theos at cnds
Mar 21, 2000, 9:34 PM
Post #1 of 1
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[mod_backhand-users] Re: [error] mod_backhand: Request tally 291 [391]
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Oleg Bartunov wrote:
>
> Hi,
>
> We have mod_backhand 1.08 and Apache 1.3.12 installed on
> dual PIII server (FreeBSD 3.4) we plan to use for serving static
> content (currently just one home page) and load balancing
> between 4 search servers. Everything is installed and running
> in test environment. We run apache benchmark and error log
> is full now with error messages like:
>
> [Tue Mar 21 11:48:54 2000] [error] mod_backhand: Request tally 2 [809]
> [Tue Mar 21 11:48:54 2000] [error] mod_backhand: Request tally 2 [810]
> [Tue Mar 21 11:48:54 2000] [error] mod_backhand: Request tally 2 [811]
>
> What does this message means ? Anybody run apache benchmark with
> concurrency about 20 ? Also, interesting to know from developers
> how stable is backhand under FreeBSD.
This message means that the request was "backhanded" (proxied). It took
2ms and the number in [] is the counter of number of requests backhanded
to that machines so far. This data was used for the addPrediction
function. This error message is of no importance, commenting it out or
removing it entirely is a good idea (I will for 1.0.9)
We always run it with concurrency of 20.. For high requests/second you
should try adding addPrediction on the END of the candidacy list. This
will reduce resource contention problems. Or, if you have more that 8
servers try byRandom then byLogWindow immediately after byAge.
(experiment and find which works best for you)
Under FreeBSD.... Hmm. Well it is solid under BSDI... But, there were
problems in 1.0.7 and I don't think that they are fixed completely under
FreeBSD. The plumbing is fine, it is the collection of local resource
utilization that doesn't work well.... feel free to submit a patch ;)
If ALL of your servers are running FreeBSD then this won't be an issue.
> btw, mod_proxy has a buffer, does it used ?
mod_proxy? mod_backhand doesn't use mod_proxy... Is you question
whether or not mod_backhand also implements a buffer? Hmm, it uses
ap_bread to read from the other server and it uses ap_rwrite to write
out to the client. I think those are buffered. I think that ap_rwrite
is heavily buffered, so in effect it would work as an http accelerator
if that was the direction of your question ;)
I welcome someone who knows the implementation of ap_rwrite better to
correct me ;)
--
Theo Schlossnagle
33131B65/2047/71 F7 95 64 49 76 5D BA 3D 90 B9 9F BE 27 24 E7
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