[opencms-dev] Tomcat tuning for OpenCms running on Linux

[Claus Priisholm]

Hi

Some suggest that on a server setting you set Xms == Xmx, 1G/2G seem 
like plenty, unless you have a lot of sessions or using a lot space for 
the flex cache. At least with tomcat 5 setting max perm size to 128M was 
a good thing, not sure if tomcat 6 is better at managing perm space but 
memory is cheap so why waste time on it :-)
I don't think I have seen stack issues with the default setting (unless 
doing some unintended loops in the code and then you never have enough 
stack space anyway :-), but 1024K seems plenty.

But one thing you may want to be on the lookout for... I have seen some 
weird issues when running tomcat via jsvc (which is default on Ubuntu 
and as of version 5 also on Debian). A long time ago I ran into the 
problem on Ubuntu and decided to stick with Debian, but since Debian now 
also is using jsvc per default, I've seen the issue pop on a couple of 
installations.
What happens is seemingly related to the nightly indexing. At some point 
(after days or weeks of smooth sailing) the jsvc process uses 100% of 
one cpu. Prior to that it seems that after the nightly index rebuild the 
process will slowly increase its cpu usage (in one example at the rate 
of appr. 1% per hour). Once it reaches 100% there will be a huge amount 
of interrupted indexing threads in the jsvc /tomcat process. I have not 
seen this happen when running tomcat directly rather than though jsvc, 
but it is probably not conclusive evidence that the culprit is jsvc.

best regards
Claus

Yves Glodt wrote:
> Hi,
> 
> I run an OpenCms instance in Ubuntu on a 4GB-box, and I wonder how I can 
> set up tomcat to best use the resources the box has.
> 
> To override the conservative defaults, for now I did:
> 
> JAVA_OPTS="-Xserver -Xss1024K -Xms1G -Xmx2G -XX:MaxPermSize=128M 
> -XX:NewSize=512m"
> 
> What do you think of these settings?
> 
> best regards,
> yves
> 
> 
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Claus Priisholm, CodeDroids ApS
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