withContext cancellation

withContext_cancellation.kt

import kotlinx.coroutines.*
import java.util.concurrent.ThreadLocalRandom

fun main() {
    val job = GlobalScope.launch {
        Thread.sleep(1000)
        try {
            println(1)
            withContext(CoroutineName("foo")) {
                val rnd = ThreadLocalRandom.current()
                val sum = (1..100_000_000).sumOf { rnd.nextInt() }
                println("Same dispatcher sum = $sum")
            }
        } catch (e: Exception) {
            println("Same dispatcher threw: $e")
            throw e
        }
        try {
            withContext(Dispatchers.IO) {
                val rnd = ThreadLocalRandom.current()
                val sum = (1..100_000_000).sumOf { rnd.nextInt() }
                println("Changed dispatcher sum = $sum")
            }
        } catch (e: Exception) {
            println("Changed dispatcher threw: $e")
            throw e
        }
    }
    job.invokeOnCompletion { cause -> println("job completed with $cause") }
    job.cancel()
    Thread.currentThread().join()
}

Output:

Same dispatcher threw: kotlinx.coroutines.JobCancellationException: StandaloneCoroutine was cancelled; job=StandaloneCoroutine{Cancelling}@58e9a128
job completed with kotlinx.coroutines.JobCancellationException: StandaloneCoroutine was cancelled; job=StandaloneCoroutine{Cancelled}@58e9a128