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.
diff --git a/include/proto/server.h b/include/proto/server.h
index 77a5312..d0b925c 100644
--- a/include/proto/server.h
+++ b/include/proto/server.h
@@ -251,7 +251,8 @@
(srv->max_idle_conns == -1 || srv->max_idle_conns > srv->curr_idle_conns) &&
!(conn->flags & CO_FL_PRIVATE) &&
((srv->proxy->options & PR_O_REUSE_MASK) != PR_O_REUSE_NEVR) &&
- !conn->mux->used_streams(conn) && conn->mux->avail_streams(conn)) {
+ !conn->mux->used_streams(conn) && conn->mux->avail_streams(conn) &&
+ ha_used_fds < global.tune.pool_low_count) {
int retadd;
retadd = _HA_ATOMIC_ADD(&srv->curr_idle_conns, 1);
diff --git a/include/types/global.h b/include/types/global.h
index f1db95e..ba3738b 100644
--- a/include/types/global.h
+++ b/include/types/global.h
@@ -161,6 +161,10 @@
int pattern_cache; /* max number of entries in the pattern cache. */
int sslcachesize; /* SSL cache size in session, defaults to 20000 */
int comp_maxlevel; /* max HTTP compression level */
+ int pool_low_ratio; /* max ratio of FDs used before we stop using new idle connections */
+ int pool_high_ratio; /* max ratio of FDs used before we start killing idle connections when creating new connections */
+ int pool_low_count; /* max number of opened fd before we stop using new idle connections */
+ int pool_high_count; /* max number of opened fd before we start killing idle connections when creating new connections */
unsigned short idle_timer; /* how long before an empty buffer is considered idle (ms) */
} tune;
struct {