我在尝试使用协程时发现了一些奇怪的行为。我想要通过suspendCoroutine()
将我的项目中的一些异步请求转换。这里展示了一段代码,显示了这个问题。
在第一个情况下,在runBlocking
协程中调用suspend函数时,来自continuation的异常被传递到catch块,然后runBlocking
成功完成。但是在第二种情况下,当创建新的async
协程时,异常通过catch块并导致整个程序崩溃。
package com.example.lib
import kotlinx.coroutines.async
import kotlinx.coroutines.runBlocking
import kotlin.coroutines.resumeWithException
import kotlin.coroutines.suspendCoroutine
object Test {
fun runSuccessfulCoroutine() {
runBlocking {
try {
Repository.fail()
} catch (ex: Throwable) {
println("Catching ex in runSuccessfulCoroutine(): $ex")
}
}
}
fun runFailingCoroutine() {
runBlocking {
try {
async { Repository.fail() }.await()
} catch (ex: Throwable) {
println("Catching ex in runFailingCoroutine(): $ex")
}
}
}
}
object Repository {
suspend fun fail(): Int = suspendCoroutine { cont ->
cont.resumeWithException(RuntimeException("Exception at ${Thread.currentThread().name}"))
}
}
fun main() {
Test.runSuccessfulCoroutine()
println()
Test.runFailingCoroutine()
println("We will never get here")
}
这就是在控制台上打印的内容:
Catching ex in runSuccessfulCoroutine(): java.lang.RuntimeException: Exception at main
Catching ex in runFailingCoroutine(): java.lang.RuntimeException: Exception at main
Exception in thread "main" java.lang.RuntimeException: Exception at main
at com.example.lib.Repository.fail(MyClass.kt:32)
at com.example.lib.Test$runFailingCoroutine$1$1.invokeSuspend(MyClass.kt:22)
at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:32)
at kotlinx.coroutines.DispatchedTask.run(Dispatched.kt:236)
at kotlinx.coroutines.EventLoopBase.processNextEvent(EventLoop.kt:123)
at kotlinx.coroutines.BlockingCoroutine.joinBlocking(Builders.kt:69)
at kotlinx.coroutines.BuildersKt__BuildersKt.runBlocking(Builders.kt:45)
at kotlinx.coroutines.BuildersKt.runBlocking(Unknown Source)
at kotlinx.coroutines.BuildersKt__BuildersKt.runBlocking$default(Builders.kt:35)
at kotlinx.coroutines.BuildersKt.runBlocking$default(Unknown Source)
at com.example.lib.Test.runFailingCoroutine(MyClass.kt:20)
at com.example.lib.MyClassKt.main(MyClass.kt:41)
at com.example.lib.MyClassKt.main(MyClass.kt)
Process finished with exit code 1
有什么想法为什么会发生这种情况 - 是一个bug,还是我使用协程的方式不对?
更新:
在 runFailingCoroutine()
中使用 coroutineScope { ... }
可以缓解问题。
fun runFailingCoroutine() = runBlocking {
try {
coroutineScope { async { fail() }.await() }
} catch (ex: Throwable) {
println("Catching ex in runFailingCoroutine(): $ex")
}
}