File: SIGNALS [Unicorn: Rack HTTP server for fast clients and Unix]

Does anyone use TTIN and TTOU with Unicorn? Thinking of adding the same to Sidekiq…

In general, signals need only be sent to the master process. However, the signals Unicorn uses internally to communicate with the worker processes are documented here as well. With the exception of TTIN/TTOU, signal handling matches the behavior of nginx so it should be possible to easily share process management scripts between Unicorn and nginx. Master Process HUP - reloads config file and gracefully restart all workers. If the “preload_app” directive is false (the default), then workers will also pick up any application code changes when restarted. If “preload_app” is true, then application code changes will have no effect; USR2 + QUIT (see below) must be used to load newer code in this case. When reloading the application, Gem.refresh will be called so updated code for your application can pick up newly installed RubyGems. It is not recommended that you uninstall libra...

Full article: http://unicorn.bogomips.org/SIGNALS.html