Op dinsdag, 22 juni 2010 18:33 schreef "Robinson, Eric"
<eric.robin...@psmnv.com>:
This is a similar question to one already being discussed in the list
with the subject "Setting the Right Amount of Memory".
We have 160 instances of tomcat on the same server, with most instances
configured to use 64-96MB of RAM. We carefully watch the logs for OOMEs.
If we see any, we increase the RAM allocation for that instance by 32MB,
which is enough to make the OOMEs go away.
Some people say this approach will lead to increased CPU utilization
from frequent GC; however, our server runs 90% idle all day long so CPU
is evidently not being driven up by much, if any.
Given the circumstances, is there anything to be gained from increasing
the heap size? Our software vendor wants us to increase each tomcat
instance to 512MB, just as a matter of policy, but I don't see a good
technical reason to do that.
Am I missing something?
--
Eric Robinson
You can monitor the gc with jstat.
jstat -gc <pid> 10s
This wil show you the memory usage of a java instance with the time spent in
GC. If it does 0.9 sec. of GC every sec. you are running inefficient. :-)
Ronald.
