Signals

Itsi responds to several Unix signals for process control. These signals are used to gracefully shut down, reload configuration, adjust worker pools, or emit internal lifecycle events.

Signal Types

Signal	Behavior
SIGINT	Triggers a graceful shutdown. If received twice in quick succession, triggers a forceful shutdown.
SIGTERM	Triggers a graceful shutdown.
SIGUSR1	Triggers a hot restart (Sockets remain open, while configuration is reloaded).
SIGUSR2	Triggers a diagnostic info dump. Causes all child processes to print detailed diagnostic information.
SIGHUP	Triggers a reload of configuration. If using preloading mode, this is equivalent to a restart. Otherwise this will cause a phased restart.
SIGTTIN	Increases the number of worker processes.
SIGTTOU	Decreases the number of worker processes.

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CLI Convenience Commands

In addition to sending the above signals through native controls, you can also use the itsi executable as a convenient shortcut for sending signals. These will work so long as the command is run inside the same directory from which Itsi was started (as this is the directory within which the pid file is located).

• itsi stop: Sends SIGINT to initiate a graceful shutdown.
• itsi restart: Sends SIGHUP to trigger a reload of configuration.
• itsi reload: Sends SIGUSR1 to trigger a hot restart.
• itsi status: Sends SIGUSR2 to trigger a diagnostic info dump.
• itsi add_worker: Sends SIGTTIN to increase the number of worker processes.
• itsi remove_worker: Sends SIGTTOU to decrease the number of worker processes.