Looking up actors in 2.0

[andy]

Hello,

When looking up an actor

context.actorFor( "myactor" )

an ActorRef will be returned for the running actor or an ActorRef that forwards messages to the dead letter actor will be returned. The path for both of these will be:

akka://MySystem/myparent/myactor

which means that I can't ever tell if I actually have an actor running. I can look up children from a parent using context.children.find(..... but as the docs mention

val badLookup = context.children find (_.path.name == "kid")
// should better be expressed as:
val goodLookup = context.actorFor("kid")

this is a slow way to look up actors especially if a parent has thousands/hundreds of thousands of children.

My path forward has been to keep a HashMap of the actor name and the actor ref and use context.watch( child ) to remove actors from the map when they shut themselves down.

Am I correct that there really isn't a way to look up a running actor in 2.0, and actually know if it is the actor you wanted?

Thanks,

Andy

[√iktor Ҡlang]

Hey Andy,

On Fri, Apr 27, 2012 at 1:17 AM, andy <andrew....@gmail.com> wrote:

Hello,

When looking up an actor

context.actorFor( "myactor" )

an ActorRef will be returned for the running actor or an ActorRef that forwards messages to the dead letter actor will be returned. The path for both of these will be:

akka://MySystem/myparent/myactor

which means that I can't ever tell if I actually have an actor running.

Which makes total sense because in an asynchronous environment something might die the same nanosecond you look at it, or a nanosecond later.

use watch() and unwatch() or in rare cases "isTerminated" to observe death.

 

I can look up children from a parent using context.children.find(..... but as the docs mention

val badLookup = context.children find (_.path.name == "kid")
// should better be expressed as:
val goodLookup = context.actorFor("kid")

this is a slow way to look up actors especially if a parent has thousands/hundreds of thousands of children.

See above

 

My path forward has been to keep a HashMap of the actor name and the actor ref and use context.watch( child ) to remove actors from the map when they shut themselves down.

See above.

 

Am I correct that there really isn't a way to look up a running actor in 2.0, and actually know if it is the actor you wanted?

See above.

Cheers,

√

 

Thanks,

Andy

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Viktor Klang

Akka Tech Lead

Typesafe - The software stack for applications that scale

Twitter: @viktorklang

[andy]

Killer thanks. Just making sure. I'm battling the upgrade beast and I almost have it licked.

-Andy

Hey Andy,

Thanks,

Andy

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[√iktor Ҡlang]

On Fri, Apr 27, 2012 at 1:28 AM, andy <andrew....@gmail.com> wrote:

Killer thanks. Just making sure. I'm battling the upgrade beast and I almost have it licked.

You're welcome,

happy hAkking

Cheers,

√

 

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[Roland Kuhn]

Hi Andy,

let me add that context.actorFor already does the book-keeping including DeathWatch, so just use 

context.actorFor("blah").isTerminated

That is the most efficient way. 

Regards,

Roland Kuhn

Typesafe — The software stack for applications that scale

twitter: @rolandkuhn

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[Roland Kuhn]

just to be clear: the book-keeping is done only for direct children.