IOException Connection closed after many requests

Hello! We are using play ws to execute requests on a highly loaded system. After running the system for about 30 - 40 minutes, we get an IOException Connection closed error and all further requests stop being executed until the system is restarted. Perhaps you know this problem and you tell me what we are doing wrong?

We use -
Scala version: 2.11.6
Play version: 2.4.11
Akka version: 2.4.0
SBT version: 0.13.8

Error stack trace -

java.io.IOException: Closed
	at com.ning.http.client.providers.netty.request.NettyRequestSender.sendRequest(NettyRequestSender.java:98) ~[com.ning.async-http-client-1.9.40.jar:na]
	at com.ning.http.client.providers.netty.NettyAsyncHttpProvider.execute(NettyAsyncHttpProvider.java:87) ~[com.ning.async-http-client-1.9.40.jar:na]
	at com.ning.http.client.AsyncHttpClient.executeRequest(AsyncHttpClient.java:506) ~[com.ning.async-http-client-1.9.40.jar:na]
	at play.api.libs.ws.ning.NingWSClient.executeRequest(NingWS.scala:47) ~[com.typesafe.play.play-ws_2.11-2.4.11.jar:2.4.11]
	at play.api.libs.ws.ning.NingWSRequest.execute(NingWS.scala:312) ~[com.typesafe.play.play-ws_2.11-2.4.11.jar:2.4.11]
	at play.api.libs.ws.ning.NingWSRequest.execute(NingWS.scala:128) ~[com.typesafe.play.play-ws_2.11-2.4.11.jar:2.4.11]
	at play.api.libs.ws.WSRequest$class.post(WS.scala:455) ~[com.typesafe.play.play-ws_2.11-2.4.11.jar:2.4.11]
	at play.api.libs.ws.ning.NingWSRequest.post(NingWS.scala:81) ~[com.typesafe.play.play-ws_2.11-2.4.11.jar:2.4.11]
	at ru.alfatell.webregistry.XmlExecutionContext$WebExecutor.callInternal(XmlExecutor.scala:338) ~[ru.alfatell.web-registry-portal-1.1.1-sans-externalized.jar:na]
	at ru.alfatell.webregistry.XmlExecutor$class.call(XmlExecutor.scala:199) ~[ru.alfatell.web-registry-portal-1.1.1-sans-externalized.jar:na]
	at ru.alfatell.webregistry.XmlExecutor$class.perform(XmlExecutor.scala:119) ~[ru.alfatell.web-registry-portal-1.1.1-sans-externalized.jar:na]
	at ru.alfatell.webregistry.XmlExecutionContext$WebExecutor.perform(XmlExecutor.scala:287) ~[ru.alfatell.web-registry-portal-1.1.1-sans-externalized.jar:na]
	at ru.alfatell.webregistry.ExternalApiGateway$$anonfun$execute$1$$anonfun$apply$12.apply(ExternalApiGateway.scala:111) ~[ru.alfatell.web-registry-portal-1.1.1-sans-externalized.jar:na]
	at ru.alfatell.webregistry.ExternalApiGateway$$anonfun$execute$1$$anonfun$apply$12.apply(ExternalApiGateway.scala:90) ~[ru.alfatell.web-registry-portal-1.1.1-sans-externalized.jar:na]
	at scala.util.Try$.apply(Try.scala:192) ~[org.scala-lang.scala-library-2.11.8.jar:na]
	at ru.alfatell.webregistry.ExternalApiGateway$$anonfun$execute$1.apply(ExternalApiGateway.scala:90) ~[ru.alfatell.web-registry-portal-1.1.1-sans-externalized.jar:na]
	at ru.alfatell.webregistry.ExternalApiGateway$$anonfun$execute$1.apply(ExternalApiGateway.scala:89) ~[ru.alfatell.web-registry-portal-1.1.1-sans-externalized.jar:na]
	at scala.util.Success.flatMap(Try.scala:231) ~[org.scala-lang.scala-library-2.11.8.jar:na]
	at ru.alfatell.webregistry.ExternalApiGateway$.execute(ExternalApiGateway.scala:89) ~[ru.alfatell.web-registry-portal-1.1.1-sans-externalized.jar:na]
	at controllers.tmp.ExtApiMain$$anonfun$xml$1$$anonfun$apply$1$$anonfun$4.apply(ExtApiMain.scala:24) ~[ru.alfatell.web-registry-portal-1.1.1-sans-externalized.jar:na]
	at controllers.tmp.ExtApiMain$$anonfun$xml$1$$anonfun$apply$1$$anonfun$4.apply(ExtApiMain.scala:24) ~[ru.alfatell.web-registry-portal-1.1.1-sans-externalized.jar:na]
	at controllers.tmp.ExtApiSecurity$class.callerAuthorize(ExtApiSecurity.scala:158) ~[ru.alfatell.web-registry-portal-1.1.1-sans-externalized.jar:na]
	at controllers.ExternalApi$.callerAuthorize(ExternalApi.scala:34) ~[ru.alfatell.web-registry-portal-1.1.1-sans-externalized.jar:na]
	at controllers.tmp.ExtApiMain$$anonfun$xml$1$$anonfun$apply$1.apply(ExtApiMain.scala:24) ~[ru.alfatell.web-registry-portal-1.1.1-sans-externalized.jar:na]
	at controllers.tmp.ExtApiMain$$anonfun$xml$1$$anonfun$apply$1.apply(ExtApiMain.scala:21) ~[ru.alfatell.web-registry-portal-1.1.1-sans-externalized.jar:na]
	at controllers.tmp.ExtApiSecurity$class.withCtx(ExtApiSecurity.scala:121) ~[ru.alfatell.web-registry-portal-1.1.1-sans-externalized.jar:na]
	at controllers.ExternalApi$.withCtx(ExternalApi.scala:34) ~[ru.alfatell.web-registry-portal-1.1.1-sans-externalized.jar:na]
	at controllers.tmp.ExtApiMain$$anonfun$xml$1.apply(ExtApiMain.scala:21) ~[ru.alfatell.web-registry-portal-1.1.1-sans-externalized.jar:na]
	at controllers.tmp.ExtApiMain$$anonfun$xml$1.apply(ExtApiMain.scala:20) ~[ru.alfatell.web-registry-portal-1.1.1-sans-externalized.jar:na]
	at play.api.mvc.Action$.invokeBlock(Action.scala:533) ~[com.typesafe.play.play_2.11-2.4.11.jar:2.4.11]
	at play.api.mvc.Action$.invokeBlock(Action.scala:530) ~[com.typesafe.play.play_2.11-2.4.11.jar:2.4.11]
	at play.api.mvc.ActionBuilder$$anon$1.apply(Action.scala:493) ~[com.typesafe.play.play_2.11-2.4.11.jar:2.4.11]
	at play.api.mvc.Action$$anonfun$apply$1$$anonfun$apply$4$$anonfun$apply$5.apply(Action.scala:105) ~[com.typesafe.play.play_2.11-2.4.11.jar:2.4.11]
	at play.api.mvc.Action$$anonfun$apply$1$$anonfun$apply$4$$anonfun$apply$5.apply(Action.scala:105) ~[com.typesafe.play.play_2.11-2.4.11.jar:2.4.11]
	at play.utils.Threads$.withContextClassLoader(Threads.scala:21) ~[com.typesafe.play.play_2.11-2.4.11.jar:2.4.11]
	at play.api.mvc.Action$$anonfun$apply$1$$anonfun$apply$4.apply(Action.scala:104) ~[com.typesafe.play.play_2.11-2.4.11.jar:2.4.11]
	at play.api.mvc.Action$$anonfun$apply$1$$anonfun$apply$4.apply(Action.scala:103) ~[com.typesafe.play.play_2.11-2.4.11.jar:2.4.11]
	at scala.Option.map(Option.scala:146) ~[org.scala-lang.scala-library-2.11.8.jar:na]
	at play.api.mvc.Action$$anonfun$apply$1.apply(Action.scala:103) ~[com.typesafe.play.play_2.11-2.4.11.jar:2.4.11]
	at play.api.mvc.Action$$anonfun$apply$1.apply(Action.scala:96) ~[com.typesafe.play.play_2.11-2.4.11.jar:2.4.11]
	at play.api.libs.iteratee.Iteratee$$anonfun$mapM$1.apply(Iteratee.scala:524) ~[com.typesafe.play.play-iteratees_2.11-2.4.11.jar:2.4.11]
	at play.api.libs.iteratee.Iteratee$$anonfun$mapM$1.apply(Iteratee.scala:524) ~[com.typesafe.play.play-iteratees_2.11-2.4.11.jar:2.4.11]
	at play.api.libs.iteratee.Iteratee$$anonfun$flatMapM$1.apply(Iteratee.scala:560) ~[com.typesafe.play.play-iteratees_2.11-2.4.11.jar:2.4.11]
	at play.api.libs.iteratee.Iteratee$$anonfun$flatMapM$1.apply(Iteratee.scala:560) ~[com.typesafe.play.play-iteratees_2.11-2.4.11.jar:2.4.11]
	at play.api.libs.iteratee.Iteratee$$anonfun$flatMap$1$$anonfun$apply$14.apply(Iteratee.scala:537) ~[com.typesafe.play.play-iteratees_2.11-2.4.11.jar:2.4.11]
	at play.api.libs.iteratee.Iteratee$$anonfun$flatMap$1$$anonfun$apply$14.apply(Iteratee.scala:537) ~[com.typesafe.play.play-iteratees_2.11-2.4.11.jar:2.4.11]
	at scala.concurrent.impl.Future$PromiseCompletingRunnable.liftedTree1$1(Future.scala:24) ~[org.scala-lang.scala-library-2.11.8.jar:na]
	at scala.concurrent.impl.Future$PromiseCompletingRunnable.run(Future.scala:24) ~[org.scala-lang.scala-library-2.11.8.jar:na]
	at akka.dispatch.TaskInvocation.run(AbstractDispatcher.scala:39) [com.typesafe.akka.akka-actor_2.11-2.4.0.jar:na]
	at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:399) [com.typesafe.akka.akka-actor_2.11-2.4.0.jar:na]
	at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260) [org.scala-lang.scala-library-2.11.8.jar:na]
	at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339) [org.scala-lang.scala-library-2.11.8.jar:na]
	at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979) [org.scala-lang.scala-library-2.11.8.jar:na]
	at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107) [org.scala-lang.scala-library-2.11.8.jar:na]

Start at play.api.libs.ws.ning.NingWSClient.executeRequest in NingWS.scala:47 and NingWSRequest.execute in NingWS.scala:312, then trace the underlying NettyRequestSender failure shown in the stack trace. Reproduce sustained requests under load and inspect client lifecycle and connection handling; done means the cause of the closed client is identified and a verified fix or workaround is documented.