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(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 =
74 MAX2(_threshold - MIN2(_threshold, cg1r()->thread_threshold_step()),
75 cg1r()->green_zone());
76 }
77
78 void ConcurrentG1RefineThread::wait_for_completed_buffers() {
79 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
80 while (!should_terminate() && !is_active()) {
81 _monitor->wait(Mutex::_no_safepoint_check_flag);
82 }
83 }
84
85 bool ConcurrentG1RefineThread::is_active() {
86 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
87 return is_primary() ? dcqs.process_completed_buffers() : _active;
88 }
89
90 void ConcurrentG1RefineThread::activate() {
91 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
92 if (!is_primary()) {
93 set_active(true);
94 } else {
95 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
96 dcqs.set_process_completed(true);
97 }
98 _monitor->notify();
99 }
100
101 void ConcurrentG1RefineThread::deactivate() {
102 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
103 if (!is_primary()) {
104 set_active(false);
105 } else {
106 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
107 dcqs.set_process_completed(false);
108 }
109 }
110
111 void ConcurrentG1RefineThread::run_service() {
112 _vtime_start = os::elapsedVTime();
113
114 while (!should_terminate()) {
115 // Wait for work
116 wait_for_completed_buffers();
117 if (should_terminate()) {
118 break;
119 }
120
121 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
122 log_debug(gc, refine)("Activated %d, on threshold: " SIZE_FORMAT ", current: " SIZE_FORMAT,
123 _worker_id, _threshold, dcqs.completed_buffers_num());
124
125 {
126 SuspendibleThreadSetJoiner sts_join;
127
128 while (!should_terminate()) {
129 if (sts_join.should_yield()) {
130 sts_join.yield();
131 continue; // Re-check for termination after yield delay.
132 }
133
134 size_t curr_buffer_num = dcqs.completed_buffers_num();
135 // If the number of the buffers falls down into the yellow zone,
136 // that means that the transition period after the evacuation pause has ended.
137 if (dcqs.completed_queue_padding() > 0 && curr_buffer_num <= cg1r()->yellow_zone()) {
138 dcqs.set_completed_queue_padding(0);
139 }
140
141 // Check if we need to activate the next thread.
142 if (_next != NULL && !_next->is_active() && curr_buffer_num > _next->_threshold) {
143 _next->activate();
144 }
145
146 // Process the next buffer, if there are enough left.
147 if (!dcqs.apply_closure_to_completed_buffer(_refine_closure,
148 _worker_id + _worker_id_offset,
149 _deactivation_threshold,
150 false /* during_pause */)) {
151 break; // Deactivate, number of buffers fell below threshold.
152 }
153 }
154 }
155
156 deactivate();
157 log_debug(gc, refine)("Deactivated %d, off threshold: " SIZE_FORMAT
158 ", current: " SIZE_FORMAT,
159 _worker_id, _deactivation_threshold,
160 dcqs.completed_buffers_num());
161
162 if (os::supports_vtime()) {
163 _vtime_accum = (os::elapsedVTime() - _vtime_start);
164 } else {
165 _vtime_accum = 0.0;
166 }
167 }
168
169 log_debug(gc, refine)("Stopping %d", _worker_id);
170 }
171
172 void ConcurrentG1RefineThread::stop_service() {
173 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
174 _monitor->notify();
175 }