01: //
02: // Copyright (C) 2005 United States Government as represented by the
03: // Administrator of the National Aeronautics and Space Administration
04: // (NASA). All Rights Reserved.
05: //
06: // This software is distributed under the NASA Open Source Agreement
07: // (NOSA), version 1.3. The NOSA has been approved by the Open Source
08: // Initiative. See the file NOSA-1.3-JPF at the top of the distribution
09: // directory tree for the complete NOSA document.
10: //
11: // THE SUBJECT SOFTWARE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY OF ANY
12: // KIND, EITHER EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT
13: // LIMITED TO, ANY WARRANTY THAT THE SUBJECT SOFTWARE WILL CONFORM TO
14: // SPECIFICATIONS, ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR
15: // A PARTICULAR PURPOSE, OR FREEDOM FROM INFRINGEMENT, ANY WARRANTY THAT
16: // THE SUBJECT SOFTWARE WILL BE ERROR FREE, OR ANY WARRANTY THAT
17: // DOCUMENTATION, IF PROVIDED, WILL CONFORM TO THE SUBJECT SOFTWARE.
18: //
19: package deadlock;
20:
21: /**
22: * This example shows a simple deadlock.
23: */
24: public class Deadlock implements Runnable {
25: /**
26: * A name for the thread.
27: */
28: String name;
29:
30: /**
31: * A fererence to the other Deadlock object running as a seperate thread.
32: */
33: Deadlock other;
34:
35: public Deadlock(String name) {
36: this .name = name;
37: }
38:
39: public static void main(String[] args) {
40: Deadlock o1 = new Deadlock("A");
41: Deadlock o2 = new Deadlock("B");
42:
43: o1.other = o2;
44: o2.other = o1;
45:
46: Thread t1 = new Thread(o1);
47: Thread t2 = new Thread(o2);
48:
49: t1.start();
50: t2.start();
51: }
52:
53: public void run() {
54: while (true) {
55: System.out.println(name + " cycle start");
56: synchronized (this ) {
57: other.foo();
58: }
59:
60: System.out.println(name + " cycle end");
61: }
62: }
63:
64: synchronized void foo() {
65: System.out.println(name + ".foo() was called");
66: }
67: }
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