ConnectionFactory raises NoSuchElementException

[tateisu]

Ktor Version and Engine Used (client or server and name) Ktor 1.2.5, using HTTP client (CIO)

Describe the bug when my app create many request to other hosts, frequenly ConnectionFactory raises NoSuchElementException.

java.util.NoSuchElementException
    at java.util.concurrent.ConcurrentHashMap$KeyIterator.next(ConcurrentHashMap.java:3416)
    at java.util.concurrent.ConcurrentHashMap$KeyIterator.nextElement(ConcurrentHashMap.java:3423)
    at io.ktor.util.cio.Semaphore.leave(Semaphore.kt:56)
    at io.ktor.client.engine.cio.ConnectionFactory.connect(ConnectionFactory.kt:25)
    at io.ktor.client.engine.cio.ConnectionFactory$connect$1.invokeSuspend(ConnectionFactory.kt)
    at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
    at kotlinx.coroutines.DispatchedTask.run(Dispatched.kt:334)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

ConcurrentHashMap.keys().nextElement may throw NoSuchElementException, but io.ktor.util.cio.Semaphore.leave() does not catch it.

To Reproduce

code to reproduce

data class SprayResult(
    val url: String,
    @Suppress("ArrayInDataClass") val bytes: ByteArray? = null,
    val ex: Throwable? = null
)

@KtorExperimentalAPI
fun main(args: Array<String>) = runBlocking {

    HttpClient(CIO).use { client ->

        val channel = Channel<SprayResult>()

        // spray requests to http://192.168.253.*/
        val list = (1..254)

        for (i in list) {
            val url = "http://192.168.253.$i/" // your lan addr
            GlobalScope.launch {
                try {
                    val bytes = client.get<ByteArray>(url)
                    channel.send(SprayResult(url, bytes = bytes))
                } catch (ex: Throwable) {
                    channel.send(SprayResult(url, ex = ex))
                }
            }
        }

        for (i in list) {
            val (url, bytes, ex) = channel.receive()
            if (bytes != null) {
                if (bytes.isNotEmpty()) println("$url ${bytes.size}bytes")
            } else when (ex) {
                null, is java.net.ConnectException, is FailToConnectException -> {
                }
                else -> {
                    println("$url ${ex.javaClass.simpleName} ${ex.message}")
                    ex.printStackTrace()
                }
            }
        }
    }
}

Expected behavior this error should not be happen.

Screenshots no, this is CLI.

[tateisu]

It may be needless to say, I use this code to detect FlashAir devices inside the LAN.

[e5l]

Hi @tateisu, thanks for the report. It was fixed with migration to kotlinx-coroutines semaphore.

[brendanw]

@e5l I am still seeing this on ktor-client-cio:1.2.6

Could you please link a commit and mention which version this get released in?

[e5l]

The fix in the 1.3.0-beta-2 update