J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2005 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 20 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 21 | * have any questions. |
| 22 | */ |
| 23 | |
| 24 | /* @test |
| 25 | @bug 4905777 |
| 26 | @summary PrintStream.println(Object) oversynchronized, can deadlock |
| 27 | */ |
| 28 | |
| 29 | import java.io.PrintStream; |
| 30 | |
| 31 | public class OversynchronizedTest extends Thread { |
| 32 | private static TestObj testObj = new TestObj("This is a test."); |
| 33 | private static int loopNum = 100; |
| 34 | |
| 35 | public void run() { |
| 36 | for(int i=0; i<loopNum; i++) { |
| 37 | testObj.test(); |
| 38 | |
| 39 | //passing an object to System.out.println might cause deadlock |
| 40 | //if the object has a synchronized toString() method. |
| 41 | //using System.out.println(testObj.toString()) won't have a problem |
| 42 | System.out.println(testObj); |
| 43 | } |
| 44 | } |
| 45 | |
| 46 | public static void main(String args[]) throws Exception { |
| 47 | // should no NullPointerException |
| 48 | System.out.println((Object)null); |
| 49 | |
| 50 | // over synch test |
| 51 | int num = 5; |
| 52 | |
| 53 | OversynchronizedTest[] t = new OversynchronizedTest[num]; |
| 54 | for(int i=0; i<num; i++) { |
| 55 | t[i] = new OversynchronizedTest(); |
| 56 | t[i].start(); |
| 57 | } |
| 58 | |
| 59 | for(int i=0; i <num; i++) { |
| 60 | t[i].join(); |
| 61 | } |
| 62 | |
| 63 | System.out.println("Test completed."); |
| 64 | } |
| 65 | } |
| 66 | |
| 67 | class TestObj { |
| 68 | String mStr; |
| 69 | |
| 70 | TestObj(String str) { |
| 71 | mStr = str; |
| 72 | } |
| 73 | |
| 74 | synchronized void test() { |
| 75 | try { |
| 76 | long t = Math.round(Math.random()*10); |
| 77 | Thread.currentThread().sleep(t); |
| 78 | } catch (InterruptedException e) { |
| 79 | // jtreg timeout? |
| 80 | // Only jtreg will interrupt this thread so it knows what to do: |
| 81 | e.printStackTrace(); |
| 82 | } |
| 83 | |
| 84 | //the following line might cause hang if there is System.out.println(testObj) |
| 85 | //called by other threads. |
| 86 | System.out.println("In test()."); |
| 87 | } |
| 88 | |
| 89 | synchronized public String toString() { |
| 90 | System.out.println("Calling toString\n"); |
| 91 | return mStr; |
| 92 | } |
| 93 | } |