1 /*
2 * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2021, 2022, Red Hat, Inc. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #include "precompiled.hpp"
27
28 #include "gc/shared/barrierSetNMethod.hpp"
29 #include "gc/shared/collectorCounters.hpp"
30 #include "gc/shared/continuationGCSupport.inline.hpp"
31 #include "gc/shenandoah/shenandoahBreakpoint.hpp"
32 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
33 #include "gc/shenandoah/shenandoahConcurrentGC.hpp"
34 #include "gc/shenandoah/shenandoahFreeSet.hpp"
35 #include "gc/shenandoah/shenandoahLock.hpp"
36 #include "gc/shenandoah/shenandoahMark.inline.hpp"
37 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
38 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
39 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
40 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
41 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
42 #include "gc/shenandoah/shenandoahStackWatermark.hpp"
43 #include "gc/shenandoah/shenandoahUtils.hpp"
44 #include "gc/shenandoah/shenandoahVerifier.hpp"
45 #include "gc/shenandoah/shenandoahVMOperations.hpp"
46 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
47 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
48 #include "memory/allocation.hpp"
49 #include "prims/jvmtiTagMap.hpp"
50 #include "runtime/vmThread.hpp"
51 #include "utilities/events.hpp"
52
53 // Breakpoint support
54 class ShenandoahBreakpointGCScope : public StackObj {
55 private:
56 const GCCause::Cause _cause;
57 public:
58 ShenandoahBreakpointGCScope(GCCause::Cause cause) : _cause(cause) {
59 if (cause == GCCause::_wb_breakpoint) {
60 ShenandoahBreakpoint::start_gc();
61 ShenandoahBreakpoint::at_before_gc();
62 }
63 }
64
65 ~ShenandoahBreakpointGCScope() {
66 if (_cause == GCCause::_wb_breakpoint) {
67 ShenandoahBreakpoint::at_after_gc();
68 }
69 }
70 };
71
72 class ShenandoahBreakpointMarkScope : public StackObj {
73 private:
74 const GCCause::Cause _cause;
75 public:
76 ShenandoahBreakpointMarkScope(GCCause::Cause cause) : _cause(cause) {
77 if (_cause == GCCause::_wb_breakpoint) {
78 ShenandoahBreakpoint::at_after_marking_started();
79 }
80 }
81
82 ~ShenandoahBreakpointMarkScope() {
83 if (_cause == GCCause::_wb_breakpoint) {
84 ShenandoahBreakpoint::at_before_marking_completed();
85 }
86 }
87 };
88
89 ShenandoahConcurrentGC::ShenandoahConcurrentGC() :
90 _mark(),
91 _degen_point(ShenandoahDegenPoint::_degenerated_unset) {
92 }
93
94 ShenandoahGC::ShenandoahDegenPoint ShenandoahConcurrentGC::degen_point() const {
95 return _degen_point;
96 }
97
98 void ShenandoahConcurrentGC::cancel() {
99 ShenandoahConcurrentMark::cancel();
100 }
101
102 bool ShenandoahConcurrentGC::collect(GCCause::Cause cause) {
103 ShenandoahHeap* const heap = ShenandoahHeap::heap();
104 ShenandoahBreakpointGCScope breakpoint_gc_scope(cause);
105
106 // Reset for upcoming marking
107 entry_reset();
108
109 // Start initial mark under STW
110 vmop_entry_init_mark();
111
112 {
113 ShenandoahBreakpointMarkScope breakpoint_mark_scope(cause);
114 // Concurrent mark roots
115 entry_mark_roots();
116 if (check_cancellation_and_abort(ShenandoahDegenPoint::_degenerated_outside_cycle)) return false;
117
118 // Continue concurrent mark
119 entry_mark();
120 if (check_cancellation_and_abort(ShenandoahDegenPoint::_degenerated_mark)) return false;
121 }
122
123 // Complete marking under STW, and start evacuation
124 vmop_entry_final_mark();
125
126 // Concurrent stack processing
127 if (heap->is_evacuation_in_progress()) {
128 entry_thread_roots();
129 }
130
131 // Process weak roots that might still point to regions that would be broken by cleanup
132 if (heap->is_concurrent_weak_root_in_progress()) {
133 entry_weak_refs();
134 entry_weak_roots();
135 }
136
137 // Final mark might have reclaimed some immediate garbage, kick cleanup to reclaim
138 // the space. This would be the last action if there is nothing to evacuate.
139 entry_cleanup_early();
140
141 {
142 ShenandoahHeapLocker locker(heap->lock());
143 heap->free_set()->log_status();
144 }
145
146 // Perform concurrent class unloading
147 if (heap->unload_classes() &&
148 heap->is_concurrent_weak_root_in_progress()) {
149 entry_class_unloading();
150 }
151
152 // Processing strong roots
153 // This may be skipped if there is nothing to update/evacuate.
154 // If so, strong_root_in_progress would be unset.
155 if (heap->is_concurrent_strong_root_in_progress()) {
156 entry_strong_roots();
157 }
158
159 // Continue the cycle with evacuation and optional update-refs.
160 // This may be skipped if there is nothing to evacuate.
161 // If so, evac_in_progress would be unset by collection set preparation code.
162 if (heap->is_evacuation_in_progress()) {
163 // Concurrently evacuate
164 entry_evacuate();
165 if (check_cancellation_and_abort(ShenandoahDegenPoint::_degenerated_evac)) return false;
166
167 // Perform update-refs phase.
168 vmop_entry_init_updaterefs();
169 entry_updaterefs();
170 if (check_cancellation_and_abort(ShenandoahDegenPoint::_degenerated_updaterefs)) return false;
171
172 // Concurrent update thread roots
173 entry_update_thread_roots();
174 if (check_cancellation_and_abort(ShenandoahDegenPoint::_degenerated_updaterefs)) return false;
175
176 vmop_entry_final_updaterefs();
177
178 // Update references freed up collection set, kick the cleanup to reclaim the space.
179 entry_cleanup_complete();
180 } else {
181 vmop_entry_final_roots();
182 }
183
184 return true;
185 }
186
187 void ShenandoahConcurrentGC::vmop_entry_init_mark() {
188 ShenandoahHeap* const heap = ShenandoahHeap::heap();
189 TraceCollectorStats tcs(heap->monitoring_support()->stw_collection_counters());
190 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::init_mark_gross);
191
192 heap->try_inject_alloc_failure();
193 VM_ShenandoahInitMark op(this);
194 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
195 }
196
197 void ShenandoahConcurrentGC::vmop_entry_final_mark() {
198 ShenandoahHeap* const heap = ShenandoahHeap::heap();
199 TraceCollectorStats tcs(heap->monitoring_support()->stw_collection_counters());
200 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::final_mark_gross);
201
202 heap->try_inject_alloc_failure();
203 VM_ShenandoahFinalMarkStartEvac op(this);
204 VMThread::execute(&op); // jump to entry_final_mark under safepoint
205 }
206
207 void ShenandoahConcurrentGC::vmop_entry_init_updaterefs() {
208 ShenandoahHeap* const heap = ShenandoahHeap::heap();
209 TraceCollectorStats tcs(heap->monitoring_support()->stw_collection_counters());
210 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::init_update_refs_gross);
211
212 heap->try_inject_alloc_failure();
213 VM_ShenandoahInitUpdateRefs op(this);
214 VMThread::execute(&op);
215 }
216
217 void ShenandoahConcurrentGC::vmop_entry_final_updaterefs() {
218 ShenandoahHeap* const heap = ShenandoahHeap::heap();
219 TraceCollectorStats tcs(heap->monitoring_support()->stw_collection_counters());
220 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::final_update_refs_gross);
221
222 heap->try_inject_alloc_failure();
223 VM_ShenandoahFinalUpdateRefs op(this);
224 VMThread::execute(&op);
225 }
226
227 void ShenandoahConcurrentGC::vmop_entry_final_roots() {
228 ShenandoahHeap* const heap = ShenandoahHeap::heap();
229 TraceCollectorStats tcs(heap->monitoring_support()->stw_collection_counters());
230 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::final_roots_gross);
231
232 // This phase does not use workers, no need for setup
233 heap->try_inject_alloc_failure();
234 VM_ShenandoahFinalRoots op(this);
235 VMThread::execute(&op);
236 }
237
238 void ShenandoahConcurrentGC::entry_init_mark() {
239 const char* msg = init_mark_event_message();
240 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::init_mark);
241 EventMark em("%s", msg);
242
243 ShenandoahWorkerScope scope(ShenandoahHeap::heap()->workers(),
244 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
245 "init marking");
246
247 op_init_mark();
248 }
249
250 void ShenandoahConcurrentGC::entry_final_mark() {
251 const char* msg = final_mark_event_message();
252 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::final_mark);
253 EventMark em("%s", msg);
254
255 ShenandoahWorkerScope scope(ShenandoahHeap::heap()->workers(),
256 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
257 "final marking");
258
259 op_final_mark();
260 }
261
262 void ShenandoahConcurrentGC::entry_init_updaterefs() {
263 static const char* msg = "Pause Init Update Refs";
264 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::init_update_refs);
265 EventMark em("%s", msg);
266
267 // No workers used in this phase, no setup required
268 op_init_updaterefs();
269 }
270
271 void ShenandoahConcurrentGC::entry_final_updaterefs() {
272 static const char* msg = "Pause Final Update Refs";
273 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::final_update_refs);
274 EventMark em("%s", msg);
275
276 ShenandoahWorkerScope scope(ShenandoahHeap::heap()->workers(),
277 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
278 "final reference update");
279
280 op_final_updaterefs();
281 }
282
283 void ShenandoahConcurrentGC::entry_final_roots() {
284 static const char* msg = "Pause Final Roots";
285 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::final_roots);
286 EventMark em("%s", msg);
287
288 op_final_roots();
289 }
290
291 void ShenandoahConcurrentGC::entry_reset() {
292 ShenandoahHeap* const heap = ShenandoahHeap::heap();
293 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
294 static const char* msg = "Concurrent reset";
295 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_reset);
296 EventMark em("%s", msg);
297
298 ShenandoahWorkerScope scope(heap->workers(),
299 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
300 "concurrent reset");
301
302 heap->try_inject_alloc_failure();
303 op_reset();
304 }
305
306 void ShenandoahConcurrentGC::entry_mark_roots() {
307 ShenandoahHeap* const heap = ShenandoahHeap::heap();
308 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
309 const char* msg = "Concurrent marking roots";
310 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_mark_roots);
311 EventMark em("%s", msg);
312
313 ShenandoahWorkerScope scope(heap->workers(),
314 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
315 "concurrent marking roots");
316
317 heap->try_inject_alloc_failure();
318 op_mark_roots();
319 }
320
321 void ShenandoahConcurrentGC::entry_mark() {
322 ShenandoahHeap* const heap = ShenandoahHeap::heap();
323 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
324 const char* msg = conc_mark_event_message();
325 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_mark);
326 EventMark em("%s", msg);
327
328 ShenandoahWorkerScope scope(heap->workers(),
329 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
330 "concurrent marking");
331
332 heap->try_inject_alloc_failure();
333 op_mark();
334 }
335
336 void ShenandoahConcurrentGC::entry_thread_roots() {
337 ShenandoahHeap* const heap = ShenandoahHeap::heap();
338 static const char* msg = "Concurrent thread roots";
339 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_thread_roots);
340 EventMark em("%s", msg);
341
342 ShenandoahWorkerScope scope(heap->workers(),
343 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
344 msg);
345
346 heap->try_inject_alloc_failure();
347 op_thread_roots();
348 }
349
350 void ShenandoahConcurrentGC::entry_weak_refs() {
351 ShenandoahHeap* const heap = ShenandoahHeap::heap();
352 static const char* msg = "Concurrent weak references";
353 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_weak_refs);
354 EventMark em("%s", msg);
355
356 ShenandoahWorkerScope scope(heap->workers(),
357 ShenandoahWorkerPolicy::calc_workers_for_conc_refs_processing(),
358 "concurrent weak references");
359
360 heap->try_inject_alloc_failure();
361 op_weak_refs();
362 }
363
364 void ShenandoahConcurrentGC::entry_weak_roots() {
365 ShenandoahHeap* const heap = ShenandoahHeap::heap();
366 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
367 static const char* msg = "Concurrent weak roots";
368 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_weak_roots);
369 EventMark em("%s", msg);
370
371 ShenandoahWorkerScope scope(heap->workers(),
372 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
373 "concurrent weak root");
374
375 heap->try_inject_alloc_failure();
376 op_weak_roots();
377 }
378
379 void ShenandoahConcurrentGC::entry_class_unloading() {
380 ShenandoahHeap* const heap = ShenandoahHeap::heap();
381 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
382 static const char* msg = "Concurrent class unloading";
383 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_class_unload);
384 EventMark em("%s", msg);
385
386 ShenandoahWorkerScope scope(heap->workers(),
387 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
388 "concurrent class unloading");
389
390 heap->try_inject_alloc_failure();
391 op_class_unloading();
392 }
393
394 void ShenandoahConcurrentGC::entry_strong_roots() {
395 ShenandoahHeap* const heap = ShenandoahHeap::heap();
396 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
397 static const char* msg = "Concurrent strong roots";
398 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_strong_roots);
399 EventMark em("%s", msg);
400
401 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_strong_roots);
402
403 ShenandoahWorkerScope scope(heap->workers(),
404 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
405 "concurrent strong root");
406
407 heap->try_inject_alloc_failure();
408 op_strong_roots();
409 }
410
411 void ShenandoahConcurrentGC::entry_cleanup_early() {
412 ShenandoahHeap* const heap = ShenandoahHeap::heap();
413 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
414 static const char* msg = "Concurrent cleanup";
415 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_cleanup_early, true /* log_heap_usage */);
416 EventMark em("%s", msg);
417
418 // This phase does not use workers, no need for setup
419 heap->try_inject_alloc_failure();
420 op_cleanup_early();
421 }
422
423 void ShenandoahConcurrentGC::entry_evacuate() {
424 ShenandoahHeap* const heap = ShenandoahHeap::heap();
425 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
426
427 static const char* msg = "Concurrent evacuation";
428 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_evac);
429 EventMark em("%s", msg);
430
431 ShenandoahWorkerScope scope(heap->workers(),
432 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
433 "concurrent evacuation");
434
435 heap->try_inject_alloc_failure();
436 op_evacuate();
437 }
438
439 void ShenandoahConcurrentGC::entry_update_thread_roots() {
440 ShenandoahHeap* const heap = ShenandoahHeap::heap();
441 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
442
443 static const char* msg = "Concurrent update thread roots";
444 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_update_thread_roots);
445 EventMark em("%s", msg);
446
447 // No workers used in this phase, no setup required
448 heap->try_inject_alloc_failure();
449 op_update_thread_roots();
450 }
451
452 void ShenandoahConcurrentGC::entry_updaterefs() {
453 ShenandoahHeap* const heap = ShenandoahHeap::heap();
454 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
455 static const char* msg = "Concurrent update references";
456 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_update_refs);
457 EventMark em("%s", msg);
458
459 ShenandoahWorkerScope scope(heap->workers(),
460 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
461 "concurrent reference update");
462
463 heap->try_inject_alloc_failure();
464 op_updaterefs();
465 }
466
467 void ShenandoahConcurrentGC::entry_cleanup_complete() {
468 ShenandoahHeap* const heap = ShenandoahHeap::heap();
469 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
470 static const char* msg = "Concurrent cleanup";
471 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_cleanup_complete, true /* log_heap_usage */);
472 EventMark em("%s", msg);
473
474 // This phase does not use workers, no need for setup
475 heap->try_inject_alloc_failure();
476 op_cleanup_complete();
477 }
478
479 void ShenandoahConcurrentGC::op_reset() {
480 ShenandoahHeap* const heap = ShenandoahHeap::heap();
481 if (ShenandoahPacing) {
482 heap->pacer()->setup_for_reset();
483 }
484
485 heap->prepare_gc();
486 }
487
488 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
489 private:
490 ShenandoahMarkingContext* const _ctx;
491 public:
492 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
493
494 void heap_region_do(ShenandoahHeapRegion* r) {
495 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
496 if (r->is_active()) {
497 // Check if region needs updating its TAMS. We have updated it already during concurrent
498 // reset, so it is very likely we don't need to do another write here.
499 if (_ctx->top_at_mark_start(r) != r->top()) {
500 _ctx->capture_top_at_mark_start(r);
501 }
502 } else {
503 assert(_ctx->top_at_mark_start(r) == r->top(),
504 "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
505 }
506 }
507
508 bool is_thread_safe() { return true; }
509 };
510
511 void ShenandoahConcurrentGC::start_mark() {
512 _mark.start_mark();
513 }
514
515 void ShenandoahConcurrentGC::op_init_mark() {
516 ShenandoahHeap* const heap = ShenandoahHeap::heap();
517 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
518 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
519
520 assert(heap->marking_context()->is_bitmap_clear(), "need clear marking bitmap");
521 assert(!heap->marking_context()->is_complete(), "should not be complete");
522 assert(!heap->has_forwarded_objects(), "No forwarded objects on this path");
523
524 if (ShenandoahVerify) {
525 heap->verifier()->verify_before_concmark();
526 }
527
528 if (VerifyBeforeGC) {
529 Universe::verify();
530 }
531
532 heap->set_concurrent_mark_in_progress(true);
533
534 start_mark();
535
536 {
537 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_region_states);
538 ShenandoahInitMarkUpdateRegionStateClosure cl;
539 heap->parallel_heap_region_iterate(&cl);
540 }
541
542 // Weak reference processing
543 ShenandoahReferenceProcessor* rp = heap->ref_processor();
544 rp->reset_thread_locals();
545 rp->set_soft_reference_policy(heap->soft_ref_policy()->should_clear_all_soft_refs());
546
547 // Make above changes visible to worker threads
548 OrderAccess::fence();
549
550 // Arm nmethods for concurrent mark
551 ShenandoahCodeRoots::arm_nmethods_for_mark();
552
553 ShenandoahStackWatermark::change_epoch_id();
554 if (ShenandoahPacing) {
555 heap->pacer()->setup_for_mark();
556 }
557 }
558
559 void ShenandoahConcurrentGC::op_mark_roots() {
560 _mark.mark_concurrent_roots();
561 }
562
563 void ShenandoahConcurrentGC::op_mark() {
564 _mark.concurrent_mark();
565 }
566
567 void ShenandoahConcurrentGC::op_final_mark() {
568 ShenandoahHeap* const heap = ShenandoahHeap::heap();
569 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
570 assert(!heap->has_forwarded_objects(), "No forwarded objects on this path");
571
572 if (ShenandoahVerify) {
573 heap->verifier()->verify_roots_no_forwarded();
574 }
575
576 if (!heap->cancelled_gc()) {
577 _mark.finish_mark();
578 assert(!heap->cancelled_gc(), "STW mark cannot OOM");
579
580 // Notify JVMTI that the tagmap table will need cleaning.
581 JvmtiTagMap::set_needs_cleaning();
582
583 heap->prepare_regions_and_collection_set(true /*concurrent*/);
584
585 // Has to be done after cset selection
586 heap->prepare_concurrent_roots();
587
588 if (!heap->collection_set()->is_empty()) {
589 if (ShenandoahVerify) {
590 heap->verifier()->verify_before_evacuation();
591 }
592
593 heap->set_evacuation_in_progress(true);
594 // From here on, we need to update references.
595 heap->set_has_forwarded_objects(true);
596
597 // Verify before arming for concurrent processing.
598 // Otherwise, verification can trigger stack processing.
599 if (ShenandoahVerify) {
600 heap->verifier()->verify_during_evacuation();
601 }
602
603 // Arm nmethods/stack for concurrent processing
604 ShenandoahCodeRoots::arm_nmethods_for_evac();
605 ShenandoahStackWatermark::change_epoch_id();
606
607 if (ShenandoahPacing) {
608 heap->pacer()->setup_for_evac();
609 }
610 } else {
611 if (ShenandoahVerify) {
612 heap->verifier()->verify_after_concmark();
613 }
614
615 if (VerifyAfterGC) {
616 Universe::verify();
617 }
618 }
619 }
620 }
621
622 class ShenandoahConcurrentEvacThreadClosure : public ThreadClosure {
623 private:
624 OopClosure* const _oops;
625
626 public:
627 ShenandoahConcurrentEvacThreadClosure(OopClosure* oops);
628 void do_thread(Thread* thread);
629 };
630
631 ShenandoahConcurrentEvacThreadClosure::ShenandoahConcurrentEvacThreadClosure(OopClosure* oops) :
632 _oops(oops) {
633 }
634
635 void ShenandoahConcurrentEvacThreadClosure::do_thread(Thread* thread) {
636 JavaThread* const jt = JavaThread::cast(thread);
637 StackWatermarkSet::finish_processing(jt, _oops, StackWatermarkKind::gc);
638 }
639
640 class ShenandoahConcurrentEvacUpdateThreadTask : public WorkerTask {
641 private:
642 ShenandoahJavaThreadsIterator _java_threads;
643
644 public:
645 ShenandoahConcurrentEvacUpdateThreadTask(uint n_workers) :
646 WorkerTask("Shenandoah Evacuate/Update Concurrent Thread Roots"),
647 _java_threads(ShenandoahPhaseTimings::conc_thread_roots, n_workers) {
648 }
649
650 void work(uint worker_id) {
651 // ShenandoahEvacOOMScope has to be setup by ShenandoahContextEvacuateUpdateRootsClosure.
652 // Otherwise, may deadlock with watermark lock
653 ShenandoahContextEvacuateUpdateRootsClosure oops_cl;
654 ShenandoahConcurrentEvacThreadClosure thr_cl(&oops_cl);
655 _java_threads.threads_do(&thr_cl, worker_id);
656 }
657 };
658
659 void ShenandoahConcurrentGC::op_thread_roots() {
660 ShenandoahHeap* const heap = ShenandoahHeap::heap();
661 assert(heap->is_evacuation_in_progress(), "Checked by caller");
662 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_thread_roots);
663 ShenandoahConcurrentEvacUpdateThreadTask task(heap->workers()->active_workers());
664 heap->workers()->run_task(&task);
665 }
666
667 void ShenandoahConcurrentGC::op_weak_refs() {
668 ShenandoahHeap* const heap = ShenandoahHeap::heap();
669 assert(heap->is_concurrent_weak_root_in_progress(), "Only during this phase");
670 // Concurrent weak refs processing
671 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_weak_refs);
672 if (heap->gc_cause() == GCCause::_wb_breakpoint) {
673 ShenandoahBreakpoint::at_after_reference_processing_started();
674 }
675 heap->ref_processor()->process_references(ShenandoahPhaseTimings::conc_weak_refs, heap->workers(), true /* concurrent */);
676 }
677
678 class ShenandoahEvacUpdateCleanupOopStorageRootsClosure : public BasicOopIterateClosure {
679 private:
680 ShenandoahHeap* const _heap;
681 ShenandoahMarkingContext* const _mark_context;
682 bool _evac_in_progress;
683 Thread* const _thread;
684
685 public:
686 ShenandoahEvacUpdateCleanupOopStorageRootsClosure();
687 void do_oop(oop* p);
688 void do_oop(narrowOop* p);
689 };
690
691 ShenandoahEvacUpdateCleanupOopStorageRootsClosure::ShenandoahEvacUpdateCleanupOopStorageRootsClosure() :
692 _heap(ShenandoahHeap::heap()),
693 _mark_context(ShenandoahHeap::heap()->marking_context()),
694 _evac_in_progress(ShenandoahHeap::heap()->is_evacuation_in_progress()),
695 _thread(Thread::current()) {
696 }
697
698 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(oop* p) {
699 const oop obj = RawAccess<>::oop_load(p);
700 if (!CompressedOops::is_null(obj)) {
701 if (!_mark_context->is_marked(obj)) {
702 shenandoah_assert_correct(p, obj);
703 ShenandoahHeap::atomic_clear_oop(p, obj);
704 } else if (_evac_in_progress && _heap->in_collection_set(obj)) {
705 oop resolved = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
706 if (resolved == obj) {
707 resolved = _heap->evacuate_object(obj, _thread);
708 }
709 ShenandoahHeap::atomic_update_oop(resolved, p, obj);
710 assert(_heap->cancelled_gc() ||
711 _mark_context->is_marked(resolved) && !_heap->in_collection_set(resolved),
712 "Sanity");
713 }
714 }
715 }
716
717 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(narrowOop* p) {
718 ShouldNotReachHere();
719 }
720
721 class ShenandoahIsCLDAliveClosure : public CLDClosure {
722 public:
723 void do_cld(ClassLoaderData* cld) {
724 cld->is_alive();
725 }
726 };
727
728 class ShenandoahIsNMethodAliveClosure: public NMethodClosure {
729 public:
730 void do_nmethod(nmethod* n) {
731 n->is_unloading();
732 }
733 };
734
735 // This task not only evacuates/updates marked weak roots, but also "null"
736 // dead weak roots.
737 class ShenandoahConcurrentWeakRootsEvacUpdateTask : public WorkerTask {
738 private:
739 ShenandoahVMWeakRoots<true /*concurrent*/> _vm_roots;
740
741 // Roots related to concurrent class unloading
742 ShenandoahClassLoaderDataRoots<true /* concurrent */>
743 _cld_roots;
744 ShenandoahConcurrentNMethodIterator _nmethod_itr;
745 ShenandoahPhaseTimings::Phase _phase;
746
747 public:
748 ShenandoahConcurrentWeakRootsEvacUpdateTask(ShenandoahPhaseTimings::Phase phase) :
749 WorkerTask("Shenandoah Evacuate/Update Concurrent Weak Roots"),
750 _vm_roots(phase),
751 _cld_roots(phase, ShenandoahHeap::heap()->workers()->active_workers(), false /*heap iteration*/),
752 _nmethod_itr(ShenandoahCodeRoots::table()),
753 _phase(phase) {}
754
755 ~ShenandoahConcurrentWeakRootsEvacUpdateTask() {
756 // Notify runtime data structures of potentially dead oops
757 _vm_roots.report_num_dead();
758 }
759
760 void work(uint worker_id) {
761 ShenandoahConcurrentWorkerSession worker_session(worker_id);
762 ShenandoahSuspendibleThreadSetJoiner sts_join;
763 {
764 ShenandoahEvacOOMScope oom;
765 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration
766 // may race against OopStorage::release() calls.
767 ShenandoahEvacUpdateCleanupOopStorageRootsClosure cl;
768 _vm_roots.oops_do(&cl, worker_id);
769 }
770
771 // If we are going to perform concurrent class unloading later on, we need to
772 // cleanup the weak oops in CLD and determinate nmethod's unloading state, so that we
773 // can cleanup immediate garbage sooner.
774 if (ShenandoahHeap::heap()->unload_classes()) {
775 // Applies ShenandoahIsCLDAlive closure to CLDs, native barrier will either null the
776 // CLD's holder or evacuate it.
777 {
778 ShenandoahIsCLDAliveClosure is_cld_alive;
779 _cld_roots.cld_do(&is_cld_alive, worker_id);
780 }
781
782 // Applies ShenandoahIsNMethodAliveClosure to registered nmethods.
783 // The closure calls nmethod->is_unloading(). The is_unloading
784 // state is cached, therefore, during concurrent class unloading phase,
785 // we will not touch the metadata of unloading nmethods
786 {
787 ShenandoahWorkerTimingsTracker timer(_phase, ShenandoahPhaseTimings::CodeCacheRoots, worker_id);
788 ShenandoahIsNMethodAliveClosure is_nmethod_alive;
789 _nmethod_itr.nmethods_do(&is_nmethod_alive);
790 }
791 }
792 }
793 };
794
795 void ShenandoahConcurrentGC::op_weak_roots() {
796 ShenandoahHeap* const heap = ShenandoahHeap::heap();
797 assert(heap->is_concurrent_weak_root_in_progress(), "Only during this phase");
798 // Concurrent weak root processing
799 {
800 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_weak_roots_work);
801 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_weak_roots_work);
802 ShenandoahConcurrentWeakRootsEvacUpdateTask task(ShenandoahPhaseTimings::conc_weak_roots_work);
803 heap->workers()->run_task(&task);
804 }
805
806 // Perform handshake to flush out dead oops
807 {
808 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_weak_roots_rendezvous);
809 heap->rendezvous_threads();
810 }
811 }
812
813 void ShenandoahConcurrentGC::op_class_unloading() {
814 ShenandoahHeap* const heap = ShenandoahHeap::heap();
815 assert (heap->is_concurrent_weak_root_in_progress() &&
816 heap->unload_classes(),
817 "Checked by caller");
818 heap->do_class_unloading();
819 }
820
821 class ShenandoahEvacUpdateCodeCacheClosure : public NMethodClosure {
822 private:
823 BarrierSetNMethod* const _bs;
824 ShenandoahEvacuateUpdateMetadataClosure _cl;
825
826 public:
827 ShenandoahEvacUpdateCodeCacheClosure() :
828 _bs(BarrierSet::barrier_set()->barrier_set_nmethod()),
829 _cl() {
830 }
831
832 void do_nmethod(nmethod* n) {
833 ShenandoahNMethod* data = ShenandoahNMethod::gc_data(n);
834 ShenandoahReentrantLocker locker(data->lock());
835 // Setup EvacOOM scope below reentrant lock to avoid deadlock with
836 // nmethod_entry_barrier
837 ShenandoahEvacOOMScope oom;
838 data->oops_do(&_cl, true/*fix relocation*/);
839 _bs->disarm(n);
840 }
841 };
842
843 class ShenandoahConcurrentRootsEvacUpdateTask : public WorkerTask {
844 private:
845 ShenandoahPhaseTimings::Phase _phase;
846 ShenandoahVMRoots<true /*concurrent*/> _vm_roots;
847 ShenandoahClassLoaderDataRoots<true /*concurrent*/>
848 _cld_roots;
849 ShenandoahConcurrentNMethodIterator _nmethod_itr;
850
851 public:
852 ShenandoahConcurrentRootsEvacUpdateTask(ShenandoahPhaseTimings::Phase phase) :
853 WorkerTask("Shenandoah Evacuate/Update Concurrent Strong Roots"),
854 _phase(phase),
855 _vm_roots(phase),
856 _cld_roots(phase, ShenandoahHeap::heap()->workers()->active_workers(), false /*heap iteration*/),
857 _nmethod_itr(ShenandoahCodeRoots::table()) {}
858
859 void work(uint worker_id) {
860 ShenandoahConcurrentWorkerSession worker_session(worker_id);
861 {
862 ShenandoahEvacOOMScope oom;
863 {
864 // vm_roots and weak_roots are OopStorage backed roots, concurrent iteration
865 // may race against OopStorage::release() calls.
866 ShenandoahContextEvacuateUpdateRootsClosure cl;
867 _vm_roots.oops_do<ShenandoahContextEvacuateUpdateRootsClosure>(&cl, worker_id);
868 }
869
870 {
871 ShenandoahEvacuateUpdateMetadataClosure cl;
872 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
873 _cld_roots.cld_do(&clds, worker_id);
874 }
875 }
876
877 // Cannot setup ShenandoahEvacOOMScope here, due to potential deadlock with nmethod_entry_barrier.
878 if (!ShenandoahHeap::heap()->unload_classes()) {
879 ShenandoahWorkerTimingsTracker timer(_phase, ShenandoahPhaseTimings::CodeCacheRoots, worker_id);
880 ShenandoahEvacUpdateCodeCacheClosure cl;
881 _nmethod_itr.nmethods_do(&cl);
882 }
883 }
884 };
885
886 void ShenandoahConcurrentGC::op_strong_roots() {
887 ShenandoahHeap* const heap = ShenandoahHeap::heap();
888 assert(heap->is_concurrent_strong_root_in_progress(), "Checked by caller");
889 ShenandoahConcurrentRootsEvacUpdateTask task(ShenandoahPhaseTimings::conc_strong_roots);
890 heap->workers()->run_task(&task);
891 heap->set_concurrent_strong_root_in_progress(false);
892 }
893
894 void ShenandoahConcurrentGC::op_cleanup_early() {
895 ShenandoahHeap::heap()->free_set()->recycle_trash();
896 }
897
898 void ShenandoahConcurrentGC::op_evacuate() {
899 ShenandoahHeap::heap()->evacuate_collection_set(true /*concurrent*/);
900 }
901
902 void ShenandoahConcurrentGC::op_init_updaterefs() {
903 ShenandoahHeap* const heap = ShenandoahHeap::heap();
904 heap->set_evacuation_in_progress(false);
905 heap->set_concurrent_weak_root_in_progress(false);
906 heap->prepare_update_heap_references(true /*concurrent*/);
907 heap->set_update_refs_in_progress(true);
908
909 if (ShenandoahPacing) {
910 heap->pacer()->setup_for_updaterefs();
911 }
912 }
913
914 void ShenandoahConcurrentGC::op_updaterefs() {
915 ShenandoahHeap::heap()->update_heap_references(true /*concurrent*/);
916 }
917
918 class ShenandoahUpdateThreadClosure : public HandshakeClosure {
919 private:
920 ShenandoahUpdateRefsClosure _cl;
921 public:
922 ShenandoahUpdateThreadClosure();
923 void do_thread(Thread* thread);
924 };
925
926 ShenandoahUpdateThreadClosure::ShenandoahUpdateThreadClosure() :
927 HandshakeClosure("Shenandoah Update Thread Roots") {
928 }
929
930 void ShenandoahUpdateThreadClosure::do_thread(Thread* thread) {
931 if (thread->is_Java_thread()) {
932 JavaThread* jt = JavaThread::cast(thread);
933 ResourceMark rm;
934 jt->oops_do(&_cl, nullptr);
935 }
936 }
937
938 void ShenandoahConcurrentGC::op_update_thread_roots() {
939 ShenandoahUpdateThreadClosure cl;
940 Handshake::execute(&cl);
941 }
942
943 void ShenandoahConcurrentGC::op_final_updaterefs() {
944 ShenandoahHeap* const heap = ShenandoahHeap::heap();
945 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
946 assert(!heap->_update_refs_iterator.has_next(), "Should have finished update references");
947
948 heap->finish_concurrent_roots();
949
950 // Clear cancelled GC, if set. On cancellation path, the block before would handle
951 // everything.
952 if (heap->cancelled_gc()) {
953 heap->clear_cancelled_gc();
954 }
955
956 // Has to be done before cset is clear
957 if (ShenandoahVerify) {
958 heap->verifier()->verify_roots_in_to_space();
959 }
960
961 heap->update_heap_region_states(true /*concurrent*/);
962
963 heap->set_update_refs_in_progress(false);
964 heap->set_has_forwarded_objects(false);
965
966 if (ShenandoahVerify) {
967 heap->verifier()->verify_after_updaterefs();
968 }
969
970 if (VerifyAfterGC) {
971 Universe::verify();
972 }
973
974 heap->rebuild_free_set(true /*concurrent*/);
975 }
976
977 void ShenandoahConcurrentGC::op_final_roots() {
978 ShenandoahHeap::heap()->set_concurrent_weak_root_in_progress(false);
979 }
980
981 void ShenandoahConcurrentGC::op_cleanup_complete() {
982 ShenandoahHeap::heap()->free_set()->recycle_trash();
983 }
984
985 bool ShenandoahConcurrentGC::check_cancellation_and_abort(ShenandoahDegenPoint point) {
986 if (ShenandoahHeap::heap()->cancelled_gc()) {
987 _degen_point = point;
988 return true;
989 }
990 return false;
991 }
992
993 const char* ShenandoahConcurrentGC::init_mark_event_message() const {
994 ShenandoahHeap* const heap = ShenandoahHeap::heap();
995 assert(!heap->has_forwarded_objects(), "Should not have forwarded objects here");
996 if (heap->unload_classes()) {
997 return "Pause Init Mark (unload classes)";
998 } else {
999 return "Pause Init Mark";
1000 }
1001 }
1002
1003 const char* ShenandoahConcurrentGC::final_mark_event_message() const {
1004 ShenandoahHeap* const heap = ShenandoahHeap::heap();
1005 assert(!heap->has_forwarded_objects(), "Should not have forwarded objects here");
1006 if (heap->unload_classes()) {
1007 return "Pause Final Mark (unload classes)";
1008 } else {
1009 return "Pause Final Mark";
1010 }
1011 }
1012
1013 const char* ShenandoahConcurrentGC::conc_mark_event_message() const {
1014 ShenandoahHeap* const heap = ShenandoahHeap::heap();
1015 assert(!heap->has_forwarded_objects(), "Should not have forwarded objects here");
1016 if (heap->unload_classes()) {
1017 return "Concurrent marking (unload classes)";
1018 } else {
1019 return "Concurrent marking";
1020 }
1021 }