Why Java process hang?

Question

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)

Erm... you pretty much already answered your question? You're in an infinite loop of invoking a recursive method.. What exactly is your question? — chzbrgla
– chzbrgla, 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. — Karl Knechtel
– Karl Knechtel, Commented Nov 30, 2010 at 11:40

pauljwilliams · Accepted Answer · 2010-11-30 11:38:24Z

2

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.

answered Nov 30, 2010 at 11:38

pauljwilliams

19.3k3 gold badges54 silver badges80 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

dogbane · Accepted Answer · 2010-11-30 11:39:53Z

1

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.

answered Nov 30, 2010 at 11:39

dogbane

276k77 gold badges407 silver badges415 bronze badges

Comments

Gábor Lipták · Accepted Answer · 2010-11-30 12:00:19Z

1

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.

answered Nov 30, 2010 at 12:00

Gábor Lipták

9,8343 gold badges62 silver badges117 bronze badges

Comments

Buhake Sindi · Accepted Answer · 2010-11-30 11:42:59Z

0

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?

answered Nov 30, 2010 at 11:42

Buhake Sindi

89.5k30 gold badges176 silver badges234 bronze badges

Collectives™ on Stack Overflow

Why Java process hang?

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related