please add to the documentation behaviors section some information regarding: tcp_keepalive, retry_timeout.

[trevorboydsmith]

in the documentation there is no mention of the behavior "tcp_keepalive". this behavior is important and necessary when running in a kubernetes or docker-compose scenario because the connection goes through something that monitors for dead connections and the thing that monitors for dead connections has a timeout of like 15 minutes or something.

so i set the memcached behavior "tcp_keepalive" to 300 to ensure that my connecitons do not get cut by the networking thing.

for more better description of the "networking thing" see zulip/zulip#12711 which describes some about pika and also mentions the pylibmc.

my request: please add to the documentation some information regarding the "tcp_keepalive".

also i noticed there was missing a mention of "retry_timeout". please add that to the documentation too. (if you do not set this value to something like 5... does the client just error out on the first error?)

---

for the tcp keepalive to work you also need to set the "tcp_keepidle" value. unfortunately your python code does not expose this feature from the underlying c library. so for now i have a patch that i wrote.

diff --git a/src/_pylibmcmodule.h b/src/_pylibmcmodule.h
index cee9772..36a28bb 100644
--- a/src/_pylibmcmodule.h
+++ b/src/_pylibmcmodule.h
@@ -202,6 +202,7 @@ static PylibMC_Behavior PylibMC_behaviors[] = {
     { MEMCACHED_BEHAVIOR_TCP_NODELAY, "tcp_nodelay" },
 #if LIBMEMCACHED_VERSION_HEX >= 0x00044000
     { MEMCACHED_BEHAVIOR_TCP_KEEPALIVE, "tcp_keepalive" },
+    { MEMCACHED_BEHAVIOR_TCP_KEEPIDLE, "tcp_keepidle" },
 #endif
     { MEMCACHED_BEHAVIOR_HASH, "hash" },
     { MEMCACHED_BEHAVIOR_KETAMA_HASH, "ketama_hash" },

and i do a pip download --no-binary=pylibmc pylibmc. extract, cd, patch, build, install.

tcp_keepalive is boolean value. see https://man7.org/linux/man-pages/man7/socket.7.html section SO_KEEPALIVE.

tcp_keepidle is integer time in seconds. see https://man7.org/linux/man-pages/man7/tcp.7.html section on TCP_KEEPIDLE.