Actor based development - implementation questions

Question

Hello, it's my first message here and I'm glad to join this community.

It looks like that everything is now going towards multi-thread development. Big fishes say that it won't take longer to reach hundreds of cores.

I've recently read about actor based development and how wonderful message passing is to handle concurrent programming. In addition, I also read that they can be implemented as a means of method call. In this case, a given object is also an actor.

In other words we no longer call methods arbitrarily. They are post in queue for late processing. A queue then ensures that a object's state(var) isn't modified at the same time because messages are all serialized.

I understand that this model is quite straightforward to implement (at least an experimental one) and perhaps that's why is too difficult to find any technical detail.

My question concerns queues. This is a typical case of multiple-producers and one consumer and I suspect they require some sort of synchronization. Is that true? There would be another solution? I heard they can be implemented as lock-free structures.

I'm not really sure about that. Any comment will be greatly appreciated.

Have a nice day pals

Answer 1

If I understood correctly, agents received the messages in a MailBox which behaves like a concurrent queue. So you do not have to care about it. If you want to play with mailbox directly, you can have a look at this nice article from the great "The busy Java developer's guide to Scala" series.

Answer 2

Multiple producers and a single consumer is a great scenario for using Actors, and doesn't require any synchronization. In Scala, you generally don't use any mutable state when working with Actors. You just send over a copy of whatever data needs processing.

You can read more about Actors in Scala in "Programming Scala", available online for free.