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From Bill Marrs <>
Subject Re: mod_deflate and load
Date Thu, 03 Jul 2003 18:08:32 GMT
At 01:23 PM 7/3/2003, Ian Holsman wrote:
>what do you mean by 'timeouts'.

Pages taking minutes to display and giving up.  I have some code that 
aborts if a page take over 2 minutes to display.

If the machine gets a lot of requests, the load goes up and this can be 
toxic as it never gets a chance to recover.  I'm use to this balancing act 
with mod_perl.  Generally, I use MaxClients to keeps things under 
control.  I'm at 20 now, but I could try going lower with mod_deflate 
on.  It could be, I'm just playing it too close to the edge.  Usually, it's 
memory consumption that I worry about (I have a ton of Perl code in my 
server), but load is sort of the same thing in the end.  Maybe I'll try 15 
and see if the server is happier.

>first.. I would examine the cpu utilization/throughput of your box.
>maybe even reverting to 1.3.x/mod_gzip for a period and see if that works 
>for you.

Yes, going back to the old release would likely work.  I'm just trying to 
be "with it", using newer versions (Also, I got a push from RedHat's 
end-of-life policy).  But, maybe I jumped the gun and should go back and 
wait (perhaps wait until I upgrade my hardware as well).

Maybe it true what they say about new versions of software compensating for 
most performance gains you might get by upgrading hardware.  :-)

>may I suggest you move to the worker MPM, I'm thinking you don't have 
>enough ram in your machine for a pre-fork/mod-perl combo.

mod_perl 2 is not suppose to be very stable under the worker MPM.  From the 
mod_perl-1.99_09/README: "mod_perl is currently considered beta when used 
with the prefork MPM.  mod_perl is currently considered alpha when used 
with a threaded MPM."

I guess this is more reason to go back to Apache 1.3.

At this point, I'm going to assume that mod_deflate isn't likely to blame 
for the decease in performance.  It's just the straw that is breaking my 
camel's back.  More likely, I've lost performance somewhere in the 
combination of Perl 5.8.0, Apache 2.0, and mod_perl 2 upgrades.

I'll try mod_defalte with a lower MaxClients (15) and see if that works.

I am able to survive without compression, so I may just stay with the new 
software rather than going back.

Thanks for the response.


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