Task.Run冻结

Question

Can anyone educate me why the following freezes after completing the lambda:

        return await Task.Run(() =>
        {
            return SuperLongMethod();
        })

...yet the following works as expected:

        return Task.Run(() =>
        {
            return SuperLongMethod();
        }).GetAwaiter().GetResult();

It seems the Task.Run in the first version doesn't recognize that the lambda has completed. I have other examples in my code where I use the first version without issue, so I'm at a loss to understand what the difference is.

For clarity, SuperLongMethod() makes a web service call and does a lot of post-processing of the resultant data

Answer 1

I'm guessing that further up your call stack you're calling Task.Wait or Task<T>.Result and thus causing the deadlock issue I describe on my blog . You should use await instead.

As a side note, SuperLongMethod should probably be broken up into a CallWebServiceAsync and DoPostProcessing , and only the DoPostProcessing should be wrapped in a Task.Run .