We're trying to work out why a single page hit on our application pushes the CPU to
100%.
Our setup is JBoss AS 4.2.3.GA + Seam 2.1.0.GA. We're using the APR and serving over
HTTPS.
The 100% CPU hit happens with any page that does any "work" (DB lookup +
rendering results). It occurs after multiple hits on the same page. It occurs on two dev
machines and a staging server.
The web application feels very slow for a single user, even running off the staging
server. I've got to do performance testing at some stage, but there seems little
point while it's so sluggish for a single user.
WRT memory, my dev machine has 2GB of RAM. The JVM config is: -Xms300m -Xmx300m
-XX:NewSize=100m -XX:MaxNewSize=100m and profiling IAW
http://www.cecmg.de/doc/tagung_2007/agenda07/24-mai/2b3-peter-johnson/ind... suggests
that the GC process is running smoothly. On this machine, there is about 800MB RAM free
before JBoss startup and our app doesn't seem to consume the 300MB heap (not in short
runs anyway).
I've been through the server optimisation/slimming process detailed at
http://www.jboss.org/community/docs/DOC-10217, with minimal impact on this issue. Not
that I was surprised as most of the recommendations in that doc appear to be targeted at
scaling performance and our problem is with a single user.
When I profile the classes to try and establish what is causing the CPU hit, 95% of the
CPU time vanishes in two APR methods: org.apache.tomcat.jni.Poll.poll and
org.apache.tomcat.jni.Socket.accept.
Almost no CPU time is consumed by our own classes.
The profiling is done with JProfiler and AFAICT, the CPU time recording is only for the
JBoss server, not other apps on this machine (browser etc.). For the record, the DB
accessed by this app is on a separate server and all tables are quite small (the largest
is 12K rows, most are < a few hundred records).
I'm not sure what this is telling me. Is this normal behaviour for JBoss serving
HTTPS or have we got our server configuration all wrong? Does anyone have any thoughts on
where I should look next?
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