1 /*
2 * Copyright (c) 2013, 2015, 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 #include "gc/shared/gcTraceTime.inline.hpp"
26 #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp"
27 #include "gc/shenandoah/shenandoahConcurrentThread.hpp"
28 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
29 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
30 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
31 #include "gc/shenandoah/vm_operations_shenandoah.hpp"
32 #include "memory/iterator.hpp"
33 #include "memory/universe.hpp"
34 #include "runtime/vmThread.hpp"
35
36 ShenandoahConcurrentThread::ShenandoahConcurrentThread() :
37 ConcurrentGCThread(),
38 _full_gc_lock(Mutex::leaf, "ShenandoahFullGC_lock", true, Monitor::_safepoint_check_always),
39 _do_full_gc(false),
40 _graceful_shutdown(0)
41 {
42 create_and_start();
43 }
44
45 ShenandoahConcurrentThread::~ShenandoahConcurrentThread() {
46 // This is here so that super is called.
47 }
48
49 void ShenandoahConcurrentThread::run_service() {
50 ShenandoahHeap* heap = ShenandoahHeap::heap();
51
52 while (!should_terminate()) {
53 if (in_graceful_shutdown()) {
54 break;
55 } else if (is_full_gc()) {
56 service_fullgc_cycle();
57 } else if (heap->shenandoahPolicy()->should_start_partial_gc()) {
58 service_partial_cycle();
59 } else if (heap->shenandoahPolicy()->should_start_concurrent_mark(heap->used(), heap->capacity())) {
60 service_normal_cycle();
61 if (heap->is_evacuation_in_progress()) {
62 heap->set_evacuation_in_progress_concurrently(false);
63 }
64 if (heap->is_update_refs_in_progress()) {
65 heap->set_update_refs_in_progress(false);
66 }
67 } else {
68 Thread::current()->_ParkEvent->park(10);
69 }
70 heap->monitoring_support()->update_counters();
71
72 // Make sure the _do_full_gc flag changes are seen.
73 OrderAccess::storeload();
74 }
75
76 // Wait for the actual stop(), can't leave run_service() earlier.
77 while (!should_terminate()) {
78 Thread::current()->_ParkEvent->park(10);
79 }
80 }
81
82 void ShenandoahConcurrentThread::service_partial_cycle() {
83 GCIdMark gc_id_mark;
84 ShenandoahHeap* heap = ShenandoahHeap::heap();
85
86 VM_ShenandoahPartialGC partial_gc;
87 heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::total_pause_gross);
88 heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::partial_gc_gross);
89 VMThread::execute(&partial_gc);
90 heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::partial_gc_gross);
91 heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::total_pause_gross);
92 }
93
94 void ShenandoahConcurrentThread::service_normal_cycle() {
95 if (check_cancellation()) return;
96
97 ShenandoahHeap* heap = ShenandoahHeap::heap();
98
99 GCTimer* gc_timer = heap->gc_timer();
100
101 gc_timer->register_gc_start();
102
103 heap->shenandoahPolicy()->increase_cycle_counter();
104
105 GCIdMark gc_id_mark;
106 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
107 TraceMemoryManagerStats tmms(false, GCCause::_no_cause_specified);
108
109 // Start initial mark under STW:
110 {
111 // Workers are setup by VM_ShenandoahInitMark
112 TraceCollectorStats tcs(heap->monitoring_support()->stw_collection_counters());
113 VM_ShenandoahInitMark initMark;
114 heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::total_pause_gross);
115 heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::init_mark_gross);
116 VMThread::execute(&initMark);
117 heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::init_mark_gross);
118 heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::total_pause_gross);
119 }
120
121 if (check_cancellation()) return;
122
123 // Continue concurrent mark:
124 {
125 // Setup workers for concurrent marking phase
126 WorkGang* workers = heap->workers();
127 uint n_workers = ShenandoahCollectorPolicy::calc_workers_for_conc_marking(workers->active_workers(),
128 (uint) Threads::number_of_non_daemon_threads());
129 ShenandoahWorkerScope scope(workers, n_workers);
130
131 GCTraceTime(Info, gc) time("Concurrent marking", gc_timer, GCCause::_no_gc, true);
132 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
133 ShenandoahHeap::heap()->concurrentMark()->mark_from_roots();
134 }
135
136 // Possibly hand over remaining marking work to final-mark phase.
137 bool clear_full_gc = false;
138 if (heap->cancelled_concgc()) {
139 heap->shenandoahPolicy()->record_cm_cancelled();
140 if (_full_gc_cause == GCCause::_allocation_failure &&
141 heap->shenandoahPolicy()->handover_cancelled_marking()) {
142 heap->clear_cancelled_concgc();
143 clear_full_gc = true;
144 heap->shenandoahPolicy()->record_cm_degenerated();
145 } else {
146 heap->gc_timer()->register_gc_end();
147 return;
148 }
149 } else {
150 heap->shenandoahPolicy()->record_cm_success();
151 }
152
153 // Proceed to complete marking under STW, and start evacuation:
154 {
155 // Workers are setup by VM_ShenandoahFinalMarkStartEvac
156 TraceCollectorStats tcs(heap->monitoring_support()->stw_collection_counters());
157 VM_ShenandoahFinalMarkStartEvac finishMark;
158 heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::total_pause_gross);
159 heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::final_mark_gross);
160 VMThread::execute(&finishMark);
161 heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::final_mark_gross);
162 heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::total_pause_gross);
163 }
164
165 if (check_cancellation()) return;
166
167 // If we handed off remaining marking work above, we need to kick off waiting Java threads
168 if (clear_full_gc) {
169 reset_full_gc();
170 }
171
172 // Continue concurrent evacuation:
173 {
174 // Setup workers for concurrent evacuation phase
175 WorkGang* workers = heap->workers();
176 uint n_workers = ShenandoahCollectorPolicy::calc_workers_for_conc_evacuation(workers->active_workers(),
177 (uint) Threads::number_of_non_daemon_threads());
178 ShenandoahWorkerScope scope(workers, n_workers);
179
180 GCTraceTime(Info, gc) time("Concurrent evacuation ", gc_timer, GCCause::_no_gc, true);
181 TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
182 heap->do_evacuation();
183 }
184
185 // Do an update-refs phase if required.
186 if (check_cancellation()) return;
187
188 if (heap->shenandoahPolicy()->update_refs_early()) {
189
190 VM_ShenandoahInitUpdateRefs init_update_refs;
191 heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::total_pause_gross);
192 heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::init_update_refs_gross);
193 VMThread::execute(&init_update_refs);
194 heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::init_update_refs_gross);
195 heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::total_pause_gross);
196
197 {
198 GCTraceTime(Info, gc) time("Concurrent update references ", gc_timer, GCCause::_no_gc, true);
199 heap->concurrent_update_heap_references();
200 }
201
202 clear_full_gc = false;
203 if (heap->cancelled_concgc()) {
204 heap->shenandoahPolicy()->record_uprefs_cancelled();
205 if (_full_gc_cause == GCCause::_allocation_failure &&
206 heap->shenandoahPolicy()->handover_cancelled_uprefs()) {
207 clear_full_gc = true;
208 heap->shenandoahPolicy()->record_uprefs_degenerated();
209 } else {
210 heap->gc_timer()->register_gc_end();
211 return;
212 }
213 } else {
214 heap->shenandoahPolicy()->record_uprefs_success();
215 }
216
217 VM_ShenandoahFinalUpdateRefs final_update_refs;
218
219 heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::total_pause_gross);
220 heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::final_update_refs_gross);
221 VMThread::execute(&final_update_refs);
222 heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::final_update_refs_gross);
223 heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::total_pause_gross);
224 }
225
226 // Prepare for the next normal cycle:
227 if (check_cancellation()) return;
228
229 if (clear_full_gc) {
230 reset_full_gc();
231 }
232
233 {
234 GCTraceTime(Info, gc) time("Concurrent reset bitmaps", gc_timer, GCCause::_no_gc);
235 heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::reset_bitmaps);
236 WorkGang* workers = heap->workers();
237 ShenandoahPushWorkerScope scope(workers, heap->max_workers());
238 heap->reset_next_mark_bitmap(workers);
239 heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::reset_bitmaps);
240 }
241
242 gc_timer->register_gc_end();
243 }
244
245 bool ShenandoahConcurrentThread::check_cancellation() {
246 ShenandoahHeap* heap = ShenandoahHeap::heap();
247 if (heap->cancelled_concgc()) {
248 assert (is_full_gc() || in_graceful_shutdown(), "Cancel GC either for Full GC, or gracefully exiting");
249 heap->gc_timer()->register_gc_end();
250 return true;
251 }
252 return false;
253 }
254
255
256 void ShenandoahConcurrentThread::stop_service() {
257 // Nothing to do here.
258 }
259
260 void ShenandoahConcurrentThread::service_fullgc_cycle() {
261 GCIdMark gc_id_mark;
262 ShenandoahHeap* heap = ShenandoahHeap::heap();
263
264 {
265 if (_full_gc_cause == GCCause::_allocation_failure) {
266 heap->shenandoahPolicy()->record_allocation_failure_gc();
267 } else {
268 heap->shenandoahPolicy()->record_user_requested_gc();
269 }
270
271 TraceCollectorStats tcs(heap->monitoring_support()->full_collection_counters());
272 TraceMemoryManagerStats tmms(true, _full_gc_cause);
273 VM_ShenandoahFullGC full_gc(_full_gc_cause);
274 VMThread::execute(&full_gc);
275 }
276
277 reset_full_gc();
278 }
279
280 void ShenandoahConcurrentThread::do_full_gc(GCCause::Cause cause) {
281 assert(Thread::current()->is_Java_thread(), "expect Java thread here");
282
283 if (try_set_full_gc()) {
284 _full_gc_cause = cause;
285
286 // Now that full GC is scheduled, we can abort everything else
287 ShenandoahHeap::heap()->cancel_concgc(cause);
288 } else {
289 if (_full_gc_cause != cause) {
290 log_info(gc)("Full GC is already pending with cause: %s; new cause is %s",
291 GCCause::to_string(_full_gc_cause),
292 GCCause::to_string(cause));
293 }
294 }
295
296 MonitorLockerEx ml(&_full_gc_lock);
297 while (is_full_gc()) {
298 ml.wait();
299 }
300 assert(!is_full_gc(), "expect full GC to have completed");
301 }
302
303 void ShenandoahConcurrentThread::reset_full_gc() {
304 OrderAccess::release_store_fence(&_do_full_gc, 0);
305 MonitorLockerEx ml(&_full_gc_lock);
306 ml.notify_all();
307 }
308
309 bool ShenandoahConcurrentThread::try_set_full_gc() {
310 jbyte old = Atomic::cmpxchg(1, &_do_full_gc, 0);
311 return old == 0; // success
312 }
313
314 bool ShenandoahConcurrentThread::is_full_gc() {
315 return OrderAccess::load_acquire(&_do_full_gc) == 1;
316 }
317
318 void ShenandoahConcurrentThread::print() const {
319 print_on(tty);
320 }
321
322 void ShenandoahConcurrentThread::print_on(outputStream* st) const {
323 st->print("Shenandoah Concurrent Thread");
324 Thread::print_on(st);
325 st->cr();
326 }
327
328 void ShenandoahConcurrentThread::sleepBeforeNextCycle() {
329 assert(false, "Wake up in the GC thread that never sleeps :-)");
330 }
331
332 void ShenandoahConcurrentThread::start() {
333 create_and_start();
334 }
335
336 void ShenandoahConcurrentThread::prepare_for_graceful_shutdown() {
337 OrderAccess::release_store_fence(&_graceful_shutdown, 1);
338 }
339
340 bool ShenandoahConcurrentThread::in_graceful_shutdown() {
341 return OrderAccess::load_acquire(&_graceful_shutdown) == 1;
342 }