This is the extract from source file server/mpm/prefork/prefork.c:

/* Limit on the total --- clients will be locked out if more servers than
 * this are needed.  It is intended solely to keep the server from crashing
 * when things get out of hand.
 * We keep a hard maximum number of servers, for two reasons --- first off,
 * in case something goes seriously wrong, we want to stop the fork bomb
 * short of actually crashing the machine we're running on by filling some
 * kernel table.  Secondly, it keeps the size of the scoreboard file small
 * enough that we can read the whole thing without worrying too much about
 * the overhead.


On 15 June 2011 09:53, Patrick Proniewski <> wrote:

I'm using Munin to monitor few Apache servers.
The apache_processes plugin parse the output of , which looks like this:

Total Accesses: 20492
Total kBytes: 833698
CPULoad: .0142742
Uptime: 67703
ReqPerSec: .302675
BytesPerSec: 12609.6
BytesPerReq: 41660.5
BusyWorkers: 3
IdleWorkers: 9
Scoreboard: __._.__._..___.KKW..................**cut**......................................

BusyWorkers and IdleWorkers numbers are ok. But Scoreboard displays twice the real number of slots configured in httpd config.

I have this config:

<IfModule mpm_prefork_module>
   StartServers          5
   MinSpareServers       5
   MaxSpareServers      10
   MaxClients          128
   MaxRequestsPerChild   10000

I expect Scoreboard to display 128 slots, but it displays 256. Does it come from the fact I'm running Apache on ports 80 AND 443?


Administrateur Système - DSI - Université Lumière Lyon 2