Re: weird balancing problem

From: Willy Tarreau <>
Date: Thu, 10 Mar 2011 02:26:13 +0100


On Wed, Mar 09, 2011 at 11:19:47PM +0100, Yves Van Wert wrote:
> Hi,
> i'm running haproxy 1.4.11 with 4 identical webservers behind it
> (oracle weblogic servers).
> We do balancing based on source ip because we need sticky sessions,
> but when i check the logfile i notice that always one of the 4 servers
> receives a lot less connections then the other 3 servers (not always
> the same server who has the least connections).
> Stats :
> 490 weblogic1
> 328 weblogic2
> 469 weblogic3
> 513 weblogic4
> Does anyone have an explanation on why this is happening (or the same
> experience for that matter) ?

That happens when you have a limited amount of clients. Source IP hashing is efficient when dealing with the whole internet. I'm used to observe really smooth numbers when dealing with tens to hundreds of thousands of IP addresses.

Also, when you're running from internal enterprise networks, it's very common to see the same pattern to address workstations on many sites, resulting in a less spread source set.

In your case, I'd say there are too few requests to be able to draw a diagnostic, but it could reflect what you'd observe in the later case.

Willy Received on 2011/03/10 02:26

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