What is "dreadlock"? (note the "R")

Heard many times of deadlocks, but what is a dreadlock in the context of multithreaded programming?

Update: IAbstract's answer links to a whitepaper which explains the algorithm named dreadlock (not a product it seems). It covers the concept quite thoroughly. However, to briefly summarize what it's about:

A common开发者_运维知识库 way of detecting deadlocks is to keep track of which threads are locking which resources. This basically produces a thread-to-resource graph, and when a cycle appears in this graph a deadlock has occurred. This method is known as a spin-lock and is also known for being expensive, so more efficient alternatives like simple locking-timeouts is also commonly used. The Dreadlock algorithm seems to be a solution for the inneffectiveness in regular spin-lock algorithms, by minimizing the amount of data needed to keep track of locking cycles.

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Dreadlock looks like a new product or toolset you can use to find or detect deadlocks (although, by the time one occurs, you will be cursing the dreaded deadlock). (link supplied by Felix Kling)

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when a process is requesting for a resource and that resource is held by some other waiting process and the process is never able to change it's state, the situation is called as deadlock.