Hello. Quick question about the Application monitoring of events [1]. Quite specifically `Applicatio...

# ktor

[Scott Rankin]

Hello. Quick question about the Application monitoring of events [1]. Quite specifically ApplicationStopPreparing and ApplicationStopping [2], [3]. While testing I'm noticing my println("ApplicationStopPreparing") is printing a couple times. Do I need to unsubscribe from the event if I am going to do things during ApplicationStopPreparing that I only want to happen once? Is there guidance or documentation on the differences between these Application shutdown states and the application lifecycle?

[1] https://ktor.io/docs/events.html
[2] https://api.ktor.io/ktor-server/ktor-server-core/io.ktor.server.application/-application-stop-preparing.html
[3] https://api.ktor.io/ktor-server/ktor-server-core/io.ktor.server.application/-application-stopping.html

[Aleksei Tirman [JB]]

What server engine do you use?

[Scott Rankin]

Netty

[Scott Rankin]

Also, embeddedServer if it makes a difference.

[Aleksei Tirman [JB]]

The ApplicationStopPreparing event is fired whenever the stop method is called and the problem is that it's called twice - when the signal to terminate a program is sent and after unblocking the thread before shutting down the server. You can use a flag to run your code only once in an event handler.

[Scott Rankin]

Thanks for the reply. I will add some logic to try to insure my stuff only runs once.