tree e019ac0f4d97210267b1fd89844c2d418f92bbd3
parent 7c49d2e213edba879fa37e1ea45e6fe5c99fb626
author Olivier Houchard <ohouchard@haproxy.com> 1555434442 +0200
committer Willy Tarreau <w@1wt.eu> 1555609923 +0200
encoding latin1

MEDIUM: connections: Add a way to control the number of idling connections.

As by default we add all keepalive connections to the idle pool, if we run
into a pathological case, where all client don't do keepalive, but the server
does, and haproxy is configured to only reuse "safe" connections, we will
soon find ourself having lots of idling, unusable for new sessions, connections,
while we won't have any file descriptors available to create new connections.

To fix this, add 2 new global settings, "pool_low_ratio" and "pool_high_ratio".
pool-low-fd-ratio  is the % of fds we're allowed to use (against the maximum
number of fds available to haproxy) before we stop adding connections to the
idle pool, and destroy them instead. The default is 20. pool-high-fd-ratio is
the % of fds we're allowed to use (against the maximum number of fds available
to haproxy) before we start killing idling connection in the event we have to
create a new outgoing connection, and no reuse is possible. The default is 25.