Terminating Actors

Actor processes will be terminated automatically when all copies of the actor handle have gone out of scope in Python, or if the original creator process dies.

Note that automatic termination of actors is not yet supported in Java or C++.

Manual termination via an actor handle

In most cases, Ray will automatically terminate actors that have gone out of scope, but you may sometimes need to terminate an actor forcefully. This should be reserved for cases where an actor is unexpectedly hanging or leaking resources, and for detached actors, which must be manually destroyed.

Python

ray.kill(actor_handle)
# This will not go through the normal Python sys.exit
# teardown logic, so any exit handlers installed in
# the actor using ``atexit`` will not be called.

Java

actorHandle.kill();
// This will not go through the normal Java System.exit teardown logic, so any
// shutdown hooks installed in the actor using ``Runtime.addShutdownHook(...)`` will
// not be called.

C++

actor_handle.Kill();
// This will not go through the normal C++ std::exit
// teardown logic, so any exit handlers installed in
// the actor using ``std::atexit`` will not be called.

This will cause the actor to immediately exit its process, causing any current, pending, and future tasks to fail with a RayActorError. If you would like Ray to automatically restart the actor, make sure to set a nonzero max_restarts in the @ray.remote options for the actor, then pass the flag no_restart=False to ray.kill.

For named and detached actors, calling ray.kill on an actor handle will destroy the actor and allow the name to be reused.

Manual termination within the actor

If necessary, you can manually terminate an actor from within one of the actor methods. This will kill the actor process and release resources associated/assigned to the actor.

Python

ray.actor.exit_actor()

This approach should generally not be necessary as actors are automatically garbage collected. The ObjectRef resulting from the task can be waited on to wait for the actor to exit (calling ray.get() on it will raise a RayActorError).

Java

Ray.exitActor();

Garbage collection for actors haven’t been implemented yet, so this is currently the only way to terminate an actor gracefully. The ObjectRef resulting from the task can be waited on to wait for the actor to exit (calling ObjectRef::get on it will throw a RayActorException).

C++

ray::ExitActor();

Garbage collection for actors haven’t been implemented yet, so this is currently the only way to terminate an actor gracefully. The ObjectRef resulting from the task can be waited on to wait for the actor to exit (calling ObjectRef::Get on it will throw a RayActorException).

Note that this method of termination will wait until any previously submitted tasks finish executing and then exit the process gracefully with sys.exit.