Deadlock check

Question

Can someone tell me how I can find out how many threads are in deadlock mode in a multi-threaded Java application? How to find out the list of blocked threads?

I heard about Thread Dump and Stack Traces, but I don't know how to implement it.

• I also want to know what new features were introduced in Java 5 for Threading?

Please let me know with your comments and suggestions.

Answer 1

The method of obtaining stream dumps:

• ctrl-break (Windows) or ctrl- \, possibly ctrl-4 kill -3on Linux / UNIX
• jstackand your process id (use jps)
• jconsole or visualvm
• just about any debugger

J2SE 5.0 ( 2004 , ):

• java.util.concurrent
• Java.

Answer 2

kill -3

Answer 3

ThreadMXBean findMonitorDeadlockedThreads(), . Windows, Ctrl + Break, .

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Answer 4

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• Nanosecond granularity - the System.nanoTime method allows you to access a time source based on nanosecond granularity for relative time measurements and methods that take timeouts (such as BlockingQueue.offer, BlockingQueue.poll, Lock.tryLock, Condition.await and Thread.sleep ) can take timeout values ​​in nanoseconds. The actual accuracy of System.nanoTime is platform dependent.