1 /*
2 * Copyright (c) 2013, 2020, Red Hat, Inc. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26
27 #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp"
28 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
29 #include "gc/shenandoah/shenandoahControlThread.hpp"
30 #include "gc/shenandoah/shenandoahFreeSet.hpp"
31 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
32 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
33 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
34 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
35 #include "gc/shenandoah/shenandoahUtils.hpp"
36 #include "gc/shenandoah/shenandoahVMOperations.hpp"
37 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
38 #include "gc/shenandoah/heuristics/shenandoahHeuristics.hpp"
39 #include "memory/iterator.hpp"
40 #include "memory/universe.hpp"
41 #include "runtime/atomic.hpp"
42
43 ShenandoahControlThread::ShenandoahControlThread() :
44 ConcurrentGCThread(),
45 _alloc_failure_waiters_lock(Mutex::leaf, "ShenandoahAllocFailureGC_lock", true, Monitor::_safepoint_check_always),
46 _gc_waiters_lock(Mutex::leaf, "ShenandoahRequestedGC_lock", true, Monitor::_safepoint_check_always),
47 _periodic_task(this),
48 _requested_gc_cause(GCCause::_no_cause_specified),
49 _degen_point(ShenandoahHeap::_degenerated_outside_cycle),
50 _allocs_seen(0) {
51
52 reset_gc_id();
53 create_and_start();
54 _periodic_task.enroll();
55 _periodic_satb_flush_task.enroll();
56 if (ShenandoahPacing) {
57 _periodic_pacer_notify_task.enroll();
58 }
59 }
60
61 ShenandoahControlThread::~ShenandoahControlThread() {
62 // This is here so that super is called.
63 }
64
65 void ShenandoahPeriodicTask::task() {
66 _thread->handle_force_counters_update();
67 _thread->handle_counters_update();
68 }
69
70 void ShenandoahPeriodicSATBFlushTask::task() {
71 ShenandoahHeap::heap()->force_satb_flush_all_threads();
72 }
73
74 void ShenandoahPeriodicPacerNotify::task() {
75 assert(ShenandoahPacing, "Should not be here otherwise");
76 ShenandoahHeap::heap()->pacer()->notify_waiters();
77 }
78
79 void ShenandoahControlThread::run_service() {
80 ShenandoahHeap* heap = ShenandoahHeap::heap();
81
82 GCMode default_mode = concurrent_normal;
83 GCCause::Cause default_cause = GCCause::_shenandoah_concurrent_gc;
84 int sleep = ShenandoahControlIntervalMin;
85
86 double last_shrink_time = os::elapsedTime();
87 double last_sleep_adjust_time = os::elapsedTime();
88
89 // Shrink period avoids constantly polling regions for shrinking.
90 // Having a period 10x lower than the delay would mean we hit the
91 // shrinking with lag of less than 1/10-th of true delay.
92 // ShenandoahUncommitDelay is in msecs, but shrink_period is in seconds.
93 double shrink_period = (double)ShenandoahUncommitDelay / 1000 / 10;
94
95 ShenandoahCollectorPolicy* policy = heap->shenandoah_policy();
96 ShenandoahHeuristics* heuristics = heap->heuristics();
97 while (!in_graceful_shutdown() && !should_terminate()) {
98 // Figure out if we have pending requests.
99 bool alloc_failure_pending = _alloc_failure_gc.is_set();
100 bool explicit_gc_requested = _gc_requested.is_set() && is_explicit_gc(_requested_gc_cause);
101 bool implicit_gc_requested = _gc_requested.is_set() && !is_explicit_gc(_requested_gc_cause);
102
103 // This control loop iteration have seen this much allocations.
104 size_t allocs_seen = Atomic::xchg(&_allocs_seen, (size_t)0);
105
106 // Choose which GC mode to run in. The block below should select a single mode.
107 GCMode mode = none;
108 GCCause::Cause cause = GCCause::_last_gc_cause;
109 ShenandoahHeap::ShenandoahDegenPoint degen_point = ShenandoahHeap::_degenerated_unset;
110
111 if (alloc_failure_pending) {
112 // Allocation failure takes precedence: we have to deal with it first thing
113 log_info(gc)("Trigger: Handle Allocation Failure");
114
115 cause = GCCause::_allocation_failure;
116
117 // Consume the degen point, and seed it with default value
118 degen_point = _degen_point;
119 _degen_point = ShenandoahHeap::_degenerated_outside_cycle;
120
121 if (ShenandoahDegeneratedGC && heuristics->should_degenerate_cycle()) {
122 heuristics->record_allocation_failure_gc();
123 policy->record_alloc_failure_to_degenerated(degen_point);
124 mode = stw_degenerated;
125 } else {
126 heuristics->record_allocation_failure_gc();
127 policy->record_alloc_failure_to_full();
128 mode = stw_full;
129 }
130
131 } else if (explicit_gc_requested) {
132 cause = _requested_gc_cause;
133 log_info(gc)("Trigger: Explicit GC request (%s)", GCCause::to_string(cause));
134
135 heuristics->record_requested_gc();
136
137 if (ExplicitGCInvokesConcurrent) {
138 policy->record_explicit_to_concurrent();
139 mode = default_mode;
140 // Unload and clean up everything
141 heap->set_process_references(heuristics->can_process_references());
142 heap->set_unload_classes(heuristics->can_unload_classes());
143 } else {
144 policy->record_explicit_to_full();
145 mode = stw_full;
146 }
147 } else if (implicit_gc_requested) {
148 cause = _requested_gc_cause;
149 log_info(gc)("Trigger: Implicit GC request (%s)", GCCause::to_string(cause));
150
151 heuristics->record_requested_gc();
152
153 if (ShenandoahImplicitGCInvokesConcurrent) {
154 policy->record_implicit_to_concurrent();
155 mode = default_mode;
156
157 // Unload and clean up everything
158 heap->set_process_references(heuristics->can_process_references());
159 heap->set_unload_classes(heuristics->can_unload_classes());
160 } else {
161 policy->record_implicit_to_full();
162 mode = stw_full;
163 }
164 } else {
165 // Potential normal cycle: ask heuristics if it wants to act
166 if (heuristics->should_start_gc()) {
167 mode = default_mode;
168 cause = default_cause;
169 }
170
171 // Ask policy if this cycle wants to process references or unload classes
172 heap->set_process_references(heuristics->should_process_references());
173 heap->set_unload_classes(heuristics->should_unload_classes());
174 }
175
176 // Blow all soft references on this cycle, if handling allocation failure,
177 // either implicit or explicit GC request, or we are requested to do so unconditionally.
178 if (alloc_failure_pending || implicit_gc_requested || explicit_gc_requested || ShenandoahAlwaysClearSoftRefs) {
179 heap->soft_ref_policy()->set_should_clear_all_soft_refs(true);
180 }
181
182 bool gc_requested = (mode != none);
183 assert (!gc_requested || cause != GCCause::_last_gc_cause, "GC cause should be set");
184
185 if (gc_requested) {
186 // GC is starting, bump the internal ID
187 update_gc_id();
188
189 heap->reset_bytes_allocated_since_gc_start();
190
191 // Use default constructor to snapshot the Metaspace state before GC.
192 metaspace::MetaspaceSizesSnapshot meta_sizes;
193
194 // If GC was requested, we are sampling the counters even without actual triggers
195 // from allocation machinery. This captures GC phases more accurately.
196 set_forced_counters_update(true);
197
198 // If GC was requested, we better dump freeset data for performance debugging
199 {
200 ShenandoahHeapLocker locker(heap->lock());
201 heap->free_set()->log_status();
202 }
203
204 switch (mode) {
205 case concurrent_normal:
206 service_concurrent_normal_cycle(cause);
207 break;
208 case stw_degenerated:
209 service_stw_degenerated_cycle(cause, degen_point);
210 break;
211 case stw_full:
212 service_stw_full_cycle(cause);
213 break;
214 default:
215 ShouldNotReachHere();
216 }
217
218 // If this was the requested GC cycle, notify waiters about it
219 if (explicit_gc_requested || implicit_gc_requested) {
220 notify_gc_waiters();
221 }
222
223 // If this was the allocation failure GC cycle, notify waiters about it
224 if (alloc_failure_pending) {
225 notify_alloc_failure_waiters();
226 }
227
228 // Report current free set state at the end of cycle, whether
229 // it is a normal completion, or the abort.
230 {
231 ShenandoahHeapLocker locker(heap->lock());
232 heap->free_set()->log_status();
233
234 // Notify Universe about new heap usage. This has implications for
235 // global soft refs policy, and we better report it every time heap
236 // usage goes down.
237 Universe::update_heap_info_at_gc();
238
239 // Signal that we have completed a visit to all live objects.
240 Universe::heap()->record_whole_heap_examined_timestamp();
241 }
242
243 // Disable forced counters update, and update counters one more time
244 // to capture the state at the end of GC session.
245 handle_force_counters_update();
246 set_forced_counters_update(false);
247
248 // Retract forceful part of soft refs policy
249 heap->soft_ref_policy()->set_should_clear_all_soft_refs(false);
250
251 // Clear metaspace oom flag, if current cycle unloaded classes
252 if (heap->unload_classes()) {
253 heuristics->clear_metaspace_oom();
254 }
255
256 // Commit worker statistics to cycle data
257 heap->phase_timings()->flush_par_workers_to_cycle();
258 if (ShenandoahPacing) {
259 heap->pacer()->flush_stats_to_cycle();
260 }
261
262 // Print GC stats for current cycle
263 {
264 LogTarget(Info, gc, stats) lt;
265 if (lt.is_enabled()) {
266 ResourceMark rm;
267 LogStream ls(lt);
268 heap->phase_timings()->print_cycle_on(&ls);
269 if (ShenandoahPacing) {
270 heap->pacer()->print_cycle_on(&ls);
271 }
272 }
273 }
274
275 // Commit statistics to globals
276 heap->phase_timings()->flush_cycle_to_global();
277
278 // Print Metaspace change following GC (if logging is enabled).
279 MetaspaceUtils::print_metaspace_change(meta_sizes);
280
281 // GC is over, we are at idle now
282 if (ShenandoahPacing) {
283 heap->pacer()->setup_for_idle();
284 }
285 } else {
286 // Allow allocators to know we have seen this much regions
287 if (ShenandoahPacing && (allocs_seen > 0)) {
288 heap->pacer()->report_alloc(allocs_seen);
289 }
290 }
291
292 double current = os::elapsedTime();
293
294 if (ShenandoahUncommit && (explicit_gc_requested || (current - last_shrink_time > shrink_period))) {
295 // Try to uncommit enough stale regions. Explicit GC tries to uncommit everything.
296 // Regular paths uncommit only occasionally.
297 double shrink_before = explicit_gc_requested ?
298 current :
299 current - (ShenandoahUncommitDelay / 1000.0);
300 service_uncommit(shrink_before);
301 heap->phase_timings()->flush_cycle_to_global();
302 last_shrink_time = current;
303 }
304
305 // Wait before performing the next action. If allocation happened during this wait,
306 // we exit sooner, to let heuristics re-evaluate new conditions. If we are at idle,
307 // back off exponentially.
308 if (_heap_changed.try_unset()) {
309 sleep = ShenandoahControlIntervalMin;
310 } else if ((current - last_sleep_adjust_time) * 1000 > ShenandoahControlIntervalAdjustPeriod){
311 sleep = MIN2<int>(ShenandoahControlIntervalMax, MAX2(1, sleep * 2));
312 last_sleep_adjust_time = current;
313 }
314 os::naked_short_sleep(sleep);
315 }
316
317 // Wait for the actual stop(), can't leave run_service() earlier.
318 while (!should_terminate()) {
319 os::naked_short_sleep(ShenandoahControlIntervalMin);
320 }
321 }
322
323 void ShenandoahControlThread::service_concurrent_normal_cycle(GCCause::Cause cause) {
324 // Normal cycle goes via all concurrent phases. If allocation failure (af) happens during
325 // any of the concurrent phases, it first degrades to Degenerated GC and completes GC there.
326 // If second allocation failure happens during Degenerated GC cycle (for example, when GC
327 // tries to evac something and no memory is available), cycle degrades to Full GC.
328 //
329 // There are also a shortcut through the normal cycle: immediate garbage shortcut, when
330 // heuristics says there are no regions to compact, and all the collection comes from immediately
331 // reclaimable regions.
332 //
333 // ................................................................................................
334 //
335 // (immediate garbage shortcut) Concurrent GC
336 // /-------------------------------------------\
337 // | |
338 // | |
339 // | |
340 // | v
341 // [START] ----> Conc Mark ----o----> Conc Evac --o--> Conc Update-Refs ---o----> [END]
342 // | | | ^
343 // | (af) | (af) | (af) |
344 // ..................|....................|.................|..............|.......................
345 // | | | |
346 // | | | | Degenerated GC
347 // v v v |
348 // STW Mark ----------> STW Evac ----> STW Update-Refs ----->o
349 // | | | ^
350 // | (af) | (af) | (af) |
351 // ..................|....................|.................|..............|.......................
352 // | | | |
353 // | v | | Full GC
354 // \------------------->o<----------------/ |
355 // | |
356 // v |
357 // Full GC --------------------------/
358 //
359 ShenandoahHeap* heap = ShenandoahHeap::heap();
360
361 if (check_cancellation_or_degen(ShenandoahHeap::_degenerated_outside_cycle)) return;
362
363 GCIdMark gc_id_mark;
364 ShenandoahGCSession session(cause);
365
366 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
367
368 // Reset for upcoming marking
369 heap->entry_reset();
370
371 // Start initial mark under STW
372 heap->vmop_entry_init_mark();
373
374 // Continue concurrent mark
375 heap->entry_mark();
376 if (check_cancellation_or_degen(ShenandoahHeap::_degenerated_mark)) return;
377
378 // If not cancelled, can try to concurrently pre-clean
379 heap->entry_preclean();
380
381 // Complete marking under STW, and start evacuation
382 heap->vmop_entry_final_mark();
383
384 // Process weak roots that might still point to regions that would be broken by cleanup
385 if (heap->is_concurrent_weak_root_in_progress()) {
386 heap->entry_weak_roots();
387 }
388
389 // Final mark might have reclaimed some immediate garbage, kick cleanup to reclaim
390 // the space. This would be the last action if there is nothing to evacuate.
391 heap->entry_cleanup_early();
392
393 {
394 ShenandoahHeapLocker locker(heap->lock());
395 heap->free_set()->log_status();
396 }
397
398 // Perform concurrent class unloading
399 if (heap->is_concurrent_weak_root_in_progress()) {
400 heap->entry_class_unloading();
401 }
402
403 // Processing strong roots
404 // This may be skipped if there is nothing to update/evacuate.
405 // If so, strong_root_in_progress would be unset.
406 if (heap->is_concurrent_strong_root_in_progress()) {
407 heap->entry_strong_roots();
408 }
409
410 // Continue the cycle with evacuation and optional update-refs.
411 // This may be skipped if there is nothing to evacuate.
412 // If so, evac_in_progress would be unset by collection set preparation code.
413 if (heap->is_evacuation_in_progress()) {
414 // Concurrently evacuate
415 heap->entry_evac();
416 if (check_cancellation_or_degen(ShenandoahHeap::_degenerated_evac)) return;
417
418 // Perform update-refs phase.
419 heap->vmop_entry_init_updaterefs();
420 heap->entry_updaterefs();
421 if (check_cancellation_or_degen(ShenandoahHeap::_degenerated_updaterefs)) return;
422
423 heap->vmop_entry_final_updaterefs();
424
425 // Update references freed up collection set, kick the cleanup to reclaim the space.
426 heap->entry_cleanup_complete();
427 } else {
428 // Concurrent weak/strong root flags are unset concurrently. We depend on updateref GC safepoints
429 // to ensure the changes are visible to all mutators before gc cycle is completed.
430 // In case of no evacuation, updateref GC safepoints are skipped. Therefore, we will need
431 // to perform thread handshake to ensure their consistences.
432 heap->entry_rendezvous_roots();
433 }
434
435 // Cycle is complete
436 heap->heuristics()->record_success_concurrent();
437 heap->shenandoah_policy()->record_success_concurrent();
438 }
439
440 bool ShenandoahControlThread::check_cancellation_or_degen(ShenandoahHeap::ShenandoahDegenPoint point) {
441 ShenandoahHeap* heap = ShenandoahHeap::heap();
442 if (heap->cancelled_gc()) {
443 assert (is_alloc_failure_gc() || in_graceful_shutdown(), "Cancel GC either for alloc failure GC, or gracefully exiting");
444 if (!in_graceful_shutdown()) {
445 assert (_degen_point == ShenandoahHeap::_degenerated_outside_cycle,
446 "Should not be set yet: %s", ShenandoahHeap::degen_point_to_string(_degen_point));
447 _degen_point = point;
448 }
449 return true;
450 }
451 return false;
452 }
453
454 void ShenandoahControlThread::stop_service() {
455 // Nothing to do here.
456 }
457
458 void ShenandoahControlThread::service_stw_full_cycle(GCCause::Cause cause) {
459 GCIdMark gc_id_mark;
460 ShenandoahGCSession session(cause);
461
462 ShenandoahHeap* heap = ShenandoahHeap::heap();
463 heap->vmop_entry_full(cause);
464
465 heap->heuristics()->record_success_full();
466 heap->shenandoah_policy()->record_success_full();
467 }
468
469 void ShenandoahControlThread::service_stw_degenerated_cycle(GCCause::Cause cause, ShenandoahHeap::ShenandoahDegenPoint point) {
470 assert (point != ShenandoahHeap::_degenerated_unset, "Degenerated point should be set");
471
472 GCIdMark gc_id_mark;
473 ShenandoahGCSession session(cause);
474
475 ShenandoahHeap* heap = ShenandoahHeap::heap();
476 heap->vmop_degenerated(point);
477
478 heap->heuristics()->record_success_degenerated();
479 heap->shenandoah_policy()->record_success_degenerated();
480 }
481
482 void ShenandoahControlThread::service_uncommit(double shrink_before) {
483 ShenandoahHeap* heap = ShenandoahHeap::heap();
484
485 // Determine if there is work to do. This avoids taking heap lock if there is
486 // no work available, avoids spamming logs with superfluous logging messages,
487 // and minimises the amount of work while locks are taken.
488
489 if (heap->committed() <= heap->min_capacity()) return;
490
491 bool has_work = false;
492 for (size_t i = 0; i < heap->num_regions(); i++) {
493 ShenandoahHeapRegion *r = heap->get_region(i);
494 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
495 has_work = true;
496 break;
497 }
498 }
499
500 if (has_work) {
501 heap->entry_uncommit(shrink_before);
502 }
503 }
504
505 bool ShenandoahControlThread::is_explicit_gc(GCCause::Cause cause) const {
506 return GCCause::is_user_requested_gc(cause) ||
507 GCCause::is_serviceability_requested_gc(cause);
508 }
509
510 void ShenandoahControlThread::request_gc(GCCause::Cause cause) {
511 assert(GCCause::is_user_requested_gc(cause) ||
512 GCCause::is_serviceability_requested_gc(cause) ||
513 cause == GCCause::_metadata_GC_clear_soft_refs ||
514 cause == GCCause::_full_gc_alot ||
515 cause == GCCause::_wb_full_gc ||
516 cause == GCCause::_scavenge_alot,
517 "only requested GCs here");
518
519 if (is_explicit_gc(cause)) {
520 if (!DisableExplicitGC) {
521 handle_requested_gc(cause);
522 }
523 } else {
524 handle_requested_gc(cause);
525 }
526 }
527
528 void ShenandoahControlThread::handle_requested_gc(GCCause::Cause cause) {
529 // Make sure we have at least one complete GC cycle before unblocking
530 // from the explicit GC request.
531 //
532 // This is especially important for weak references cleanup and/or native
533 // resources (e.g. DirectByteBuffers) machinery: when explicit GC request
534 // comes very late in the already running cycle, it would miss lots of new
535 // opportunities for cleanup that were made available before the caller
536 // requested the GC.
537
538 MonitorLocker ml(&_gc_waiters_lock);
539 size_t current_gc_id = get_gc_id();
540 size_t required_gc_id = current_gc_id + 1;
541 while (current_gc_id < required_gc_id) {
542 _gc_requested.set();
543 _requested_gc_cause = cause;
544 ml.wait();
545 current_gc_id = get_gc_id();
546 }
547 }
548
549 void ShenandoahControlThread::handle_alloc_failure(ShenandoahAllocRequest& req) {
550 ShenandoahHeap* heap = ShenandoahHeap::heap();
551
552 assert(current()->is_Java_thread(), "expect Java thread here");
553
554 if (try_set_alloc_failure_gc()) {
555 // Only report the first allocation failure
556 log_info(gc)("Failed to allocate %s, " SIZE_FORMAT "%s",
557 req.type_string(),
558 byte_size_in_proper_unit(req.size() * HeapWordSize), proper_unit_for_byte_size(req.size() * HeapWordSize));
559
560 // Now that alloc failure GC is scheduled, we can abort everything else
561 heap->cancel_gc(GCCause::_allocation_failure);
562 }
563
564 MonitorLocker ml(&_alloc_failure_waiters_lock);
565 while (is_alloc_failure_gc()) {
566 ml.wait();
567 }
568 }
569
570 void ShenandoahControlThread::handle_alloc_failure_evac(size_t words) {
571 ShenandoahHeap* heap = ShenandoahHeap::heap();
572
573 if (try_set_alloc_failure_gc()) {
574 // Only report the first allocation failure
575 log_info(gc)("Failed to allocate " SIZE_FORMAT "%s for evacuation",
576 byte_size_in_proper_unit(words * HeapWordSize), proper_unit_for_byte_size(words * HeapWordSize));
577 }
578
579 // Forcefully report allocation failure
580 heap->cancel_gc(GCCause::_shenandoah_allocation_failure_evac);
581 }
582
583 void ShenandoahControlThread::notify_alloc_failure_waiters() {
584 _alloc_failure_gc.unset();
585 MonitorLocker ml(&_alloc_failure_waiters_lock);
586 ml.notify_all();
587 }
588
589 bool ShenandoahControlThread::try_set_alloc_failure_gc() {
590 return _alloc_failure_gc.try_set();
591 }
592
593 bool ShenandoahControlThread::is_alloc_failure_gc() {
594 return _alloc_failure_gc.is_set();
595 }
596
597 void ShenandoahControlThread::notify_gc_waiters() {
598 _gc_requested.unset();
599 MonitorLocker ml(&_gc_waiters_lock);
600 ml.notify_all();
601 }
602
603 void ShenandoahControlThread::handle_counters_update() {
604 if (_do_counters_update.is_set()) {
605 _do_counters_update.unset();
606 ShenandoahHeap::heap()->monitoring_support()->update_counters();
607 }
608 }
609
610 void ShenandoahControlThread::handle_force_counters_update() {
611 if (_force_counters_update.is_set()) {
612 _do_counters_update.unset(); // reset these too, we do update now!
613 ShenandoahHeap::heap()->monitoring_support()->update_counters();
614 }
615 }
616
617 void ShenandoahControlThread::notify_heap_changed() {
618 // This is called from allocation path, and thus should be fast.
619
620 // Update monitoring counters when we took a new region. This amortizes the
621 // update costs on slow path.
622 if (_do_counters_update.is_unset()) {
623 _do_counters_update.set();
624 }
625 // Notify that something had changed.
626 if (_heap_changed.is_unset()) {
627 _heap_changed.set();
628 }
629 }
630
631 void ShenandoahControlThread::pacing_notify_alloc(size_t words) {
632 assert(ShenandoahPacing, "should only call when pacing is enabled");
633 Atomic::add(&_allocs_seen, words);
634 }
635
636 void ShenandoahControlThread::set_forced_counters_update(bool value) {
637 _force_counters_update.set_cond(value);
638 }
639
640 void ShenandoahControlThread::reset_gc_id() {
641 Atomic::store(&_gc_id, (size_t)0);
642 }
643
644 void ShenandoahControlThread::update_gc_id() {
645 Atomic::inc(&_gc_id);
646 }
647
648 size_t ShenandoahControlThread::get_gc_id() {
649 return Atomic::load(&_gc_id);
650 }
651
652 void ShenandoahControlThread::print() const {
653 print_on(tty);
654 }
655
656 void ShenandoahControlThread::print_on(outputStream* st) const {
657 st->print("Shenandoah Concurrent Thread");
658 Thread::print_on(st);
659 st->cr();
660 }
661
662 void ShenandoahControlThread::start() {
663 create_and_start();
664 }
665
666 void ShenandoahControlThread::prepare_for_graceful_shutdown() {
667 _graceful_shutdown.set();
668 }
669
670 bool ShenandoahControlThread::in_graceful_shutdown() {
671 return _graceful_shutdown.is_set();
672 }