Akka BufferOverflowException when send many singleRequest

Question

Here's my code

Future.sequence((2 to firstPage.pages).map
{ count =>
    getCommentPage(av, count)
}).map(//do something)

In getCommentPage, one Http().singleRequest is used to get data, like this:

val responseFuture: Future[HttpResponse] =
    Http(system).singleRequest(HttpRequest(GET, uri = requestUri))
responseFuture
    .map(_.entity)
    .flatMap(_.toStrict(10 seconds)(materializer))
    .map(_.data)
    .map(_.utf8String)
    .map((jsonString: String) => {
        //do something to extract data
    }

Small firstPage.pages will work well, but when firstPage.pages is large (about 50 or larger), there will be an exception:

akka.stream.BufferOverflowException: Exceeded configured max-open-requests value of [32]. This means that the request queue of this pool (HostConnectionPoolSetup(api.bilibili.cn,80,ConnectionPoolSetup(ConnectionPoolSettings(4,0,5,32,1,30 seconds,ClientConnectionSettings(Some(User-Agent: akka-http/10.0.9),10 seconds,1 minute,512,None,,List(),ParserSettings(2048,16,64,64,8192,64,8388608,256,1048576,Strict,RFC6265,true,Full,Error,Map(If-Range -> 0, If-Modified-Since -> 0, If-Unmodified-Since -> 0, default -> 12, Content-MD5 -> 0, Date -> 0, If-Match -> 0, If-None-Match -> 0, User-Agent -> 32),false,akka.stream.impl.ConstantFun$$$Lambda$244/19208387@4780bf,akka.stream.impl.ConstantFun$$$Lambda$244/19208387@4780bf,akka.stream.impl.ConstantFun$$$Lambda$245/6903324@1d25a2e),None),TCPTransport),akka.http.scaladsl.HttpConnectionContext$@796a3e,akka.event.MarkerLoggingAdapter@1cc552a))) has completely filled up because the pool currently does not process requests fast enough to handle the incoming request load. Please retry the request later. See http://doc.akka.io/docs/akka-http/current/scala/http/client-side/pool-overflow.html for more information.

How to solve it?

Akka BufferOverflowException when send many singleRequest

3 Answers