| /* |
| * 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 PrintStream.println(Object) oversynchronized, can deadlock |
| @key randomness |
| */ |
| |
| import java.io.PrintStream; |
| |
| public class OversynchronizedTest extends Thread { |
| private static TestObj testObj = new TestObj("This is a test."); |
| private static int loopNum = 100; |
| |
| public void run() { |
| for(int i=0; i<loopNum; i++) { |
| testObj.test(); |
| |
| //passing an object to System.out.println might cause deadlock |
| //if the object has a synchronized toString() method. |
| //using System.out.println(testObj.toString()) won't have a problem |
| System.out.println(testObj); |
| } |
| } |
| |
| public static void main(String args[]) throws Exception { |
| // should no NullPointerException |
| System.out.println((Object)null); |
| |
| // over synch test |
| 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) { |
| mStr = str; |
| } |
| |
| 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 System.out.println(testObj) |
| //called by other threads. |
| System.out.println("In test()."); |
| } |
| |
| public synchronized String toString() { |
| System.out.println("Calling toString\n"); |
| return mStr; |
| } |
| } |