Fix nits about the "Async programming scenarios" page #49098
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| var html = await s_httpClient.GetStringAsync(URL); | ||
| return Regex.Matches(html, @"\.NET").Count; | ||
| return await Task.Run(() => | ||
| { | ||
| var html = s_httpClient.GetStringAsync(URL).Result; | ||
| return Regex.Matches(html, @"\.NET").Count; | ||
| }); |
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I don't understand the reason for this change. The original code already used an async method that was correctly awaited. Now, it looks like you are using a blocking call is a second thread. I don't see the benefit.
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Honestly, I got confused too, by the words: "method should return await". Method can't have the return type of await, hence I came up with this proposal.
I'm totally OK with reverting it, maybe replacing with some other implementation if you, @BillWagner have an idea of what the requirement can be for this point I mentioned.
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I see. I'm answering assuming you mean the text in the "Use await inside async() method body".
First a nit: Let's remove the () on async. That reads wrong.
The reason you should have an await expression if you add the async modifier to a method is efficiency.
Adding the async modifier requires the compiler to generate the async state machine, which is complicated IL. If you don't need it, it's a fair amount of overhead.
Instead, maybe we should state this as "Only add the async modifier if the method includes an await expression.
It's perfectly valid to have a method that returns a Task or Task<T> that is synchronous! (Some of the examples in this article could be modified to use that idiom: mainly if the last line of the method is return await <method>.
There is an important difference in the two idioms: A synchronous method that returns a task type is a normal "synchronous" method. If it has the async modifier, the return statement must return the T (or nothing) and the compiler generates the code that creates the continuation when the asynchronous work completes, and packages the return in a Task (or ValueTask) as needed. It also generates the necessary code to create a Faulted task with the Exception property in case of failure.
This reverts commit 57fb6e6.
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This pull request fixes #47630
It updates the "Async programming scenarios" page as listed in the issue.