Mark,
Thanks for your information.
I am not certain where the glibc versions I previously gave came from
because... as you noted, they are not correct. The correct glibc version is
2.9 and the threading version (I hope I am stating this correctly) is NPTL
2.9.
The kernel version is 2.6.29.6. From the Slackware 13.0 release notes,
'We've used the well-tested and recently patched 2.6.29.6 kernel'. I
assumed that was about as good a kernel as I could get... was I wrong?
I will try LD_ASSUME_KERNEL=2.4.1 (the Slackware site seems to indicate my
version supports this setting) on one of the servers (so I can quickly
revert to the other one if the setting doesn't work.)
I will add the 'XX:ParallelGCThreads=1 option to one of the servers and see
how that works.
I am moving a litlle slowly because I don't want to make a nbad situation
worse and want to be certain I can account for any improvements or screwups.
Thanks for your insights.
Carl
----- Original Message -----
From: "Mark Eggers" <its_toas...@yahoo.com>
To: "Tomcat Users List" <users@tomcat.apache.org>
Sent: Saturday, February 06, 2010 9:46 PM
Subject: Re: Tomcat dies suddenly
--- On Fri, 2/5/10, Carl <c...@etrak-plus.com> wrote:
Carl,
1. The application runs fine on an older system. Do we have
the glibc and kernel versions for all systems?
The old system: P4. 1GB memory, 1.3GB swap.
Uses swap on a regular basis. kernel is 2.4.25.
Java is 1.5.0_01-b08. Tomcat is 5.5.23. Glibc is
version 2.3..1.
New systems: Server A (Dell T110) is a Xeon 3440, sever B
(Dell T105) is an AMD. A has 4GB memory and 19GB swap
which is never used. B has 6GB memory and 10GB swap
which is never used. A and B both use kernel version
2.6.29.6, Java 1.6.0_18-b07 and Tomcat 6.0.24.. Glibc
version is 4.3.3 for both A and B.
A couple of observations here:
Both the old new kernels end in odd numbers. From memory, I thought the odd
kernel numbers were experimental, while the even numbers were production or
mainline. I don't remember when this numbering system took place, but
certainly by the time the 2.6 kernels were released.
From kernel.org, I didn't see a 2.6.29 release marked as stable.
The thread implementation has changed between the 2.4 and 2.6 kernels. You
can see the thread implementation change by running:
getconf GNU_LIBPTHREAD_VERSION
I'd be interested in knowing the result of that and
getconf GNU_LIBC_VERSION
on both systems, since I don't recognize 4.3.3 as a glibc version (latest
stable is 2.11.1, so I'm assuming 2.4.3.3?).
glibc has some thread bugs that were fixed, but not until 2.8 or 2.9. There
was also a persistent bug for 32-bit systems that bites Java applications
(not your concern since you're running 64-bit) that wasn't fixed until
2.10.1.
So in short, I'm guessing this may be a glibc NPTL issue.
There are some observations that don't match, in that you're using Java 6
(most problems are reported with Java 1.4 and Java 5), and that you've used
OpenSuSE (kernel, glibc version?) with the same Tomcat failure.
However:
For some of the earlier 2.6 kernels, you could get around NPTL problems by
setting this environment variable:
export LD_ASSUME_KERNEL=2.4.1
which forces the use of the old linuxthreads model. I don't know if that
option is available with the 2.6 kernel that you are using.
Another work-around has been posted on the Java bugs forum, albeit for a
different threading problem and Java 5:
-XX:ParallelGCThreads=1
sets GC to single threads. It's not fixed in the Java bugs database, because
later versions of RedHat Linux don't exhibit the SIGSEGV problem.
Some people report that single-threading GC solves their problems, while
other people report that it doesn't.
Some things to try I guess:
1. export LD_ASSUME_KERNEL=2.4.1 (maybe in startup.sh?) if your kernel
supports this..
2. set -XX:ParallelGCThreads=1 in catalina.sh (JAVA_OPTS). This is an
experimental switch, not documented here:
http://java.sun.com/javase/technologies/hotspot/vmoptions.jsp, but
documented here:
http://java.sun.com/javase/technologies/hotspot/gc/gc_tuning_6.html
3. Move to an even-numbered kernel with a glibc of 2.10.1 or better. 2.10
might be OK for your environment since the bug fixed in 2.10.1 causes
problems for 32-bit systems only.
just my two cents . . . .
/mde/
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