1 /*
2 * Copyright (c) 2021, Amazon.com, Inc. 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 #include "precompiled.hpp"
25
26 #include "gc/shenandoah/heuristics/shenandoahHeuristics.hpp"
27 #include "gc/shenandoah/mode/shenandoahMode.hpp"
28 #include "gc/shenandoah/shenandoahControlThread.hpp"
29 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
30 #include "gc/shenandoah/shenandoahOldGeneration.hpp"
31 #include "gc/shenandoah/shenandoahRegulatorThread.hpp"
32 #include "gc/shenandoah/shenandoahYoungGeneration.hpp"
33 #include "logging/log.hpp"
34
35 static ShenandoahHeuristics* get_heuristics(ShenandoahGeneration* nullable) {
36 return nullable != nullptr ? nullable->heuristics() : nullptr;
37 }
38
39 ShenandoahRegulatorThread::ShenandoahRegulatorThread(ShenandoahControlThread* control_thread) :
40 ConcurrentGCThread(),
41 _control_thread(control_thread),
42 _sleep(ShenandoahControlIntervalMin),
43 _last_sleep_adjust_time(os::elapsedTime()) {
44
45 ShenandoahHeap* heap = ShenandoahHeap::heap();
46 _old_heuristics = get_heuristics(heap->old_generation());
47 _young_heuristics = get_heuristics(heap->young_generation());
48 _global_heuristics = get_heuristics(heap->global_generation());
49
50 create_and_start();
51 }
52
53 void ShenandoahRegulatorThread::run_service() {
54 if (ShenandoahHeap::heap()->mode()->is_generational()) {
55 if (ShenandoahAllowOldMarkingPreemption) {
56 regulate_concurrent_cycles();
57 } else {
58 regulate_interleaved_cycles();
59 }
60 } else {
61 regulate_heap();
62 }
63
64 log_info(gc)("%s: Done.", name());
65 }
66
67 void ShenandoahRegulatorThread::regulate_concurrent_cycles() {
68 assert(_young_heuristics != nullptr, "Need young heuristics.");
69 assert(_old_heuristics != nullptr, "Need old heuristics.");
70
71 while (!should_terminate()) {
72 ShenandoahControlThread::GCMode mode = _control_thread->gc_mode();
73 if (mode == ShenandoahControlThread::none) {
74 if (should_unload_classes()) {
75 if (_control_thread->request_concurrent_gc(GLOBAL)) {
76 log_info(gc)("Heuristics request for global (unload classes) accepted.");
77 }
78 } else {
79 if (start_old_cycle()) {
80 log_info(gc)("Heuristics request for old collection accepted");
81 } else if (start_young_cycle()) {
82 log_info(gc)("Heuristics request for young collection accepted");
83 }
84 }
85 } else if (mode == ShenandoahControlThread::servicing_old) {
86 if (start_young_cycle()) {
87 log_info(gc)("Heuristics request to interrupt old for young collection accepted");
88 }
89 }
90
91 regulator_sleep();
92 }
93 }
94
95 void ShenandoahRegulatorThread::regulate_interleaved_cycles() {
96 assert(_young_heuristics != nullptr, "Need young heuristics.");
97 assert(_global_heuristics != nullptr, "Need global heuristics.");
98
99 while (!should_terminate()) {
100 if (_control_thread->gc_mode() == ShenandoahControlThread::none) {
101 if (start_global_cycle()) {
102 log_info(gc)("Heuristics request for global collection accepted.");
103 } else if (start_young_cycle()) {
104 log_info(gc)("Heuristics request for young collection accepted.");
105 }
106 }
107
108 regulator_sleep();
109 }
110 }
111
112 void ShenandoahRegulatorThread::regulate_heap() {
113 assert(_global_heuristics != nullptr, "Need global heuristics.");
114
115 while (!should_terminate()) {
116 if (_control_thread->gc_mode() == ShenandoahControlThread::none) {
117 if (start_global_cycle()) {
118 log_info(gc)("Heuristics request for global collection accepted.");
119 }
120 }
121
122 regulator_sleep();
123 }
124 }
125
126 void ShenandoahRegulatorThread::regulator_sleep() {
127 // Wait before performing the next action. If allocation happened during this wait,
128 // we exit sooner, to let heuristics re-evaluate new conditions. If we are at idle,
129 // back off exponentially.
130 double current = os::elapsedTime();
131
132 if (_heap_changed.try_unset()) {
133 _sleep = ShenandoahControlIntervalMin;
134 } else if ((current - _last_sleep_adjust_time) * 1000 > ShenandoahControlIntervalAdjustPeriod){
135 _sleep = MIN2<int>(ShenandoahControlIntervalMax, MAX2(1, _sleep * 2));
136 _last_sleep_adjust_time = current;
137 }
138
139 os::naked_short_sleep(_sleep);
140 }
141
142 bool ShenandoahRegulatorThread::start_old_cycle() {
143 return _old_heuristics->should_start_gc() && _control_thread->request_concurrent_gc(OLD);
144 }
145
146 bool ShenandoahRegulatorThread::start_young_cycle() {
147 return _young_heuristics->should_start_gc() && _control_thread->request_concurrent_gc(YOUNG);
148 }
149
150 bool ShenandoahRegulatorThread::start_global_cycle() {
151 return _global_heuristics->should_start_gc() && _control_thread->request_concurrent_gc(GLOBAL);
152 }
153
154 void ShenandoahRegulatorThread::stop_service() {
155 log_info(gc)("%s: Stop requested.", name());
156 }
157
158 bool ShenandoahRegulatorThread::should_unload_classes() {
159 // The heuristics delegate this decision to the collector policy, which is based on the number
160 // of cycles started.
161 return _global_heuristics->should_unload_classes();
162 }
163