java heap dump file gets too big

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petereakin@gmail.com - 21 Apr 2006 09:57 GMT

Hi all

I have a tomcat server running on linux, there appears to have been a
crash last night and a massive heap file has been created which has
taken up all available disk space I think. As a result the core file
has not been created and I therefore don't have any meaningful
information as to why the crash occured.

Is there a way to tell tomcat or the JVM not to create the heap dump
file or can i limit the size of the file?

Also I need to make sure that the core file is still created?

Thanks
Peter

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badjomoise@gmail.com - 21 Apr 2006 11:43 GMT

Hi,
I am very happy to write you this message because i have to know more
about programmation.I will be much gratefull if you could help me by
teaching me or by sending me some books..

Reply to this Message

Roedy Green - 21 Apr 2006 22:48 GMT

>I am very happy to write you this message because i have to know more
>about programmation.I will be much gratefull if you could help me by
>teaching me or by sending me some books..

see http://mindprod.com/jgloss/gettingstarted.html
and http://mindprod.com/jgloss/personalbookshelf.html
for free books you can read online.

Try asking locally. Lots of us may have old books, but it costs quite
bit to ship them.

Signature

Canadian Mind Products, Roedy Green.
http://mindprod.com Java custom programming, consulting and coaching.

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petereakin@gmail.com - 24 Apr 2006 08:53 GMT

Guys can any1 give me any help with my original question? I really need
some advice on this.

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petereakin@gmail.com - 24 Apr 2006 08:57 GMT

OK I have just learned that the java is not running through tomcat but
is running on a unix server and is using AIX 5.1 I think. I don't have
much experience with this but I'm guessing there should be a setting in
the java virtual machine?

Any help would be appreciated.
Peter

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Gordon Beaton - 24 Apr 2006 09:29 GMT

> OK I have just learned that the java is not running through tomcat
> but is running on a unix server and is using AIX 5.1 I think. I
> don't have much experience with this but I'm guessing there should
> be a setting in the java virtual machine?

I believe the size of the heap dump is directly related to the size of
the heap itself. On AIX I suspect you're using IBM's rather than Sun's
JVM, but you should still be able to type "java -X" to see what
options you can use to limit the size of the heap (-Xmx for example).

Note that if *no* core dump was created (not even an empty file), it
is likely due to a ulimit setting affecting the Java process. Type
"ulimit -a" in a shell. If corefile size is 0, no attempt will be made
to create a corefile regardless of its size or the available space.
Note that this is a per-process setting, so changing the ulimit value
in *your* shell won't have the desired effect.

I suspect the heap dump is more useful than the corefile, for example
if your application is running out of memory. IBM Alphaworks has some
tools to help analyze the Java heap dump, use Google.

/gordon

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petereakin@gmail.com - 25 Apr 2006 08:46 GMT

Yea i thought the heap dump size would be related to the heap itself
but is there a way I can leave the heap size as it is but when a crash
occurs not create a dump file which is so large?

Is there a way to limit the size of the dump file?

Thanks again.
Peter

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java heap dump file gets too big

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