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From Martijn Schoemaker <mart...@osp.nl>
Subject OutOfMemory when doing concurrent requests
Date Tue, 15 Oct 2002 13:56:12 GMT
Hi all,

My name is Martijn Schoemaker and I currently work for a
big company in which we have a combination of apache (1.3.26),
jserv (1.1.2), tomcat (3.2.3) running with an IBM supplied JVM
version 1.3.0-01. Under tomcat are JSP's which via beans make
RMI calls to the backend server running WebSphere 3.5.Every-
thing runs on HP-UX boxes.

Still with me ? ;)

Now we are tied to the crappy IBM JVM otherwise the RMI-IIOP
calls to the WebSphere backend screw-up. And I lately up-
graded to the 1.3 JVM because of the performance increase
it has opposed to the IBM 1.2 JVM we ran earlyer.

Now everything on Tomcat runs fine, except that when one of
our testers starts a testscript which does 5 simultanious
requests the first one receives an OutOfMemory exception
(see attachment below for detailed info).In normal proceedings
I rarely see this happening, but only at that test it always
happens. I'm also pretty baffled by the lack of pointer as
to which resource seems to be depleted, since we all know
that 'OutOfMemory' does not nessecarily means 'Memory' but
can also mean FD's, threads etc.Oh, if the user just retries
everything works ok. Also, all other requests get handled
e-ok. As the load increases, the amount of failures seems
to be stable (only when the users connect for the first
time).

I am really pulling my hair on this one because even if I
start the Tomcat just before the test, it still happens.

The user open file limit is 2048, the per-proces thread limit
is 3000, the -Xmx = 512Mb, the -Xms = 256Mb and the tomcat thread
pool is 200/100/50 (max, max-spare, min-spare). All JSP's are
compiled an ready for immediate use. JVM stats show that there
is 200Mb available when the test starts.

Has anybody got an idea about what this can be ? I personally
think it must be some system limit, I cannot seem to find it
however since they all seem to remain well within boundaries.

I really hope someone has seen this behaviour before, 'cause
I'm getting premature baldness out of this ;)

Cheers,
Martijn Schoemaker

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