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There are many threads in my Java server. It hangs when one thread recursive invoke a method infinitely. After the method is invoked 54 times, the process hang, and there is no any log like "StackOverFlow" or "OutOfMemory".

However, as I know, only the thread with the problem will crash, other threads can work normally.

environment:

Linux version 2.6.31-20-server (buildd@crested) (gcc version 4.4.1 (Ubuntu 4.4.1-4ubuntu8) ) java version "1.6.0_18" Java(TM) SE Runtime Environment (build 1.6.0_18-b07) Java HotSpot(TM) 64-Bit Server VM (build 16.0-b13, mixed mode)

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  • Erm... you pretty much already answered your question? You're in an infinite loop of invoking a recursive method.. What exactly is your question? Commented Nov 30, 2010 at 11:39
  • "It hangs when one thread recursive invoke a method infinitely." Yes, that's why it hangs. So why are you asking why it hangs? We aren't psychic; we can't see the code for that thread, so we can't help you fix the infinite recursion unless you show the code. Commented Nov 30, 2010 at 11:40

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All threads require stack space. Every time you invoke a method recursively the stack expands - eventually you're gonna run out.

The number of iterations you manage depends on the exact code being run.

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Generate a thread dump which will show you a stack trace for each Java thread in the VM. This will tell you what the threads are doing when the JVM hangs.

To generate a thread dump, on UNIX platforms, you can use the command kill -QUIT process_id, where process_id is the process id of your Java program.

On Windows, you can enter the key sequence <ctrl><break> in the window where the Java program was started. Sending this signal instructs a signal handler in the JVM, to recursively print out all the information on the threads and monitors inside the JVM.

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Ask for a thread dump to see what your threads do. Set name for each thread you fork to identify them correctly. I suppose there could be also a dead lock on object monitors as well. I suggest use JProfiler to find the object the threads are blocked on.

On the other hand infinite recursion is not soo good. Avoid this, or define limit for it.

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You've answered your question:

It hangs when one thread recursive invoke a method infinitely.

My suggestion is to not invoke a method infinitely, you're expanding your stack very quickly as you're recursively calling a method.

What are you trying to do with threads? Can you optimise your code to invoke the method without an infinite loop?

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