例子程序：
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
/**
* Hello world!
*/
public class App {
public static void main(String[] args) throws InterruptedException {
System.out.println("Hello World!");
ExecutorService executorService = Executors.newFixedThreadPool(2);
byte[] i = new byte[0];
byte[] j = new byte[0];
final CountDownLatch countDownLatch = new CountDownLatch(2);
executorService.execute(new DeadThread1(i, j,countDownLatch));
executorService.execute(new DeadThread2(i, j,countDownLatch));
countDownLatch.await();
System.out.println("done !!!");
}
public static class DeadThread1 implements Runnable {
private byte[] i;
private byte[] j;
private CountDownLatch countDownLatch;
public DeadThread1(byte[] i, byte[] j, CountDownLatch countDownLatch) {
this.i = i;
this.j = j;
this.countDownLatch = countDownLatch;
}
@Override
public void run() {
synchronized (i) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
synchronized (j) {
System.out.println(Thread.currentThread().getName() + "is running!!");
countDownLatch.countDown();
}
}
}
}
public static class DeadThread2 implements Runnable {
private byte[] i;
private byte[] j;
private CountDownLatch countDownLatch;
public DeadThread2(byte[] i, byte[] j, CountDownLatch countDownLatch) {
this.i = i;
this.j = j;
this.countDownLatch = countDownLatch;
}
@Override
public void run() {
synchronized (j) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
synchronized (i) {
System.out.println(Thread.currentThread().getName() + "is running!!");
countDownLatch.countDown();
}
}
}
}
}
通过jps找到当前进程号：
guohaozhao116008@GUOHAOZHAO11600 /d $ jps 7448 RemoteMavenServer 6600 JConsole 6340 Jps 6272 7268 AppMain
通过jstack查看堆栈信息：
guohaozhao116008@GUOHAOZHAO11600 /d
$ jstack
Usage:
jstack [-l] <pid>
(to connect to running process)
jstack -F [-m] [-l] <pid>
(to connect to a hung process)
jstack [-m] [-l] <executable> <core>
(to connect to a core file)
jstack [-m] [-l] [server_id@]<remote server IP or hostname>
(to connect to a remote debug server)
Options:
-F to force a thread dump. Use when jstack <pid> does not respond (process is hung)
-m to print both java and native frames (mixed mode)
-l long listing. Prints additional information about locks
-h or -help to print this help message
guohaozhao116008@GUOHAOZHAO11600 /d
$ jps
7448 RemoteMavenServer
6600 JConsole
6340 Jps
6272
7268 AppMain
guohaozhao116008@GUOHAOZHAO11600 /d
$ jstack -l 7268
2013-05-30 18:36:41
Full thread dump Java HotSpot(TM) 64-Bit Server VM (20.14-b01 mixed mode):
Found one Java-level deadlock:
=============================
"pool-1-thread-2":
waiting to lock monitor 0x000000000677c208 (object 0x00000000eafc3e18, a [B),
which is held by "pool-1-thread-1"
"pool-1-thread-1":
waiting to lock monitor 0x0000000006771be8 (object 0x00000000eafc3e28, a [B),
which is held by "pool-1-thread-2"
Java stack information for the threads listed above:
===================================================
"pool-1-thread-2":
at com.sohu.suc.App$DeadThread2.run(App.java:74)
- waiting to lock <0x00000000eafc3e18> (a [B)
- locked <0x00000000eafc3e28> (a [B)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:662)
"pool-1-thread-1":
at com.sohu.suc.App$DeadThread1.run(App.java:45)
- waiting to lock <0x00000000eafc3e28> (a [B)
- locked <0x00000000eafc3e18> (a [B)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:662)
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：
