We have been seeing some major performance and stability issues since upgrading to Moodle 2.9. I am not the system administrator, but I had our IT staff send me a list of our setup. Can anyone help us out here? I can forward any questions or needs for additional information to out IT staff.
Running PHP 5.6.12 and mariadb 5.5.45
Two virtual frontends with 2 processors and 4G memory each behind an F5 load balancer.
Each frontend runs nginx, php-fpm and memcached.
Memcached is setup to use the default port with a 1G maximum cache.
Moodle 2.9 memcached setup
Prefix key: m_
Hash method: default
Buffer writes: no
Enable clustered servers: checked
Set Servers: IP address of each frontend with port set to 11211
As the number of users in Moodle increases the number of connections to memcached starts to increase dramticaly. The connections are to both 127.0.0.1 and the IPs of the frontends. With approximately 20 users the number of connections grow to over 900 on each frontend in about 2 hours and Moodle shows extreme lag in performing operations. Memory usage is around 75% and CPU at aprox 10%. Restarting the memcached server immediately causes Moodle to begin running normally but the number of connections quickly builds.