android–Kotlin协程取消后无法捕获异常抛出

概述使用kotlinx.coroutineslib如果在取消协程后抛出异常,我就无法捕获异常.这会导致应用崩溃.funfoo(){valjob=launch(UI){try{Log.d("TAG","Startcoroutine")run(CommonPool){Log.d("TAG","Startbgtask")

使用kotlinx.coroutines lib如果在取消协程后抛出异常,我就无法捕获异常.这会导致应用崩溃.

fun foo() {  val job = launch(UI) {     try {        Log.d("TAG", "Start coroutine")        run(CommonPool) {           Log.d("TAG", "Start bg task")           // Intentionally make bg task running for a long time           SystemClock.sleep(2000)           Log.d("TAG", "Throw bg task exception")           throw RuntimeException("Bg task exception")        }     } catch (e: Exception) {        Log.e("TAG", "Handle coroutine exception", e)     }  }  launch(UI) {     delay(1000)     Log.d("TAG", "Cancel job = ${job.cancel()}")  }

}

在AndroID上运行此功能会生成以下日志输出

07-26 15:09:10.038 31518-31518/co.foo.bar D/MainActivity: Start coroutine07-26 15:09:10.044 31518-31547/co.foo.bar D/MainActivity: Start bg task07-26 15:09:11.046 31518-31518/co.foo.bar D/MainActivity: Cancel job = true07-26 15:09:11.047 31518-31518/co.foo.bar E/MainActivity: Handled coroutine exception                           java.util.concurrent.CancellationException: Job was cancelled                           at kotlinx.coroutines.experimental.JobSupport$CompletedExceptionally.getException(Job.kt:921)                           at kotlinx.coroutines.experimental.runcompletion.afterCompletion(Builders.kt:198)                           ...                           at com.androID.internal.os.ZygoteInit.main(ZygoteInit.java:776)07-26 15:09:12.046 31518-31547/co.foo.bar D/MainActivity: Throwing bg task exception--------- beginning of crash07-26 15:09:12.046 31518-31547/co.foo.bar E/AndroIDRuntime: FATAL EXCEPTION: ForkJoinPool.commonPool-worker-1Process: co.foo.bar, PID: 31518                           java.lang.RuntimeException: Bg task exception                           at co.foo.barsample.MainActivity$onCreate$job.doResume(MainActivity.kt:36)                           at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:54)                           at kotlinx.coroutines.experimental.dispatchTask.run(Coroutinedispatcher.kt:120)                           at java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1383)                           at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:256)                           at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1123)                           at java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1961)                           at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1909)                           at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:128)07-26 15:09:12.050 1705-2190/system_process W/ActivityManager:   Force finishing activity co.foo.bar/co.foo.barsample.MainActivity

似乎是调用cancel()抛出了成功捕获的CancellationException.但是没有捕获后续的RuntimeException.我认为在取消作业后,以下异常应该被lib忽略？或者如何在不抛出CancellationException异常的情况下静默取消作业？

解决方法:

使用CoroutineExceptionHandler作为additinoal coroutine上下文来处理异常,用于启动或运行

run(CommonPool + CoroutineExceptionHandler({ _, e ->   Log.e("TAG", "CoroutineExceptionHandler", e)})) {    ...}

要么

launch(UI + CoroutineExceptionHandler({ _, e ->   Log.e("TAG", "CoroutineExceptionHandler", e)})) {   ...}

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