How to exit a sbt task?

Question

I run a sbt task. Normal scenario after it finishes, it should stop in the terminal. But the terminal is not waiting for next input meaning : my task keeps running. I assume some called threads were not exited after the task launched them.

How to exit clean and kill all processes started by the sbt task ? I could debug which service was not stopped but it will take a long time to figure out.

More details

In the build.sbt

lazy val refreshTranslations = taskKey[Unit]("blabla")
fullRunTask(refreshTranslations, Compile, "tasks.TranslationTask")

In the task

object TranslationTask {

  def main(args: Array[String]): Unit = {
    // background stuff with ActorSystem() , AhcWSClient()
    Await.result(service.get, 20.seconds)
    ...
  }
}

I know how to exit in the terminal with cmd + C . I'm asking specifically in SBT. — Raymond Chenon, Jan 08 '17 at 21:48
your task is running an externally defined function? Why not define it and run it as a regular Task? — marios, Jan 08 '17 at 22:57
Is this related to this: http://stackoverflow.com/a/24600377/1553233 — marios, Jan 08 '17 at 23:07
@marios , it seems like. But as 2017, it looks quite deprecated for SBT — Raymond Chenon, Jan 09 '17 at 10:54
If you had a copy-pastable (best word ever?) example I could reproduce it and give it a shot. — marios, Jan 09 '17 at 21:19
I put the example code already in my post. But yes , I am running a client using ActorSystem(). I don't know what's is not shutting down. So I'd like to kill the whole SBT process. — Raymond Chenon, Jan 10 '17 at 11:15
akka ActorSystem uses non-daemon threads. You need to call [terminate](http://doc.akka.io/japi/akka/2.4/akka/actor/ActorSystem.html#terminate--) on the ActorSystem prior to JVM exit. Within sbt, you probably want this in a [shutdown hook](https://docs.oracle.com/javase/8/docs/api/java/lang/Runtime.html#addShutdownHook-java.lang.Thread-). — jkinkead, Jan 11 '17 at 19:33

score 0 · Accepted Answer · edited May 23 '17 at 10:29

I found a way to exit the ActorSystem after the SBT task finishes.

In the build.sbt , start the task in the different thread.

lazy val refreshTranslationsFallback = taskKey[Unit]("Refresh the translations file fallback")
fullRunTask(refreshTranslationsFallback, Compile, "tasks.TranslationTask")
fork in refreshTranslationsFallback := true

In the task,

object TranslationTask {

  def main(args: Array[String]): Unit = {
    // background stuff with ActorSystem() , AhcWSClient()
    ...
    scala.sys.exit() // important
  }
}

Special thanks to SBT stop run without exiting

How to exit a sbt task?

1 Answers1