97 lines
3.0 KiB
Java
97 lines
3.0 KiB
Java
/*
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* Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/* @test
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@bug 4905777
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@summary PrintWriter.println(Object) oversynchronized, can deadlock
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*/
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import java.io.PrintWriter;
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public class OversynchronizedTest extends Thread {
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private static PrintWriter writer = new PrintWriter(System.out);
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private static TestObj testObj = new TestObj("This is a test.", writer);
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private static int loopNum = 100;
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public void run() {
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for(int i=0; i<loopNum; i++) {
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testObj.test();
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//passing an object to PrintWriter.println might cause deadlock
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//if the object has a synchronized toString() method.
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//using PrintWriter.println(testObj.toString()) won't have a problem
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writer.println(testObj);
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}
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}
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public static void main(String args[]) throws Exception {
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// should no NullPointerException
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writer.println((Object)null);
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int num = 5;
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OversynchronizedTest[] t = new OversynchronizedTest[num];
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for(int i=0; i<num; i++) {
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t[i] = new OversynchronizedTest();
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t[i].start();
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}
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for(int i=0; i <num; i++) {
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t[i].join();
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}
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System.out.println("Test completed");
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}
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}
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class TestObj {
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String mStr;
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TestObj(String str, PrintWriter writer) {
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mStr = str;
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this.writer = writer;
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}
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synchronized void test() {
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try {
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long t = Math.round(Math.random()*10);
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Thread.currentThread().sleep(t);
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} catch (InterruptedException e) {
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// jtreg timeout?
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// Only jtreg will interrupt this thread so it knows what to do:
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e.printStackTrace();
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}
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//the following line might cause hang if there is PrintWriter.println(testObj)
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//called by other threads.
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writer.println("In test().");
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}
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public synchronized String toString() {
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writer.println("Calling toString\n");
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return mStr;
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}
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private PrintWriter writer;
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}
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