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From Remy Maucherat <>
Subject Re: Tomcat arbitrarily freezes
Date Tue, 11 Jan 2005 14:14:54 GMT
On Tue, 11 Jan 2005 13:51:13 +0100, Oliver Schoenwald
<> wrote:
> Hi!
> five days after my first question and no answer in sight. To bad.
> So far, we have switched from JDK 1.4.2 to JDK 1.5 and from Tomcat
> 5.0.27 to 5.5.4 and the problem persists.
> However, while under JDK 1.4.2 it was always the thread with id #2 under
> JDK 1.5
> it is still the thread "VM Thread", but now under id #4.
> Using the better debugging features of JDK 1.5 (jstack, jmap) we could
> pin down the problem in more detail:
> whenever the problem starts, the output of jstack and jmap shows that
> these debugging-tools have
> more and more problems to give information about certain memory areas.
> When the problem reaches its
> climax, a bug number of memory areas are marked by jstack with an "Error
> occurred during stack walking:"-Message
> or by jmap with "UnmappedAddressException".
> You see, at the moment we are only guessing what problem we have here.
> Maybe someone has an idea how to analyze the problem more properly or
> even know how to solve it (without changing some of the components like
> using another servlet container engine or another JVM).

If you don't get any answers, it is that people don't have any ideas
and / or nothing useful to say.

For example, this is the first time I hear about a problem with this
internal VM thread. While other "Tomcat arbitrarily freezes" issues
are well known on some OSes, this one is brand new to me. You seem to
assert that this is a common problem encountered by many people, and
you also seem certain that your problems come for that (which means
bad luck, as this is an internal VM thread). Can you give links giving
more details about this ?

Rémy Maucherat
Developer & Consultant
JBoss Group (Europe) SàRL

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