exception disappear when forgot to await an async method

最新推荐文章于 2023-10-21 18:09:47 发布

转载最新推荐文章于 2023-10-21 18:09:47 发布 · 52 阅读

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原文链接：http://www.cnblogs.com/chucklu/p/10444031.html

本文详细探讨了在C#中使用async/await时的异常处理机制。解释了当调用async方法未使用await时，异常如何被忽略，以及如何通过await或Wait()正确捕获这些异常。同时提醒开发者注意使用Wait()可能引起的程序阻塞问题。

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https://github.com/aspnet/AspNetWebStack/issues/235

https://stackoverflow.com/questions/5383310/catch-an-exception-thrown-by-an-async-void-method

如果异常发生在1个async方法中，而调用这个方法的地方，没有做await。那么异常就会消失。

It's somewhat weird to read but yes, the exception will bubble up to the calling code - but only if you await or Wait() the call to Foo.

public async void DoFoo() { try { await Foo(); } catch (ProtocolException ex) { // The exception will be caught because you've awaited // the call in an async method. } } //or// public void DoFoo() { try { Foo().Wait(); } catch (ProtocolException ex) { /* The exception will be caught because you've waited for the completion of the call. */ } }

Async void methods have different error-handling semantics. When an exception is thrown out of an async Task or async Task method, that exception is captured and placed on the Task object. With async void methods, there is no Task object, so any exceptions thrown out of an async void method will be raised directly on the SynchronizationContext that was active when the async void method started. - https://msdn.microsoft.com/en-us/magazine/jj991977.aspx

Note that using Wait() may cause your application to block, if .Net decides to execute your method synchronously.

This explanation http://www.interact-sw.co.uk/iangblog/2010/11/01/csharp5-async-exceptions is pretty good - it discusses the steps the compiler takes to achieve this magic.

Async/Await - Best Practices in Asynchronous Programming

转载于:https://www.cnblogs.com/chucklu/p/10444031.html