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From Glenn Nielsen <>
Subject Re: jk2 new shmem using APR
Date Wed, 17 Mar 2004 04:49:42 GMT
On Tue, Mar 16, 2004 at 02:48:26PM -0000, wrote:
> > Greg,
> As an aside our team will be looking at apache2 and tomcat5 sooner rather
> than later as it would appear that more development effort is taking place
> on these platforms.  However balancing lots of apps and infrastructure
> upgrades and testing with day to day support means this will not happen
> soon.

I went through the process of upgrading our servers to Apache2 over
the last 9 months. These are Sun servers running Solaris and using
the Apache 2 worker MPM.  There are alot of advantages to upgrading.
My testing found Apache 2 to require a great deal fewer system resources
(CPU,memory) when using the worker MPM and be much more scaleable.
I also like the way filters work. You can now have Tomcat generate HTML
with SSI which mod_include can then parse. This can help scaling for
Tomcat.  We use it with Tomcat4 and mod_jk 1.2.5, both are working very
reliably for us.

I did run into a number of problems at first. Most of them were
Solaris specific.  And some bugs which caused problems. I ended
up learning a whole lot more about apache internals than I really
wanted to, and even submitted a number of patches which got rolled
into later releases.

All in all it is working pretty well for us but we still get some
core dumps once in a while, nothing that causes apache to completely
fail though. We do have one nasty bug we hope the 2.0.49 release will
fix.  That is a runaway apache process which consumes all memory on
the server.  That was pretty nasty until we used ulimit on solaris
to limit the size of the data and virtual memory segments for apache
processes. Now the infrequent times this bug is triggered the apache
process core dumps when it hits these memory limits rather than 
causing general failures on the server due to exhausing all physical
and virtual memory.

The biggest effort had to be put into making sure all the third
party apache modules we use were thread safe. This included patches
to mod_jk 1.2 to fix a few thread safe problems. The mod_jk 1.2.5
includes all these patches.

All in all it was worth the effort, 9 months later it should be
easier for someone with a similar environment to mine to upgrade
to apache 2.



Glenn Nielsen    | /* Spelin donut madder    |
MOREnet System Programming               |  * if iz ina coment.      |
Missouri Research and Education Network  |  */                       |

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