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