memcached_socket_keepalive
This directive enables or disables the TCP keepalive feature for the memcached socket connection.
Description
The memcached_socket_keepalive directive is used to manage the TCP keepalive settings for connections to a memcached server. By enabling this directive, the NGINX server will periodically send keepalive packets to ensure that idle connections to the memcached server remain open, preventing them from being closed due to inactivity. This is particularly useful in scenarios where NGINX handles a high volume of requests and needs to maintain stable connections to the memcached server to enhance performance. The directive's usage is context-sensitive: it can be set at the http, server, or location levels, allowing for flexible configuration based on the scope of application.
The directive accepts a flag as its parameter, which can either be set to 'on' or 'off'. When set to 'on', keepalive packets will be sent, whereas 'off' will disable this feature. Keepalive settings can vary based on the underlying operating system’s socket options, and it may be important to ensure that keepalive is supported and configured correctly on both the client (NGINX) and server (memcached) sides to utilize this functionality effectively. If unset, NGINX will not send keepalive packets, potentially leading to connection drops under network constraints or inactivity periods.
Config Example
http {
memcached_socket_keepalive on;
server {
location /cache {
memcached_pass 127.0.0.1:11211;
}
}
}Enabling keepalive can increase the number of open connections, potentially exhausting system resources if not monitored.
Not all versions of memcached support TCP keepalive, ensure compatibility before using.
Keepalive configurations on the operating system may need to be adjusted for optimal performance.