1 /*
2 * Copyright (c) 2001, 2016, Oracle and/or its affiliates. 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 #include "gc/g1/concurrentG1Refine.hpp"
27 #include "gc/g1/concurrentG1RefineThread.hpp"
28 #include "gc/g1/g1CollectedHeap.inline.hpp"
29 #include "gc/g1/g1CollectorPolicy.hpp"
30 #include "gc/g1/suspendibleThreadSet.hpp"
31 #include "logging/log.hpp"
32 #include "memory/resourceArea.hpp"
33 #include "runtime/handles.inline.hpp"
34 #include "runtime/mutexLocker.hpp"
35
36 ConcurrentG1RefineThread::
37 ConcurrentG1RefineThread(ConcurrentG1Refine* cg1r, ConcurrentG1RefineThread *next,
38 CardTableEntryClosure* refine_closure,
39 uint worker_id_offset, uint worker_id) :
40 ConcurrentGCThread(),
41 _refine_closure(refine_closure),
42 _worker_id_offset(worker_id_offset),
43 _worker_id(worker_id),
44 _active(false),
45 _next(next),
46 _monitor(NULL),
47 _cg1r(cg1r),
48 _vtime_accum(0.0)
49 {
50
51 // Each thread has its own monitor. The i-th thread is responsible for signaling
52 // to thread i+1 if the number of buffers in the queue exceeds a threshold for this
53 // thread. Monitors are also used to wake up the threads during termination.
54 // The 0th (primary) worker is notified by mutator threads and has a special monitor.
55 if (!is_primary()) {
56 _monitor = new Monitor(Mutex::nonleaf, "Refinement monitor", true,
57 Monitor::_safepoint_check_never);
58 } else {
59 _monitor = DirtyCardQ_CBL_mon;
60 }
61 initialize();
62
63 // set name
64 set_name("G1 Refine#%d", worker_id);
65 create_and_start();
66 }
67
68 void ConcurrentG1RefineThread::initialize() {
69 // Current thread activation threshold
70 _threshold = MIN2<int>(cg1r()->thread_threshold_step() * (_worker_id + 1) + cg1r()->green_zone(),
71 cg1r()->yellow_zone());
72 // A thread deactivates once the number of buffer reached a deactivation threshold
73 _deactivation_threshold = MAX2<int>(_threshold - cg1r()->thread_threshold_step(), cg1r()->green_zone());
74 }
75
76 void ConcurrentG1RefineThread::wait_for_completed_buffers() {
77 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
78 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
79 while (!_should_terminate && !is_active()) {
80 _monitor->wait(Mutex::_no_safepoint_check_flag);
81 }
82 }
83
84 bool ConcurrentG1RefineThread::is_active() {
85 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
86 return is_primary() ? dcqs.process_completed_buffers() : _active;
87 }
88
89 void ConcurrentG1RefineThread::activate() {
90 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
91 if (!is_primary()) {
92 log_debug(gc, refine)("G1-Refine-activated worker %d, on threshold %d, current %d",
93 _worker_id, _threshold, JavaThread::dirty_card_queue_set().completed_buffers_num());
94 set_active(true);
95 } else {
96 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
97 dcqs.set_process_completed(true);
98 }
99 _monitor->notify();
100 }
101
102 void ConcurrentG1RefineThread::deactivate() {
103 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
104 if (!is_primary()) {
105 log_debug(gc, refine)("G1-Refine-deactivated worker %d, off threshold %d, current %d",
106 _worker_id, _deactivation_threshold, JavaThread::dirty_card_queue_set().completed_buffers_num());
107 set_active(false);
108 } else {
109 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
110 dcqs.set_process_completed(false);
111 }
112 }
113
114 void ConcurrentG1RefineThread::run() {
115 initialize_in_thread();
116 wait_for_universe_init();
117
118 run_service();
119
120 terminate();
121 }
122
123 void ConcurrentG1RefineThread::run_service() {
124 _vtime_start = os::elapsedVTime();
125
126 while (!_should_terminate) {
127 // Wait for work
128 wait_for_completed_buffers();
129 if (_should_terminate) {
130 break;
131 }
132
133 {
134 SuspendibleThreadSetJoiner sts_join;
135 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
136
137 do {
138 int curr_buffer_num = (int)dcqs.completed_buffers_num();
139 // If the number of the buffers falls down into the yellow zone,
140 // that means that the transition period after the evacuation pause has ended.
141 if (dcqs.completed_queue_padding() > 0 && curr_buffer_num <= cg1r()->yellow_zone()) {
142 dcqs.set_completed_queue_padding(0);
143 }
144
145 if (!is_primary() && curr_buffer_num <= _deactivation_threshold) {
146 // If the number of the buffer has fallen below our threshold
147 // we should deactivate. The predecessor will reactivate this
148 // thread should the number of the buffers cross the threshold again.
149 deactivate();
150 break;
151 }
152
153 // Check if we need to activate the next thread.
154 if (_next != NULL && !_next->is_active() && curr_buffer_num > _next->_threshold) {
155 _next->activate();
156 }
157 } while (dcqs.apply_closure_to_completed_buffer(_refine_closure,
158 _worker_id + _worker_id_offset,
159 cg1r()->green_zone(),
160 false /* during_pause */));
161
162 // We can exit the loop above while being active if there was a yield request.
163 if (is_active()) {
164 deactivate();
165 }
166 }
167
168 if (os::supports_vtime()) {
169 _vtime_accum = (os::elapsedVTime() - _vtime_start);
170 } else {
171 _vtime_accum = 0.0;
172 }
173 }
174
175 log_debug(gc, refine)("G1-Refine-stop");
176 }
177
178 void ConcurrentG1RefineThread::stop() {
179 // it is ok to take late safepoints here, if needed
180 {
181 MutexLockerEx mu(Terminator_lock);
182 _should_terminate = true;
183 }
184
185 stop_service();
186
187 {
188 MutexLockerEx mu(Terminator_lock);
189 while (!_has_terminated) {
190 Terminator_lock->wait();
191 }
192 }
193 }
194
195 void ConcurrentG1RefineThread::stop_service() {
196 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
197 _monitor->notify();
198 }