On Mar 4, 2008, at 11:29 AM, Chuck Hill wrote:

On Mar 4, 2008, at 1:20 PM, Mike Schrag wrote:


Max had some really good info on all these values in the WO scalability session from a few WWDC's ago ... He talked about how the defaults are actually really terrible and will make your app fall over under load. Does anyone have their notes from that? It was really useful info that's hard to find anywhere else.

IIRC he said about 7-8 worker threads and 2-3 listen queue ones. Of course that depends on your app and what average requests are doing etc etc. But above that limit, if the app slows, the requests pile up to where it has no hope of meaningful recovery (the app may recover, but the users have gotten an error message long before).


Based on Max's comments, I have set the listen queue size to 2, minimum adaptor threads to 2, and maximum adaptor threads to 4 on my deployed WO apps. Yes, these seem extremely low compared with the defaults, but as Chuck (and Max) stated, higher values can cause poor performance at high loads. With these low settings, you'll get a warning at app startup, but ignoring this warning hasn't caused any obvious problem.

Performance tuning is a bit of a black art, but I'd try setting these values low to see whether your performance improves under high load.

Aloha,
Art

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