deadlock.java

Java Thread Programming (Source

public class Deadlock extends Object {
	private String objID;

	public Deadlock(String id) {
		objID = id;
	}

	public synchronized void checkOther(Deadlock other) {
		print("entering checkOther()");

		// simulate some lengthy process
		try { Thread.sleep(2000); } 
		catch ( InterruptedException x ) { }

		print("in checkOther() - about to " +
				"invoke 'other.action()'");
		other.action();

		print("leaving checkOther()");
	}

	public synchronized void action() {
		print("entering action()");

		// simulate some work here
		try { Thread.sleep(500); } 
		catch ( InterruptedException x ) { }

		print("leaving action()");
	}

	public void print(String msg) {
		threadPrint("objID=" + objID + " - " + msg);
	}

	public static void threadPrint(String msg) {
		String threadName = Thread.currentThread().getName();
		System.out.println(threadName + ": " + msg);
	}

	public static void main(String[] args) {
		final Deadlock obj1 = new Deadlock("obj1");
		final Deadlock obj2 = new Deadlock("obj2");

		Runnable runA = new Runnable() {
				public void run() {
					obj1.checkOther(obj2);
				}
			};

		Thread threadA = new Thread(runA, "threadA");
		threadA.start();

		try { Thread.sleep(200); } 
		catch ( InterruptedException x ) { }

		Runnable runB = new Runnable() {
				public void run() {
					obj2.checkOther(obj1);
				}
			};

		Thread threadB = new Thread(runB, "threadB");
		threadB.start();

		try { Thread.sleep(5000); } 
		catch ( InterruptedException x ) { }

		threadPrint("finished sleeping");

		threadPrint("about to interrupt() threadA");
		threadA.interrupt();

		try { Thread.sleep(1000); } 
		catch ( InterruptedException x ) { }

		threadPrint("about to interrupt() threadB");
		threadB.interrupt();

		try { Thread.sleep(1000); } 
		catch ( InterruptedException x ) { }

		threadPrint("did that break the deadlock?");
	}
}