MaxServers/StartServers

[Beth Frank <ef...@ncsa.uiuc.edu>]

I have a vague memory of a discussion with Bob McGrath
about when they were trying find a way to handle the
large number of requests coming in to the www.ncsa site.

When they limited the number of servers spawned, they
had some kind of overflow occurring in a TCP/IP buffer
that caused a ton of problems (and brought down one
of their systems).  I don't really remember what exactly
the problem was, but it raised the issue of what to do
when you've reached your pre-spawned limit.  It may have
been related to the way the old (pre-1.3) server handled
incoming requests.   I'm pretty sure it was related to
some system code the server called, not server code itself. 

In any event, I suggest that someone test the apache
server with a low absolute maximum and a high network
load just to make sure that you don't run into anything
worse than horrible performance if the absolute maximum
is set way too low.

	Sincerely,

		Elizabeth (Beth) Frank
		NCSA Server Development Team
		efrank@ncsa.uiuc.edu

Re: MaxServers/StartServers

[Brian Behlendorf <br...@organic.com>]

On Tue, 25 Jul 1995, Beth Frank wrote:
> In any event, I suggest that someone test the apache
> server with a low absolute maximum and a high network
> load just to make sure that you don't run into anything
> worse than horrible performance if the absolute maximum
> is set way too low.

Part of the algorithm should be a determination of when to send a "503" 
code, indicating the server was just to busy to respond to the request,
and to try again later. Those should be very easy to send (no path 
analysis or disk I/O needed).

	Brian

--=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--
brian@organic.com  brian@hyperreal.com  http://www.[hyperreal,organic].com/