i have played a bit around with different memcached library and plugin version to enable real persistence between PHP memcache client and memcached server.
The problem is that still connections are opened and closed so that the connection counter goes up instead of the reusage of a existing persistent connection.
I have compiled the memcached daemon on from newest source on a redhat machine. I use the version memcached-1.4.14 and started with "#/opt/memcached/bin/memcached -vvvv"
The php plugin i have also compiled from newest source version memcached-2.0.1, i have compiled it against libmemcached-1.0.9 to have it up to date. Currently it does not compile against libmemcached-1.0.10.
My PHP script looks like this:
<?php
header("Cache-Control: no-cache, must-revalidate");
header("Expires: Sat, 26 Jul 1997 05:00:00 GMT");
$key = "key_" . uniqid();
$memcached = new Memcached( 'persistent' );
$memcached->setOption(Memcached::OPT_LIBKETAMA_COMPATIBLE, true);
$memcached->setOption(Memcached::OPT_RECV_TIMEOUT, 1000);
$memcached->setOption(Memcached::OPT_SEND_TIMEOUT, 3000);
$memcached->setOption(Memcached::OPT_TCP_NODELAY, true);
$memcached->setOption(Memcached::OPT_PREFIX_KEY, 'persistent');
if( !count($memcached->getServerList() ) )
{
$memcached->addServer( 'localhost', 11211 );
}
$memcached->set($key, 'value');
$value = $memcached->get($key);
print_r( $memcached->getStats() );
?>
On firing the script i see in the output that servers are not added, only after timeout period.
Array ( [@�qVG:11211] => Array ( [pid] => 3728 [uptime] => 73 [threads] => 4 [time] => 1343813688 [pointer_size] => 64 [rusage_user_seconds] => 0 [rusage_user_microseconds] => 6998 [rusage_system_seconds] => 0 [rusage_system_microseconds] => 31995 [curr_items] => 37 [total_items] => 37 [limit_maxbytes] => 67108864 [curr_connections] => 38 [total_connections] => 47 [connection_structures] => 39 [bytes] => 3589 [cmd_get] => 37 [cmd_set] => 37 [get_hits] => 37 [get_misses] => 0 [evictions] => 0 [bytes_read] => 3267 [bytes_written] => 39458 [version] => 1.4.14 ) )
But the connection counter still goes up and i suppose that the client creates a connection and on server side the persistent connection is re-used.
#netstat -an | grep 11211 | wc -l
tcp 0 0 ::1:11211 ::1:55941 VERBUNDEN
tcp 0 0 ::1:55961 ::1:11211 VERBUNDEN
tcp 0 0 ::1:55959 ::1:11211 VERBUNDEN
tcp 0 0 ::1:11211 ::1:56005 VERBUNDEN
...and so on
On server side i get verbous output that tells me that persistence is used:
...
<43 get persistentkey_5018f83903ded
> FOUND KEY persistentkey_5018f83903ded
>43 sending key persistentkey_5018f83903ded
>43 END
...
We want to use memcache on a high performance environment with a lot of incomming connections, and the connection amout does kill the apache childs currently. Any ideas how to enable real persistence?
Used software:
- Red Hat Enterprise Linux Server release 6.2 (Santiago)
- PHP Version 5.3.3
- Apache/2.2.15 in Prefork
- Memcache server 1.4.14
- libmemcached 1.0.9
- PHP memcached plugin 2.0.1