DO NOT REPLY [Bug 37850] New: - Core dumps on Solaris under concurrent load.

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http://issues.apache.org/bugzilla/show_bug.cgi?id=37850

           Summary: Core dumps on Solaris under concurrent load.
           Product: Tomcat 5
           Version: Unknown
          Platform: Sun
        OS/Version: Solaris
            Status: NEW
          Severity: major
          Priority: P2
         Component: Native:JK
        AssignedTo: tomcat-dev@jakarta.apache.org
        ReportedBy: jorge.degraciasantos@telefonica.es


Hi! We've been trying to set up Apache + Tomcat + mod_jk on both Solaris 8 and
9, but we keep comming across the following notice in Apache's error_log:

[Wed Dec 07 10:57:20 2005] [notice] child pid 2198 exit signal Segmentation
fault (11), possible coredump in [/apache's/server/root/directory]

Here's the setup:

UltraSPARC hardware (Sun ES 450 on 4GB RAM and 4 440MHz processors)
Solaris 9 (tried on another machine with Solaris 8 too)
JDK1.4.2
Apache 2.0.54 mpm=worker
Tomcat 5.0.28
mod_jk1.2.15 (we've tried compiling every version from 1.2.10 to 1.2.15 and
we've tried the binary versions available on the official download site. Same
results on ALL of them).

We've tried other scenarios, such as Apache on one machine and Tomcat on
another, or one Apache and several Tomcats on other machines in a load balancing
setup, and in every case we get the same problem. The server works just fine
under light load, but...

We are performing some load tests on the server. We get a core dump notice,
together with the actual core dump every few seconds or so, whenever the server
goes through heavy (or even fairly mild) loads. At first, we felt that we might
be pushing the limit on performance, and that the core dump was a result of
that. However, our tests show that the core dump starts appearing under very
light load for a server of this kind. Apparently, 10 or 20 concurrent users
throwing page requests is our thresshold. Below that load, there are no errors.
Above it, they reappear consistently. The server seems to be able to work very
well on user loads much bigger than 20 concurrent users,(ie: 100-200) and the
core dumping hardly seems to affect performance, because the requests keep being
served anyway. We hardly noticed during the initial tests that something was
going so wrong - until we checked the logs.

We are blaming the problem on mod_jk because we've tried both Apache and Tomcat
standalone with no errors under the same load scenario. However, but the mod_jk
log doesn't seem to show anything relevant - even in debug mode. Only the notice
on Apache's log shows up.

My knowledge of core dump analysis is next to none. Can anyone help me with that
so that we can work out how to fix it?

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