Tomcat sporadic halts

[Neeraj Vora <ne...@hotmail.com>]

Hello,

I have been using Tomcat 5.5.7 for a long time without any issues on Solaris 
10 and Oracle 9. Recently I added a couple of apps (total is under a dozen 
and load is quite low) and something very strange is observed. Around once a 
day a user will report that one or the other app (sometimes 2-3 at the same 
time) does not respond. Upon looking into it, it seems the browser seems to 
wait for a minute or so and then everything is normal. Does not seem to be 
any load on Tomcat or the system. How to debug this one? Checked Database 
connectivity, requested network monitoring and observing truss output on 
Tomcat process. Here and there a thread will show a large delta number like 
20's or 60's (truss with -D option).

These are old apps being maintained and uses old JDBC drivers and custom 
connection pooling.

Thanks in advance for any and all input and suggestions.

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Re: Tomcat sporadic halts

[Jacob Bunk Nielsen <jb...@bunk.cc>]

"Neeraj Vora" <ne...@hotmail.com> writes:

> I have been using Tomcat 5.5.7 for a long time without any issues on Solaris 
> 10 and Oracle 9. Recently I added a couple of apps (total is under a dozen 
> and load is quite low) and something very strange is observed. Around once a 
> day a user will report that one or the other app (sometimes 2-3 at the same 
> time) does not respond. [ ... ]

Could it be the garbage collector running?

Try adding '-verbose:gc -XX:+PrintGCTimeStamps' to your CATALINA_OPTS,
and have a look in your catalina.out when then problems occurs.

Unfortunately the timestamps printed by the garbage collector is
seconds since the JVM was started, which can be a bit confusing.

You can tune the garbage collector to be more efficient or to aim for
shorter pauses, but be aware that some of the collector options might
cause instability of the JVM.

-- 
Jacob


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