Actor Selection for Remote Actors

[Paul Cleary]

I am looking into using Akka Remoting, I am using akka 2.2.3.

I have to communicate with a bunch of remote actors.  I have a few questions about the best way to do this:

1. Do I simply send messages through an Actor Selection itself (there is a tell on actor selection)?  My concern is that this will not perform as well as using an Actor Ref directly.  Also, I am concerned about the behavior in the event that the remote actor is down, does the Actor Selection deliver the messages to dead letter until the remote actor comes back to life?

- if not -

2. Do I instead get an Actor Ref and use that actor ref to send messages (using the resolve method or Identify)?  My concern here is, what happens to the ActorRef if the remote actor dies?  Do we "need" to watch the remote actor and handle Terminated?

- are there other options? -

It would "seem" as though option 1 insulates me from having to care if the remote actor is there or not, because in my use case, I really don't care.

Option 2 seems like I have to do my own gymnastics to handle remote actor availability, but perhaps is better performing (or maybe is the recommended approach?)

Any help is greatly appreciated.

Thanks!

[Patrik Nordwall]

Hi Paul,

I think you have identified the two options and understood the differences and trade-offs. To make it clear, some comments inline...

On Thu, Aug 14, 2014 at 3:17 PM, Paul Cleary <pcle...@gmail.com> wrote:

I am looking into using Akka Remoting, I am using akka 2.2.3.

I have to communicate with a bunch of remote actors.  I have a few questions about the best way to do this:

1. Do I simply send messages through an Actor Selection itself (there is a tell on actor selection)?  My concern is that this will not perform as well as using an Actor Ref directly.

It is not as performant as with ActorRef, since it has to traverse the hierarchy of actors in the path. If you use remote sends the actor selection traversal will unlikely be the bottleneck, but you have to verify that for your specific usage. We optimized ActorSelection in 2.3.x, so it will be faster when you update to that version.

 

 Also, I am concerned about the behavior in the event that the remote actor is down, does the Actor Selection deliver the messages to dead letter until the remote actor comes back to life?

Yes, that is correct

 

- if not -

2. Do I instead get an Actor Ref and use that actor ref to send messages (using the resolve method or Identify)?  My concern here is, what happens to the ActorRef if the remote actor dies?  Do we "need" to watch the remote actor and handle Terminated?

Yes

 

- are there other options? -

It would "seem" as though option 1 insulates me from having to care if the remote actor is there or not, because in my use case, I really don't care.

Option 2 seems like I have to do my own gymnastics to handle remote actor availability, but perhaps is better performing (or maybe is the recommended approach?)

Right

Regards,

Patrik

 

Any help is greatly appreciated.

Thanks!

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Patrik Nordwall
Typesafe -  Reactive apps on the JVM
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[Paul Cleary]

Thanks Patrik!

Just one more question, what do you mean by "If you use remote sends the actor selection traversal will unlikely be the bottleneck"?

[Patrik Nordwall]

On Fri, Aug 15, 2014 at 1:24 PM, Paul Cleary <pcle...@gmail.com> wrote:

Thanks Patrik!

Just one more question, what do you mean by "If you use remote sends the actor selection traversal will unlikely be the bottleneck"?

I mean that the performance difference between ActorRef and ActorSelection might be small compared to the sending a message over the wire (network, serialization).

/Patrik