1 /*
2 * Copyright (c) 2024, 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. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25 package com.sun.management.internal;
26
27 import java.util.concurrent.ForkJoinPool;
28 import java.util.concurrent.ThreadPoolExecutor;
29 import javax.management.ObjectName;
30 import jdk.management.VirtualThreadSchedulerMXBean;
31 import jdk.internal.access.JavaLangAccess;
32 import jdk.internal.access.SharedSecrets;
33 import jdk.internal.vm.ContinuationSupport;
34 import sun.management.Util;
35
36 /**
37 * Provides the implementation of the management interface for the JDK's virtual thread scheduler.
38 */
39 public class VirtualThreadSchedulerImpls {
40 private static final JavaLangAccess JLA = SharedSecrets.getJavaLangAccess();
41
42 private VirtualThreadSchedulerImpls() {
43 }
44
45 /**
46 * Creates the VirtualThreadSchedulerMXBean.
47 */
48 public static VirtualThreadSchedulerMXBean create() {
49 // -XX:-VMContinuations
50 if (!ContinuationSupport.isSupported()) {
51 return new BoundVirtualThreadSchedulerImpl();
52 }
53
54 // built-in scheduler
55 if (System.getProperty("jdk.virtualThreadScheduler.implClass") == null) {
56 return new BuiltinVirtualThreadSchedulerImpl();
57 }
58
59 // custom scheduler implements VirtualThreadSchedulerMXBean
60 if (JLA.defaultVirtualThreadScheduler() instanceof VirtualThreadSchedulerMXBean bean) {
61 return bean;
62 }
63
64 // custom scheduler does not implement VirtualThreadSchedulerMXBean
65 return new CustomVirtualThreadSchedulerImpl();
66 }
67
68 /**
69 * Base implementation of VirtualThreadSchedulerMXBean.
70 */
71 private abstract static class BaseVirtualThreadSchedulerImpl
72 implements VirtualThreadSchedulerMXBean {
73
74 @Override
75 public final ObjectName getObjectName() {
76 return Util.newObjectName("jdk.management:type=VirtualThreadScheduler");
77 }
78
79 @Override
80 public String toString() {
81 var sb = new StringBuilder("[parallelism=");
82 sb.append(getParallelism());
83 append(sb, "size", getPoolSize());
84 append(sb, "mounted", getMountedVirtualThreadCount());
85 append(sb, "queued", getQueuedVirtualThreadCount());
86 sb.append(']');
87 return sb.toString();
88 }
89
90 private void append(StringBuilder sb, String name, long value) {
91 sb.append(", ").append(name).append('=');
92 if (value >= 0) {
93 sb.append(value);
94 } else {
95 sb.append("<unavailable>");
96 }
97 }
98 }
99
100 /**
101 * Implementation of VirtualThreadSchedulerMXBean when virtual threads are
102 * implemented with continuations and the built-in scheduler.
103 */
104 private static final class BuiltinVirtualThreadSchedulerImpl
105 extends BaseVirtualThreadSchedulerImpl {
106
107 private Thread.VirtualThreadScheduler builtinScheduler() {
108 return JLA.builtinVirtualThreadScheduler();
109 }
110
111 @Override
112 public int getParallelism() {
113 return switch (builtinScheduler()) {
114 case ForkJoinPool pool -> pool.getParallelism();
115 case ThreadPoolExecutor pool -> pool.getMaximumPoolSize();
116 default -> -1;
117 };
118 }
119
120 @Override
121 public void setParallelism(int size) {
122 if (builtinScheduler() instanceof ForkJoinPool pool) {
123 pool.setParallelism(size);
124 } else {
125 throw new UnsupportedOperationException();
126 }
127 }
128
129 @Override
130 public int getPoolSize() {
131 return switch (builtinScheduler()) {
132 case ForkJoinPool pool -> pool.getPoolSize();
133 case ThreadPoolExecutor pool -> pool.getPoolSize();
134 default -> -1;
135 };
136 }
137
138 @Override
139 public int getMountedVirtualThreadCount() {
140 return switch (builtinScheduler()) {
141 case ForkJoinPool pool -> pool.getActiveThreadCount();
142 case ThreadPoolExecutor pool -> pool.getActiveCount();
143 default -> -1;
144 };
145 }
146
147 @Override
148 public long getQueuedVirtualThreadCount() {
149 return switch (builtinScheduler()) {
150 case ForkJoinPool pool -> pool.getQueuedTaskCount() + pool.getQueuedSubmissionCount();
151 case ThreadPoolExecutor pool -> pool.getQueue().size();
152 default -> -1L;
153 };
154 }
155 }
156
157 /**
158 * Implementation of VirtualThreadSchedulerMXBean when virtual threads are backed
159 * by platform threads.
160 */
161 private static final class BoundVirtualThreadSchedulerImpl
162 extends BaseVirtualThreadSchedulerImpl {
163 @Override
164 public int getParallelism() {
165 return Integer.MAX_VALUE;
166 }
167
168 @Override
169 public void setParallelism(int size) {
170 throw new UnsupportedOperationException();
171 }
172
173 @Override
174 public int getPoolSize() {
175 return -1;
176 }
177
178 @Override
179 public int getMountedVirtualThreadCount() {
180 return -1;
181 }
182
183 @Override
184 public long getQueuedVirtualThreadCount() {
185 return -1L;
186 }
187 }
188
189 /**
190 * Implementation of VirtualThreadSchedulerMXBean when using a custom virtual
191 * thread scheduler that does not implement VirtualThreadSchedulerMXBean.
192 */
193 private static final class CustomVirtualThreadSchedulerImpl
194 extends BaseVirtualThreadSchedulerImpl {
195
196 @Override
197 public int getParallelism() {
198 return 1;
199 }
200
201 @Override
202 public void setParallelism(int size) {
203 throw new UnsupportedOperationException();
204 }
205
206 @Override
207 public int getPoolSize() {
208 return -1;
209 }
210
211 @Override
212 public int getMountedVirtualThreadCount() {
213 return -1;
214 }
215
216 @Override
217 public long getQueuedVirtualThreadCount() {
218 return -1L;
219 }
220 }
221 }
222