Many threads and OutOfMemoryError: Java heap size

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jacek - 10 May 2006 13:51 GMT

Hi,

I have an application with about 1500 threads and a PC with 1 GB RAM. I
start the application with following vm arguments: -Xms512m -Xmx512m
-Xss64k, but still getting the OutOfMemoryError: Java heap size for
threads. Maybe somebody knows a tool which could help me to locate the
problem? Or anybody has maybe any idea why it happens?

jacek

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Oliver Wong - 10 May 2006 16:43 GMT

> Hi,
>
[quoted text clipped - 3 lines]
> threads. Maybe somebody knows a tool which could help me to locate the
> problem? Or anybody has maybe any idea why it happens?

Perhaps the problem is that you have 1500 threads. Do you have 1500
processors on that PC with 1GB RAM? If not, why do you have 1500 threads?

- Oliver

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jacek - 11 May 2006 09:24 GMT

The framework I'm using starts so many threads. I know 1500 threads is
really a lot, I just thought maybe somebody had similar problem and
found a solution. I set the -Xss64k after reading this link
http://blogs.msdn.com/oldnewthing/archive/2005/07/29/444912.aspx , I
thought it should work. 1500 threads * 64k = 96M.

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Chris Uppal - 11 May 2006 15:16 GMT

> The framework I'm using starts so many threads.

What framework is it that uses so many many ? Seems odd to me...

>I set the -Xss64k after reading this link
> http://blogs.msdn.com/oldnewthing/archive/2005/07/29/444912.aspx , I
> thought it should work. 1500 threads * 64k = 96M.

At a guess the problem is more about fragmenting the address space, than
running out of RAM as such. Also, don't forget that the JVM will take more
memory than the -Xmx flag implies. For instance, it'll need space for its own
code -- code dynamically generated by the JIT and the static code in the JVM
DLL itself.

Maybe jconsole (standard tool in 1.5) would help you find out more.

-- chris

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jacek - 16 May 2006 09:06 GMT

www.jooneworld.com

Basic idea of the framework is nice, but it's not good for the size of
neural networks I need.

did anyone have some positive experience with other monitoring and
management java tools than jconsole? Because of
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6301562 I cannot use
it and I'm looking for some different tools of this kind.

--jacek

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Chris Uppal - 16 May 2006 13:07 GMT

> www.jooneworld.com

Thanks.

> did anyone have some positive experience with other monitoring and
> management java tools than jconsole?

Not me.

> Because of
> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6301562 I cannot use
> it and I'm looking for some different tools of this kind.

Is it really so difficult to get a temporary new login ? Your system
adminstrators much be real monsters ;-)

-- chris

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Many threads and OutOfMemoryError: Java heap size

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