An arbitrary actor can be told to
monitor other actors or Julia tasks. Monitored actors or tasks send a
Down message with an exit reason to their monitor(s) before they terminate. A monitor then gives a warning or executes a specified action dispatched on the received reason.
Monitors do not forward
Down messages. They give warnings or execute specified actions for
Down signals (even with reason
:normal). Monitoring is not bidirectional. If a monitor fails, the monitored actor gets no notification. Monitoring can be stopped with
demonitor. An actor can have several monitors (if that makes sense).
You can see a script illustrating monitoring in the How-to section.