Lesson learned: Apache2 MaxClients Variable.
Submitted by James on Thu, 2006-11-30 11:56.
This post has now moved to my new blog. You can find it at http://jamesandres.com/post/show/Lesson-Learned--Apache2-Max-Clients-Variable-2
Yea, I finally got around to reading about what the MaxClients variable in the apache2.conf is for. Please keep your laughter to yourself, but i thought what MaxClients meant was "how many clients can connect at one time." So logically, I set it at 255. Well, I'm not sure if MaxClients is a cryptic name, or maybe I just missed the boat, but actually this variable controls how many server processes will run simultaneously!
Visually stated: MaxClients == MaximumNumberOfApacheInstancesRunningAtTheSameTime
So what? Well, when load got high, apache would start spawing "hefty" Drupal processes @ between 20MB and 80MB each.
Simple math: 255 x 60MB = 15,300 MB RAM usage (hint: we don't have 15 GB of RAM)
As you can see this is a bad situation.
I changed the nubmer to 40 this morning and systems haven't been happier 
Lessons learned ... lessons learned
James.
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