This section describes the processes that NGINX starts at run time and how to control them.
In This Section
Master and Worker Processes
NGINX has one master process and one or more worker processes. If caching is enabled, the cache loader and cache manager processes also run at startup.
The main purpose of the master process is to read and evaluate configuration files, as well as maintain the worker processes.
The worker processes do the actual processing of requests. NGINX relies on OS-dependent mechanisms to efficiently distribute requests among worker processes. The number of worker processes is defined in the nginx.conf configuration file and can be fixed for a given configuration or automatically adjusted to the number of available CPU cores (see
To reload your configuration, you can stop or restart NGINX, or send signals to the master process. A signal can be sent by running the
nginx command (invoking the NGINX executable) with the
nginx -s signal
signal value can be one of the following:
quit– Shut down gracefully
reload– Reload the configuration file
reopen– Reopen log files
stop– Shut down immediately (fast shutdown)
kill utility can also be used, to send a signal directly to the master process. The process ID of the master process is written, by default, to the nginx.pid file, which is located in the /usr/local/nginx/logs or /var/run directory.
You can read more about advanced signals (for performing live binary upgrades, for example) in Controlling NGINX.