Syntax: fastcgi_keep_conn on | off; Default: fastcgi_keep_conn off; Context: http, server, location
This directive appeared in version 1.1.4.
By default, a FastCGI server will close a connection right after sending the response. However, when this directive is set to the value on, nginx will instruct a FastCGI server to keep connections open. This is necessary, in particular, for keepalive connections to FastCGI servers to function.