[opencms] [opencms-dev] Optimizing OpenCMS performance.

[Jonathan Woods]

I wonder which package the regexp functionality is using.  If it's a third
party's, you could go for the latest release and see if that helps. 

-----Original Message-----
From: opencms-dev-bounces at opencms.org
[mailto:opencms-dev-bounces at opencms.org] On Behalf Of Nigel Kersten
Sent: 21 June 2006 23:38
To: The OpenCms mailing list
Subject: Re: [opencms] [opencms-dev] Optimizing OpenCMS performance.


On 22/06/2006, at 6:58 AM, <justin.spies at sbcglobal.net>
<justin.spies at sbcglobal.net> wrote:

> To answer your question about the garbage collection issues, I've 
> still seen many posts about garbage collection in Java 1.5.  In fact, 
> there is a known garbage collection bug in JDK1.5 that is not 
> scheduled to be fixed until 1.5_08.

ahah, I'm on:

java version "1.5.0_06"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_06-112) Java
HotSpot(TM) Client VM (build 1.5.0_06-64, mixed mode, sharing)

A few people have mentioned that there are some PPC specific problems with
garbage collection, so I'm toying with the idea of moving OpenCMS over to
one of my Linux x86 boxes rather than a PPC Xserve.

> Also, despite the performance improvements (I've read of people using 
> 12GB heap sizes on 64bit machines, but have no way to verify this), 
> the system still spends a large amount of time processing the memory.  
> I'm working on a project now that involves a BEA server using the Sun 
> 1.4 JDK and a full GC of a 400MB heap is still taking about 1.0 - 1.5 
> seconds.  From what I've read, there are two approaches to tuning 
> GC--the first is to setup the system to perform frequent, but short 
> (low pause) collections (i.e. using a small heap) and the other is to 
> tune the system using infrequent but long collections (i.e., using a 
> large heap.)  The route taken depends on the application.

So unlike with java prior to 1.5, you can't actually modify the garbage
collection method with -Xincgc as you could with 1.4, and this is all up to
the application developer?

It really seems like having those regular expressions I mentioned seem to
trigger some kind of bug where CPU usage goes through the roof. I've
disabled them for now, but will try and test them out with garbage
collection logging on so that I can see if that's the problem.

I've gone down to 128-512Mb memory allocation, and that seems to be ok.
Setting up mod_cache with apache in front has made the biggest difference in
terms of performance. It's nice to be able to have a system that responds
happily to content-header settings regarding caching, so you can tune the
cache for different areas of the site.

thanks for the response.

--
Nigel Kersten [Senior Technical Officer] College of Fine Arts, University of
NSW, Australia.
CRICOS Provider Code: 00098G




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