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/suspendibleThreadSet.hpp"
30 #include "logging/log.hpp"
31 #include "memory/resourceArea.hpp"
32 #include "runtime/handles.inline.hpp"
33 #include "runtime/mutexLocker.hpp"
34
35 ConcurrentG1RefineThread::
36 ConcurrentG1RefineThread(ConcurrentG1Refine* cg1r, ConcurrentG1RefineThread *next,
37 CardTableEntryClosure* refine_closure,
38 uint worker_id_offset, uint worker_id,
39 size_t activate, size_t deactivate) :
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 _activation_threshold(activate),
50 _deactivation_threshold(deactivate)
51 {
52
53 // Each thread has its own monitor. The i-th thread is responsible for signaling
54 // to thread i+1 if the number of buffers in the queue exceeds a threshold for this
55 // thread. Monitors are also used to wake up the threads during termination.
56 // The 0th (primary) worker is notified by mutator threads and has a special monitor.
57 if (!is_primary()) {
58 _monitor = new Monitor(Mutex::nonleaf, "Refinement monitor", true,
59 Monitor::_safepoint_check_never);
60 } else {
61 _monitor = DirtyCardQ_CBL_mon;
62 }
63
64 // set name
65 set_name("G1 Refine#%d", worker_id);
66 create_and_start();
67 }
68
69 void ConcurrentG1RefineThread::update_thresholds(size_t activate,
70 size_t deactivate) {
71 assert(deactivate < activate, "precondition");
72 _activation_threshold = activate;
73 _deactivation_threshold = deactivate;
74 }
75
76 void ConcurrentG1RefineThread::wait_for_completed_buffers() {
77 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
78 while (!should_terminate() && !is_active()) {
79 _monitor->wait(Mutex::_no_safepoint_check_flag);
80 }
81 }
82
83 bool ConcurrentG1RefineThread::is_active() {
84 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
85 return is_primary() ? dcqs.process_completed_buffers() : _active;
86 }
87
88 void ConcurrentG1RefineThread::activate() {
89 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
90 if (!is_primary()) {
91 set_active(true);
92 } else {
93 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
94 dcqs.set_process_completed(true);
95 }
96 _monitor->notify();
97 }
98
99 void ConcurrentG1RefineThread::deactivate() {
100 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
101 if (!is_primary()) {
102 set_active(false);
103 } else {
104 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
105 dcqs.set_process_completed(false);
106 }
107 }
108
109 void ConcurrentG1RefineThread::run_service() {
110 _vtime_start = os::elapsedVTime();
111
112 while (!should_terminate()) {
113 // Wait for work
114 wait_for_completed_buffers();
115 if (should_terminate()) {
116 break;
117 }
118
119 size_t buffers_processed = 0;
120 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
121 log_debug(gc, refine)("Activated %d, on threshold: " SIZE_FORMAT ", current: " SIZE_FORMAT,
122 _worker_id, _activation_threshold, dcqs.completed_buffers_num());
123
124 {
125 SuspendibleThreadSetJoiner sts_join;
126
127 while (!should_terminate()) {
128 if (sts_join.should_yield()) {
129 sts_join.yield();
130 continue; // Re-check for termination after yield delay.
131 }
132
133 size_t curr_buffer_num = dcqs.completed_buffers_num();
134 // If the number of the buffers falls down into the yellow zone,
135 // that means that the transition period after the evacuation pause has ended.
136 if (dcqs.completed_queue_padding() > 0 && curr_buffer_num <= cg1r()->yellow_zone()) {
137 dcqs.set_completed_queue_padding(0);
138 }
139
140 // Check if we need to activate the next thread.
141 if ((_next != NULL) &&
142 !_next->is_active() &&
143 (curr_buffer_num > _next->_activation_threshold)) {
144 _next->activate();
145 }
146
147 // Process the next buffer, if there are enough left.
148 if (!dcqs.apply_closure_to_completed_buffer(_refine_closure,
149 _worker_id + _worker_id_offset,
150 _deactivation_threshold,
151 false /* during_pause */)) {
152 break; // Deactivate, number of buffers fell below threshold.
153 }
154 ++buffers_processed;
155 }
156 }
157
158 deactivate();
159 log_debug(gc, refine)("Deactivated %d, off threshold: " SIZE_FORMAT
160 ", current: " SIZE_FORMAT ", processed: " SIZE_FORMAT,
161 _worker_id, _deactivation_threshold,
162 dcqs.completed_buffers_num(),
163 buffers_processed);
164
165 if (os::supports_vtime()) {
166 _vtime_accum = (os::elapsedVTime() - _vtime_start);
167 } else {
168 _vtime_accum = 0.0;
169 }
170 }
171
172 log_debug(gc, refine)("Stopping %d", _worker_id);
173 }
174
175 void ConcurrentG1RefineThread::stop_service() {
176 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
177 _monitor->notify();
178 }