Red Hat Bugzilla – Bug 115154
Possible memory leak with kernel 2.4.21-4 when using Resin-2.1.6
Last modified: 2008-08-02 19:40:32 EDT
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Description of problem:
When running Resin-2.1.6, the swap space utilization of the system
seems to get larger and larger. This is being run on the
kernel-2.4.21-4. This could be a possible kernel leak. This does not
happen when running this software of Solaris systems.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
2.check swap space with the "top" command
Actual Results: Swap Space utilization keeps increasing
Expected Results: Swap space utilization should not keep rising
Right -- there's absolutely nothing to work with here...
Please re-run the application, and while it is running and presumably
taking up swap space, give us the output of several Alt-Sysrq-m
I can reproduce this on 188.8.131.52EL.smp thusly:
I run tomcat 5.5.16 JAVA 1.5.0_6-b5 VM with a couple of deployed webapp.
The Box is a 2 cpu 32 bit box with 2GB of memory.
What made me start searching for clues was that Garbage collection in the VM
would consistently take longer and longer each time a full GC was executed in
the Java VM. My first suspicion was the Java VM itself and the GC routines.
When I setup the VM to log GC information I saw very odd behavior.
When in Parallel GC mode, Full GC's would continue to take longer upon each
subsequent run. the first under 10 seconds and the last - when tomcat had to
be shutdown finally would be upwards of 20 minutes! When the Full GC's would
run, the Java VM process would be in the "uninteruptable sleep" mode making it
impossible to get a thread dump.
I modified the settings to switch to ConcurrentMarksweep and the first Full GC
completely freezes the VM though other tools do not seem to suffer.
I noticed that the swap and memory utilization just continues to climb until
all physical memory and swap become completely allocated in spite of the fact
that I have only allocated 1GB to the java vm. Killing the Java VM will free
up some memory and some swap but not nearly what I would expect. Only a reboot
allows used memory to return to expected levels. Rinse and repeat. It is
As I said, I originally thought this was a tomcat or java issue until I
discovered this article on the java developer list:
I believe my problem and the above are related. His problem was solved by
upgrading to a 4.x release which included a 2.6.x kernel.
Do you have an alternative to "Alt-Sysrq-m"? This does not result in anything
other han a beep in a ssh term window. All of my servers are headless and
accessed via ssh or terminal server.
echo m > /proc/sysrq-trigger
This bug is filed against RHEL 3, which is in maintenance phase.
During the maintenance phase, only security errata and select mission
critical bug fixes will be released for enterprise products. Since
this bug does not meet that criteria, it is now being closed.
For more information of the RHEL errata support policy, please visit:
If you feel this bug is indeed mission critical, please contact your
support representative. You may be asked to provide detailed
information on how this bug is affecting you.