tree e69577371ff64e76fde77a74cd6343839b7ab581
parent 57bc8917c31ec34f0ac3e12a2738a7166e58ee5e
author Nenad Merdanovic <nmerdan@anine.io> 1461532206 +0200
committer Willy Tarreau <w@1wt.eu> 1461597830 +0200
encoding latin1

MINOR: Add ability for agent-check to set server maxconn

This is very useful in complex architecture systems where HAproxy
is balancing DB connections for example. We want to keep the maxconn
high in order to avoid issues with queueing on the LB level when
there is slowness on another part of the system. Example is a case of
an architecture where each thread opens multiple DB connections, which
if get stuck in queue cause a snowball effect (old connections aren't
closed, new ones cannot be established). These connections are mostly
idle and the DB server has no problem handling thousands of them.

Allowing us to dynamically set maxconn depending on the backend usage
(LA, CPU, memory, etc.) enables us to have high maxconn for situations
like above, but lowering it in case there are real issues where the
backend servers become overloaded (cache issues, DB gets hit hard).