How do I rewrite a for loop with a shared dependency using actors
- by Thomas Rynne
We have some code which needs to run faster. Its already profiled so we would like to make use of multiple threads. Usually I would setup an in memory queue, and have a number of threads taking jobs of the queue and calculating the results. For the shared data I would use a ConcurrentHashMap or similar.
I don't really want to go down that route again. From what I have read using actors will result in cleaner code and if I use akka migrating to more than 1 jvm should be easier. Is that true?
However, I don't know how to think in actors so I am not sure where to start.
To give a better idea of the problem here is some sample code:
case class Trade(price:Double, volume:Int, stock:String) {
def value(priceCalculator:PriceCalculator) =
(priceCalculator.priceFor(stock)-> price)*volume
}
class PriceCalculator {
def priceFor(stock:String) = {
Thread.sleep(20)//a slow operation which can be cached
50.0
}
}
object ValueTrades {
def valueAll(trades:List[Trade],
priceCalculator:PriceCalculator):List[(Trade,Double)] = {
trades.map { trade => (trade,trade.value(priceCalculator)) }
}
def main(args:Array[String]) {
val trades = List(
Trade(30.5, 10, "Foo"),
Trade(30.5, 20, "Foo")
//usually much longer
)
val priceCalculator = new PriceCalculator
val values = valueAll(trades, priceCalculator)
}
}
I'd appreciate it if someone with experience using actors could suggest how this would map on to actors.
