Java 的死锁分析

(*)JDK: 提供强大诊断工具：Thread Dump ----> 文本信息

(*)windows: ctrl+break /(fn+B) 打印锁信息

linux: kill -3 pid ----> 命令：jps 打印锁信息

Java stack information for the threads listed above:

===================================================

"Thread-1":

at ThreadB.run(DeadLock.java:68)

-waiting to lock <0x244f6498> (a java.lang.Object)

-locked <0x244f64a0> (a java.lang.Object) "Thread-0":
at ThreadA.run(DeadLock.java:41)

-waiting to lock <0x244f64a0> (a java.lang.Object)

-locked <0x244f6498> (a java.lang.Object)

Found 1 deadlock.

代码如下
public class DeadLock {

final Object lockA = new Object();final Object lockB = new Object();public static void main(String[] args) { DeadLock demo = new DeadLock(); demo.startLock();}public void startLock(){ ThreadA a= new ThreadA(lockA,lockB); ThreadB b= new ThreadB(lockA,lockB); //start threads a.start(); b.start();}

}

class ThreadA extends Thread{

private Object lockA = null;private Object lockB = null;public ThreadA(Object a, Object b){ this.lockA = a; this.lockB = b;}public void run() { synchronized (lockA) { System.out.println("*** Thread A: ***: Lock A" ); try { sleep(3000); } catch (InterruptedException e) { e.printStackTrace(); } synchronized (lockB) { System.out.println("*** Thread A: ***: Lock B" ); } } System.out.println("*** Thread A: ***: Finished" );}

}

class ThreadB extends Thread{

private Object lockA = null;private Object lockB = null;public ThreadB(Object a, Object b){ this.lockA = a; this.lockB = b;}public void run() { synchronized (lockB) { System.out.println("*** Thread B: ***: Lock B" ); try { sleep(3000); } catch (InterruptedException e) { e.printStackTrace(); } synchronized (lockA) { System.out.println("*** Thread B: ***: Lock A" ); } } System.out.println("*** Thread B: ***: Finished" );}

}