommit the bitmap slice:
2722 size_t slice = r->index() / _bitmap_regions_per_slice;
2723 size_t off = _bitmap_bytes_per_slice * slice;
2724 size_t len = _bitmap_bytes_per_slice;
2725 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2726 return false;
2727 }
2728 return true;
2729 }
2730
2731 void ShenandoahHeap::safepoint_synchronize_begin() {
2732 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2733 SuspendibleThreadSet::synchronize();
2734 }
2735 }
2736
2737 void ShenandoahHeap::safepoint_synchronize_end() {
2738 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2739 SuspendibleThreadSet::desynchronize();
2740 }
2741 }
2742
2743 void ShenandoahHeap::vmop_entry_init_mark() {
2744 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2745 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::init_mark_gross);
2746
2747 try_inject_alloc_failure();
2748 VM_ShenandoahInitMark op;
2749 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2750 }
2751
2752 void ShenandoahHeap::vmop_entry_final_mark() {
2753 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2754 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::final_mark_gross);
2755
2756 try_inject_alloc_failure();
2757 VM_ShenandoahFinalMarkStartEvac op;
2758 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2759 }
2760
2761 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2762 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2763 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::init_update_refs_gross);
2764
2765 try_inject_alloc_failure();
2766 VM_ShenandoahInitUpdateRefs op;
2767 VMThread::execute(&op);
2768 }
2769
2770 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2771 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2772 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::final_update_refs_gross);
2773
2774 try_inject_alloc_failure();
2775 VM_ShenandoahFinalUpdateRefs op;
2776 VMThread::execute(&op);
2777 }
2778
2779 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2780 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2781 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::full_gc_gross);
2782
2783 try_inject_alloc_failure();
2784 VM_ShenandoahFullGC op(cause);
2785 VMThread::execute(&op);
2786 }
2787
2788 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2789 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2790 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::degen_gc_gross);
2791
2792 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2793 VMThread::execute(°enerated_gc);
2794 }
2795
2796 void ShenandoahHeap::entry_init_mark() {
2797 const char* msg = init_mark_event_message();
2798 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::init_mark);
2799 EventMark em("%s", msg);
2800
2801 ShenandoahWorkerScope scope(workers(),
2802 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2803 "init marking");
2804
2805 op_init_mark();
2806 }
2807
2808 void ShenandoahHeap::entry_final_mark() {
2809 const char* msg = final_mark_event_message();
2810 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::final_mark);
2811 EventMark em("%s", msg);
2812
2813 ShenandoahWorkerScope scope(workers(),
2814 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2815 "final marking");
2816
2817 op_final_mark();
2818 }
2819
2820 void ShenandoahHeap::entry_init_updaterefs() {
2821 static const char* msg = "Pause Init Update Refs";
2822 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::init_update_refs);
2823 EventMark em("%s", msg);
2824
2825 // No workers used in this phase, no setup required
2826
2827 op_init_updaterefs();
2828 }
2829
2830 void ShenandoahHeap::entry_final_updaterefs() {
2831 static const char* msg = "Pause Final Update Refs";
2832 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::final_update_refs);
2833 EventMark em("%s", msg);
2834
2835 ShenandoahWorkerScope scope(workers(),
2836 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2837 "final reference update");
2838
2839 op_final_updaterefs();
2840 }
2841
2842 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2843 static const char* msg = "Pause Full";
2844 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::full_gc, true /* log_heap_usage */);
2845 EventMark em("%s", msg);
2846
2847 ShenandoahWorkerScope scope(workers(),
2848 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2849 "full gc");
2850
2851 op_full(cause);
2852 }
2853
2854 void ShenandoahHeap::entry_degenerated(int point) {
2855 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2856 const char* msg = degen_event_message(dpoint);
2857 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::degen_gc, true /* log_heap_usage */);
2858 EventMark em("%s", msg);
2859
2860 ShenandoahWorkerScope scope(workers(),
2861 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2862 "stw degenerated gc");
2863
2864 set_degenerated_gc_in_progress(true);
2865 op_degenerated(dpoint);
2866 set_degenerated_gc_in_progress(false);
2867 }
2868
2869 void ShenandoahHeap::entry_mark() {
2870 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2871
2872 const char* msg = conc_mark_event_message();
2873 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_mark);
2874 EventMark em("%s", msg);
2875
2876 ShenandoahWorkerScope scope(workers(),
2877 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2878 "concurrent marking");
2879
2880 try_inject_alloc_failure();
2881 op_mark();
2882 }
2883
2884 void ShenandoahHeap::entry_evac() {
2885 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2886
2887 static const char* msg = "Concurrent evacuation";
2888 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_evac);
2889 EventMark em("%s", msg);
2890
2891 ShenandoahWorkerScope scope(workers(),
2892 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2893 "concurrent evacuation");
2894
2895 try_inject_alloc_failure();
2896 op_conc_evac();
2897 }
2898
2899 void ShenandoahHeap::entry_updaterefs() {
2900 static const char* msg = "Concurrent update references";
2901 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_update_refs);
2902 EventMark em("%s", msg);
2903
2904 ShenandoahWorkerScope scope(workers(),
2905 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2906 "concurrent reference update");
2907
2908 try_inject_alloc_failure();
2909 op_updaterefs();
2910 }
2911
2912 void ShenandoahHeap::entry_weak_roots() {
2913 static const char* msg = "Concurrent weak roots";
2914 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_weak_roots);
2915 EventMark em("%s", msg);
2916
2917 ShenandoahWorkerScope scope(workers(),
2918 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2919 "concurrent weak root");
2920
2921 try_inject_alloc_failure();
2922 op_weak_roots();
2923 }
2924
2925 void ShenandoahHeap::entry_class_unloading() {
2926 static const char* msg = "Concurrent class unloading";
2927 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_class_unload);
2928 EventMark em("%s", msg);
2929
2930 ShenandoahWorkerScope scope(workers(),
2931 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2932 "concurrent class unloading");
2933
2934 try_inject_alloc_failure();
2935 op_class_unloading();
2936 }
2937
2938 void ShenandoahHeap::entry_strong_roots() {
2939 static const char* msg = "Concurrent strong roots";
2940 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_strong_roots);
2941 EventMark em("%s", msg);
2942
2943 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_strong_roots);
2944
2945 ShenandoahWorkerScope scope(workers(),
2946 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2947 "concurrent strong root");
2948
2949 try_inject_alloc_failure();
2950 op_strong_roots();
2951 }
2952
2953 void ShenandoahHeap::entry_cleanup_early() {
2954 static const char* msg = "Concurrent cleanup";
2955 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_cleanup_early, true /* log_heap_usage */);
2956 EventMark em("%s", msg);
2957
2958 // This phase does not use workers, no need for setup
2959
2960 try_inject_alloc_failure();
2961 op_cleanup_early();
2962 }
2963
2964 void ShenandoahHeap::entry_cleanup_complete() {
2965 static const char* msg = "Concurrent cleanup";
2966 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_cleanup_complete, true /* log_heap_usage */);
2967 EventMark em("%s", msg);
2968
2969 // This phase does not use workers, no need for setup
2970
2971 try_inject_alloc_failure();
2972 op_cleanup_complete();
2973 }
2974
2975 void ShenandoahHeap::entry_reset() {
2976 static const char* msg = "Concurrent reset";
2977 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_reset);
2978 EventMark em("%s", msg);
2979
2980 ShenandoahWorkerScope scope(workers(),
2981 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2982 "concurrent reset");
2983
2984 try_inject_alloc_failure();
2985 op_reset();
2986 }
2987
2988 void ShenandoahHeap::entry_preclean() {
2989 if (ShenandoahPreclean && process_references()) {
2990 static const char* msg = "Concurrent precleaning";
2991 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_preclean);
2992 EventMark em("%s", msg);
2993
2994 ShenandoahWorkerScope scope(workers(),
2995 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2996 "concurrent preclean",
2997 /* check_workers = */ false);
2998
2999 try_inject_alloc_failure();
3000 op_preclean();
3001 }
3002 }
3003
3004 void ShenandoahHeap::entry_uncommit(double shrink_before) {
3005 static const char *msg = "Concurrent uncommit";
3006 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */);
3007 EventMark em("%s", msg);
3008
3009 op_uncommit(shrink_before);
3010 }
3011
3012 void ShenandoahHeap::try_inject_alloc_failure() {
3013 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
3014 _inject_alloc_failure.set();
3015 os::naked_short_sleep(1);
3016 if (cancelled_gc()) {
3017 log_info(gc)("Allocation failure was successfully injected");
3018 }
3019 }
3020 }
3021
3022 bool ShenandoahHeap::should_inject_alloc_failure() {
3023 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
3024 }
3025
3026 void ShenandoahHeap::initialize_serviceability() {
3027 _memory_pool = new ShenandoahMemoryPool(this);
3028 _cycle_memory_manager.add_pool(_memory_pool);
3029 _stw_memory_manager.add_pool(_memory_pool);
3030 }
3031
3032 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
3033 GrowableArray<GCMemoryManager*> memory_managers(2);
3034 memory_managers.append(&_cycle_memory_manager);
3035 memory_managers.append(&_stw_memory_manager);
3036 return memory_managers;
3037 }
3038
3039 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
3040 GrowableArray<MemoryPool*> memory_pools(1);
3041 memory_pools.append(_memory_pool);
3042 return memory_pools;
3043 }
3044
3045 MemoryUsage ShenandoahHeap::memory_usage() {
3046 return _memory_pool->get_memory_usage();
3047 }
3048
3049 ShenandoahRegionIterator::ShenandoahRegionIterator() :
3050 _heap(ShenandoahHeap::heap()),
3051 _index(0) {}
3052
3053 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
3054 _heap(heap),
3055 _index(0) {}
3056
3057 void ShenandoahRegionIterator::reset() {
3058 _index = 0;
3059 }
3060
3061 bool ShenandoahRegionIterator::has_next() const {
3062 return _index < _heap->num_regions();
3063 }
3064
3065 char ShenandoahHeap::gc_state() const {
3066 return _gc_state.raw_value();
3067 }
3068
3069 void ShenandoahHeap::deduplicate_string(oop str) {
3070 assert(java_lang_String::is_instance(str), "invariant");
3071
3072 if (ShenandoahStringDedup::is_enabled()) {
3073 ShenandoahStringDedup::deduplicate(str);
3074 }
3075 }
3076
3077 const char* ShenandoahHeap::init_mark_event_message() const {
3078 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3079
3080 bool proc_refs = process_references();
3081 bool unload_cls = unload_classes();
3082
3083 if (proc_refs && unload_cls) {
3084 return "Pause Init Mark (process weakrefs) (unload classes)";
3085 } else if (proc_refs) {
3086 return "Pause Init Mark (process weakrefs)";
3087 } else if (unload_cls) {
3088 return "Pause Init Mark (unload classes)";
3089 } else {
3090 return "Pause Init Mark";
3091 }
3092 }
3093
3094 const char* ShenandoahHeap::final_mark_event_message() const {
3095 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3096
3097 bool proc_refs = process_references();
3098 bool unload_cls = unload_classes();
3099
3100 if (proc_refs && unload_cls) {
3101 return "Pause Final Mark (process weakrefs) (unload classes)";
3102 } else if (proc_refs) {
3103 return "Pause Final Mark (process weakrefs)";
3104 } else if (unload_cls) {
3105 return "Pause Final Mark (unload classes)";
3106 } else {
3107 return "Pause Final Mark";
3108 }
3109 }
3110
3111 const char* ShenandoahHeap::conc_mark_event_message() const {
3112 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3113
3114 bool proc_refs = process_references();
3115 bool unload_cls = unload_classes();
3116
3117 if (proc_refs && unload_cls) {
3118 return "Concurrent marking (process weakrefs) (unload classes)";
3119 } else if (proc_refs) {
3120 return "Concurrent marking (process weakrefs)";
3121 } else if (unload_cls) {
3122 return "Concurrent marking (unload classes)";
3123 } else {
3124 return "Concurrent marking";
3125 }
3126 }
3127
3128 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
3129 switch (point) {
3130 case _degenerated_unset:
3131 return "Pause Degenerated GC (<UNSET>)";
3132 case _degenerated_outside_cycle:
3133 return "Pause Degenerated GC (Outside of Cycle)";
3134 case _degenerated_mark:
3135 return "Pause Degenerated GC (Mark)";
3136 case _degenerated_evac:
3137 return "Pause Degenerated GC (Evacuation)";
3138 case _degenerated_updaterefs:
3139 return "Pause Degenerated GC (Update Refs)";
3140 default:
3141 ShouldNotReachHere();
3142 return "ERROR";
3143 }
3144 }
3145
3146 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
3147 #ifdef ASSERT
3148 assert(_liveness_cache != NULL, "sanity");
3149 assert(worker_id < _max_workers, "sanity");
3150 for (uint i = 0; i < num_regions(); i++) {
3151 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
3152 }
3153 #endif
3154 return _liveness_cache[worker_id];
3155 }
3156
3157 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
3158 assert(worker_id < _max_workers, "sanity");
3159 assert(_liveness_cache != NULL, "sanity");
3160 ShenandoahLiveData* ld = _liveness_cache[worker_id];
3161 for (uint i = 0; i < num_regions(); i++) {
3162 ShenandoahLiveData live = ld[i];
3163 if (live > 0) {
3164 ShenandoahHeapRegion* r = get_region(i);
3165 r->increase_live_data_gc_words(live);
3166 ld[i] = 0;
3167 }
3168 }
3169 }