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From "Shaun Barriball" <sbarr...@yahoo.co.uk>
Subject Model 2 deployments on Tomcat: Ensure logging is explicitly disabled
Date Tue, 27 Mar 2007 10:33:17 GMT
.....following on from my email titled "Profiling shows Session management to
be a hotspot - session pooling etc"

After further analysis a lot the CPU time was spent in
This was called by various blocks surronded by "if (log.isDebugEnabled())"
within JackRabbit. When using a Model 2 deployment with the JackRabbit Jars
within Tomcat common/lib be aware that you need to explicitly ensure that
logging is disabled (even though I'm not seeing debug in any logs).

So by adding a log4j.xml to Tomcat common/classes with a <root> appender set
to WARN this bottle neck has improved.
releaseSession() is now 1.7% of CPU time instead of 11.4%.

My comment on pooling sessions still stands though.

-----Original Message-----
From: Shaun Barriball [mailto:sbarriba@yahoo.co.uk] 
Sent: 27 March 2007 11:06
To: users@jackrabbit.apache.org
Subject: Profiling shows Session management to be a hotspot - session
pooling etc

Hi all,
We're currently CPU profiling an application which uses the SessionInView
pattern to create a new JCR session (with JackRabbit) for each request.

Profiling shows that around:
 - 11.4% of the CPU time is in releaseSession(). In particular around 5% of
this is in ItemManager.evictItem().
 - 0.08% of the CPU time is in getSession()

For each request the application is just reading a set of nodes (upto around
100) to generate a web page. We're using JackRabbit 1.2.1 with Oracle.

Any recommendations for how to resolve this overhead?
 - should we consider pooling sessions?
 - any way to optimise the session usage given the nodes are all read-only?

All help appreciated.

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