What are the "Conventional Techniques" to avoid deadlock?

开发者_StackOverflowI saw the below statement in Java Specifications.

Programs where threads hold (directly or indirectly) locks on multiple objects should use conventional techniques for deadlock avoidance, creating higher-level locking primitives that don't deadlock, if necessary.

So, What are the "Conventional Techniques" to follow to avoid deadlock? I'm not pretty clear with this (not understood properly, explanation needed).

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The most common technique is to acquire resources (locks) in some consistent well-defined order.

The following article by Brian Goetz might be helpful: http://www.javaworld.com/javaworld/jw-10-2001/jw-1012-deadlock.html

It's pretty old, but explains the issues well.

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As a somewhat absract suggestion, an answer to this might be "Have a plan for handling locks and stick to it".

The danger of locking is where, in short, one thread holds lock A and is trying to get lock B, while another thread holds lock B and is trying to get lock A. As noted by another answer, the clasic way to avoid this is to get locks in a consistent order. However, a good discipline is to minimize the amount of work that your code does with a lock held. Any code that calls another function with a lock held is a potential problem: what if that other function tries to get another lock? What if someone else later modifies that function to get a lock? Try to form a clear pattern of what functions can be called with locks held, and what cannot, and make sure the comments in your code make this all clear.

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Don't do locking! Seriously. We get immense performance (100k's of transactions at sub-millisecond latency) at my work by keeping all our business logic single threaded.