withTimeoutOrNull throw TimeoutCancellationException

[kobe2000]

Hi,
I understand that withTimeoutOrNull never throw timeout exception, does it?

I will try to reproduce it.

The code sample is

val ch = cudChannel.openSubscription()
try {
    var lastPingTime = System.currentTimeMillis()
    while (true) {
        val cud = withTimeoutOrNull(1000) {
            ch.receive()
        }
        if (cud != null) {
            wc.writeString(cud.first)
            wc.writeBoolean(cud.second)
        } else if (System.currentTimeMillis() - lastPingTime > 6000) {
            wc.writeString("")
            wc.writeBoolean(false)
        } else {
            continue
        }
        lastPingTime = System.currentTimeMillis()
        withTimeout(30000) {
            rc.readInt()
        }
    }
} finally {
    ch.cancel()
}

The stacktrace is

kotlinx.coroutines.experimental.TimeoutCancellationException: Timed out waiting for 1000 MILLISECONDS
        at kotlinx.coroutines.experimental.ScheduledKt.TimeoutCancellationException(Scheduled.kt:202)
        at kotlinx.coroutines.experimental.TimeoutCoroutine.run(Scheduled.kt:100)
        at kotlinx.coroutines.experimental.EventLoopBase$DelayedRunnableTask.run(EventLoop.kt:322)
        at kotlinx.coroutines.experimental.EventLoopBase.processNextEvent(EventLoop.kt:148)
        at kotlinx.coroutines.experimental.DefaultExecutor.run(DefaultExecutor.kt:60)
        at java.lang.Thread.run(Thread.java:745)

[qwwdfsad]

Hi, could you please a self-contained example?
What types are rc and wc?

[kobe2000]

Hi,
rc wc are socket read channel and write channel. the cudChannel is a BroadcastChannel.
This is the first time I meet the problem, I worry that the self-contained example maybe just a single piece of withTimeoutOrNull API invocation code

[qwwdfsad]

 val channel = Channel<Int>(1)
        val value = withTimeoutOrNull(timeout) {
            channel.receive()
        }

        println(value)

prints null for timeout = 100 and throws exception for timeout = 1