記一次簡單的線程死鎖調優 - springsource－IT工程師數位筆記本

文章出處

如果是內存調優，請看我以前一篇博文 http://www.cnblogs.com/springsource/archive/2013/01/11/2856968.html

調優演示

1. 先寫一個死鎖小程序，如下

package com.he.jin.bin;

/**
 * QQ 277803242
 * 
 * @author 何錦彬 2014.1.29
 * 
 * 線程死鎖演示調優
 * 
 */
public class Test4DeadLock extends Thread {
    public static Object obj1 = new Object();
    public static Object obj2 = new Object();

    public static void main(String[] args) {
        new Thread(new Runnable() {
            public void run() {
                synchronized (obj1) {
                    System.out.println("have in obj1 lock");
                    try {
                        Thread.sleep(100);
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                    System.out.println("wait for obj2 lock");
                    synchronized (obj2) {
                        System.out.println("lock2 have been done");
                    }
                }
            }
        }).start();
        new Thread(new Runnable() {

            @Override
            public void run() {
                synchronized (obj2) {
                    System.out.println("have in obj2 lock");
                    try {
                        Thread.sleep(100);
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                    System.out.println("wait for obj1 lock");
                    synchronized (obj1) {
                        System.out.println("lock1 have been done");
                    }
                }
            }
        }).start();
    }
}

運行，輸出如下，被死鎖

have in obj1 lock
have in obj2 lock
wait for obj1 lock
wait for obj2 lock

為了發現這個死鎖，可以先用JDK自帶工具 JPS查看所有JAVA進程

C:\Users\Administrator>jps
6048 Jps
5304 Test4DeadLock
1376 org.eclipse.equinox.launcher_1.3.0.v20130327-1440.jar

發現線程死鎖的進程ID

用jstack -l 5404 ，打印出死鎖描述

C:\Users\Administrator>jstack -l 5304
2014-01-29 10:19:28
Full thread dump Java HotSpot(TM) 64-Bit Server VM (24.51-b03 mixed mode):

"DestroyJavaVM" prio=6 tid=0x00000000025cd800 nid=0x143c waiting on condition [0
x0000000000000000]
java.lang.Thread.State: RUNNABLE

Locked ownable synchronizers:
- None

"Thread-1" prio=6 tid=0x000000000a23a800 nid=0x11e4 waiting for monitor entry [0
x000000000ac3e000]
java.lang.Thread.State: BLOCKED (on object monitor)
at com.he.jin.bin.Test4DeadLock$2.run(Test4DeadLock.java:39)
- waiting to lock <0x00000000eb519e78> (a java.lang.Object)
- locked <0x00000000eb519e88> (a java.lang.Object)
at java.lang.Thread.run(Unknown Source)

Locked ownable synchronizers:
- None

"Thread-0" prio=6 tid=0x000000000a239800 nid=0xd64 waiting for monitor entry [0x
000000000a9cf000]
java.lang.Thread.State: BLOCKED (on object monitor)
at com.he.jin.bin.Test4DeadLock$1.run(Test4DeadLock.java:20)
- waiting to lock <0x00000000eb519e88> (a java.lang.Object)
- locked <0x00000000eb519e78> (a java.lang.Object)
at java.lang.Thread.run(Unknown Source)

Locked ownable synchronizers:
- None

附上 JDK其它調優命令

http://blog.csdn.net/feihong247/article/details/7874063

alert("test");

</script>

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