1 /*
2 * Copyright (c) 2020, 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 /*
26 * @test HandshakeDirectTest
27 * @summary This test tries to stress direct handshakes between threads while suspending them.
28 * @library /testlibrary /test/lib
29 * @build HandshakeDirectTest
30 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+SafepointALot -XX:BiasedLockingDecayTime=100000000 -XX:BiasedLockingBulkRebiasThreshold=1000000 -XX:BiasedLockingBulkRevokeThreshold=1000000 HandshakeDirectTest
31 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:GuaranteedSafepointInterval=10 -XX:+HandshakeALot -XX:+SafepointALot -XX:BiasedLockingDecayTime=100000000 -XX:BiasedLockingBulkRebiasThreshold=1000000 -XX:BiasedLockingBulkRevokeThreshold=1000000 HandshakeDirectTest
32 */
33
34 import java.util.concurrent.atomic.AtomicInteger;
35 import java.util.concurrent.ThreadLocalRandom;
36 import java.util.concurrent.Semaphore;
37 import java.io.*;
38
39 public class HandshakeDirectTest implements Runnable {
40 static final int WORKING_THREADS = 32;
41 static final int DIRECT_HANDSHAKES_MARK = 50000;
42 static Thread[] workingThreads = new Thread[WORKING_THREADS];
43 static Semaphore[] handshakeSem = new Semaphore[WORKING_THREADS];
44 static Object[] locks = new Object[WORKING_THREADS];
45 static boolean[] isBiased = new boolean[WORKING_THREADS];
46 static AtomicInteger handshakeCount = new AtomicInteger(0);
47
48 @Override
49 public void run() {
50 int me = Integer.parseInt(Thread.currentThread().getName());
51
52 while (true) {
53 try {
54 if (!isBiased[me]) {
55 handshakeSem[me].acquire();
56 synchronized(locks[me]) {
57 isBiased[me] = true;
58 }
59 handshakeSem[me].release();
60 }
61
62 // Handshake directly some other worker
63 int handshakee = ThreadLocalRandom.current().nextInt(0, WORKING_THREADS-1);
64 if (handshakee == me) {
65 handshakee = handshakee != 0 ? handshakee - 1 : handshakee + 1;
66 }
67 handshakeSem[handshakee].acquire();
68 if (isBiased[handshakee]) {
69 // Revoke biased lock
70 synchronized(locks[handshakee]) {
71 handshakeCount.incrementAndGet();
72 }
73 // Create new lock to be biased
74 locks[handshakee] = new Object();
75 isBiased[handshakee] = false;
76 }
77 handshakeSem[handshakee].release();
78 if (handshakeCount.get() >= DIRECT_HANDSHAKES_MARK) {
79 break;
80 }
81 } catch(InterruptedException ie) {
82 throw new Error("Unexpected interrupt");
83 }
84 }
85 }
86
87 public static void main(String... args) throws Exception {
88 HandshakeDirectTest test = new HandshakeDirectTest();
89
90 // Initialize semaphores
91 for (int i = 0; i < WORKING_THREADS; i++) {
92 handshakeSem[i] = new Semaphore(1);
93 }
94
95 // Initialize locks
96 for (int i = 0; i < WORKING_THREADS; i++) {
97 locks[i] = new Object();
98 }
99
100 // Fire-up working threads.
101 for (int i = 0; i < WORKING_THREADS; i++) {
102 workingThreads[i] = new Thread(test, Integer.toString(i));
103 workingThreads[i].start();
104 }
105
106 // Fire-up suspend-resume thread
107 Thread suspendResumeThread = new Thread() {
108 @Override
109 public void run() {
110 while (true) {
111 int i = ThreadLocalRandom.current().nextInt(0, WORKING_THREADS-1);
112 workingThreads[i].suspend();
113 try {
114 Thread.sleep(1); // sleep for 1 ms
115 } catch(InterruptedException ie) {
116 }
117 workingThreads[i].resume();
118 }
119 }
120 };
121 suspendResumeThread.setDaemon(true);
122 suspendResumeThread.start();
123
124 // Wait until the desired number of direct handshakes is reached
125 // and check that all workers exited
126 for (int i = 0; i < WORKING_THREADS; i++) {
127 workingThreads[i].join();
128 }
129 }
130 }