(Related to my earlier post on mod_status.)

Found this useful tidbit today from IBM HTTP Server Performance Tuning:

For IBM HTTP Server 7.0 and later, mod_mpmstats is enabled automatically.

  • Check entries like this in the error log to determine how many simultaneous connections were in use at different times of the day:

    [Thu Aug 19 14:01:00 2004] [notice] mpmstats: rdy 712 **bsy 312** rd 121 wr 173 ka 0 log 0 dns 0 cls 18
[Thu Aug 19 14:02:30 2004] [notice] mpmstats: rdy 809 **bsy 215** rd 131 wr 44 ka 0 log 0 dns 0 cls 40
[Thu Aug 19 14:04:01 2004] [notice] mpmstats: rdy 707 **bsy 317** rd 193 wr 97 ka 0 log 0 dns 0 cls 27
[Thu Aug 19 14:05:32 2004] [notice] mpmstats: rdy 731 **bsy 293** rd 196 wr 39 ka 0 log 0 dns 0 cls 58

This is a quick way to look at your IHS load over time.

The fields logged are described in the table below:

field description
rdy (ready) the number of web server threads started and ready to process new client connections
bsy (busy) the number of web server threads already processing a client connection
rd (reading) the number of busy web server threads currently reading the request from the client
wr (writing) the number of busy web server threads that have read the request from the client but are either processing the request (e.g., waiting on a response from WebSphere Application Server) or are writing the response back to the client
ka (keepalive) the number of busy web server threads that are not processing a request but instead are waiting to see if the client will send another request on the same connection; refer to the KeepAliveTimeout directive to decrease the amount of time that a web server thread remains in this state
log (logging) the number of busy web server threads that are writing to the access log
dns (dns lookup) the number of busy web server threads that are performing a dns lookup
cls (closing) the number of busy web server threads that are waiting for the client to acknowledge that the entire response has been received so that the connection can be closed