Do Rev CGI Suffer Performance HIts?

[Alex Tweedly]

Richard Gaskin wrote:

> Dan Shafer wrote:
>
>> On another thread, jbv (JB) wrote about using Rev as a CGI engine on  
>> Linux as a matter of regular course.
>>
>> I'm curious. I've been laying out a design for an INternet-based app  
>> and figuring I'd have to use Python (which is OK because I love it  
>> but in some ways it may be overkill for this project) because of my  
>> understanding that a Rev CGI can't handle even modest volumes of  
>> traffic. This is apparently because a separate instance of the CGI 
>> is  launched for each HTTP request received.
>>
>> True or myth? 
>
>
> It's true on all non-Mac servers (Macs can use Apple events), but how 
> is this different from Perl or Python?
>
It's the same, for Perl as CGI and Python as CGI. But both mod_perl and 
mod_python exist, and are (reputedly, haven't seen any figures or 
benchmark numbers) much faster than starting a new interpreter each time.

> I know that in recent years there's an option in Apache to keep Perl 
> resident in memory, but behaviorally it still acts as a separate 
> instance.
>
> If there isn't commonly the same sort of option for Python, then my 
> hunch is that the resource demand would be measured by a combination 
> of engine size (load time) and engine efficiency, and may not differ 
> dramatically from the Rev engine.  Jacque recalls Scott Raney once 
> noting that when called as a CGI, the "faceless" engine does a lot 
> less work at startup and loads almost instantaneously, even faster 
> than a scriptless standalone.
>
> Do I misunderstand something about CGI and/or Python?
>
> Anyone have any hard comparison data about relative efficiencies 
> between Rev and Python?

Yeah - they're both faster than the other for some things.  Tell me 
which area you're interested in and I'll concoct a benchmark to prove 
that one is faster than the other; you tell me which one you want to 
win, and I'll make it win :-)

There is always the other option, of running a Rev (or Python, or Perl, 
...) server, and serving requests directly from that. This can give 
significantly better response times and significantly higher transaction 
rates - but it means the server needs to satisfy all requests - even 
those that could have been left to basic html. And it means that you 
have a single instance - so in some cases the programming gets orders of 
magnitude harder, while in others it might get easier.

-- 
Alex Tweedly       http://www.tweedly.net



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