Custom Scheduler in Akka

[Sébastien]

Hello,

I've been looking at Akka today in the perspective of implementing a
custom scheduler for an Actor-base Web system. I found Scala scheduler
to be a little bit hairy, and looking at Akka's documentation, I was
impressed by its clarity and the features offered by Akka.

So my problem is as follows:

- I have Actors (type A) that process incoming HTTP requests
- I have Actors (type B) that log these requests in a Redis DB

Currently, using Scala Actors, the scheduler does not interleave
execution of A and B. So when you have a burst of requests, the type A
actors get all busy, and then type B actors get busy, killing the
response time for the next requests.

So instead of scheduling like this:

A A A A A B B B B B

I would like to schedule like this:

A B A B A B A B A B

Or even better, be able to decide at each step if it's better to
execute an A or a B.

Could anyone point me on how to do this with Akka ?

Thanks,

-- Sébastien

[Sébastien Pierre]

Hello,

I've been looking at Akka today in the perspective of implementing a

custom scheduler for an Actor-based Web system. I found Scala scheduler

to be a little bit hairy, and looking at Akka's documentation, I was

impressed by its clarity and the richness of features.

So my problem is as follows:

- I have Actors (type A) that process incoming HTTP requests
- I have Actors (type B) that log these requests in a Redis DB

Currently, using Scala Actors, the scheduler does not fully interleave

[Jonas Bonér]

Hi Sébastien.

Thanks for your interest in Akka.

I think it would be hard to enforce what you need with the
out-of-the-box event-based dispatcher (the default), since it runs on
a thread pool its impossible to control the actual OS thread
dispatching (which is done by the OS scheduler).

The thread-based dispatcher might give you more what you need. Try that.

One that will give you the exact interleaving is the single-thread
dispatcher in which each event is ordered and executed one by one on
the same thread. But this one has no scalability and is dangerous
since one actor can block all.

You can also implement your own dispatcher by implementing the
MessageDispatcher trait.

Hope it helps, Jonas.

2010/1/5 Sébastien Pierre <sebastie...@gmail.com>:

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Jonas Bonér

twitter: @jboner
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also: http://letitcrash.com

[Sergio Bossa]

The reactor based dispatcher should indeed give the requested
behavior, scheduling messages to waiting actors while "ignoring"
messages to busy ones.

Cheers

Sergio Bossa
Sent by iPhone

Il giorno 05/gen/2010, alle ore 21.21, Jonas Bonér <jbo...@gmail.com>
ha scritto: