java死锁分析

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" );
}

}