Faced with similar problem we went following route:
1. increased max connections to 64 for a host - default 4 is ususally way
to low for high-traffic scenarios
2. added a queue that holds incoming requests, with overflow strategy
DropNew. Yes, it is not perfect solution, but nothing crashes, in worst
case requests are not handled
val cps = ConnectionPoolSettings(system).withMaxConnections(64
).withPipeliningLimit(1).withMaxOpenRequests(64)
val clientFlow = Http().cachedHostConnectionPoolHttps[Int](host =
"mandrillapp.com", settings = cps)
val queueFlow =
Http().cachedHostConnectionPoolHttps[Promise[HttpResponse]](host
= "mandrillapp.com", settings = cps)
val queue = Source.queue[(HttpRequest, Promise[HttpResponse])](1024,
OverflowStrategy.dropNew)
.via(queueFlow)
.toMat(Sink.foreach({
case ((Success(resp), p)) => p.success(resp)
case ((Failure(e), p)) => p.failure(e)
}))(Keep.left)
.run
and actual request is done via
val promise = Promise[HttpResponse]
val r = request -> promise
queue.offer(r) flatMap {
_ match {
case Enqueued => promise.future
case _ => Future.failed(new RuntimeException("request not
enqueued"))
}
}
whole thing can be seen:
https://github.com/sgrouples/scamandrill/blob/master/src/main/scala/com/joypeg/scamandrill/client/ScamandrillSendReceive.scala
While not perfect solution, it handles both very slow and crashed service,
without slowing or crashing other parts of the system.
Depending on your use-case you might experiment with different overflow
strategies, add circuit-breakers, etc.
W dniu środa, 25 maja 2016 11:07:04 UTC+2 użytkownik Loïc napisał:
>
> HI,
>
> I would like to use Akka Http client to call a webservice in a non
> blocking way.
> The app that will use this client must never block and should never crash,
> even if the webservice that it will call becomes very slow (for example if
> the traffic is too high).
> When the client registers a callback, I guess it's memorized somewhere, so
> what is happening if a lot of queries and callbacks are kept in memory
> because the webservice takes too much time to respond?
> I guess it can cause some memory issues, so is it possible to cancel and
> drop some queries when this happens?
>
> Thanks :)
>
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