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From Rob Hartill <r...@imdb.com>
Subject HARD_SERVER_LIMIT (fwd)
Date Wed, 09 Oct 1996 15:32:32 GMT

not acked

----- Forwarded message from Lydia Leong -----

Message-Id: <199610091415.KAA14596@theurgy.digex.net>
From: Lydia Leong <lydia@theurgy.digex.net>
Date: Wed, 9 Oct 1996 10:15:35 EDT
X-Mailer: Mail User's Shell (7.2.5 10/14/92)
To: webmaster@apache.org, apache-bugs@apache.org
Subject: HARD_SERVER_LIMIT

http://www.apache.org/docs/process-model.html
(and the corresponding page for the 1.0 docs)

contains an error, as follows.

> There is a compile-time limit of 150 absolute maximum number of
> simultaneous children that will be allowed, which can be overruled by
> "MaxClients", though we don't recommend changing that number unless
>    1. You know you have the server resources to handle more 

That compile-time limit is a hard limit; it CANNOT be made greater
than 150, as point (1) above would seem to imply.

The HARD_SERVER_LIMIT (Apache 1.1.1) and HARD_SERVER_MAX (the Apache
1.0.5 equivalent) determine the size of the scoreboard, and Apache
1.1.1 explicitly sets daemon_limit (MaxClients) to HARD_SERVER_LIMIT
if you try to specify daemon_limit > HARD_SERVER_LIMIT

Personally, I find 150 much too low; the hard server limit should,
in my opinion, be as high as a sane user might want to set it; the
original 256 noted in the comments in scoreboard.h is somewhat
more reasonable (if you have a small machine that you want to 
not fill the process table on, set MaxClients to something
reasonable).

I have Sparc 5s here that have MaxClients set to 300 (after making
HARD_SERVER_MAX higher and recompiling), and which actually hit the
limit of 300, and still haven't reached the capacity of the machine
for hits-per-unit-time.

At least, if you keep HARD_SERVER_LIMIT at its current level, please
provide for it to be easily overridden in the initial Configuration
file, and clearly documented that if you want your MaxClients to be
above 150, you must change this hard limit.

+-----------------+--------------------------------+----------------------+
| Lydia Leong     | Lead Unix Systems Programmer   | We will find a way,  |
| lydia@digex.net | DIGEX Internet Servers Group   | or we will make one! |
| (301) 847-6437  | http://theurgy.digex.net:8000/ |    - Hannibal        |
+-----------------+--------------------------------+----------------------+

----- End of forwarded message from Lydia Leong -----


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