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