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From Paul Querna <c...@force-elite.com>
Subject Re: Question on multi-process CGID
Date Tue, 20 Jun 2006 21:18:01 GMT
Mendonce, Kiran (STSD) wrote:
> I am looking into the probable bottlenecks. 
> 
> Agreed that the worker MPM has its advantages. But for a customer who is
> being asked to move to Apache 2.0, we are falling short on the
> performance and that makes it hard to sell. Since worker + mod_cgid was
> supposed to improve performance, how is it that the benchmarking numbers
> fall short ? 

It falls short on the CGI benchmarks, because of how mod_cgid works --
it has to communicate across a pipe.  In the real world Ive never seen
that as a bottleneck.  You can use mod_cgi with the Worker MPM, it might
or might not be safe, depending on your operating system.

The worker MPM will generally use less ram (less ram = more concurrency
is possible), be faster for static files, etc.

-Paul

> -----Original Message-----
> From: Paul Querna [mailto:chip@force-elite.com] 
> Sent: Tuesday, June 20, 2006 1:44 PM
> To: dev@httpd.apache.org
> Subject: Re: Question on multi-process CGID
> 
> Mendonce, Kiran (STSD) wrote:
>>  
>>> It depends on where the real bottleneck is.
>>>
>>> Most of the time, if you are unable to cope with the volume of 
>>> incoming
>> CGI requests, its because your CGIs themselves are slow to start.
>>> For example, if your CGIs are coded in Perl, just starting them can
>> take a long time, which is independent of mod_cgi(d).
>>> If your CGIs are written in C, then the startup time is minimal.
>> No, the CGIs are not in perl. They are either shell scripts or C 
>> programs. Strangely, Apache 1.3 performs better than Apache 2.0.xx 
>> with the worker MPM when the CGIs are C programs or shell scripts. We 
>> did the benchmarking with the ab utility. Anyone has similar 
>> experiences ? And any idea why that should be the case ?
> 
> I believe you really need to look at identifying the bottleneck. I have
> a hard time believing the speed of fork()+execv() is truly the cause of
> your problems.
> 
> Last time I tested 2.x, C-programs for me were about 1-2% slower with
> the Worker MPM, compared to the prefork MPM+mod_cgi.
> 
> I don't consider it significant, because of the other advantages to the
> worker MPM.


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