[Bug 134274] Re: TCP_DEFER_ACCEPT causes random HTTP connection failures in load-balanced web-server farms
pierre.gauthier at twd-industries.com
Sat Jan 30 17:53:30 GMT 2010
When TCP_DEFER_ACCEPT is enabled on the listening socket:
- HTTP-Keep-Alive requests get a boost;
- non-HTTP-Keep-Alive requests are delayed after a while.
The problem happens with high concurrencies only.
This has been tested with various HTTP servers and is a consistant
behavior on Linux Ubuntu 8.1+.
The higher the value for TCP_DEFER_ACCEPT, the faster HTTP servers get
into trouble (when they receive ab connections without -k):
ab -t 100 -c900 http://a.b.c.d/100.html (a 100-byte file)
Anyone having a clue why this is happening?
(HTTP Keep-Alives being a persistant TCP connection, it is strange to see TCP_DEFER_ACCEPT giving them a boost)
(inversely, non-HTTP Keep-Alives being new TCP connections, it is strange to see TCP_DEFER_ACCEPT delaying them)
Thanks for any pointer.
** Changed in: apache2 (Ubuntu)
Status: Triaged => Invalid
** Converted to question:
TCP_DEFER_ACCEPT causes random HTTP connection failures in load-balanced web-server farms
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