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From "Steven Roussey" <>
Subject RE: What is the source of this 'Thundering herd' redux?
Date Thu, 02 Jan 2003 20:00:03 GMT
From: "Bill Stoddard" <>
I assume you are using the lastest version of 1.3.  Try 
experimenting with the AcceptMutex config directive 
and see if selecting different values changes the
behaviour you are seeing.


Thanks, I tried that. I used all that were available with no discernable
difference. I don't think it is really the 'thundering herd' problem,
just one that looks sort of like it. My gut instinct (from looking at
the vmstat) is that some process was set to take the connection but
fails for some reason and holds up everyone else. Perhaps the kernel
gets impatient with the process not handling it and then puts it up for
grabs for everyone to try.

I have no knowledge of the kernel internals and only some of Apache's
(well, a lot more lately...), so this interpretation is based on
observation not knowledge of the software algorithms at work. Hopefully
someone with better understanding of the systems at work will recognize
what is going on.


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