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From "Jeff Trawick" <>
Subject Re: RFE -- external overload procedure
Date Fri, 20 Apr 2007 11:57:35 GMT
On 4/20/07, Juerg Umhang <> wrote:
> hello
> please consider this posting as a request for enhancement
> httpd knows about his overload situation.
> ---- [error] server reached MaxClients setting, consider raising the
> MaxClients setting
> this overload is easily created by an external attacker. in case of an
> attack you have to react.
> best done on a lower osi-layer (iptables, pf, ...).
> realtime log analysis has his own odds and twists. we would prefer a call
> to an 'external helper procedure'.

> in this context we have some questions:
> -- do you think it makes sense to implement this feature ?
> -- could it be done in a module (without the overhead of going through the
> scoreboard for each pre_connection call) ?

It is reasonable to me for httpd to provide a module interface (hook)
so that a third-party module can take action when httpd reaches the
MaxClients (Unix) or ThreadsPerChild (Windows) condition.  (Maybe the
hook just provides some basic statistics, and the module can determine
whether the absolute limit has been reached or its own configurable
threshhold has been reached.)

A way that a module can do something reasonable without modifying the
server is to create a separate child process that monitors the
scoreboard at its own interval, and takes whatever action is
appropriate.  That check can be infrequent enough that the performance
overhead is negligible.

> -- can we expect this enhancement in a future release ?

Some other committer can speak for themselves, but I wouldn't expect
it without a patch submitted.

> btw: we hope to see separately configurable timeouts (
> ) very soon.

I don't recall anyone here interested in fulfilling the goal expressed
in that comment.

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