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From <cmanola...@yahoo.com>
Subject Re: tomcat hangging problem
Date Tue, 25 Sep 2001 17:10:12 GMT
Hi Joseph,

I assume this is happening only on SMP machines ( i.e. with multiple
CPUs).

My bet is that this is related with the VM/libraries. It can of course be
a bug in tomcat, like a deadlock or something - but then it would fail
on all SMP machines.

Could you check with the 'latest' 1.3.0 and make sure you have all the
patches installed  ( pthred.so, etc ). Also, check the version of the
libraries between the AIX machines that work and those that don't.

If you get a core dump - again, this is a clear sign something is wrong
with the VM/libraries. A java program shouldn't be able to coredump
regardless of the code inside ( unless JNI is used ), and there's nothing
we can do in tomcat ( even if we find a workaround, some user code can
crash the server as well ).

Is anyone else running SMP machines ? I remember long time ago a problem
on linux/smp, but was solved by using a newer VM.

Costin

>
> Here is the description of current problem I try to solve...
> I have already mailed to tomcat-user, but since nobody has a beginning
> of an answer, and since we can't go on production launch anymore, I try
> here.
>
> environment:
> - AIX 4.3.3 SMP,
> - JRE 1.2.2 (several builds), then 1.3.0
> - tomcat 3.2.1, 3.2.3 then 3.3.b2 (sorry, did not try 3.3.rc1 yet!)
>
> problem is: tomcat "hangs" after some time (may be 3 minutes or some
> hours). I mean tomcat is running ("ps" shows it), but no answer is
> received to requests when tomcat hangs (telnetting it with a http get
> request results in no response). Even a kill -3 does nothing.
>
> Strangely, problem occurs only on _some_ of AIX 4.3.3 machines where I run
> tomcat.
> Some machines, with same jre/tomcat/code, run with no problem (well,
> maybe problem would occur after a much longer time, I don't really know).
> And I did not met that on winNT4 (with a Sun jdk: I got to try with
> an ibm jvm).
> Note that I got a javacore twice, if somebody can interpret it...
>
> I wrote a simple servlet which shows tomcat hangging, if that can help:
> a singleton deals with doGet: first time it launches 'n' threads, each of
> them will http-request same singleton every 't' seconds and print result to stdout.
> other request to singleton only prints text/plain string to response's writer.
>
> Thanks
> --
> Joseph Vallot
>
>
>
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