java 线程死锁的检测

java 线程死锁的检测

 

例子程序：

1. import java.util.concurrent.CountDownLatch;
2. import java.util.concurrent.ExecutorService;
3. import java.util.concurrent.Executors;
4. /**
5. * Hello world!
6. */
7. public class App {
8. public static void main(String[] args) throws InterruptedException {
9. System.out.println("Hello World!");
10. ExecutorService executorService = Executors.newFixedThreadPool(2);
11. byte[] i = new byte[0];
12. byte[] j = new byte[0];
13. final CountDownLatch countDownLatch = new CountDownLatch(2);
14. executorService.execute(new DeadThread1(i, j,countDownLatch));
15. executorService.execute(new DeadThread2(i, j,countDownLatch));
16. countDownLatch.await();
17. System.out.println("done !!!");
18. }
19. public static class DeadThread1 implements Runnable {
20. private byte[] i;
21. private byte[] j;
22. private CountDownLatch countDownLatch;
23. public DeadThread1(byte[] i, byte[] j, CountDownLatch countDownLatch) {
24. this.i = i;
25. this.j = j;
26. this.countDownLatch = countDownLatch;
27. }
28. @Override
29. public void run() {
30. synchronized (i) {
31. try {
32. Thread.sleep(1000);
33. } catch (InterruptedException e) {
34. e.printStackTrace();
35. }
36. synchronized (j) {
37. System.out.println(Thread.currentThread().getName() + "is running!!");
38. countDownLatch.countDown();
39. }
40. }
41. }
42. }
43. public static class DeadThread2 implements Runnable {
44. private byte[] i;
45. private byte[] j;
46. private CountDownLatch countDownLatch;
47. public DeadThread2(byte[] i, byte[] j, CountDownLatch countDownLatch) {
48. this.i = i;
49. this.j = j;
50. this.countDownLatch = countDownLatch;
51. }
52. @Override
53. public void run() {
54. synchronized (j) {
55. try {
56. Thread.sleep(1000);
57. } catch (InterruptedException e) {
58. e.printStackTrace();
59. }
60. synchronized (i) {
61. System.out.println(Thread.currentThread().getName() + "is running!!");
62. countDownLatch.countDown();
63. }
64. }
65. }
66. }
67. }

通过jps找到当前进程号：

1. guohaozhao116008@GUOHAOZHAO11600 /d
2. $ jps
3. 7448 RemoteMavenServer
4. 6600 JConsole
5. 6340 Jps
6. 6272
7. 7268 AppMain

通过jstack查看堆栈信息：

1. guohaozhao116008@GUOHAOZHAO11600 /d
2. $ jstack
3. Usage:
4. jstack [-l] <pid>
5. (to connect to running process)
6. jstack -F [-m] [-l] <pid>
7. (to connect to a hung process)
8. jstack [-m] [-l] <executable> <core>
9. (to connect to a core file)
10. jstack [-m] [-l] [server_id@]<remote server IP or hostname>
11. (to connect to a remote debug server)
12. Options:
13. -F  to force a thread dump. Use when jstack <pid> does not respond (process is hung)
14. -m  to print both java and native frames (mixed mode)
15. -l  long listing. Prints additional information about locks
16. -h or -help to print this help message
17. guohaozhao116008@GUOHAOZHAO11600 /d
18. $ jps
19. 7448 RemoteMavenServer
20. 6600 JConsole
21. 6340 Jps
22. 6272
23. 7268 AppMain
24. guohaozhao116008@GUOHAOZHAO11600 /d
25. $ jstack -l 7268
26. 2013-05-30 18:36:41
27. Full thread dump Java HotSpot(TM) 64-Bit Server VM (20.14-b01 mixed mode):
28. Found one Java-level deadlock:
29. =============================
30. "pool-1-thread-2":
31. waiting to lock monitor 0x000000000677c208 (object 0x00000000eafc3e18, a [B),
32. which is held by "pool-1-thread-1"
33. "pool-1-thread-1":
34. waiting to lock monitor 0x0000000006771be8 (object 0x00000000eafc3e28, a [B),
35. which is held by "pool-1-thread-2"
36. Java stack information for the threads listed above:
37. ===================================================
38. "pool-1-thread-2":
39. at com.sohu.suc.App$DeadThread2.run(App.java:74)
40. - waiting to lock <0x00000000eafc3e18> (a [B)
41. - locked <0x00000000eafc3e28> (a [B)
42. at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
43. at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
44. at java.lang.Thread.run(Thread.java:662)
45. "pool-1-thread-1":
46. at com.sohu.suc.App$DeadThread1.run(App.java:45)
47. - waiting to lock <0x00000000eafc3e28> (a [B)
48. - locked <0x00000000eafc3e18> (a [B)
49. at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
50. at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
51. at java.lang.Thread.run(Thread.java:662)
52. Found 1 deadlock.

可以看到：

这里发生了死锁。

使用图形工具 jconsole 同样可以检测到：

• 查看图片附件