1 /*
2 * Copyright (c) 2018, Red Hat, Inc. and/or its affiliates.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #include "precompiled.hpp"
25
26 #include "gc/shared/gcTraceTime.inline.hpp"
27 #include "gc/shared/markBitMap.inline.hpp"
28 #include "gc/shared/workgroup.hpp"
29 #include "gc/shared/taskqueue.inline.hpp"
30 #include "gc/shared/weakProcessor.hpp"
31 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
32 #include "gc/shenandoah/shenandoahConnectionMatrix.hpp"
33 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
34 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
35 #include "gc/shenandoah/shenandoahFreeSet.hpp"
36 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
37 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
38 #include "gc/shenandoah/shenandoahHeap.hpp"
39 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
40 #include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp"
41 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
42 #include "gc/shenandoah/shenandoahTraversalGC.hpp"
43 #include "gc/shenandoah/shenandoahRootProcessor.hpp"
44 #include "gc/shenandoah/shenandoahStringDedup.hpp"
45 #include "gc/shenandoah/shenandoahStrDedupQueue.inline.hpp"
46 #include "gc/shenandoah/shenandoahTaskqueue.hpp"
47 #include "gc/shenandoah/shenandoahUtils.hpp"
48 #include "gc/shenandoah/shenandoahVerifier.hpp"
49 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
50 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
51
52 #include "memory/iterator.hpp"
53
54 /**
55 * NOTE: We are using the SATB buffer in thread.hpp and satbMarkQueue.hpp, however, it is not an SATB algorithm.
56 * We're using the buffer as generic oop buffer to enqueue new values in concurrent oop stores, IOW, the algorithm
57 * is incremental-update-based.
58 *
59 * NOTE on interaction with TAMS: we want to avoid traversing new objects for
60 * several reasons:
61 * - We will not reclaim them in this cycle anyway, because they are not in the
62 * cset
63 * - It makes up for the bulk of work during final-pause
64 * - It also shortens the concurrent cycle because we don't need to
65 * pointlessly traverse through newly allocated objects.
66 * - As a nice side-effect, it solves the I-U termination problem (mutators
67 * cannot outrun the GC by allocating like crazy)
68 * - It is an easy way to achieve MWF. What MWF does is to also enqueue the
69 * target object of stores if it's new. Treating new objects live implicitely
70 * achieves the same, but without extra barriers. I think the effect of
71 * shortened final-pause (mentioned above) is the main advantage of MWF. In
72 * particular, we will not see the head of a completely new long linked list
73 * in final-pause and end up traversing huge chunks of the heap there.
74 * - We don't need to see/update the fields of new objects either, because they
75 * are either still null, or anything that's been stored into them has been
76 * evacuated+enqueued before (and will thus be treated later).
77 *
78 * We achieve this by setting TAMS for each region, and everything allocated
79 * beyond TAMS will be 'implicitely marked'.
80 *
81 * Gotchas:
82 * - While we want new objects to be implicitely marked, we don't want to count
83 * them alive. Otherwise the next cycle wouldn't pick them up and consider
84 * them for cset. This means that we need to protect such regions from
85 * getting accidentally thrashed at the end of traversal cycle. This is why I
86 * keep track of alloc-regions and check is_alloc_region() in the trashing
87 * code.
88 * - We *need* to traverse through evacuated objects. Those objects are
89 * pre-existing, and any references in them point to interesting objects that
90 * we need to see. We also want to count them as live, because we just
91 * determined that they are alive :-) I achieve this by upping TAMS
92 * concurrently for every gclab/gc-shared alloc before publishing the
93 * evacuated object. This way, the GC threads will not consider such objects
94 * implictely marked, and traverse through them as normal.
95 */
96 class ShenandoahTraversalSATBBufferClosure : public SATBBufferClosure {
97 private:
98 ShenandoahObjToScanQueue* _queue;
99 ShenandoahTraversalGC* _traversal_gc;
100 ShenandoahHeap* _heap;
101 ShenandoahHeapRegionSet* _traversal_set;
102
103 public:
104 ShenandoahTraversalSATBBufferClosure(ShenandoahObjToScanQueue* q) :
105 _queue(q), _traversal_gc(ShenandoahHeap::heap()->traversal_gc()),
106 _heap(ShenandoahHeap::heap()),
107 _traversal_set(ShenandoahHeap::heap()->traversal_gc()->traversal_set())
108 { }
109
110 void do_buffer(void** buffer, size_t size) {
111 for (size_t i = 0; i < size; ++i) {
112 oop* p = (oop*) &buffer[i];
113 oop obj = RawAccess<>::oop_load(p);
114 shenandoah_assert_not_forwarded(p, obj);
115 if (_traversal_set->is_in((HeapWord*) obj) && !_heap->is_marked_next(obj) && _heap->mark_next(obj)) {
116 _queue->push(ShenandoahMarkTask(obj));
117 }
118 }
119 }
120 };
121
122 class ShenandoahTraversalSATBThreadsClosure : public ThreadClosure {
123 ShenandoahTraversalSATBBufferClosure* _satb_cl;
124
125 public:
126 ShenandoahTraversalSATBThreadsClosure(ShenandoahTraversalSATBBufferClosure* satb_cl) :
127 _satb_cl(satb_cl) {}
128
129 void do_thread(Thread* thread) {
130 if (thread->is_Java_thread()) {
131 JavaThread* jt = (JavaThread*)thread;
132 ShenandoahThreadLocalData::satb_mark_queue(jt).apply_closure_and_empty(_satb_cl);
133 } else if (thread->is_VM_thread()) {
134 ShenandoahBarrierSet::satb_mark_queue_set().shared_satb_queue()->apply_closure_and_empty(_satb_cl);
135 }
136 }
137 };
138
139 // Like CLDToOopClosure, but clears has_modified_oops, so that we can record modified CLDs during traversal
140 // and remark them later during final-traversal.
141 class ShenandoahMarkCLDClosure : public CLDClosure {
142 private:
143 OopClosure* _cl;
144 public:
145 ShenandoahMarkCLDClosure(OopClosure* cl) : _cl(cl) {}
146 void do_cld(ClassLoaderData* cld) {
147 cld->oops_do(_cl, true, true);
148 }
149 };
150
151 // Like CLDToOopClosure, but only process modified CLDs
152 class ShenandoahRemarkCLDClosure : public CLDClosure {
153 private:
154 OopClosure* _cl;
155 public:
156 ShenandoahRemarkCLDClosure(OopClosure* cl) : _cl(cl) {}
157 void do_cld(ClassLoaderData* cld) {
158 if (cld->has_modified_oops()) {
159 cld->oops_do(_cl, true, true);
160 }
161 }
162 };
163
164 class ShenandoahInitTraversalCollectionTask : public AbstractGangTask {
165 private:
166 ShenandoahRootProcessor* _rp;
167 ShenandoahHeap* _heap;
168 public:
169 ShenandoahInitTraversalCollectionTask(ShenandoahRootProcessor* rp) :
170 AbstractGangTask("Shenandoah Init Traversal Collection"),
171 _rp(rp),
172 _heap(ShenandoahHeap::heap()) {}
173
174 void work(uint worker_id) {
175 ShenandoahEvacOOMScope oom_evac_scope;
176 ShenandoahObjToScanQueueSet* queues = _heap->traversal_gc()->task_queues();
177 ShenandoahObjToScanQueue* q = queues->queue(worker_id);
178
179 bool process_refs = _heap->process_references();
180 bool unload_classes = _heap->unload_classes();
181 ReferenceProcessor* rp = NULL;
182 if (process_refs) {
183 rp = _heap->ref_processor();
184 }
185
186 // Step 1: Process ordinary GC roots.
187 {
188 ShenandoahTraversalClosure roots_cl(q, rp);
189 ShenandoahMarkCLDClosure cld_cl(&roots_cl);
190 MarkingCodeBlobClosure code_cl(&roots_cl, CodeBlobToOopClosure::FixRelocations);
191 if (unload_classes) {
192 _rp->process_strong_roots(&roots_cl, process_refs ? NULL : &roots_cl, &cld_cl, NULL, &code_cl, NULL, worker_id);
193 } else {
194 _rp->process_all_roots(&roots_cl, process_refs ? NULL : &roots_cl, &cld_cl, &code_cl, NULL, worker_id);
195 }
196 }
197 }
198 };
199
200 class ShenandoahConcurrentTraversalCollectionTask : public AbstractGangTask {
201 private:
202 ParallelTaskTerminator* _terminator;
203 ShenandoahHeap* _heap;
204 public:
205 ShenandoahConcurrentTraversalCollectionTask(ParallelTaskTerminator* terminator) :
206 AbstractGangTask("Shenandoah Concurrent Traversal Collection"),
207 _terminator(terminator),
208 _heap(ShenandoahHeap::heap()) {}
209
210 void work(uint worker_id) {
211 ShenandoahEvacOOMScope oom_evac_scope;
212 ShenandoahTraversalGC* traversal_gc = _heap->traversal_gc();
213 ShenandoahObjToScanQueueSet* queues = traversal_gc->task_queues();
214 ShenandoahObjToScanQueue* q = queues->queue(worker_id);
215
216 // Drain all outstanding work in queues.
217 traversal_gc->main_loop(worker_id, _terminator, true);
218 }
219 };
220
221 class ShenandoahFinalTraversalCollectionTask : public AbstractGangTask {
222 private:
223 ShenandoahRootProcessor* _rp;
224 ParallelTaskTerminator* _terminator;
225 ShenandoahHeap* _heap;
226 public:
227 ShenandoahFinalTraversalCollectionTask(ShenandoahRootProcessor* rp, ParallelTaskTerminator* terminator) :
228 AbstractGangTask("Shenandoah Final Traversal Collection"),
229 _rp(rp),
230 _terminator(terminator),
231 _heap(ShenandoahHeap::heap()) {}
232
233 void work(uint worker_id) {
234 ShenandoahEvacOOMScope oom_evac_scope;
235 ShenandoahTraversalGC* traversal_gc = _heap->traversal_gc();
236
237 ShenandoahObjToScanQueueSet* queues = traversal_gc->task_queues();
238 ShenandoahObjToScanQueue* q = queues->queue(worker_id);
239
240 bool process_refs = _heap->process_references();
241 bool unload_classes = _heap->unload_classes();
242 ReferenceProcessor* rp = NULL;
243 if (process_refs) {
244 rp = _heap->ref_processor();
245 }
246
247 // Step 1: Drain outstanding SATB queues.
248 // NOTE: we piggy-back draining of remaining thread SATB buffers on the final root scan below.
249 ShenandoahTraversalSATBBufferClosure satb_cl(q);
250 {
251 // Process remaining finished SATB buffers.
252 SATBMarkQueueSet& satb_mq_set = ShenandoahBarrierSet::satb_mark_queue_set();
253 while (satb_mq_set.apply_closure_to_completed_buffer(&satb_cl));
254 // Process remaining threads SATB buffers below.
255 }
256
257 // Step 1: Process ordinary GC roots.
258 if (!_heap->is_degenerated_gc_in_progress()) {
259 ShenandoahTraversalClosure roots_cl(q, rp);
260 CLDToOopClosure cld_cl(&roots_cl);
261 MarkingCodeBlobClosure code_cl(&roots_cl, CodeBlobToOopClosure::FixRelocations);
262 ShenandoahTraversalSATBThreadsClosure tc(&satb_cl);
263 if (unload_classes) {
264 ShenandoahRemarkCLDClosure weak_cld_cl(&roots_cl);
265 _rp->process_strong_roots(&roots_cl, process_refs ? NULL : &roots_cl, &cld_cl, &weak_cld_cl, &code_cl, &tc, worker_id);
266 } else {
267 _rp->process_all_roots(&roots_cl, process_refs ? NULL : &roots_cl, &cld_cl, &code_cl, &tc, worker_id);
268 }
269 } else {
270 ShenandoahTraversalDegenClosure roots_cl(q, rp);
271 CLDToOopClosure cld_cl(&roots_cl);
272 MarkingCodeBlobClosure code_cl(&roots_cl, CodeBlobToOopClosure::FixRelocations);
273 ShenandoahTraversalSATBThreadsClosure tc(&satb_cl);
274 if (unload_classes) {
275 ShenandoahRemarkCLDClosure weak_cld_cl(&roots_cl);
276 _rp->process_strong_roots(&roots_cl, process_refs ? NULL : &roots_cl, &cld_cl, &weak_cld_cl, &code_cl, &tc, worker_id);
277 } else {
278 _rp->process_all_roots(&roots_cl, process_refs ? NULL : &roots_cl, &cld_cl, &code_cl, &tc, worker_id);
279 }
280 }
281
282 {
283 ShenandoahWorkerTimings *worker_times = _heap->phase_timings()->worker_times();
284 ShenandoahWorkerTimingsTracker timer(worker_times, ShenandoahPhaseTimings::FinishQueues, worker_id);
285
286 // Step 3: Finally drain all outstanding work in queues.
287 traversal_gc->main_loop(worker_id, _terminator, false);
288 }
289
290 }
291 };
292
293 void ShenandoahTraversalGC::flush_liveness(uint worker_id) {
294 jushort* ld = get_liveness(worker_id);
295 for (uint i = 0; i < _heap->num_regions(); i++) {
296 ShenandoahHeapRegion* r = _heap->get_region(i);
297 jushort live = ld[i];
298 if (live > 0) {
299 r->increase_live_data_gc_words(live);
300 ld[i] = 0;
301 }
302 }
303 }
304
305 ShenandoahTraversalGC::ShenandoahTraversalGC(ShenandoahHeap* heap, size_t num_regions) :
306 _heap(heap),
307 _task_queues(new ShenandoahObjToScanQueueSet(heap->max_workers())),
308 _traversal_set(new ShenandoahHeapRegionSet()),
309 _root_regions(new ShenandoahHeapRegionSet()),
310 _root_regions_iterator(_root_regions->iterator()),
311 _matrix(heap->connection_matrix()) {
312
313 uint num_queues = heap->max_workers();
314 for (uint i = 0; i < num_queues; ++i) {
315 ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue();
316 task_queue->initialize();
317 _task_queues->register_queue(i, task_queue);
318 }
319
320 uint workers = heap->max_workers();
321 _liveness_local = NEW_C_HEAP_ARRAY(jushort*, workers, mtGC);
322 for (uint worker = 0; worker < workers; worker++) {
323 _liveness_local[worker] = NEW_C_HEAP_ARRAY(jushort, num_regions, mtGC);
324 }
325
326 }
327
328 ShenandoahTraversalGC::~ShenandoahTraversalGC() {
329 }
330
331 void ShenandoahTraversalGC::prepare_regions() {
332 ShenandoahHeap* heap = ShenandoahHeap::heap();
333 size_t num_regions = heap->num_regions();
334 ShenandoahConnectionMatrix* matrix = _heap->connection_matrix();
335
336 for (size_t i = 0; i < num_regions; i++) {
337 ShenandoahHeapRegion* region = heap->get_region(i);
338 if (heap->is_bitmap_slice_committed(region)) {
339 if (_traversal_set->is_in(i)) {
340 heap->set_next_top_at_mark_start(region->bottom(), region->top());
341 region->clear_live_data();
342 assert(heap->is_next_bitmap_clear_range(region->bottom(), region->end()), "bitmap for traversal regions must be cleared");
343 } else {
344 // Everything outside the traversal set is always considered live.
345 heap->set_next_top_at_mark_start(region->bottom(), region->bottom());
346 }
347 if (_root_regions->is_in(i)) {
348 assert(!region->in_collection_set(), "roots must not overlap with cset");
349 matrix->clear_region_outbound(i);
350 // Since root region can be allocated at, we should bound the scans
351 // in it at current top. Otherwise, one thread may evacuate objects
352 // to that root region, while another would try to scan newly evac'ed
353 // objects under the race.
354 region->set_concurrent_iteration_safe_limit(region->top());
355 }
356 }
357 }
358 }
359
360 void ShenandoahTraversalGC::prepare() {
361 _heap->collection_set()->clear();
362 assert(_heap->collection_set()->count() == 0, "collection set not clear");
363
364 _heap->make_tlabs_parsable(true);
365
366 assert(_heap->is_next_bitmap_clear(), "need clean mark bitmap");
367
368 ShenandoahFreeSet* free_set = _heap->free_set();
369 ShenandoahCollectionSet* collection_set = _heap->collection_set();
370
371 // Find collection set
372 _heap->shenandoahPolicy()->choose_collection_set(collection_set);
373 prepare_regions();
374
375 // Rebuild free set
376 free_set->rebuild();
377
378 log_info(gc,ergo)("Got "SIZE_FORMAT" collection set regions and "SIZE_FORMAT" root set regions", collection_set->count(), _root_regions->count());
379 }
380
381 void ShenandoahTraversalGC::init_traversal_collection() {
382 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "STW traversal GC");
383
384 if (ShenandoahVerify) {
385 _heap->verifier()->verify_before_traversal();
386 }
387
388 {
389 ShenandoahGCPhase phase_prepare(ShenandoahPhaseTimings::traversal_gc_prepare);
390 ShenandoahHeapLocker lock(_heap->lock());
391 prepare();
392 }
393
394 _heap->set_concurrent_traversal_in_progress(true);
395
396 bool process_refs = _heap->process_references();
397 if (process_refs) {
398 ReferenceProcessor* rp = _heap->ref_processor();
399 rp->enable_discovery(true /*verify_no_refs*/);
400 rp->setup_policy(false);
401 }
402
403 {
404 ShenandoahGCPhase phase_work(ShenandoahPhaseTimings::init_traversal_gc_work);
405 assert(_task_queues->is_empty(), "queues must be empty before traversal GC");
406
407 #if defined(COMPILER2) || INCLUDE_JVMCI
408 DerivedPointerTable::clear();
409 #endif
410
411 {
412 uint nworkers = _heap->workers()->active_workers();
413 task_queues()->reserve(nworkers);
414 ShenandoahRootProcessor rp(_heap, nworkers, ShenandoahPhaseTimings::init_traversal_gc_work);
415
416 if (UseShenandoahOWST) {
417 ShenandoahTaskTerminator terminator(nworkers, task_queues());
418 ShenandoahInitTraversalCollectionTask traversal_task(&rp);
419 _heap->workers()->run_task(&traversal_task);
420 } else {
421 ParallelTaskTerminator terminator(nworkers, task_queues());
422 ShenandoahInitTraversalCollectionTask traversal_task(&rp);
423 _heap->workers()->run_task(&traversal_task);
424 }
425 }
426
427 #if defined(COMPILER2) || INCLUDE_JVMCI
428 DerivedPointerTable::update_pointers();
429 #endif
430 }
431
432 if (ShenandoahPacing) {
433 _heap->pacer()->setup_for_traversal();
434 }
435
436 _root_regions_iterator = _root_regions->iterator();
437 }
438
439 void ShenandoahTraversalGC::main_loop(uint worker_id, ParallelTaskTerminator* terminator, bool do_satb) {
440 if (do_satb) {
441 main_loop_prework<true>(worker_id, terminator);
442 } else {
443 main_loop_prework<false>(worker_id, terminator);
444 }
445 }
446
447 template <bool DO_SATB>
448 void ShenandoahTraversalGC::main_loop_prework(uint w, ParallelTaskTerminator* t) {
449 ShenandoahObjToScanQueue* q = task_queues()->queue(w);
450
451 // Initialize live data.
452 jushort* ld = get_liveness(w);
453 Copy::fill_to_bytes(ld, _heap->num_regions() * sizeof(jushort));
454
455 ReferenceProcessor* rp = NULL;
456 if (_heap->process_references()) {
457 rp = _heap->ref_processor();
458 }
459 if (UseShenandoahMatrix) {
460 if (!_heap->is_degenerated_gc_in_progress()) {
461 if (_heap->unload_classes()) {
462 if (ShenandoahStringDedup::is_enabled()) {
463 ShenandoahStrDedupQueue* dq = ShenandoahStringDedup::queue(w);
464 ShenandoahTraversalMetadataDedupMatrixClosure cl(q, rp, dq);
465 main_loop_work<ShenandoahTraversalMetadataDedupMatrixClosure, DO_SATB>(&cl, ld, w, t);
466 } else {
467 ShenandoahTraversalMetadataMatrixClosure cl(q, rp);
468 main_loop_work<ShenandoahTraversalMetadataMatrixClosure, DO_SATB>(&cl, ld, w, t);
469 }
470 } else {
471 if (ShenandoahStringDedup::is_enabled()) {
472 ShenandoahStrDedupQueue* dq = ShenandoahStringDedup::queue(w);
473 ShenandoahTraversalDedupMatrixClosure cl(q, rp, dq);
474 main_loop_work<ShenandoahTraversalDedupMatrixClosure, DO_SATB>(&cl, ld, w, t);
475 } else {
476 ShenandoahTraversalMatrixClosure cl(q, rp);
477 main_loop_work<ShenandoahTraversalMatrixClosure, DO_SATB>(&cl, ld, w, t);
478 }
479 }
480 } else {
481 if (_heap->unload_classes()) {
482 if (ShenandoahStringDedup::is_enabled()) {
483 ShenandoahStrDedupQueue* dq = ShenandoahStringDedup::queue(w);
484 ShenandoahTraversalMetadataDedupDegenMatrixClosure cl(q, rp, dq);
485 main_loop_work<ShenandoahTraversalMetadataDedupDegenMatrixClosure, DO_SATB>(&cl, ld, w, t);
486 } else {
487 ShenandoahTraversalMetadataDegenMatrixClosure cl(q, rp);
488 main_loop_work<ShenandoahTraversalMetadataDegenMatrixClosure, DO_SATB>(&cl, ld, w, t);
489 }
490 } else {
491 if (ShenandoahStringDedup::is_enabled()) {
492 ShenandoahStrDedupQueue* dq = ShenandoahStringDedup::queue(w);
493 ShenandoahTraversalDedupDegenMatrixClosure cl(q, rp, dq);
494 main_loop_work<ShenandoahTraversalDedupDegenMatrixClosure, DO_SATB>(&cl, ld, w, t);
495 } else {
496 ShenandoahTraversalDegenMatrixClosure cl(q, rp);
497 main_loop_work<ShenandoahTraversalDegenMatrixClosure, DO_SATB>(&cl, ld, w, t);
498 }
499 }
500 }
501 } else {
502 if (!_heap->is_degenerated_gc_in_progress()) {
503 if (_heap->unload_classes()) {
504 if (ShenandoahStringDedup::is_enabled()) {
505 ShenandoahStrDedupQueue* dq = ShenandoahStringDedup::queue(w);
506 ShenandoahTraversalMetadataDedupClosure cl(q, rp, dq);
507 main_loop_work<ShenandoahTraversalMetadataDedupClosure, DO_SATB>(&cl, ld, w, t);
508 } else {
509 ShenandoahTraversalMetadataClosure cl(q, rp);
510 main_loop_work<ShenandoahTraversalMetadataClosure, DO_SATB>(&cl, ld, w, t);
511 }
512 } else {
513 if (ShenandoahStringDedup::is_enabled()) {
514 ShenandoahStrDedupQueue* dq = ShenandoahStringDedup::queue(w);
515 ShenandoahTraversalDedupClosure cl(q, rp, dq);
516 main_loop_work<ShenandoahTraversalDedupClosure, DO_SATB>(&cl, ld, w, t);
517 } else {
518 ShenandoahTraversalClosure cl(q, rp);
519 main_loop_work<ShenandoahTraversalClosure, DO_SATB>(&cl, ld, w, t);
520 }
521 }
522 } else {
523 if (_heap->unload_classes()) {
524 if (ShenandoahStringDedup::is_enabled()) {
525 ShenandoahStrDedupQueue* dq = ShenandoahStringDedup::queue(w);
526 ShenandoahTraversalMetadataDedupDegenClosure cl(q, rp, dq);
527 main_loop_work<ShenandoahTraversalMetadataDedupDegenClosure, DO_SATB>(&cl, ld, w, t);
528 } else {
529 ShenandoahTraversalMetadataDegenClosure cl(q, rp);
530 main_loop_work<ShenandoahTraversalMetadataDegenClosure, DO_SATB>(&cl, ld, w, t);
531 }
532 } else {
533 if (ShenandoahStringDedup::is_enabled()) {
534 ShenandoahStrDedupQueue* dq = ShenandoahStringDedup::queue(w);
535 ShenandoahTraversalDedupDegenClosure cl(q, rp, dq);
536 main_loop_work<ShenandoahTraversalDedupDegenClosure, DO_SATB>(&cl, ld, w, t);
537 } else {
538 ShenandoahTraversalDegenClosure cl(q, rp);
539 main_loop_work<ShenandoahTraversalDegenClosure, DO_SATB>(&cl, ld, w, t);
540 }
541 }
542 }
543 }
544 flush_liveness(w);
545
546 }
547
548 template <class T, bool DO_SATB>
549 void ShenandoahTraversalGC::main_loop_work(T* cl, jushort* live_data, uint worker_id, ParallelTaskTerminator* terminator) {
550 ShenandoahObjToScanQueueSet* queues = task_queues();
551 ShenandoahObjToScanQueue* q = queues->queue(worker_id);
552 ShenandoahConcurrentMark* conc_mark = _heap->concurrentMark();
553
554 uintx stride = ShenandoahMarkLoopStride;
555
556 ShenandoahMarkTask task;
557
558 // Process outstanding queues, if any.
559 q = queues->claim_next();
560 while (q != NULL) {
561 if (_heap->check_cancelled_concgc_and_yield()) {
562 ShenandoahCancelledTerminatorTerminator tt;
563 ShenandoahEvacOOMScopeLeaver oom_scope_leaver;
564 while (!terminator->offer_termination(&tt));
565 return;
566 }
567
568 for (uint i = 0; i < stride; i++) {
569 if (q->pop_buffer(task) ||
570 q->pop_local(task) ||
571 q->pop_overflow(task)) {
572 conc_mark->do_task<T, true>(q, cl, live_data, &task);
573 } else {
574 assert(q->is_empty(), "Must be empty");
575 q = queues->claim_next();
576 break;
577 }
578 }
579 }
580
581 if (check_and_handle_cancelled_gc(terminator)) return;
582
583 // Step 2: Process all root regions.
584 // TODO: Interleave this in the normal mark loop below.
585 ShenandoahHeapRegion* r = _root_regions_iterator.claim_next();
586 while (r != NULL) {
587 _heap->marked_object_oop_safe_iterate(r, cl);
588 if (ShenandoahPacing) {
589 _heap->pacer()->report_partial(r->get_live_data_words());
590 }
591 if (check_and_handle_cancelled_gc(terminator)) return;
592 r = _root_regions_iterator.claim_next();
593 }
594
595 if (check_and_handle_cancelled_gc(terminator)) return;
596
597 // Normal loop.
598 q = queues->queue(worker_id);
599 ShenandoahTraversalSATBBufferClosure satb_cl(q);
600 SATBMarkQueueSet& satb_mq_set = ShenandoahBarrierSet::satb_mark_queue_set();
601
602 int seed = 17;
603
604 while (true) {
605 if (check_and_handle_cancelled_gc(terminator)) return;
606
607 for (uint i = 0; i < stride; i++) {
608 if (q->pop_buffer(task) ||
609 q->pop_local(task) ||
610 q->pop_overflow(task) ||
611 (DO_SATB && satb_mq_set.apply_closure_to_completed_buffer(&satb_cl) && q->pop_buffer(task)) ||
612 queues->steal(worker_id, &seed, task)) {
613 conc_mark->do_task<T, true>(q, cl, live_data, &task);
614 } else {
615 ShenandoahEvacOOMScopeLeaver oom_scope_leaver;
616 if (terminator->offer_termination()) return;
617 }
618 }
619 }
620 }
621
622 bool ShenandoahTraversalGC::check_and_handle_cancelled_gc(ParallelTaskTerminator* terminator) {
623 if (_heap->cancelled_concgc()) {
624 ShenandoahCancelledTerminatorTerminator tt;
625 ShenandoahEvacOOMScopeLeaver oom_scope_leaver;
626 while (! terminator->offer_termination(&tt));
627 return true;
628 }
629 return false;
630 }
631
632 void ShenandoahTraversalGC::concurrent_traversal_collection() {
633 ClassLoaderDataGraph::clear_claimed_marks();
634
635 ShenandoahGCPhase phase_work(ShenandoahPhaseTimings::conc_traversal);
636 if (!_heap->cancelled_concgc()) {
637 uint nworkers = _heap->workers()->active_workers();
638 task_queues()->reserve(nworkers);
639 if (UseShenandoahOWST) {
640 ShenandoahTaskTerminator terminator(nworkers, task_queues());
641 ShenandoahConcurrentTraversalCollectionTask traversal_task(&terminator);
642 _heap->workers()->run_task(&traversal_task);
643 } else {
644 ParallelTaskTerminator terminator(nworkers, task_queues());
645 ShenandoahConcurrentTraversalCollectionTask traversal_task(&terminator);
646 _heap->workers()->run_task(&traversal_task);
647 }
648 }
649
650 if (!_heap->cancelled_concgc() && ShenandoahPreclean && _heap->process_references()) {
651 ShenandoahEvacOOMScope oom_evac_scope;
652 preclean_weak_refs();
653 }
654 }
655
656 void ShenandoahTraversalGC::final_traversal_collection() {
657
658 _heap->make_tlabs_parsable(true);
659
660 if (!_heap->cancelled_concgc()) {
661 #if defined(COMPILER2) || INCLUDE_JVMCI
662 DerivedPointerTable::clear();
663 #endif
664 ShenandoahGCPhase phase_work(ShenandoahPhaseTimings::final_traversal_gc_work);
665 uint nworkers = _heap->workers()->active_workers();
666 task_queues()->reserve(nworkers);
667
668 // Finish traversal
669 ShenandoahRootProcessor rp(_heap, nworkers, ShenandoahPhaseTimings::final_traversal_gc_work);
670 if (UseShenandoahOWST) {
671 ShenandoahTaskTerminator terminator(nworkers, task_queues());
672 ShenandoahFinalTraversalCollectionTask traversal_task(&rp, &terminator);
673 _heap->workers()->run_task(&traversal_task);
674 } else {
675 ParallelTaskTerminator terminator(nworkers, task_queues());
676 ShenandoahFinalTraversalCollectionTask traversal_task(&rp, &terminator);
677 _heap->workers()->run_task(&traversal_task);
678 }
679 #if defined(COMPILER2) || INCLUDE_JVMCI
680 DerivedPointerTable::update_pointers();
681 #endif
682 }
683
684 if (!_heap->cancelled_concgc() && _heap->process_references()) {
685 weak_refs_work();
686 }
687
688 if (!_heap->cancelled_concgc() && _heap->unload_classes()) {
689 _heap->unload_classes_and_cleanup_tables(false);
690 fixup_roots();
691 }
692
693 if (!_heap->cancelled_concgc()) {
694 // Still good? We can now trash the cset, and make final verification
695 {
696 ShenandoahGCPhase phase_cleanup(ShenandoahPhaseTimings::traversal_gc_cleanup);
697 ShenandoahHeapLocker lock(_heap->lock());
698
699 // Trash everything
700 // Clear immediate garbage regions.
701 size_t num_regions = _heap->num_regions();
702
703 ShenandoahHeapRegionSet* traversal_regions = traversal_set();
704 ShenandoahFreeSet* free_regions = _heap->free_set();
705 free_regions->clear();
706 for (size_t i = 0; i < num_regions; i++) {
707 ShenandoahHeapRegion* r = _heap->get_region(i);
708 bool not_allocated = _heap->next_top_at_mark_start(r->bottom()) == r->top();
709
710 bool candidate = traversal_regions->is_in(r) && !r->has_live() && not_allocated;
711 if (r->is_humongous_start() && candidate) {
712 // Trash humongous.
713 HeapWord* humongous_obj = r->bottom() + BrooksPointer::word_size();
714 assert(!_heap->is_marked_next(oop(humongous_obj)), "must not be marked");
715 r->make_trash();
716 while (i + 1 < num_regions && _heap->get_region(i + 1)->is_humongous_continuation()) {
717 i++;
718 r = _heap->get_region(i);
719 assert(r->is_humongous_continuation(), "must be humongous continuation");
720 r->make_trash();
721 }
722 } else if (!r->is_empty() && candidate) {
723 // Trash regular.
724 assert(!r->is_humongous(), "handled above");
725 assert(!r->is_trash(), "must not already be trashed");
726 r->make_trash();
727 }
728 }
729 _heap->collection_set()->clear();
730 _heap->free_set()->rebuild();
731 reset();
732 }
733
734 if (ShenandoahVerify) {
735 _heap->verifier()->verify_after_traversal();
736 }
737
738 assert(_task_queues->is_empty(), "queues must be empty after traversal GC");
739 _heap->set_concurrent_traversal_in_progress(false);
740 assert(!_heap->cancelled_concgc(), "must not be cancelled when getting out here");
741 }
742 }
743
744 class ShenandoahTraversalFixRootsClosure : public OopClosure {
745 private:
746
747 template <class T>
748 inline void do_oop_work(T* p) {
749 T o = RawAccess<>::oop_load(p);
750 if (!CompressedOops::is_null(o)) {
751 oop obj = CompressedOops::decode_not_null(o);
752 oop forw = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
753 if (!oopDesc::unsafe_equals(obj, forw)) {
754 RawAccess<OOP_NOT_NULL>::oop_store(p, forw);
755 }
756 }
757 }
758 public:
759 inline void do_oop(oop* p) { do_oop_work(p); }
760 inline void do_oop(narrowOop* p) { do_oop_work(p); }
761 };
762
763 class ShenandoahTraversalFixRootsTask : public AbstractGangTask {
764 ShenandoahRootProcessor* _rp;
765 public:
766
767 ShenandoahTraversalFixRootsTask(ShenandoahRootProcessor* rp) :
768 AbstractGangTask("Shenandoah traversal fix roots"),
769 _rp(rp)
770 {
771 // Nothing else to do.
772 }
773
774 void work(uint worker_id) {
775 ShenandoahTraversalFixRootsClosure cl;
776 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
777 CLDToOopClosure cldCl(&cl);
778 _rp->process_all_roots(&cl, &cl, &cldCl, &blobsCl, NULL, worker_id);
779 }
780 };
781
782 void ShenandoahTraversalGC::fixup_roots() {
783 #if defined(COMPILER2) || INCLUDE_JVMCI
784 DerivedPointerTable::clear();
785 #endif
786 ShenandoahHeap* heap = ShenandoahHeap::heap();
787 ShenandoahRootProcessor rp(heap, heap->workers()->active_workers(), ShenandoahPhaseTimings::final_traversal_update_roots);
788 ShenandoahTraversalFixRootsTask update_roots_task(&rp);
789 heap->workers()->run_task(&update_roots_task);
790 #if defined(COMPILER2) || INCLUDE_JVMCI
791 DerivedPointerTable::update_pointers();
792 #endif
793 }
794
795 void ShenandoahTraversalGC::reset() {
796 _task_queues->clear();
797 }
798
799 ShenandoahObjToScanQueueSet* ShenandoahTraversalGC::task_queues() {
800 return _task_queues;
801 }
802
803 jushort* ShenandoahTraversalGC::get_liveness(uint worker_id) {
804 return _liveness_local[worker_id];
805 }
806
807 class ShenandoahTraversalCancelledGCYieldClosure : public YieldClosure {
808 private:
809 ShenandoahHeap* const _heap;
810 public:
811 ShenandoahTraversalCancelledGCYieldClosure() : _heap(ShenandoahHeap::heap()) {};
812 virtual bool should_return() { return _heap->cancelled_concgc(); }
813 };
814
815 class ShenandoahTraversalPrecleanCompleteGCClosure : public VoidClosure {
816 public:
817 void do_void() {
818 ShenandoahHeap* sh = ShenandoahHeap::heap();
819 ShenandoahTraversalGC* traversal_gc = sh->traversal_gc();
820 assert(sh->process_references(), "why else would we be here?");
821 ParallelTaskTerminator terminator(1, traversal_gc->task_queues());
822 shenandoah_assert_rp_isalive_installed();
823 traversal_gc->main_loop((uint) 0, &terminator, false);
824 }
825 };
826
827 class ShenandoahTraversalKeepAliveUpdateClosure : public OopClosure {
828 private:
829 ShenandoahObjToScanQueue* _queue;
830 Thread* _thread;
831 ShenandoahTraversalGC* _traversal_gc;
832 template <class T>
833 inline void do_oop_nv(T* p) {
834 _traversal_gc->process_oop<T, false /* string dedup */, false /* degen */, false /* matrix */>(p, _thread, _queue, NULL);
835 }
836
837 public:
838 ShenandoahTraversalKeepAliveUpdateClosure(ShenandoahObjToScanQueue* q) :
839 _queue(q), _thread(Thread::current()),
840 _traversal_gc(ShenandoahHeap::heap()->traversal_gc()) {}
841
842 void do_oop(narrowOop* p) { do_oop_nv(p); }
843 void do_oop(oop* p) { do_oop_nv(p); }
844 };
845
846 class ShenandoahTraversalKeepAliveUpdateDegenClosure : public OopClosure {
847 private:
848 ShenandoahObjToScanQueue* _queue;
849 Thread* _thread;
850 ShenandoahTraversalGC* _traversal_gc;
851 template <class T>
852 inline void do_oop_nv(T* p) {
853 _traversal_gc->process_oop<T, false /* string dedup */, true /* degen */, false /* matrix */>(p, _thread, _queue, NULL);
854 }
855
856 public:
857 ShenandoahTraversalKeepAliveUpdateDegenClosure(ShenandoahObjToScanQueue* q) :
858 _queue(q), _thread(Thread::current()),
859 _traversal_gc(ShenandoahHeap::heap()->traversal_gc()) {}
860
861 void do_oop(narrowOop* p) { do_oop_nv(p); }
862 void do_oop(oop* p) { do_oop_nv(p); }
863 };
864
865 class ShenandoahTraversalKeepAliveUpdateMatrixClosure : public OopClosure {
866 private:
867 ShenandoahObjToScanQueue* _queue;
868 Thread* _thread;
869 ShenandoahTraversalGC* _traversal_gc;
870 template <class T>
871 inline void do_oop_nv(T* p) {
872 // TODO: Need to somehow pass base_obj here?
873 _traversal_gc->process_oop<T, false /* string dedup */, false /* degen */, true /* matrix */>(p, _thread, _queue, NULL);
874 }
875
876 public:
877 ShenandoahTraversalKeepAliveUpdateMatrixClosure(ShenandoahObjToScanQueue* q) :
878 _queue(q), _thread(Thread::current()),
879 _traversal_gc(ShenandoahHeap::heap()->traversal_gc()) {}
880
881 void do_oop(narrowOop* p) { do_oop_nv(p); }
882 void do_oop(oop* p) { do_oop_nv(p); }
883 };
884
885 class ShenandoahTraversalKeepAliveUpdateDegenMatrixClosure : public OopClosure {
886 private:
887 ShenandoahObjToScanQueue* _queue;
888 Thread* _thread;
889 ShenandoahTraversalGC* _traversal_gc;
890 template <class T>
891 inline void do_oop_nv(T* p) {
892 // TODO: Need to somehow pass base_obj here?
893 _traversal_gc->process_oop<T, false /* string dedup */, true /* degen */, true /* matrix */>(p, _thread, _queue, NULL);
894 }
895
896 public:
897 ShenandoahTraversalKeepAliveUpdateDegenMatrixClosure(ShenandoahObjToScanQueue* q) :
898 _queue(q), _thread(Thread::current()),
899 _traversal_gc(ShenandoahHeap::heap()->traversal_gc()) {}
900
901 void do_oop(narrowOop* p) { do_oop_nv(p); }
902 void do_oop(oop* p) { do_oop_nv(p); }
903 };
904
905 void ShenandoahTraversalGC::preclean_weak_refs() {
906 // Pre-cleaning weak references before diving into STW makes sense at the
907 // end of concurrent mark. This will filter out the references which referents
908 // are alive. Note that ReferenceProcessor already filters out these on reference
909 // discovery, and the bulk of work is done here. This phase processes leftovers
910 // that missed the initial filtering, i.e. when referent was marked alive after
911 // reference was discovered by RP.
912
913 assert(_heap->process_references(), "sanity");
914
915 ShenandoahHeap* sh = ShenandoahHeap::heap();
916 ReferenceProcessor* rp = sh->ref_processor();
917
918 // Shortcut if no references were discovered to avoid winding up threads.
919 if (!rp->has_discovered_references()) {
920 return;
921 }
922
923 ReferenceProcessorMTDiscoveryMutator fix_mt_discovery(rp, false);
924
925 shenandoah_assert_rp_isalive_not_installed();
926 ReferenceProcessorIsAliveMutator fix_isalive(rp, sh->is_alive_closure());
927
928 // Interrupt on cancelled GC
929 ShenandoahTraversalCancelledGCYieldClosure yield;
930
931 assert(task_queues()->is_empty(), "Should be empty");
932 assert(!sh->is_degenerated_gc_in_progress(), "must be in concurrent non-degenerated phase");
933
934 ShenandoahTraversalPrecleanCompleteGCClosure complete_gc;
935 ShenandoahForwardedIsAliveClosure is_alive;
936 if (UseShenandoahMatrix) {
937 ShenandoahTraversalKeepAliveUpdateMatrixClosure keep_alive(task_queues()->queue(0));
938 ResourceMark rm;
939 rp->preclean_discovered_references(&is_alive, &keep_alive,
940 &complete_gc, &yield,
941 NULL);
942 } else {
943 ShenandoahTraversalKeepAliveUpdateClosure keep_alive(task_queues()->queue(0));
944 ResourceMark rm;
945 rp->preclean_discovered_references(&is_alive, &keep_alive,
946 &complete_gc, &yield,
947 NULL);
948 }
949 assert(!sh->cancelled_concgc() || task_queues()->is_empty(), "Should be empty");
950 }
951
952 // Weak Reference Closures
953 class ShenandoahTraversalDrainMarkingStackClosure: public VoidClosure {
954 uint _worker_id;
955 ParallelTaskTerminator* _terminator;
956 bool _reset_terminator;
957
958 public:
959 ShenandoahTraversalDrainMarkingStackClosure(uint worker_id, ParallelTaskTerminator* t, bool reset_terminator = false):
960 _worker_id(worker_id),
961 _terminator(t),
962 _reset_terminator(reset_terminator) {
963 }
964
965 void do_void() {
966 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");
967
968 ShenandoahHeap* sh = ShenandoahHeap::heap();
969 ShenandoahTraversalGC* traversal_gc = sh->traversal_gc();
970 assert(sh->process_references(), "why else would we be here?");
971 shenandoah_assert_rp_isalive_installed();
972
973 traversal_gc->main_loop(_worker_id, _terminator, false);
974
975 if (_reset_terminator) {
976 _terminator->reset_for_reuse();
977 }
978 }
979 };
980
981 void ShenandoahTraversalGC::weak_refs_work() {
982 assert(_heap->process_references(), "sanity");
983
984 ShenandoahHeap* sh = ShenandoahHeap::heap();
985
986 ShenandoahPhaseTimings::Phase phase_root = ShenandoahPhaseTimings::weakrefs;
987
988 ShenandoahGCPhase phase(phase_root);
989
990 ReferenceProcessor* rp = sh->ref_processor();
991
992 // NOTE: We cannot shortcut on has_discovered_references() here, because
993 // we will miss marking JNI Weak refs then, see implementation in
994 // ReferenceProcessor::process_discovered_references.
995 weak_refs_work_doit();
996
997 rp->verify_no_references_recorded();
998 assert(!rp->discovery_enabled(), "Post condition");
999
1000 }
1001
1002 class ShenandoahTraversalRefProcTaskProxy : public AbstractGangTask {
1003
1004 private:
1005 AbstractRefProcTaskExecutor::ProcessTask& _proc_task;
1006 ParallelTaskTerminator* _terminator;
1007 public:
1008
1009 ShenandoahTraversalRefProcTaskProxy(AbstractRefProcTaskExecutor::ProcessTask& proc_task,
1010 ParallelTaskTerminator* t) :
1011 AbstractGangTask("Process reference objects in parallel"),
1012 _proc_task(proc_task),
1013 _terminator(t) {
1014 }
1015
1016 void work(uint worker_id) {
1017 ShenandoahEvacOOMScope oom_evac_scope;
1018 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");
1019 ShenandoahHeap* heap = ShenandoahHeap::heap();
1020 ShenandoahTraversalDrainMarkingStackClosure complete_gc(worker_id, _terminator);
1021
1022 ShenandoahForwardedIsAliveClosure is_alive;
1023 if (UseShenandoahMatrix) {
1024 if (!heap->is_degenerated_gc_in_progress()) {
1025 ShenandoahTraversalKeepAliveUpdateMatrixClosure keep_alive(heap->traversal_gc()->task_queues()->queue(worker_id));
1026 _proc_task.work(worker_id, is_alive, keep_alive, complete_gc);
1027 } else {
1028 ShenandoahTraversalKeepAliveUpdateDegenMatrixClosure keep_alive(heap->traversal_gc()->task_queues()->queue(worker_id));
1029 _proc_task.work(worker_id, is_alive, keep_alive, complete_gc);
1030 }
1031 } else {
1032 if (!heap->is_degenerated_gc_in_progress()) {
1033 ShenandoahTraversalKeepAliveUpdateClosure keep_alive(heap->traversal_gc()->task_queues()->queue(worker_id));
1034 _proc_task.work(worker_id, is_alive, keep_alive, complete_gc);
1035 } else {
1036 ShenandoahTraversalKeepAliveUpdateDegenClosure keep_alive(heap->traversal_gc()->task_queues()->queue(worker_id));
1037 _proc_task.work(worker_id, is_alive, keep_alive, complete_gc);
1038 }
1039 }
1040 }
1041 };
1042
1043 class ShenandoahTraversalRefEnqueueTaskProxy : public AbstractGangTask {
1044
1045 private:
1046 AbstractRefProcTaskExecutor::EnqueueTask& _enqueue_task;
1047
1048 public:
1049
1050 ShenandoahTraversalRefEnqueueTaskProxy(AbstractRefProcTaskExecutor::EnqueueTask& enqueue_task) :
1051 AbstractGangTask("Enqueue reference objects in parallel"),
1052 _enqueue_task(enqueue_task) {
1053 }
1054
1055 void work(uint worker_id) {
1056 _enqueue_task.work(worker_id);
1057 }
1058 };
1059
1060 class ShenandoahTraversalRefProcTaskExecutor : public AbstractRefProcTaskExecutor {
1061
1062 private:
1063 WorkGang* _workers;
1064
1065 public:
1066
1067 ShenandoahTraversalRefProcTaskExecutor(WorkGang* workers) :
1068 _workers(workers) {
1069 }
1070
1071 // Executes a task using worker threads.
1072 void execute(ProcessTask& task) {
1073 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");
1074
1075 // Shortcut execution if task is empty.
1076 // This should be replaced with the generic ReferenceProcessor shortcut,
1077 // see JDK-8181214, JDK-8043575, JDK-6938732.
1078 if (task.is_empty()) {
1079 return;
1080 }
1081
1082 ShenandoahHeap* heap = ShenandoahHeap::heap();
1083 ShenandoahTraversalGC* traversal_gc = heap->traversal_gc();
1084 uint nworkers = _workers->active_workers();
1085 traversal_gc->task_queues()->reserve(nworkers);
1086 if (UseShenandoahOWST) {
1087 ShenandoahTaskTerminator terminator(nworkers, traversal_gc->task_queues());
1088 ShenandoahTraversalRefProcTaskProxy proc_task_proxy(task, &terminator);
1089 _workers->run_task(&proc_task_proxy);
1090 } else {
1091 ParallelTaskTerminator terminator(nworkers, traversal_gc->task_queues());
1092 ShenandoahTraversalRefProcTaskProxy proc_task_proxy(task, &terminator);
1093 _workers->run_task(&proc_task_proxy);
1094 }
1095 }
1096
1097 void execute(EnqueueTask& task) {
1098 ShenandoahTraversalRefEnqueueTaskProxy enqueue_task_proxy(task);
1099 _workers->run_task(&enqueue_task_proxy);
1100 }
1101 };
1102
1103 void ShenandoahTraversalGC::weak_refs_work_doit() {
1104 ShenandoahHeap* sh = ShenandoahHeap::heap();
1105
1106 ReferenceProcessor* rp = sh->ref_processor();
1107
1108 ShenandoahPhaseTimings::Phase phase_process = ShenandoahPhaseTimings::weakrefs_process;
1109 ShenandoahPhaseTimings::Phase phase_enqueue = ShenandoahPhaseTimings::weakrefs_enqueue;
1110
1111 shenandoah_assert_rp_isalive_not_installed();
1112 ReferenceProcessorIsAliveMutator fix_isalive(rp, sh->is_alive_closure());
1113
1114 WorkGang* workers = sh->workers();
1115 uint nworkers = workers->active_workers();
1116
1117 // Setup collector policy for softref cleaning.
1118 bool clear_soft_refs = sh->soft_ref_policy()->use_should_clear_all_soft_refs(true /* bogus arg*/);
1119 log_develop_debug(gc, ref)("clearing soft refs: %s", BOOL_TO_STR(clear_soft_refs));
1120 rp->setup_policy(clear_soft_refs);
1121 rp->set_active_mt_degree(nworkers);
1122
1123 assert(task_queues()->is_empty(), "Should be empty");
1124
1125 // complete_gc and keep_alive closures instantiated here are only needed for
1126 // single-threaded path in RP. They share the queue 0 for tracking work, which
1127 // simplifies implementation. Since RP may decide to call complete_gc several
1128 // times, we need to be able to reuse the terminator.
1129 uint serial_worker_id = 0;
1130 ParallelTaskTerminator terminator(1, task_queues());
1131 ShenandoahTraversalDrainMarkingStackClosure complete_gc(serial_worker_id, &terminator, /* reset_terminator = */ true);
1132
1133 ShenandoahTraversalRefProcTaskExecutor executor(workers);
1134
1135 ReferenceProcessorPhaseTimes pt(sh->gc_timer(), rp->num_q());
1136
1137 {
1138 ShenandoahGCPhase phase(phase_process);
1139
1140 ShenandoahForwardedIsAliveClosure is_alive;
1141 if (UseShenandoahMatrix) {
1142 if (!_heap->is_degenerated_gc_in_progress()) {
1143 ShenandoahTraversalKeepAliveUpdateMatrixClosure keep_alive(task_queues()->queue(serial_worker_id));
1144 rp->process_discovered_references(&is_alive, &keep_alive,
1145 &complete_gc, &executor,
1146 &pt);
1147 pt.print_all_references();
1148 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
1149 } else {
1150 ShenandoahTraversalKeepAliveUpdateDegenMatrixClosure keep_alive(task_queues()->queue(serial_worker_id));
1151 rp->process_discovered_references(&is_alive, &keep_alive,
1152 &complete_gc, &executor,
1153 &pt);
1154 pt.print_all_references();
1155 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
1156 }
1157 } else {
1158 if (!_heap->is_degenerated_gc_in_progress()) {
1159 ShenandoahTraversalKeepAliveUpdateClosure keep_alive(task_queues()->queue(serial_worker_id));
1160 rp->process_discovered_references(&is_alive, &keep_alive,
1161 &complete_gc, &executor,
1162 &pt);
1163 pt.print_all_references();
1164 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
1165 } else {
1166 ShenandoahTraversalKeepAliveUpdateDegenClosure keep_alive(task_queues()->queue(serial_worker_id));
1167 rp->process_discovered_references(&is_alive, &keep_alive,
1168 &complete_gc, &executor,
1169 &pt);
1170 pt.print_all_references();
1171 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
1172 }
1173 }
1174
1175 assert(!_heap->cancelled_concgc() || task_queues()->is_empty(), "Should be empty");
1176 }
1177
1178 if (_heap->cancelled_concgc()) return;
1179
1180 {
1181 ShenandoahGCPhase phase(phase_enqueue);
1182 rp->enqueue_discovered_references(&executor, &pt);
1183 pt.print_enqueue_phase();
1184 }
1185 }