Question About Deadlock Situation in Java

Question

I\'m learning about deadlocks in Java, and there\'s this sample code from Sun\'s official tutorial:

Alphonse and Gaston are friends, and great belie

Answer 1

One important point to note is that it is not methods which are locked but object instances.

When you call alphonse.bow(gaston), it tries to acquire the lock on alphonse. Once it has the lock, it prints a message, then calls gaston.bowBack(alphonse). At this point, it tries to acquire the lock on gaston. Once it has the lock, it prints a message, then releases the lock, and finally the lock on alphonse is released.

In deadlock, the locks are acquired in such an order that there's no way for either thread to proceed.

• Thread 1: acquires lock on alphonse
• Thread 2: acquires lock on gaston
• Thread 1: prints message
• Thread 1: tries to acquire lock on gaston - can't, because Thread 2 already has it.
• Thread 2: prints message
• Thread 2: tries to acquire lock on alphonse - can't, because Thread 1 already has it.