On Tue, 5 Dec 2000, Roger Espel Llima wrote:
> Stas Bekman <[EMAIL PROTECTED]> wrote:
> > Very cool!
> > Any benchmarks? The theoretical explanation, is quite good for those who
> > understand the problem, but far from being convincing for those who don't.
>
> Yep. Benchmarking with a copy of 'ab' modified to keep the client
> sockets open for a while (like NS and IE do), doing 12 concurrent
> requests on a slow dynamic Apache/mod_perl page, I get:
>
> * without lingerd: number of Apache processes grows from 10 to 39,
> with a peak at 43. Load average reaches 14.
>
> * with lingerd: number of Apache processes grows from 10 to 20, with
> a peak at 22. Load average reaches 10.
>
> The speed of the server improved slightly (from 17 to 20 pages per
> second), probably because of the lessened memory and scheduling
> pressure.
Yup, that't the exact reason. I've seen the same behavior.
> With only 6 concurrent requests, the speed stayed exactly the same
> with or without lingerd, but the number of servers went from 27 to
> 12.
Very nice. Of course this significant reduce in a number of processes
required to do the same job, is due to the fast execution time, where the
lingering close time had a significant wait in the request completion
time.
> > Also I suppose that you must say that Lingerd becomes the new Achilles
> > heel, since if this daemon goes down the whole server won't work.
>
> By default, if Apache can't find lingerd, it will do the lingering
> itself, the usual (slow) way.
That's cool. You didn't mention that.
> If you come to depend on the extra scalability that lingerd brings,
> you can configure Apache to not do lingering_close at all if lingerd
> fails. It sucks, but it's better to having the server fall over
> with the load... then again, that's what MaxClients is for.
>
> > May I suggest a correction here? "It removes the need for a front-end
> > proxy server only if you needed it in first place to solve the downstream
> > client feeding problem."
>
> Yep, you're right :)
>
> A proxy front-end can also serve images and do load-balancing. In
> the `README' for lingerd I suggest using thttpd and Piranha for each
> of these, but it's true that mod_proxy or mod_rewrite works too.
or even kernel level khttpd if you are on linux.
_____________________________________________________________________
Stas Bekman JAm_pH -- Just Another mod_perl Hacker
http://stason.org/ mod_perl Guide http://perl.apache.org/guide
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