Master process

• QUIT, INT: Quick shutdown
• TERM: Graceful shutdown. Waits for workers to finish their current requests up to the graceful_timeout.
• HUP: Reload the configuration, start the new worker processes with a new configuration and gracefully shutdown older workers. If the application is not preloaded (using the preload_app option), Gunicorn will also load the new version of it.
• TTIN: Increment the number of processes by one
• TTOU: Decrement the number of processes by one
• USR1: Reopen the log files
• USR2: Upgrade Gunicorn on the fly. A separate TERM signal should be used to kill the old master process. This signal can also be used to use the new versions of pre-loaded applications. See Upgrading to a new binary on the fly for more information.
• WINCH: Gracefully shutdown the worker processes when Gunicorn is daemonized.