1 /*
2 * Copyright (c) 2021, 2022, 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
27 #include "gc/shared/barrierSetNMethod.hpp"
28 #include "gc/shared/collectorCounters.hpp"
29 #include "gc/shared/continuationGCSupport.inline.hpp"
30 #include "gc/shenandoah/shenandoahBreakpoint.hpp"
31 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
32 #include "gc/shenandoah/shenandoahConcurrentGC.hpp"
33 #include "gc/shenandoah/shenandoahFreeSet.hpp"
34 #include "gc/shenandoah/shenandoahGeneration.hpp"
35 #include "gc/shenandoah/shenandoahOldGeneration.hpp"
36 #include "gc/shenandoah/shenandoahYoungGeneration.hpp"
37 #include "gc/shenandoah/shenandoahLock.hpp"
38 #include "gc/shenandoah/shenandoahMark.inline.hpp"
39 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
40 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
41 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
42 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
43 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
44 #include "gc/shenandoah/shenandoahStackWatermark.hpp"
45 #include "gc/shenandoah/shenandoahUtils.hpp"
46 #include "gc/shenandoah/shenandoahVerifier.hpp"
47 #include "gc/shenandoah/shenandoahVMOperations.hpp"
48 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
49 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
50 #include "memory/allocation.hpp"
51 #include "prims/jvmtiTagMap.hpp"
52 #include "runtime/vmThread.hpp"
53 #include "utilities/events.hpp"
54
55 // Breakpoint support
56 class ShenandoahBreakpointGCScope : public StackObj {
57 private:
58 const GCCause::Cause _cause;
59 public:
60 ShenandoahBreakpointGCScope(GCCause::Cause cause) : _cause(cause) {
61 if (cause == GCCause::_wb_breakpoint) {
62 ShenandoahBreakpoint::start_gc();
63 ShenandoahBreakpoint::at_before_gc();
64 }
65 }
66
67 ~ShenandoahBreakpointGCScope() {
68 if (_cause == GCCause::_wb_breakpoint) {
69 ShenandoahBreakpoint::at_after_gc();
70 }
71 }
72 };
73
74 class ShenandoahBreakpointMarkScope : public StackObj {
75 private:
76 const GCCause::Cause _cause;
77 public:
78 ShenandoahBreakpointMarkScope(GCCause::Cause cause) : _cause(cause) {
79 if (_cause == GCCause::_wb_breakpoint) {
80 ShenandoahBreakpoint::at_after_marking_started();
81 }
82 }
83
84 ~ShenandoahBreakpointMarkScope() {
85 if (_cause == GCCause::_wb_breakpoint) {
86 ShenandoahBreakpoint::at_before_marking_completed();
87 }
88 }
89 };
90
91 ShenandoahConcurrentGC::ShenandoahConcurrentGC(ShenandoahGeneration* generation, bool do_old_gc_bootstrap) :
92 _mark(generation),
93 _degen_point(ShenandoahDegenPoint::_degenerated_unset),
94 _abbreviated(false),
95 _do_old_gc_bootstrap(do_old_gc_bootstrap),
96 _generation(generation) {
97 }
98
99 ShenandoahGC::ShenandoahDegenPoint ShenandoahConcurrentGC::degen_point() const {
100 return _degen_point;
101 }
102
103 bool ShenandoahConcurrentGC::collect(GCCause::Cause cause) {
104 ShenandoahHeap* const heap = ShenandoahHeap::heap();
105 heap->start_conc_gc();
106
107 ShenandoahBreakpointGCScope breakpoint_gc_scope(cause);
108
109 // Reset for upcoming marking
110 entry_reset();
111
112 // Start initial mark under STW
113 vmop_entry_init_mark();
114
115 {
116 ShenandoahBreakpointMarkScope breakpoint_mark_scope(cause);
117
118 // Reset task queue stats here, rather than in mark_concurrent_roots
119 // because remembered set scan will `push` oops into the queues and
120 // resetting after this happens will lose those counts.
121 TASKQUEUE_STATS_ONLY(_mark.task_queues()->reset_taskqueue_stats());
122
123 // Concurrent remembered set scanning
124 entry_scan_remembered_set();
125 // When RS scanning yields, we will need a check_cancellation_and_abort()
126 // degeneration point here.
127
128 // Concurrent mark roots
129 entry_mark_roots();
130 if (check_cancellation_and_abort(ShenandoahDegenPoint::_degenerated_roots)) return false;
131
132 // Continue concurrent mark
133 entry_mark();
134 if (check_cancellation_and_abort(ShenandoahDegenPoint::_degenerated_mark)) return false;
135 }
136
137 // Complete marking under STW, and start evacuation
138 vmop_entry_final_mark();
139
140 // If GC was cancelled before final mark, then the safepoint operation will do nothing
141 // and the concurrent mark will still be in progress. In this case it is safe to resume
142 // the degenerated cycle from the marking phase. On the other hand, if the GC is cancelled
143 // after final mark (but before this check), then the final mark safepoint operation
144 // will have finished the mark (setting concurrent mark in progress to false). Final mark
145 // will also have setup state (in concurrent stack processing) that will not be safe to
146 // resume from the marking phase in the degenerated cycle. That is, if the cancellation
147 // occurred after final mark, we must resume the degenerated cycle after the marking phase.
148 if (_generation->is_concurrent_mark_in_progress() && check_cancellation_and_abort(ShenandoahDegenPoint::_degenerated_mark)) {
149 assert(!heap->is_concurrent_weak_root_in_progress(), "Weak roots should not be in progress when concurrent mark is in progress");
150 return false;
151 }
152
153 // Concurrent stack processing
154 if (heap->is_evacuation_in_progress()) {
155 entry_thread_roots();
156 }
157
158 // Process weak roots that might still point to regions that would be broken by cleanup
159 if (heap->is_concurrent_weak_root_in_progress()) {
160 entry_weak_refs();
161 entry_weak_roots();
162 }
163
164 // Final mark might have reclaimed some immediate garbage, kick cleanup to reclaim
165 // the space. This would be the last action if there is nothing to evacuate. Note that
166 // we will not age young-gen objects in the case that we skip evacuation.
167 entry_cleanup_early();
168
169 {
170 ShenandoahHeapLocker locker(heap->lock());
171 heap->free_set()->log_status();
172 }
173
174 // Perform concurrent class unloading
175 if (heap->unload_classes() &&
176 heap->is_concurrent_weak_root_in_progress()) {
177 entry_class_unloading();
178 }
179
180 // Processing strong roots
181 // This may be skipped if there is nothing to update/evacuate.
182 // If so, strong_root_in_progress would be unset.
183 if (heap->is_concurrent_strong_root_in_progress()) {
184 entry_strong_roots();
185 }
186
187 // Global marking has completed. We need to fill in any unmarked objects in the old generation
188 // so that subsequent remembered set scans will not walk pointers into reclaimed memory.
189 if (!heap->cancelled_gc() && heap->mode()->is_generational() && _generation->generation_mode() == GLOBAL) {
190 entry_global_coalesce_and_fill();
191 }
192
193 // Continue the cycle with evacuation and optional update-refs.
194 // This may be skipped if there is nothing to evacuate.
195 // If so, evac_in_progress would be unset by collection set preparation code.
196 if (heap->is_evacuation_in_progress()) {
197 // Concurrently evacuate
198 entry_evacuate();
199 if (check_cancellation_and_abort(ShenandoahDegenPoint::_degenerated_evac)) return false;
200
201 // Perform update-refs phase.
202 vmop_entry_init_updaterefs();
203 entry_updaterefs();
204 if (check_cancellation_and_abort(ShenandoahDegenPoint::_degenerated_updaterefs)) return false;
205
206 // Concurrent update thread roots
207 entry_update_thread_roots();
208 if (check_cancellation_and_abort(ShenandoahDegenPoint::_degenerated_updaterefs)) return false;
209
210 vmop_entry_final_updaterefs();
211
212 // Update references freed up collection set, kick the cleanup to reclaim the space.
213 entry_cleanup_complete();
214 } else {
215 // We chose not to evacuate because we found sufficient immediate garbage.
216 vmop_entry_final_roots(heap->is_aging_cycle());
217 _abbreviated = true;
218 }
219
220 if (heap->mode()->is_generational()) {
221 size_t old_available, young_available;
222 {
223 ShenandoahYoungGeneration* young_gen = heap->young_generation();
224 ShenandoahGeneration* old_gen = heap->old_generation();
225 ShenandoahHeapLocker locker(heap->lock());
226
227 size_t old_usage_before_evac = heap->capture_old_usage(0);
228 size_t old_usage_now = old_gen->used();
229 size_t promoted_bytes = old_usage_now - old_usage_before_evac;
230 heap->set_previous_promotion(promoted_bytes);
231
232 young_gen->unadjust_available();
233 old_gen->unadjust_available();
234 // No need to old_gen->increase_used().
235 // That was done when plabs were allocated, accounting for both old evacs and promotions.
236
237 young_available = young_gen->adjusted_available();
238 old_available = old_gen->adjusted_available();
239
240 heap->set_alloc_supplement_reserve(0);
241 heap->set_young_evac_reserve(0);
242 heap->set_old_evac_reserve(0);
243 heap->reset_old_evac_expended();
244 heap->set_promoted_reserve(0);
245 }
246 }
247 return true;
248 }
249
250 void ShenandoahConcurrentGC::vmop_entry_init_mark() {
251 ShenandoahHeap* const heap = ShenandoahHeap::heap();
252 TraceCollectorStats tcs(heap->monitoring_support()->stw_collection_counters());
253 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::init_mark_gross);
254
255 heap->try_inject_alloc_failure();
256 VM_ShenandoahInitMark op(this);
257 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
258 }
259
260 void ShenandoahConcurrentGC::vmop_entry_final_mark() {
261 ShenandoahHeap* const heap = ShenandoahHeap::heap();
262 TraceCollectorStats tcs(heap->monitoring_support()->stw_collection_counters());
263 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::final_mark_gross);
264
265 heap->try_inject_alloc_failure();
266 VM_ShenandoahFinalMarkStartEvac op(this);
267 VMThread::execute(&op); // jump to entry_final_mark under safepoint
268 }
269
270 void ShenandoahConcurrentGC::vmop_entry_init_updaterefs() {
271 ShenandoahHeap* const heap = ShenandoahHeap::heap();
272 TraceCollectorStats tcs(heap->monitoring_support()->stw_collection_counters());
273 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::init_update_refs_gross);
274
275 heap->try_inject_alloc_failure();
276 VM_ShenandoahInitUpdateRefs op(this);
277 VMThread::execute(&op);
278 }
279
280 void ShenandoahConcurrentGC::vmop_entry_final_updaterefs() {
281 ShenandoahHeap* const heap = ShenandoahHeap::heap();
282 TraceCollectorStats tcs(heap->monitoring_support()->stw_collection_counters());
283 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::final_update_refs_gross);
284
285 heap->try_inject_alloc_failure();
286 VM_ShenandoahFinalUpdateRefs op(this);
287 VMThread::execute(&op);
288 }
289
290 void ShenandoahConcurrentGC::vmop_entry_final_roots(bool increment_region_ages) {
291 ShenandoahHeap* const heap = ShenandoahHeap::heap();
292 TraceCollectorStats tcs(heap->monitoring_support()->stw_collection_counters());
293 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::final_roots_gross);
294
295 // This phase does not use workers, no need for setup
296 heap->try_inject_alloc_failure();
297 VM_ShenandoahFinalRoots op(this, increment_region_ages);
298 VMThread::execute(&op);
299 }
300
301 void ShenandoahConcurrentGC::entry_init_mark() {
302 char msg[1024];
303 init_mark_event_message(msg, sizeof(msg));
304 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::init_mark);
305 EventMark em("%s", msg);
306
307 ShenandoahWorkerScope scope(ShenandoahHeap::heap()->workers(),
308 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
309 "init marking");
310
311 op_init_mark();
312 }
313
314 void ShenandoahConcurrentGC::entry_final_mark() {
315 char msg[1024];
316 final_mark_event_message(msg, sizeof(msg));
317 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::final_mark);
318 EventMark em("%s", msg);
319
320 ShenandoahWorkerScope scope(ShenandoahHeap::heap()->workers(),
321 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
322 "final marking");
323
324 op_final_mark();
325 }
326
327 void ShenandoahConcurrentGC::entry_init_updaterefs() {
328 static const char* msg = "Pause Init Update Refs";
329 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::init_update_refs);
330 EventMark em("%s", msg);
331
332 // No workers used in this phase, no setup required
333 op_init_updaterefs();
334 }
335
336 void ShenandoahConcurrentGC::entry_final_updaterefs() {
337 static const char* msg = "Pause Final Update Refs";
338 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::final_update_refs);
339 EventMark em("%s", msg);
340
341 ShenandoahWorkerScope scope(ShenandoahHeap::heap()->workers(),
342 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
343 "final reference update");
344
345 op_final_updaterefs();
346 }
347
348 void ShenandoahConcurrentGC::entry_final_roots() {
349 static const char* msg = "Pause Final Roots";
350 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::final_roots);
351 EventMark em("%s", msg);
352
353 op_final_roots();
354 }
355
356 void ShenandoahConcurrentGC::entry_reset() {
357 ShenandoahHeap* const heap = ShenandoahHeap::heap();
358 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
359 static const char* msg = "Concurrent reset";
360 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_reset);
361 EventMark em("%s", msg);
362
363 ShenandoahWorkerScope scope(heap->workers(),
364 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
365 "concurrent reset");
366
367 heap->try_inject_alloc_failure();
368 op_reset();
369 }
370
371 void ShenandoahConcurrentGC::entry_scan_remembered_set() {
372 if (_generation->generation_mode() == YOUNG) {
373 ShenandoahHeap* const heap = ShenandoahHeap::heap();
374 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
375 const char* msg = "Concurrent remembered set scanning";
376 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::init_scan_rset);
377 EventMark em("%s", msg);
378
379 ShenandoahWorkerScope scope(heap->workers(),
380 ShenandoahWorkerPolicy::calc_workers_for_rs_scanning(),
381 msg);
382
383 heap->try_inject_alloc_failure();
384 _generation->scan_remembered_set(true /* is_concurrent */);
385 }
386 }
387
388 void ShenandoahConcurrentGC::entry_mark_roots() {
389 ShenandoahHeap* const heap = ShenandoahHeap::heap();
390 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
391 const char* msg = "Concurrent marking roots";
392 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_mark_roots);
393 EventMark em("%s", msg);
394
395 ShenandoahWorkerScope scope(heap->workers(),
396 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
397 "concurrent marking roots");
398
399 heap->try_inject_alloc_failure();
400 op_mark_roots();
401 }
402
403 void ShenandoahConcurrentGC::entry_mark() {
404 char msg[1024];
405 ShenandoahHeap* const heap = ShenandoahHeap::heap();
406 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
407 conc_mark_event_message(msg, sizeof(msg));
408 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_mark);
409 EventMark em("%s", msg);
410
411 ShenandoahWorkerScope scope(heap->workers(),
412 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
413 "concurrent marking");
414
415 heap->try_inject_alloc_failure();
416 op_mark();
417 }
418
419 void ShenandoahConcurrentGC::entry_thread_roots() {
420 ShenandoahHeap* const heap = ShenandoahHeap::heap();
421 static const char* msg = "Concurrent thread roots";
422 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_thread_roots);
423 EventMark em("%s", msg);
424
425 ShenandoahWorkerScope scope(heap->workers(),
426 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
427 msg);
428
429 heap->try_inject_alloc_failure();
430 op_thread_roots();
431 }
432
433 void ShenandoahConcurrentGC::entry_weak_refs() {
434 ShenandoahHeap* const heap = ShenandoahHeap::heap();
435 static const char* msg = "Concurrent weak references";
436 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_weak_refs);
437 EventMark em("%s", msg);
438
439 ShenandoahWorkerScope scope(heap->workers(),
440 ShenandoahWorkerPolicy::calc_workers_for_conc_refs_processing(),
441 "concurrent weak references");
442
443 heap->try_inject_alloc_failure();
444 op_weak_refs();
445 }
446
447 void ShenandoahConcurrentGC::entry_weak_roots() {
448 ShenandoahHeap* const heap = ShenandoahHeap::heap();
449 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
450 static const char* msg = "Concurrent weak roots";
451 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_weak_roots);
452 EventMark em("%s", msg);
453
454 ShenandoahWorkerScope scope(heap->workers(),
455 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
456 "concurrent weak root");
457
458 heap->try_inject_alloc_failure();
459 op_weak_roots();
460 }
461
462 void ShenandoahConcurrentGC::entry_class_unloading() {
463 ShenandoahHeap* const heap = ShenandoahHeap::heap();
464 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
465 static const char* msg = "Concurrent class unloading";
466 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_class_unload);
467 EventMark em("%s", msg);
468
469 ShenandoahWorkerScope scope(heap->workers(),
470 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
471 "concurrent class unloading");
472
473 heap->try_inject_alloc_failure();
474 op_class_unloading();
475 }
476
477 void ShenandoahConcurrentGC::entry_strong_roots() {
478 ShenandoahHeap* const heap = ShenandoahHeap::heap();
479 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
480 static const char* msg = "Concurrent strong roots";
481 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_strong_roots);
482 EventMark em("%s", msg);
483
484 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_strong_roots);
485
486 ShenandoahWorkerScope scope(heap->workers(),
487 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
488 "concurrent strong root");
489
490 heap->try_inject_alloc_failure();
491 op_strong_roots();
492 }
493
494 void ShenandoahConcurrentGC::entry_cleanup_early() {
495 ShenandoahHeap* const heap = ShenandoahHeap::heap();
496 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
497 static const char* msg = "Concurrent cleanup";
498 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_cleanup_early, true /* log_heap_usage */);
499 EventMark em("%s", msg);
500
501 // This phase does not use workers, no need for setup
502 heap->try_inject_alloc_failure();
503 op_cleanup_early();
504 }
505
506 void ShenandoahConcurrentGC::entry_evacuate() {
507 ShenandoahHeap* const heap = ShenandoahHeap::heap();
508 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
509
510 static const char* msg = "Concurrent evacuation";
511 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_evac);
512 EventMark em("%s", msg);
513
514 ShenandoahWorkerScope scope(heap->workers(),
515 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
516 "concurrent evacuation");
517
518 heap->try_inject_alloc_failure();
519 op_evacuate();
520 }
521
522 void ShenandoahConcurrentGC::entry_update_thread_roots() {
523 ShenandoahHeap* const heap = ShenandoahHeap::heap();
524 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
525
526 static const char* msg = "Concurrent update thread roots";
527 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_update_thread_roots);
528 EventMark em("%s", msg);
529
530 // No workers used in this phase, no setup required
531 heap->try_inject_alloc_failure();
532 op_update_thread_roots();
533 }
534
535 void ShenandoahConcurrentGC::entry_updaterefs() {
536 ShenandoahHeap* const heap = ShenandoahHeap::heap();
537 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
538 static const char* msg = "Concurrent update references";
539 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_update_refs);
540 EventMark em("%s", msg);
541
542 ShenandoahWorkerScope scope(heap->workers(),
543 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
544 "concurrent reference update");
545
546 heap->try_inject_alloc_failure();
547 op_updaterefs();
548 }
549
550 void ShenandoahConcurrentGC::entry_cleanup_complete() {
551 ShenandoahHeap* const heap = ShenandoahHeap::heap();
552 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
553 static const char* msg = "Concurrent cleanup";
554 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_cleanup_complete, true /* log_heap_usage */);
555 EventMark em("%s", msg);
556
557 // This phase does not use workers, no need for setup
558 heap->try_inject_alloc_failure();
559 op_cleanup_complete();
560 }
561
562 void ShenandoahConcurrentGC::entry_global_coalesce_and_fill() {
563 ShenandoahHeap* const heap = ShenandoahHeap::heap();
564
565 const char* msg = "Coalescing and filling old regions in global collect";
566 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::coalesce_and_fill);
567
568 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
569 EventMark em("%s", msg);
570 ShenandoahWorkerScope scope(heap->workers(),
571 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
572 "concurrent coalesce and fill");
573
574 op_global_coalesce_and_fill();
575 }
576
577 void ShenandoahConcurrentGC::op_reset() {
578 ShenandoahHeap* const heap = ShenandoahHeap::heap();
579 if (ShenandoahPacing) {
580 heap->pacer()->setup_for_reset();
581 }
582 _generation->prepare_gc();
583 }
584
585 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
586 private:
587 ShenandoahMarkingContext* const _ctx;
588 public:
589 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
590
591 void heap_region_do(ShenandoahHeapRegion* r) {
592 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
593 if (r->is_active()) {
594 // Check if region needs updating its TAMS. We have updated it already during concurrent
595 // reset, so it is very likely we don't need to do another write here. Since most regions
596 // are not "active", this path is relatively rare.
597 if (_ctx->top_at_mark_start(r) != r->top()) {
598 _ctx->capture_top_at_mark_start(r);
599 }
600 } else {
601 assert(_ctx->top_at_mark_start(r) == r->top(),
602 "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
603 }
604 }
605
606 bool is_thread_safe() { return true; }
607 };
608
609 void ShenandoahConcurrentGC::start_mark() {
610 _mark.start_mark();
611 }
612
613 void ShenandoahConcurrentGC::op_init_mark() {
614 ShenandoahHeap* const heap = ShenandoahHeap::heap();
615 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
616 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
617
618 assert(_generation->is_bitmap_clear(), "need clear marking bitmap");
619 assert(!_generation->is_mark_complete(), "should not be complete");
620 assert(!heap->has_forwarded_objects(), "No forwarded objects on this path");
621
622
623 if (heap->mode()->is_generational()) {
624 if (_generation->generation_mode() == YOUNG || (_generation->generation_mode() == GLOBAL && ShenandoahVerify)) {
625 // The current implementation of swap_remembered_set() copies the write-card-table
626 // to the read-card-table. The remembered sets are also swapped for GLOBAL collections
627 // so that the verifier works with the correct copy of the card table when verifying.
628 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_swap_rset);
629 _generation->swap_remembered_set();
630 }
631
632 if (_generation->generation_mode() == GLOBAL) {
633 heap->cancel_old_gc();
634 } else if (heap->is_concurrent_old_mark_in_progress()) {
635 // Purge the SATB buffers, transferring any valid, old pointers to the
636 // old generation mark queue. Any pointers in a young region will be
637 // abandoned.
638 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_transfer_satb);
639 heap->transfer_old_pointers_from_satb();
640 }
641 }
642
643 if (ShenandoahVerify) {
644 heap->verifier()->verify_before_concmark();
645 }
646
647 if (VerifyBeforeGC) {
648 Universe::verify();
649 }
650
651 _generation->set_concurrent_mark_in_progress(true);
652
653 start_mark();
654
655 if (_do_old_gc_bootstrap) {
656 // Update region state for both young and old regions
657 // TODO: We should be able to pull this out of the safepoint for the bootstrap
658 // cycle. The top of an old region will only move when a GC cycle evacuates
659 // objects into it. When we start an old cycle, we know that nothing can touch
660 // the top of old regions.
661 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_region_states);
662 ShenandoahInitMarkUpdateRegionStateClosure cl;
663 heap->parallel_heap_region_iterate(&cl);
664 } else {
665 // Update region state for only young regions
666 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_region_states);
667 ShenandoahInitMarkUpdateRegionStateClosure cl;
668 _generation->parallel_heap_region_iterate(&cl);
669 }
670
671 // Weak reference processing
672 ShenandoahReferenceProcessor* rp = _generation->ref_processor();
673 rp->reset_thread_locals();
674 rp->set_soft_reference_policy(heap->soft_ref_policy()->should_clear_all_soft_refs());
675
676 // Make above changes visible to worker threads
677 OrderAccess::fence();
678
679 // Arm nmethods for concurrent marking. When a nmethod is about to be executed,
680 // we need to make sure that all its metadata are marked. alternative is to remark
681 // thread roots at final mark pause, but it can be potential latency killer.
682 if (heap->unload_classes()) {
683 ShenandoahCodeRoots::arm_nmethods();
684 }
685
686 ShenandoahStackWatermark::change_epoch_id();
687 if (ShenandoahPacing) {
688 heap->pacer()->setup_for_mark();
689 }
690 }
691
692 void ShenandoahConcurrentGC::op_mark_roots() {
693 _mark.mark_concurrent_roots();
694 }
695
696 void ShenandoahConcurrentGC::op_mark() {
697 _mark.concurrent_mark();
698 }
699
700 void ShenandoahConcurrentGC::op_final_mark() {
701 ShenandoahHeap* const heap = ShenandoahHeap::heap();
702 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
703 assert(!heap->has_forwarded_objects(), "No forwarded objects on this path");
704
705 if (ShenandoahVerify) {
706 heap->verifier()->verify_roots_no_forwarded();
707 }
708
709 if (!heap->cancelled_gc()) {
710 _mark.finish_mark();
711 assert(!heap->cancelled_gc(), "STW mark cannot OOM");
712
713 // Notify JVMTI that the tagmap table will need cleaning.
714 JvmtiTagMap::set_needs_cleaning();
715
716 // The collection set is chosen by prepare_regions_and_collection_set().
717 //
718 // TODO: Under severe memory overload conditions that can be checked here, we may want to limit
719 // the inclusion of old-gen candidates within the collection set. This would allow us to prioritize efforts on
720 // evacuating young-gen, This remediation is most appropriate when old-gen availability is very high (so there
721 // are negligible negative impacts from delaying completion of old-gen evacuation) and when young-gen collections
722 // are "under duress" (as signalled by very low availability of memory within young-gen, indicating that/ young-gen
723 // collections are not triggering frequently enough).
724 _generation->prepare_regions_and_collection_set(true /*concurrent*/);
725
726 // Upon return from prepare_regions_and_collection_set(), certain parameters have been established to govern the
727 // evacuation efforts that are about to begin. In particular:
728 //
729 // heap->get_promoted_reserve() represents the amount of memory within old-gen's available memory that has
730 // been set aside to hold objects promoted from young-gen memory. This represents an estimated percentage
731 // of the live young-gen memory within the collection set. If there is more data ready to be promoted than
732 // can fit within this reserve, the promotion of some objects will be deferred until a subsequent evacuation
733 // pass.
734 //
735 // heap->get_old_evac_reserve() represents the amount of memory within old-gen's available memory that has been
736 // set aside to hold objects evacuated from the old-gen collection set.
737 //
738 // heap->get_young_evac_reserve() represents the amount of memory within young-gen's available memory that has
739 // been set aside to hold objects evacuated from the young-gen collection set. Conservatively, this value
740 // equals the entire amount of live young-gen memory within the collection set, even though some of this memory
741 // will likely be promoted.
742 //
743 // heap->get_alloc_supplement_reserve() represents the amount of old-gen memory that can be allocated during evacuation
744 // and update-refs phases of gc. The young evacuation reserve has already been removed from this quantity.
745
746 // Has to be done after cset selection
747 heap->prepare_concurrent_roots();
748
749 if (!heap->collection_set()->is_empty()) {
750 if (ShenandoahVerify) {
751 heap->verifier()->verify_before_evacuation();
752 }
753
754 heap->set_evacuation_in_progress(true);
755 // From here on, we need to update references.
756 heap->set_has_forwarded_objects(true);
757
758 // Verify before arming for concurrent processing.
759 // Otherwise, verification can trigger stack processing.
760 if (ShenandoahVerify) {
761 heap->verifier()->verify_during_evacuation();
762 }
763
764 // Arm nmethods/stack for concurrent processing
765 ShenandoahCodeRoots::arm_nmethods();
766 ShenandoahStackWatermark::change_epoch_id();
767
768 if (heap->mode()->is_generational()) {
769 // Calculate the temporary evacuation allowance supplement to young-gen memory capacity (for allocations
770 // and young-gen evacuations).
771 size_t young_available = heap->young_generation()->adjust_available(heap->get_alloc_supplement_reserve());
772 // old_available is memory that can hold promotions and evacuations. Subtract out the memory that is being
773 // loaned for young-gen allocations or evacuations.
774 size_t old_available = heap->old_generation()->adjust_available(-heap->get_alloc_supplement_reserve());
775
776 log_info(gc, ergo)("After generational memory budget adjustments, old available: " SIZE_FORMAT
777 "%s, young_available: " SIZE_FORMAT "%s",
778 byte_size_in_proper_unit(old_available), proper_unit_for_byte_size(old_available),
779 byte_size_in_proper_unit(young_available), proper_unit_for_byte_size(young_available));
780 }
781
782 if (ShenandoahPacing) {
783 heap->pacer()->setup_for_evac();
784 }
785 } else {
786 if (ShenandoahVerify) {
787 heap->verifier()->verify_after_concmark();
788 }
789
790 if (VerifyAfterGC) {
791 Universe::verify();
792 }
793 }
794 }
795 }
796
797 class ShenandoahConcurrentEvacThreadClosure : public ThreadClosure {
798 private:
799 OopClosure* const _oops;
800
801 public:
802 ShenandoahConcurrentEvacThreadClosure(OopClosure* oops);
803 void do_thread(Thread* thread);
804 };
805
806 ShenandoahConcurrentEvacThreadClosure::ShenandoahConcurrentEvacThreadClosure(OopClosure* oops) :
807 _oops(oops) {
808 }
809
810 void ShenandoahConcurrentEvacThreadClosure::do_thread(Thread* thread) {
811 JavaThread* const jt = JavaThread::cast(thread);
812 StackWatermarkSet::finish_processing(jt, _oops, StackWatermarkKind::gc);
813 }
814
815 class ShenandoahConcurrentEvacUpdateThreadTask : public WorkerTask {
816 private:
817 ShenandoahJavaThreadsIterator _java_threads;
818
819 public:
820 ShenandoahConcurrentEvacUpdateThreadTask(uint n_workers) :
821 WorkerTask("Shenandoah Evacuate/Update Concurrent Thread Roots"),
822 _java_threads(ShenandoahPhaseTimings::conc_thread_roots, n_workers) {
823 }
824
825 void work(uint worker_id) {
826 // ShenandoahEvacOOMScope has to be setup by ShenandoahContextEvacuateUpdateRootsClosure.
827 // Otherwise, may deadlock with watermark lock
828 ShenandoahContextEvacuateUpdateRootsClosure oops_cl;
829 ShenandoahConcurrentEvacThreadClosure thr_cl(&oops_cl);
830 _java_threads.threads_do(&thr_cl, worker_id);
831 }
832 };
833
834 void ShenandoahConcurrentGC::op_thread_roots() {
835 ShenandoahHeap* const heap = ShenandoahHeap::heap();
836 assert(heap->is_evacuation_in_progress(), "Checked by caller");
837 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_thread_roots);
838 ShenandoahConcurrentEvacUpdateThreadTask task(heap->workers()->active_workers());
839 heap->workers()->run_task(&task);
840 }
841
842 void ShenandoahConcurrentGC::op_weak_refs() {
843 ShenandoahHeap* const heap = ShenandoahHeap::heap();
844 assert(heap->is_concurrent_weak_root_in_progress(), "Only during this phase");
845 // Concurrent weak refs processing
846 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_weak_refs);
847 if (heap->gc_cause() == GCCause::_wb_breakpoint) {
848 ShenandoahBreakpoint::at_after_reference_processing_started();
849 }
850 _generation->ref_processor()->process_references(ShenandoahPhaseTimings::conc_weak_refs, heap->workers(), true /* concurrent */);
851 }
852
853 class ShenandoahEvacUpdateCleanupOopStorageRootsClosure : public BasicOopIterateClosure {
854 private:
855 ShenandoahHeap* const _heap;
856 ShenandoahMarkingContext* const _mark_context;
857 bool _evac_in_progress;
858 Thread* const _thread;
859
860 public:
861 ShenandoahEvacUpdateCleanupOopStorageRootsClosure();
862 void do_oop(oop* p);
863 void do_oop(narrowOop* p);
864 };
865
866 ShenandoahEvacUpdateCleanupOopStorageRootsClosure::ShenandoahEvacUpdateCleanupOopStorageRootsClosure() :
867 _heap(ShenandoahHeap::heap()),
868 _mark_context(ShenandoahHeap::heap()->marking_context()),
869 _evac_in_progress(ShenandoahHeap::heap()->is_evacuation_in_progress()),
870 _thread(Thread::current()) {
871 }
872
873 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(oop* p) {
874 const oop obj = RawAccess<>::oop_load(p);
875 if (!CompressedOops::is_null(obj)) {
876 if (!_mark_context->is_marked(obj)) {
877 if (_heap->is_in_active_generation(obj)) {
878 // TODO: This worries me. Here we are asserting that an unmarked from-space object is 'correct'.
879 // Normally, I would call this a bogus assert, but there seems to be a legitimate use-case for
880 // accessing from-space objects during class unloading. However, the from-space object may have
881 // been "filled". We've made no effort to prevent old generation classes being unloaded by young
882 // gen (and vice-versa).
883 shenandoah_assert_correct(p, obj);
884 ShenandoahHeap::atomic_clear_oop(p, obj);
885 }
886 } else if (_evac_in_progress && _heap->in_collection_set(obj)) {
887 oop resolved = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
888 if (resolved == obj) {
889 resolved = _heap->evacuate_object(obj, _thread);
890 }
891 ShenandoahHeap::atomic_update_oop(resolved, p, obj);
892 assert(_heap->cancelled_gc() ||
893 _mark_context->is_marked(resolved) && !_heap->in_collection_set(resolved),
894 "Sanity");
895 }
896 }
897 }
898
899 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(narrowOop* p) {
900 ShouldNotReachHere();
901 }
902
903 class ShenandoahIsCLDAliveClosure : public CLDClosure {
904 public:
905 void do_cld(ClassLoaderData* cld) {
906 cld->is_alive();
907 }
908 };
909
910 class ShenandoahIsNMethodAliveClosure: public NMethodClosure {
911 public:
912 void do_nmethod(nmethod* n) {
913 n->is_unloading();
914 }
915 };
916
917 // This task not only evacuates/updates marked weak roots, but also "NULL"
918 // dead weak roots.
919 class ShenandoahConcurrentWeakRootsEvacUpdateTask : public WorkerTask {
920 private:
921 ShenandoahVMWeakRoots<true /*concurrent*/> _vm_roots;
922
923 // Roots related to concurrent class unloading
924 ShenandoahClassLoaderDataRoots<true /* concurrent */>
925 _cld_roots;
926 ShenandoahConcurrentNMethodIterator _nmethod_itr;
927 ShenandoahPhaseTimings::Phase _phase;
928
929 public:
930 ShenandoahConcurrentWeakRootsEvacUpdateTask(ShenandoahPhaseTimings::Phase phase) :
931 WorkerTask("Shenandoah Evacuate/Update Concurrent Weak Roots"),
932 _vm_roots(phase),
933 _cld_roots(phase, ShenandoahHeap::heap()->workers()->active_workers(), false /*heap iteration*/),
934 _nmethod_itr(ShenandoahCodeRoots::table()),
935 _phase(phase) {
936 if (ShenandoahHeap::heap()->unload_classes()) {
937 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
938 _nmethod_itr.nmethods_do_begin();
939 }
940 }
941
942 ~ShenandoahConcurrentWeakRootsEvacUpdateTask() {
943 if (ShenandoahHeap::heap()->unload_classes()) {
944 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
945 _nmethod_itr.nmethods_do_end();
946 }
947 // Notify runtime data structures of potentially dead oops
948 _vm_roots.report_num_dead();
949 }
950
951 void work(uint worker_id) {
952 ShenandoahConcurrentWorkerSession worker_session(worker_id);
953 {
954 ShenandoahEvacOOMScope oom;
955 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration
956 // may race against OopStorage::release() calls.
957 ShenandoahEvacUpdateCleanupOopStorageRootsClosure cl;
958 _vm_roots.oops_do(&cl, worker_id);
959 }
960
961 // If we are going to perform concurrent class unloading later on, we need to
962 // cleanup the weak oops in CLD and determinate nmethod's unloading state, so that we
963 // can cleanup immediate garbage sooner.
964 if (ShenandoahHeap::heap()->unload_classes()) {
965 // Applies ShenandoahIsCLDAlive closure to CLDs, native barrier will either NULL the
966 // CLD's holder or evacuate it.
967 {
968 ShenandoahIsCLDAliveClosure is_cld_alive;
969 _cld_roots.cld_do(&is_cld_alive, worker_id);
970 }
971
972 // Applies ShenandoahIsNMethodAliveClosure to registered nmethods.
973 // The closure calls nmethod->is_unloading(). The is_unloading
974 // state is cached, therefore, during concurrent class unloading phase,
975 // we will not touch the metadata of unloading nmethods
976 {
977 ShenandoahWorkerTimingsTracker timer(_phase, ShenandoahPhaseTimings::CodeCacheRoots, worker_id);
978 ShenandoahIsNMethodAliveClosure is_nmethod_alive;
979 _nmethod_itr.nmethods_do(&is_nmethod_alive);
980 }
981 }
982 }
983 };
984
985 void ShenandoahConcurrentGC::op_weak_roots() {
986 ShenandoahHeap* const heap = ShenandoahHeap::heap();
987 assert(heap->is_concurrent_weak_root_in_progress(), "Only during this phase");
988 // Concurrent weak root processing
989 {
990 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_weak_roots_work);
991 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_weak_roots_work);
992 ShenandoahConcurrentWeakRootsEvacUpdateTask task(ShenandoahPhaseTimings::conc_weak_roots_work);
993 heap->workers()->run_task(&task);
994 }
995
996 // Perform handshake to flush out dead oops
997 {
998 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_weak_roots_rendezvous);
999 heap->rendezvous_threads();
1000 }
1001 }
1002
1003 void ShenandoahConcurrentGC::op_class_unloading() {
1004 ShenandoahHeap* const heap = ShenandoahHeap::heap();
1005 assert (heap->is_concurrent_weak_root_in_progress() &&
1006 heap->unload_classes(),
1007 "Checked by caller");
1008 heap->do_class_unloading();
1009 }
1010
1011 class ShenandoahEvacUpdateCodeCacheClosure : public NMethodClosure {
1012 private:
1013 BarrierSetNMethod* const _bs;
1014 ShenandoahEvacuateUpdateMetadataClosure _cl;
1015
1016 public:
1017 ShenandoahEvacUpdateCodeCacheClosure() :
1018 _bs(BarrierSet::barrier_set()->barrier_set_nmethod()),
1019 _cl() {
1020 }
1021
1022 void do_nmethod(nmethod* n) {
1023 ShenandoahNMethod* data = ShenandoahNMethod::gc_data(n);
1024 ShenandoahReentrantLocker locker(data->lock());
1025 // Setup EvacOOM scope below reentrant lock to avoid deadlock with
1026 // nmethod_entry_barrier
1027 ShenandoahEvacOOMScope oom;
1028 data->oops_do(&_cl, true/*fix relocation*/);
1029 _bs->disarm(n);
1030 }
1031 };
1032
1033 class ShenandoahConcurrentRootsEvacUpdateTask : public WorkerTask {
1034 private:
1035 ShenandoahPhaseTimings::Phase _phase;
1036 ShenandoahVMRoots<true /*concurrent*/> _vm_roots;
1037 ShenandoahClassLoaderDataRoots<true /*concurrent*/>
1038 _cld_roots;
1039 ShenandoahConcurrentNMethodIterator _nmethod_itr;
1040
1041 public:
1042 ShenandoahConcurrentRootsEvacUpdateTask(ShenandoahPhaseTimings::Phase phase) :
1043 WorkerTask("Shenandoah Evacuate/Update Concurrent Strong Roots"),
1044 _phase(phase),
1045 _vm_roots(phase),
1046 _cld_roots(phase, ShenandoahHeap::heap()->workers()->active_workers(), false /*heap iteration*/),
1047 _nmethod_itr(ShenandoahCodeRoots::table()) {
1048 if (!ShenandoahHeap::heap()->unload_classes()) {
1049 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
1050 _nmethod_itr.nmethods_do_begin();
1051 }
1052 }
1053
1054 ~ShenandoahConcurrentRootsEvacUpdateTask() {
1055 if (!ShenandoahHeap::heap()->unload_classes()) {
1056 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
1057 _nmethod_itr.nmethods_do_end();
1058 }
1059 }
1060
1061 void work(uint worker_id) {
1062 ShenandoahConcurrentWorkerSession worker_session(worker_id);
1063 {
1064 ShenandoahEvacOOMScope oom;
1065 {
1066 // vm_roots and weak_roots are OopStorage backed roots, concurrent iteration
1067 // may race against OopStorage::release() calls.
1068 ShenandoahContextEvacuateUpdateRootsClosure cl;
1069 _vm_roots.oops_do<ShenandoahContextEvacuateUpdateRootsClosure>(&cl, worker_id);
1070 }
1071
1072 {
1073 ShenandoahEvacuateUpdateMetadataClosure cl;
1074 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
1075 _cld_roots.cld_do(&clds, worker_id);
1076 }
1077 }
1078
1079 // Cannot setup ShenandoahEvacOOMScope here, due to potential deadlock with nmethod_entry_barrier.
1080 if (!ShenandoahHeap::heap()->unload_classes()) {
1081 ShenandoahWorkerTimingsTracker timer(_phase, ShenandoahPhaseTimings::CodeCacheRoots, worker_id);
1082 ShenandoahEvacUpdateCodeCacheClosure cl;
1083 _nmethod_itr.nmethods_do(&cl);
1084 }
1085 }
1086 };
1087
1088 void ShenandoahConcurrentGC::op_strong_roots() {
1089 ShenandoahHeap* const heap = ShenandoahHeap::heap();
1090 assert(heap->is_concurrent_strong_root_in_progress(), "Checked by caller");
1091 ShenandoahConcurrentRootsEvacUpdateTask task(ShenandoahPhaseTimings::conc_strong_roots);
1092 heap->workers()->run_task(&task);
1093 heap->set_concurrent_strong_root_in_progress(false);
1094 }
1095
1096 void ShenandoahConcurrentGC::op_cleanup_early() {
1097 ShenandoahHeap::heap()->free_set()->recycle_trash();
1098 }
1099
1100 void ShenandoahConcurrentGC::op_evacuate() {
1101 ShenandoahHeap::heap()->evacuate_collection_set(true /*concurrent*/);
1102 }
1103
1104 void ShenandoahConcurrentGC::op_init_updaterefs() {
1105 ShenandoahHeap* const heap = ShenandoahHeap::heap();
1106 heap->set_evacuation_in_progress(false);
1107 heap->set_concurrent_weak_root_in_progress(false);
1108 heap->prepare_update_heap_references(true /*concurrent*/);
1109 heap->set_update_refs_in_progress(true);
1110 if (ShenandoahVerify) {
1111 heap->verifier()->verify_before_updaterefs();
1112 }
1113 if (ShenandoahPacing) {
1114 heap->pacer()->setup_for_updaterefs();
1115 }
1116 }
1117
1118 void ShenandoahConcurrentGC::op_updaterefs() {
1119 ShenandoahHeap::heap()->update_heap_references(true /*concurrent*/);
1120 }
1121
1122 class ShenandoahUpdateThreadClosure : public HandshakeClosure {
1123 private:
1124 ShenandoahUpdateRefsClosure _cl;
1125 public:
1126 ShenandoahUpdateThreadClosure();
1127 void do_thread(Thread* thread);
1128 };
1129
1130 ShenandoahUpdateThreadClosure::ShenandoahUpdateThreadClosure() :
1131 HandshakeClosure("Shenandoah Update Thread Roots") {
1132 }
1133
1134 void ShenandoahUpdateThreadClosure::do_thread(Thread* thread) {
1135 if (thread->is_Java_thread()) {
1136 JavaThread* jt = JavaThread::cast(thread);
1137 ResourceMark rm;
1138 jt->oops_do(&_cl, NULL);
1139 }
1140 }
1141
1142 void ShenandoahConcurrentGC::op_update_thread_roots() {
1143 ShenandoahUpdateThreadClosure cl;
1144 Handshake::execute(&cl);
1145 }
1146
1147 void ShenandoahConcurrentGC::op_final_updaterefs() {
1148 ShenandoahHeap* const heap = ShenandoahHeap::heap();
1149 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
1150 assert(!heap->_update_refs_iterator.has_next(), "Should have finished update references");
1151
1152 heap->finish_concurrent_roots();
1153
1154 // Clear cancelled GC, if set. On cancellation path, the block before would handle
1155 // everything.
1156 if (heap->cancelled_gc()) {
1157 heap->clear_cancelled_gc(true /* clear oom handler */);
1158 }
1159
1160 // Has to be done before cset is clear
1161 if (ShenandoahVerify) {
1162 heap->verifier()->verify_roots_in_to_space();
1163 }
1164
1165 if (heap->mode()->is_generational() && heap->is_concurrent_old_mark_in_progress()) {
1166 // When the SATB barrier is left on to support concurrent old gen mark, it may pick up writes to
1167 // objects in the collection set. After those objects are evacuated, the pointers in the
1168 // SATB are no longer safe. Once we have finished update references, we are guaranteed that
1169 // no more writes to the collection set are possible.
1170 //
1171 // This will transfer any old pointers in _active_ regions from the SATB to the old gen
1172 // mark queues. All other pointers will be discarded. This would also discard any pointers
1173 // in old regions that were included in a mixed evacuation. We aren't using the SATB filter
1174 // methods here because we cannot control when they execute. If the SATB filter runs _after_
1175 // a region has been recycled, we will not be able to detect the bad pointer.
1176 //
1177 // We are not concerned about skipping this step in abbreviated cycles because regions
1178 // with no live objects cannot have been written to and so cannot have entries in the SATB
1179 // buffers.
1180 heap->transfer_old_pointers_from_satb();
1181 }
1182
1183 heap->update_heap_region_states(true /*concurrent*/);
1184
1185 heap->set_update_refs_in_progress(false);
1186 heap->set_has_forwarded_objects(false);
1187
1188 // Aging_cycle is only relevant during evacuation cycle for individual objects and during final mark for
1189 // entire regions. Both of these relevant operations occur before final update refs.
1190 heap->set_aging_cycle(false);
1191
1192 if (ShenandoahVerify) {
1193 heap->verifier()->verify_after_updaterefs();
1194 }
1195
1196 if (VerifyAfterGC) {
1197 Universe::verify();
1198 }
1199
1200 heap->rebuild_free_set(true /*concurrent*/);
1201 heap->adjust_generation_sizes();
1202 }
1203
1204 void ShenandoahConcurrentGC::op_final_roots() {
1205 ShenandoahHeap::heap()->set_concurrent_weak_root_in_progress(false);
1206 }
1207
1208 void ShenandoahConcurrentGC::op_cleanup_complete() {
1209 ShenandoahHeap::heap()->free_set()->recycle_trash();
1210 }
1211
1212 void ShenandoahConcurrentGC::op_global_coalesce_and_fill() {
1213 ShenandoahHeap::heap()->coalesce_and_fill_old_regions();
1214 }
1215
1216 bool ShenandoahConcurrentGC::check_cancellation_and_abort(ShenandoahDegenPoint point) {
1217 if (ShenandoahHeap::heap()->cancelled_gc()) {
1218 _degen_point = point;
1219 return true;
1220 }
1221 return false;
1222 }
1223
1224 void ShenandoahConcurrentGC::init_mark_event_message(char* buf, size_t len) const {
1225 ShenandoahHeap* const heap = ShenandoahHeap::heap();
1226 assert(!heap->has_forwarded_objects(), "Should not have forwarded objects here");
1227 if (heap->unload_classes()) {
1228 jio_snprintf(buf, len, "Pause Init Mark (%s) (unload classes)", _generation->name());
1229 } else {
1230 jio_snprintf(buf, len, "Pause Init Mark (%s)", _generation->name());
1231 }
1232 }
1233
1234 void ShenandoahConcurrentGC::final_mark_event_message(char* buf, size_t len) const {
1235 ShenandoahHeap* const heap = ShenandoahHeap::heap();
1236 assert(!heap->has_forwarded_objects() || heap->is_concurrent_old_mark_in_progress(),
1237 "Should not have forwarded objects during final mark (unless old gen concurrent mark is running)");
1238 if (heap->unload_classes()) {
1239 jio_snprintf(buf, len, "Pause Final Mark (%s) (unload classes)", _generation->name());
1240 } else {
1241 jio_snprintf(buf, len, "Pause Final Mark (%s)", _generation->name());
1242 }
1243 }
1244
1245 void ShenandoahConcurrentGC::conc_mark_event_message(char* buf, size_t len) const {
1246 ShenandoahHeap* const heap = ShenandoahHeap::heap();
1247 assert(!heap->has_forwarded_objects() || heap->is_concurrent_old_mark_in_progress(),
1248 "Should not have forwarded objects concurrent mark (unless old gen concurrent mark is running");
1249 if (heap->unload_classes()) {
1250 jio_snprintf(buf, len, "Concurrent marking (%s) (unload classes)", _generation->name());
1251 } else {
1252 jio_snprintf(buf, len, "Concurrent marking (%s)", _generation->name());
1253 }
1254 }