Glassthought

cancel-parent-cancel-children

2 min read

Here we cancel the parent scope and that automatically cancels children.

Code

package com.glassthought.sandbox
 
import gt.sandbox.util.output.Out
import kotlinx.coroutines.CancellationException
import kotlinx.coroutines.async
import kotlinx.coroutines.cancel
import kotlinx.coroutines.coroutineScope
import kotlinx.coroutines.launch
import kotlinx.coroutines.runBlocking
import kotlin.system.exitProcess
import kotlin.time.Duration.Companion.milliseconds
import kotlin.time.Duration.Companion.seconds
 
private val out = Out.standard()
private suspend fun mainImpl(out: Out) {
  coroutineScope {
    foo("msg-1")
  }
}
 
private suspend fun foo(msg: String) {
  out.actionWithMsg("fooImpl", { fooImpl(msg) })
}
 
private suspend fun fooImpl(msg: String) {
  coroutineScope {
    val deferred3 = async {
      out.delayNamed(3.seconds, "delayed([${msg}])")
 
      "res-3"
    }
    val deferred2 = async {
      out.delayNamed(2.seconds, "delayed([${msg}])")
 
      "res-2"
    }
    val deferred1 = async {
      out.delayNamed(1.seconds, "delayed([${msg}])")
 
      "res-1"
    }
 
 
    out.info("Just launched co-routines")
    out.delayNamed(500.milliseconds, "delay before scope cancel")
    this.cancel()
 
    out.info("deferred-1.result=" + deferred1.await())
    out.info("deferred-2.result=" + deferred2.await())
    out.info("deferred-3.result=" + deferred3.await())
  }
 
}
 
fun main(): Unit = runBlocking {
  out.info("START - ON MAIN")
 
  try {
    mainImpl(out)
  } catch (e: Exception) {
    out.error("back at MAIN got an exception! of type=[${e::class.simpleName}] with msg=[${e.message}] cause=[${e.cause}]. Exiting with error code 1")
 
    exitProcess(1)
  }
 
  out.info("DONE - WITHOUT errors on MAIN")
}

Command to reproduce:

gt.sandbox.checkout.commit a2df237045869c0a8e1b \
&& cd "${GT_SANDBOX_REPO}" \
&& cmd.run.announce "./gradlew run --quiet"

Recorded output of command:

Picked up JAVA_TOOL_OPTIONS: -Dkotlinx.coroutines.debug
Picked up JAVA_TOOL_OPTIONS: -Dkotlinx.coroutines.debug
[INFO][elapsed:   39ms][🥇][①][coroutname:@coroutine#1][tname:main/tid:1] START - ON MAIN
[INFO][elapsed:   56ms][🥇][①][coroutname:@coroutine#1][tname:main/tid:1] [>] Starting action=[fooImpl] 
[INFO][elapsed:   58ms][🥇][①][coroutname:@coroutine#1][tname:main/tid:1]    Just launched co-routines
[INFO][elapsed:   60ms][🥇][①][coroutname:@coroutine#1][tname:main/tid:1]    Delaying for 500ms what_for=[delay before scope cancel]
[INFO][elapsed:   63ms][🥇][⓶][coroutname:@coroutine#2][tname:main/tid:1] Delaying for 3s what_for=[delayed([msg-1])]
[INFO][elapsed:   63ms][🥇][⓷][coroutname:@coroutine#3][tname:main/tid:1] Delaying for 2s what_for=[delayed([msg-1])]
[INFO][elapsed:   63ms][🥇][⓸][coroutname:@coroutine#4][tname:main/tid:1] Delaying for 1s what_for=[delayed([msg-1])]
[INFO][elapsed:  562ms][🥇][①][coroutname:@coroutine#1][tname:main/tid:1]    Done delaying for 500ms what_for=[delay before scope cancel]
[WARN][elapsed:  615ms][🥇][⓶][coroutname:@coroutine#2][tname:main/tid:1] 🫡 I have caught [JobCancellationException/ScopeCoroutine was cancelled], and rethrowing it 🫡
[WARN][elapsed:  615ms][🥇][⓷][coroutname:@coroutine#3][tname:main/tid:1] 🫡 I have caught [JobCancellationException/ScopeCoroutine was cancelled], and rethrowing it 🫡
[WARN][elapsed:  616ms][🥇][⓸][coroutname:@coroutine#4][tname:main/tid:1] 🫡 I have caught [JobCancellationException/ScopeCoroutine was cancelled], and rethrowing it 🫡
[INFO][elapsed:  616ms][🥇][①][coroutname:@coroutine#1][tname:main/tid:1] [>][🫡] Cancellation Exception - rethrowing.
[ERROR][elapsed:  617ms][🥇][①][coroutname:@coroutine#1][tname:main/tid:1] back at MAIN got an exception! of type=[JobCancellationException] with msg=[ScopeCoroutine was cancelled] cause=[kotlinx.coroutines.JobCancellationException: ScopeCoroutine was cancelled; job="coroutine#1":ScopeCoroutine{Cancelled}@768b970c]. Exiting with error code 1
 
FAILURE: Build failed with an exception.
 
* What went wrong:
Execution failed for task ':app:run'.
> Process 'command '/home/nickolaykondratyev/.jdks/corretto-21.0.7/bin/java'' finished with non-zero exit value 1
 
* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
> Get more help at https://help.gradle.org.
 
BUILD FAILED in 1s

Graph View

Backlinks