假设我有以下代码:
private static void Run()
{
TaskScheduler.UnobservedTaskException += delegate { Console.WriteLine("Unobserved task exception!"); };
try
{
RunAsync().Wait();
}
catch (Exception)
{
}
GC.Collect();
GC.WaitForPendingFinalizers();
GC.Collect();
Thread.Sleep(Timeout.InfiniteTimeSpan);
}
private static async Task RunAsync()
{
var task1 = ThrowAsync();
var task2 = ThrowAsync();
await task1;
await task2;
}
private static async Task ThrowAsync()
{
throw new Exception("Test exception");
}
这段代码输出 Unobserved task exception!
因为 task2
中的异常没有被观察到。
我的问题如下:有没有办法以编程方式确定哪个任务有未观察到的异常?例如,我想获取调用任务或类似这样的方法的堆栈跟踪:
Unobserved exception: task2 in RunAsync()
遗憾的是,异常堆栈跟踪是不够的。上面的代码只是一个演示,在真实世界的应用程序中,我有时会遇到未观察到的任务异常,堆栈跟踪如下:
System.AggregateException: A Task's exception(s) were not observed either by Waiting on the Task or accessing its Exception property. As a result, the unobserved exception was rethrown by the finalizer thread. ---> System.NullReferenceException: Object reference not set to an instance of an object.
at System.Web.HttpApplication.get_CurrentModuleContainer()
at System.Web.HttpApplication.PipelineStepManager.ResumeSteps(Exception error)
最佳答案
人们将能够分辨出哪个 Task 实例的异常未被观察到。那将是第二个 await
task2
await task1;
await task2;
因为第一个await
“观察”了task1
的结果。
然后,如果事件处理程序被修改为呈现 TaskScheduler.UnobservedTaskException
提供的实际任务异常
TaskScheduler.UnobservedTaskException += delegate(object o, UnobservedTaskExceptionEventArgs ea)
{
Console.WriteLine($"Unobserved task exception! {ea.Exception.ToString()}");
};
然后可以通过观察异常的堆栈跟踪来追踪任务代码的失败区域:
Unobserved task exception!
System.AggregateException: A Task's exception(s) were not observed either by Waiting on the Task or accessing its Exception property. As a result, the unobserved exception was rethrown by the finalizer thread. (Test exception)
---> System.Exception: Test exception
at ConsoleApp1.Program.ThrowAsync() in C:\Users\sergepavlov\Desktop\ConsoleApp1\ConsoleApp1\Program.cs:line 42
--- End of inner exception stack trace ---
---> (Inner Exception #0) System.Exception: Test exception
at ConsoleApp1.Program.ThrowAsync() in C:\Users\sergepavlov\Desktop\ConsoleApp1\ConsoleApp1\Program.cs:line 42
<---
希望这是有道理的。
关于c# - 查找具有未观察到异常的任务的最佳策略,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/34065942/