WebSocket throws a vague IOException when internet is disconnected

Ktor Version

1.2.0-rc

Ktor Engine Used(client or server and name)

Client/CIO

JVM Version, Operating System and Relevant Context

OpenJDK 11.0.3, Arch Linux.

Feedback

When the internet is disconnected, a vague java.io.IOException is thrown twice, and it cannot be caught.

Exception in thread "pool-2-thread-3" java.io.IOException: Connection reset by peer
	at java.base/sun.nio.ch.FileDispatcherImpl.read0(Native Method)
	at java.base/sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:39)
	at java.base/sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:276)
	at java.base/sun.nio.ch.IOUtil.read(IOUtil.java:233)
	at java.base/sun.nio.ch.IOUtil.read(IOUtil.java:223)
	at java.base/sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:358)
	at kotlinx.io.nio.ChannelsKt.read(Channels.kt:117)
	at io.ktor.network.sockets.CIOReaderKt$attachForReadingDirectImpl$1$1.invokeSuspend(CIOReader.kt:75)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
	at kotlinx.coroutines.ResumeModeKt.resumeMode(ResumeMode.kt:67)
	at kotlinx.coroutines.DispatchedKt.resume(Dispatched.kt:309)
	at kotlinx.coroutines.DispatchedKt.resumeUnconfined(Dispatched.kt:49)
	at kotlinx.coroutines.DispatchedKt.dispatch(Dispatched.kt:295)
	at kotlinx.coroutines.CancellableContinuationImpl.dispatchResume(CancellableContinuationImpl.kt:250)
	at kotlinx.coroutines.CancellableContinuationImpl.resumeImpl(CancellableContinuationImpl.kt:260)
	at kotlinx.coroutines.CancellableContinuationImpl.resumeWith(CancellableContinuationImpl.kt:189)
	at io.ktor.network.selector.SelectorManagerSupport.handleSelectedKey(SelectorManagerSupport.kt:83)
	at io.ktor.network.selector.SelectorManagerSupport.handleSelectedKeys(SelectorManagerSupport.kt:63)
	at io.ktor.network.selector.ActorSelectorManager.process(ActorSelectorManager.kt:74)
	at io.ktor.network.selector.ActorSelectorManager$process$1.invokeSuspend(ActorSelectorManager.kt)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
	at kotlinx.coroutines.DispatchedTask.run(Dispatched.kt:238)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:834)

[brendanw]

Is this exception supposed to be thrown when the internet is disconnected? I am seeing this exception on a benchmarking test when attempting to make 100,000 concurrent requests.

Exception in thread "main" java.net.SocketException: Connection reset by peer
        at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
        at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
        at io.ktor.network.sockets.SocketImpl.connect$ktor_network(SocketImpl.kt:34)
        at io.ktor.network.sockets.SocketImpl$connect$1.invokeSuspend(SocketImpl.kt)
        at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
        at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:56)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)

https://github.com/brendanw/profilehttp

Are clients expected to handle this error? It would be great to see some guidance from the ktor team.

[rocketraman]

This is not limited to websockets, nor is it limited to a network link disruption. I have this situation for a straight persistent HTTP CIO connection, and it happens when the remote server disconnects the socket. The exception output is distracting and unnecessary, as there is nothing the client code can do about it.

I am using ktor 1.2.1.