Deadlock detection in Java

Question

Long time ago, I saved a sentence from a Java reference book: \"Java has no mechanism to handle deadlock. it won\'t even know deadlock occurred.\" (Head First Java 2nd E

Answer 1

JDK 5 and 6 will dump held lock information in a full thread dump (obtained with kill -3, jstack, jconsole, etc). JDK 6 even contains information about ReentrantLock and ReentrantReadWriteLock. It is possible from this information to diagnose a deadlock by finding a lock cycle: Thread A holds lock 1, Thread B holds lock 2, and either A is requesting 2 or B is requesting 1. From my experience, this is usually pretty obvious.

Other analysis tools can actually find potential deadlocks even if they don't occur. Thread tools from vendors like OptimizeIt, JProbe, Coverity, etc are good places to look.