// deadlock sample class,
// illustrates a thread deadlock
public class deadlock
	implements Runnable
{
	private final Object resource1_;
	private final Object resource2_;
	private final String messageIn_;
	private final String messageOut_;
	// program entry point
	public static void main(String[] args)
	{
		boolean order = false;
		if (args != null && args.length>= 1 && args[0].equals("order")) {
			order = true;
		}
		final Object resource1 = new Object();
		final Object resource2 = new Object();
		// create sample runners and start them
		(new Thread(new deadlock(resource1, resource2, "+", "-"))).start();
		// second possibly in oposite order; different markers
		(new Thread(new deadlock(
			(order ? resource1 : resource2),
			(order ? resource2 : resource1), "*", "/"))).start();
		// suspend main thread
		synchronized (deadlock.class) {
			try {
				deadlock.class.wait();
			} catch (InterruptedException ignored) {
			}
		}
	}
	public deadlock(Object resource1, Object resource2, String messageIn, String messageOut)
	{
		resource1_ = resource1;
		resource2_ = resource2;
		messageIn_ = messageIn;
		messageOut_ = messageOut;
	}
	public void run()
	{
		for (;;) {
			// acquire #1
			print(messageIn_);
			synchronized (resource1_) {
				// acquire #2
				print(messageIn_);
				synchronized (resource2_) {
					print(messageOut_);
				}
				print(messageOut_);
			}
		}
	}
	private static void print(String s)
	{
		synchronized (System.out) {
			System.out.print(s);
			System.out.flush();
		}
	}
}
/*
"Thread-1" prio=1 tid=0xa86160d8 nid=0x2a9f waiting for monitor entry [0xa8366000..0xa8366ed0]
 at deadlock.run(deadlock.java:59)
 - waiting to lock <0xa8a8dc50> (a java.lang.Object)
 - locked <0xa8a8dc58> (a java.lang.Object)
 at java.lang.Thread.run(Thread.java:595)
"Thread-0" prio=1 tid=0xa8615b20 nid=0x2a9e waiting for monitor entry [0xa83e8000..0xa83e8150]
 at deadlock.run(deadlock.java:59)
 - waiting to lock <0xa8a8dc58> (a java.lang.Object)
 - locked <0xa8a8dc50> (a java.lang.Object)
 at java.lang.Thread.run(Thread.java:595)
Found one Java-level deadlock:
=============================
"Thread-1":
 waiting to lock monitor 0x080b92a4 (object 0xa8a8dc50, a java.lang.Object),
 which is held by "Thread-0"
"Thread-0":
 waiting to lock monitor 0x080b9264 (object 0xa8a8dc58, a java.lang.Object),
 which is held by "Thread-1"
*/
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