From: Leandro Santi (lesantiuolsinectis.com.ar)
Date: Fri Jun 13 2003 - 10:13:15 CDT

• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

On Wed, Jun 11, 2003, Victor.Duchovnimorganstanley.com wrote:
> Wietse's point is that lack of load-balancing is not important unless it
> leads to query latency. Query latency will cause the proxymap service to
> be busy and therefor more instances will be spawned. If 5 proxymap
> instances are all it takes to handle the load, the load-balancing is
> adequate.
>
> So it is unlikely that assymetric loading will make any one of the MySQL
> servers so tardy as to be unusable for other applications, there may also
> be connection setup costs in MySQL that you are not measuring.
>
> Try it with statistical load balancing first, and if evidence emerges that
> this is not good enough, solve the more complex problem later.

Well, I've been running the proxymap for a few days, and it seems that one
of its instances is getting most part of the work:

% ps -f -p "`pgrep proxymap`"
     UID PID PPID C STIME TTY TIME CMD
 postfix 21272 12361 1 08:55:33 ? 2:04 proxymap -t unix -u
 postfix 151 12361 1 07:20:31 ? 3:22 proxymap -t unix -u
 postfix 16736 12361 1 12:15:12 ? 29:03 proxymap -t unix -u

I already understood that, when lots of work requests arrive, the Postfix
daemons will "naturally" discover and connect to the less active ones,
because of its (ingenious) design. However, I think that its a desirable
feature (second of third order if you like :) to spread the load evenly not
just when the whole (ie Postfix + backend) system is somewhat near saturation
but when working at cruise speed, too.

Regards,
Leandro

• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]