Well after turning on vebose garbage collect I found out what the "hang"
really is. For some reason the garbage collector gets in a state where
it tries to do a full GC but cannot for some unknown reason. Here is
what the verbose gc looks like on the hang:

7007.950: [Full GC [PSYoungGen: 157503K->157492K(206656K)] [PSOldGen:
699071K->699071K(699072K)
] 856575K->856564K(905728K) [PSPermGen: 115222K->115222K(115520K)],
1.1234380 secs]
7009.075: [Full GC [PSYoungGen: 157504K->157504K(206656K)] [PSOldGen:
699071K->699071K(699072K)
] 856575K->856575K(905728K) [PSPermGen: 115222K->115222K(115520K)],
1.1220980 secs]
7010.198: [Full GC [PSYoungGen: 157504K->157504K(206656K)] [PSOldGen:
699071K->699071K(699072K)
] 856575K->856575K(905728K) [PSPermGen: 115222K->115222K(115520K)],
1.1215690 secs]

this repeats forever...

I was actually able to get a thread dump but I don't really know what to
look for. I realize this is almost certainly not a tomcat issue so I
won't post anymore about it, but I thought I would just give an
update.  Thanks for all the suggestions.

--Brian.

Brian Cross wrote:
> Hello and thanks in advance for any advice.
>
> We have Tomcat 5.5.20 running standalone on the following system:
>
> Dual AMD Opteron
> 4 gig of memory
> Debian Linux 2.6.8 amd64 smp kernel
> latest sun java 1.5, 1.6, ibm 1.5 (happens on all 3 VM's)
> Tomcat 5.5.20 (originally happened on 5.5.16, upgrade didn't help)
>
> Randomly it will hang and stop accepting connections on port 80,
> sometimes even late at night when there is not much traffic.
>
> When the hang occurs:
>
> * Can't access any web app on tomcat including the tomcat manager
> * Telnet to port 80 hangs(Coyote running on port 80)
> * load goes up, but only slightly (from < 1 to maybe 3 or 4)
> * sometimes after a couple of minutes it starts responding again,
> sometimes it doesn't.
> * when I run shutdown.sh the java process continues to run and I have
> to kill -9 to stop it
> * I try to do a kill -3 or kill -QUIT on the java process to get a
> thread dump, but it does not work
>
> I have tried many different jvm settings and tomcat connector
> settings, here is what I have currently:
>
> <Connector port="80" maxHttpHeaderSize="8192"
>       maxThreads="1000" minSpareThreads="50" maxSpareThreads="100"
>       enableLookups="false" redirectPort="8443" acceptCount="100"
>       connectionTimeout="20000" strategy="ms"
> disableUploadTimeout="false" />
>
> CATALINA_OPTS="-server -XX:MaxPermSize=256m -ms512m -mx1280m -Xss96k
> -Djava.awt.headless=true"
>
> I would really appreciate any advice, I really don't know where to go
> from here to try and figure it out. If I can't figure it out soon my
> plan is to use apache2 as the webserver and connect to tomcat via JK.
>
> Thanks so much for your expert advice!
>
> --Brian.
>
> ---------------------------------------------------------------------
> To start a new topic, e-mail: users@(protected)
> To unsubscribe, e-mail: users-unsubscribe@(protected)
> For additional commands, e-mail: users-help@(protected)
>

---------------------------------------------------------------------
To start a new topic, e-mail: users@(protected)
To unsubscribe, e-mail: users-unsubscribe@(protected)
For additional commands, e-mail: users-help@(protected)