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From "Arnab Chakravarty" <>
Subject Issues | Suggestion any?
Date Thu, 23 Oct 2003 06:18:52 GMT
Hi all,

The application that we run is based on MVC architecture and is built on
Jsp, Java and oracle.

The (4) production servers are running Solaris OS with 4CPU, 4GB RAM and
7GB of swap space. In all we have 12 tomcats and 4 Apaches.

Each machine is equipped with one apache and 3 tomcats.

The Database machines is also running Solaris with 16CPU's, 20 GB RAM
and 20GB swap space.

We have apache (1.3.27) and tomcat(3.3) in our production servers with
JVM (1.4.2 recently upgraded). The frequent problems we face are:

- High GC (increased pause time when the NewSize=128m -ms=256m -mx=778m
and using the default LWP synchronization scheme with GC parameters
PrintGCDetails and Time Stamps to analyse in GCportal)(these setting are
for individual tomcats)

- The Process running the JVM reached 1GB of size in the 'TOP' list
recently, which at this point had to be killed on one of the tomcats.

- The load balancing scheme in the are

4,3,2,1 (Production Machine)

where the load is seen mostly on production machine 4. On this machine
the first tomcat spikes up with high threads and Database connections
and sometime with high GC and CPU usage. The 3rd production machine
causes high number of thread due to High GC most of the times and on
this machine the tomcat took around 1GB of memory. The JDBC connections
are also high sometime from this machien and thus increased in the pause
time causes this tomcat to stop responnding after some time.

On running pmap, it was seen 123MB was taken as heap, there were other
listing of high memories of 450, 136 and 65 MB in the anon listing. I
read in one of the articles that anon was something called anonymous
pages and was caused due to swapping. But, does that mean that there is
excessive swapping which can cause this GC time to go high because
swapping increasing some overhead here of writting this 450MB + other
chunks as part of the swap space?

Once the database connections are high with an increased number of
threads, they are unable to come back to the normal condition and we
have to kill this tomcat as after some time when the load increases,
apache starts backing up because of tomcat not accepting connections and
then the whole scenario is even worse. All tomcat show high threads

Please help me in case you have any pointers to resolve this scenario.

One last thing, there are some occasional tomcat death (JVM crashes)
once in a while.

Thanks in Advance,
Arnab Chakravarty

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