/* Run this application once on my pc, deadlock occured when count == 80.

Then the inner critical section can not be accessed by both threads while the app still on.

You can press control and 'c' key simultaneously to force terminating the app. */

public class DeadlockDemo{

private Object lock1 = new Object();

private Object lock2 = new Object();

public static volatile int count = 0;

public static final int MAX_COUNT = 10000;

public void instanceMethod1(){

synchronized(lock1){

synchronized(lock2){

System.out.println(Thread.currentThread().getName() + " in instanceMethod1." + count);

// Critical section guarded first by lock1 and then by lock2.

}

}

}

public void instanceMethod2(){

synchronized(lock2){

synchronized(lock1){

System.out.println(Thread.currentThread().getName() + " in instanceMethod2." + count);

// Critical section guarded first by lock2 and then by lock1.

}

}

}

public static void main(String[] args){

final DeadlockDemo dld = new DeadlockDemo();

Thread threadA = new Thread(new Runnable(){

@Override

public void run(){

while(count < MAX_COUNT){

dld.instanceMethod1();

try{

Thread.sleep(50);

}catch(InterruptedException ie){

ie.printStackTrace();

}

count++;

}

}

}, "Thread-A");

Thread threadB = new Thread(new Runnable(){

@Override

public void run(){

while(count < MAX_COUNT){

dld.instanceMethod2();

try{

Thread.sleep(50);

}catch(InterruptedException ie){

ie.printStackTrace();

}

count++;

}

}

}, "Thread-B");

threadA.start();

threadB.start();

}

}