Re: Haproxy server timeouts?

From: Willy Tarreau <>
Date: Tue, 8 Dec 2009 06:24:22 +0100


On Sat, Dec 05, 2009 at 12:11:54AM +0100, XANi wrote:
> Dnia 2009-12-04, pi?? o godzinie 17:57 -0500, Naveen Ayyagari pisze:
> > The issue we have is that our scripts are dependent on external resources, so php execution time can vary wildly.
> Yes i meant processor cores, basically if you have extreme cases like 80
> processes on 8 cores then imo its better to use less processes and queue
> reqests in proxy (too much content switching is bad thing for
> performance), but if in your case its just because php "waits for
> something" and not because server is overloaded it wont change much. You
> might want to consider checking if other http servers liek lighttpd also
> have that "bug"

If you are fetching data from external resources, you may want to split the access between 2 distinct haproxy backends (which might very well point to the same servers). That implies you know what URLs remain local and which ones fetch remote data. Then you can proceed like this :

frontend www

	acl remote_content path_beg /x/y/z
	use_backend bk_remote if remote_content
	default_backend bk_local

backend bk_local
	timeout server 5s
	server www1 maxconn 100 check

backend bk_remote
	timeout server 50s
	server www1 maxconn 5 track bk_local/www1

That way, you allow more time for remote resources, but you don't permit them to fill your queues, as they have a dedicated queue and maxconn.

It's a very basic QoS principle but it works very well because you prevent expensive processing from saturating your servers.

Willy Received on 2009/12/08 06:24

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