F＃无法捕获TimeoutException [英] F# can't catch TimeoutException

问题描述

我的问题很简单。请看看截图：

如何发生？我明确地将Async.RunSyncronly调用到 try ... with 。

解决方案

在F＃异步工作流程中尝试/使用不直接映射到CLR保护的块 - 相反，如果在用户代码中引发异常，则库代码将捕获并重新路由到最近的错误继续（可以是，块， finally block ，定制错误继续在 Async.StartWithContinueations etc ...）。这有一个后果，调试器可能会报告用户代码中未处理的异常，可以在稍后处理和处理。

下面的代码片段报告了调试器中的类似错误，但执行完成成功

  let error（）：int = raise（System.TimeoutException（））
 
让运行（）= async {
 try 
 let result = error（）
 return result 
 with 
：？ System.TimeoutException  - >返回-1 
} 
 
 let r = Async.RunSynchronously（run（））
 printfn％dr 
  pre> 
My question is really simple. Please take a look at screenshot:



How could that happen? I explicitly put call to Async.RunSyncronously into try ... with.
解决方案
try/with in F# async workflows do not map directly to CLR protected blocks - instead if exception is raised in user code, library code will catch it and re-route to the nearest error continuation (which can be i.e with block, finally block, custom error continuation supplied in Async.StartWithContinuations etc...). This has a consequence that debugger might report about unhandled exceptions in user code that can be handled and processed later.

Snippet below reports the similar error in debugger but nevertheless execution is finished successfully
let error (): int = raise (System.TimeoutException())

let run() = async {
    try 
        let result = error()
        return result
    with
    :? System.TimeoutException -> return -1
}

let r = Async.RunSynchronously (run())
printfn "%d" r


                        
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