ktor: ktor websocket client crashes with java.io.IOException: Software caused connection in Android abort

Version: 1.2.2, client, io.ktor:ktor-client-cio, io.ktor:ktor-client-websockets Android 7.0

When using websocket client

To Reproduce code:

val uri = URLBuilder().takeFrom(configuration.url).build()
val httpClientEngine = CIO.create { }
val client = HttpClient(httpClientEngine).config {
    install(WebSockets)
}

suspend fun process(session: DefaultClientWebSocketSession): ConnectionStatus {
            while (session.isActive && !session.closeReason.isCompleted) {
                try {
                    select<Unit> {
                         session.incoming.onReceiveOrNull { frame ->
                            when (frame) {
                                null -> { // channel has been closed
                                    println("closed")
                                    session.close()
                                }
                                else -> Unit
                            }
                        }
                    }
                } catch (e: IOException) {
                    println("io exception: ${e}")
                    session.close()
                } catch (e: Throwable) {
                    println("exception: ${e}")
                    session.close()
                }
            }
}
runBlocking {
  try {
    when (uri.protocol.isSecure()) {
        true -> client.wss(host = uri.host, port = uri.port, path = uri.encodedPath) { process(this) }
        false -> client.ws(host = uri.host, port = uri.port, path = uri.encodedPath) { process(this) }
    }
  } catch (ex: Exception) {
    println("catched: ${ex}")
  }
}

Start code with internet enabled and with some websocket url
disconnect internet IOException will be thrown, but not caught anywhere.

Expected behavior I’m expecting that this IOException won’t leak and can be caught by try/catch.

About this issue

Original URL
State: closed
Created 5 years ago
Reactions: 7
Comments: 16 (3 by maintainers)

Commits related to this issue

Use okhttp engine for java instead of cio workaround https://github.com/ktorio/ktor/issues/1237 — committed to luca992/kEasySocket by luca992 5 years ago
Prevent propagating exception to top-level Fix #1356 #1237 — committed to ktorio/ktor by e5l 4 years ago
Prevent propagating exception to top-level Fix #1356 #1237 — committed to ktorio/ktor by e5l 4 years ago

Most upvoted comments

Investigation history:

maybe problem is here: Socket.tls(coroutineContext: CoroutineContext, config: TLSConfig) function:

calls val reader = openReadChannel()
which calls attachForReading(channel: ByteChannel): WriterJob
which calls CoroutineScope.attachForReadingDirectImpl(...) // <— this is implemented in internal abstract class NIOSocketImpl<out S> with CoroutineScope
which call writer(Dispatchers.Unconfined, channel) { .. block .. }
and it this block there is “val rc = nioChannel.read(buffer)” <<- which throws that IOException code:

internal abstract class NIOSocketImpl<out S> implements CoroutineScope:

    override val socketContext: CompletableJob = Job()

    override val coroutineContext: CoroutineContext
        get() = socketContext

and attachForReadingDirectImpl() is called on this coroutineScope which is just Job() without any specified dispatchers nor any parent contexts, so this scope is not bound to any of coroutines nor callees of tls() nor ktor CIO context, this just runs on Dispatchers.Default with Job() So there is no way to catch this exception and its bubbled to global exception handler.
app fatally crashes.

antanas-arvasevicius on Jul 18, 2019

We are still waiting while ktor team will fix this critical bug which was introduced in some versions later and never got fixed. This bug cause crashes not only android but also server side thus making multiplatform websockets unusable.

On 2020-01-12, Sun at 21:03, David Alan Cohen notifications@github.com wrote:

This may not be applicable to every application that is running into this issue, but if you want to swallow this IOException so that the app doesn’t fatally crash, you can override the thread’s default exception handler with custom behavior using Thread.setDefaultUncaughtExceptionHandler() in MainActivity.onCreate().

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub https://github.com/ktorio/ktor/issues/1237?email_source=notifications&email_token=ABABZHB4WLWQTOXJYYMJIEDQ5OATVA5CNFSM4IE3THVKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEIXEEXI#issuecomment-573456989, or unsubscribe https://github.com/notifications/unsubscribe-auth/ABABZHFP2WXR3BCG2OYPRVLQ5OATVANCNFSM4IE3THVA .

antanas-arvasevicius on Jan 13, 2020

This may not be applicable to every application that is running into this issue, but if you want to swallow this IOException so that the app doesn’t fatally crash, you can override the thread’s default exception handler with custom behavior using Thread.setDefaultUncaughtExceptionHandler() in MainActivity.onCreate().

dcohen21 on Jan 12, 2020

I think it’s not reliable solution, maybe with this fix probability of crash will be lower, but not impossible, as by looking inside the ktor’s code there is no way to handle exception if it will be thrown during non blocking socket read.

antanas-arvasevicius on Aug 6, 2019

No, currently there is no way to use ktor websockets in android platform to prevent crash. We’ve temporarily removed websocket from our app as it was used only for telemetry data.

I had hope that this will be fixed with latest release, but seems it’s not trivial to fix.

On Mon, 5 Aug 2019 at 13:29, Saddam Asmatullayev notifications@github.com wrote:

Have you found any temporary solution for that? And also, how the sockets are connected back when you turn your connection on?

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub https://github.com/ktorio/ktor/issues/1237?email_source=notifications&email_token=ABABZHCRZJU2EKZUISCFRL3QC76IDA5CNFSM4IE3THVKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD3RMY5I#issuecomment-518179957, or mute the thread https://github.com/notifications/unsubscribe-auth/ABABZHHNST2RY2APKMIIDNTQC76IDANCNFSM4IE3THVA .

antanas-arvasevicius on Aug 5, 2019