Sessions support

Memcached provides a custom session handler that can be used to store user sessions in memcache. A completely separate memcached instance is used for that internally, so you can use a different server pool if necessary. The session keys are stored under the prefix memc.sess.key., so be aware of this if you use the same server pool for sessions and generic caching.

session.save_handler string: Set to memcached to enable sessions support.
session.save_path string: Defines a comma separated of hostname:port entries to use for session server pool, for example "sess1:11211, sess2:11211".

User Contributed Notes

nfoo at naver dot com

5 years ago


If you want to use 'memcacheD' extention not 'memcache' (there are two diffrent extentions) for session control,  you should pay attention to modify php.ini



Most web resource from google is based on memcache because It's earlier version than memcacheD. They will say as following



session.save_handler = memcache

session.save_path = "tcp://localhost:11211"



But it's not valid when it comes to memcacheD



you should modify php.ini like that



session.save_handler = memcached

session.save_path = "localhost:11211"



Look, there is no protocol indentifier

Ian Maddox

1 year ago


If you are setting data to the session and it immediately disappears and you aren't getting any warnings in your PHP error log, it's probably because your sessions expired sometime in the 1970s.

Somewhere between memcached 1.0.2 and 2.1.0, the memcached session handler became sensitive to the 30-day TTL gotcha (aka "transparent failover").  If your session.gc_maxlifetime is greater than 2592000 (30 days), the value is treated as a unix timestamp instead of a relative seconds count.

This issue is likely to impact anyone with long-running sessions who is upgrading from Ubuntu 12.04 to 14.04.

taubers at gmail dot com

3 years ago


If you are using the memcache class for session handling your key is the PHP session ID.  This is different than when using the  memcached class.

Example with memcache:
GET nphu2u8eo5niltfgdbc33ajb62

Example with memcached:
GET memc.sess.key.nphu2u8eo5niltfgdbc33ajb62

For memcached, the prefix is set in the config:
memcached.sess_prefix = "memc.sess.key."

Andrei Darashenka

6 years ago


This extension supports Session-locking!

by default
MEMC_SESS_LOCK_ATTEMPTS   30
MEMC_SESS_LOCK_WAIT       100000
MEMC_SESS_LOCK_EXPIRATION 30

richard at fussenegger dot info

2 years ago


The documentation is not complete, you can also pass the weight of each server and you can use sockets if you want. In your PHP ini:

<?php

// Sockets with weight in the format socket_path:port:weight
session.save_path = "/path/to/socket:0:42"

// Or more than one so that weight makes sense?
session.save_path = "/path/to/socket_x:0:42,/path/to/socket_y:0:666"

?>

And if you should ever want to access these servers in PHP:

<?php

$servers = explode(",", ini_get("session.save_path"));
$c = count($servers);
for ($i = 0; $i < $c; ++$i) {
  $servers[$i] = explode(":", $servers[$i]);
}
$memcached = new \Memcached();
call_user_func_array([ $memcached, "addServers" ], $servers);
print_r($memcached->getAllKeys());

?>

madalin at mgiworx dot co dot uk

9 months ago


short mention: Memcached has authentication support.

sstratton at php dot net

4 years ago


While the previous poster has a point that Memcached can and will cleanup to make room for it's keys, the likelihood of active sessions (due to the likelihood that they will be written to again within 30 seconds) is fairly low provided you have your memory allocation properly alloted.

me at nileshgr dot com

2 years ago


It seems a few people think saving sessions in memcache is more secure compared to saving in file-system (/tmp) especially when the discussion is about shared hosting.

This is not true. memcache has NO authentication; everybody & anybody can read session.save_path (which will contain the memcached daemon address).

FastCGI (PHP-FPM) is much much better when you're considering security and shared hosting.

If you want to share sessions across multiple servers transparently without having headaches of adding custom handlers, you can use NFS or something similar.