I can't change the API (i.e., convert return values to Task) because that would require that all callers change. This method is intended for compiler use rather than for use in application code. What is ConfigureAwait? Need extra configuration? Calling async methods from non-async code. Applies to. Problem: deadlock. 1) Calling GetResult() or reading Result, as above, blocks the main thread which is the thread most of the Unity code I want to test is designed to run from. In the above code snippet .NET's HttpClient class is returning a Task instance, but we're calling GetAwaiter().GetResult() on the task, which is a blocking call. Now, I am giving you two options, one that I tried and works and one that I found on a Microsoft forum. var result = MyMethodAsync ().Result; (I put var type because we have T instead of data type) When you are working with console type of applications, this would be perfect. In order to maximize device resources and not block UI, you should really try to use asynchronous programming wherever you can. Your EncryptionProvider() is calling GetAwaiter().GetResult(). This post gives a gentle, high up look at why this may happen. Task.Run(() => LogAndAuditAsync()).GetAwaiter().GetResult(); This will still block the synchronization context but LogAndAuditAsync will execute on the task pool scheduler and not deadlock because it does not have to enter the synchronization context that is blocked. Deadlocks come from two threads trying to enter the same single-threaded synchronization context at the same time. In your situation the deadlock occurred because you run Demo.Raise() from the UI Thread and (because of the mentioned above) this thread becomes blocked until all event handlers are executed. This blog post continues the series which is a guide through the code analyzers available on the market and their possibilities. This is very risky and problematic. member this.GetAwaiter : unit -> System.Runtime.CompilerServices.TaskAwaiter Public Function GetAwaiter As TaskAwaiter Returns TaskAwaiter. If you really must use .GetAwaiter().GetResult() and rewriting to true async isn't an option, then I strongly recommend using a pattern like AsyncHelper.RunSync which takes some performance penalties in exchange for the guarantee that it won't deadlock. We'll see in following parts of this series examples of deadlocks with most, if not all of those statements. しかし、なぜそのConfigureAwait.GetAwaiter.GetResultパターンが私に問題を引き起こしているのかを知りたいのです。私の理解ではGetAwaiter.GetResult、署名を変更するオプションがない場合に、同期メソッドから非同期メソッドを呼び出す方法でした。 10 comments Labels. This is group of properties and methods calls, .Result, .GetAwaiter ().GetResult () and .Wait (). There are a few hacks that can make this better by using GetAwaiter().GetResult() and a number of others, but ultimately these workarounds just reduce the probability of a failure marginally, and the problem of deadlocks is still an issue. Hi Saeed57, As far as I think, Task.Run(. question. •No effort has been made to prevent a present SynchonizationContext Dispatcher.Invoke () when working in WPF. Solving the Nested-Lock Deadlock 2) It avoids using Task.Run() (which will run code via a thread pool), again because most of the Unity code I'm looking to test is designed to run on the main thread (or will handle . Synchronously block on some async code; b. The following code is the same as yours is but separates things to facilitate explanation. Ask questions Deadlock in sync GetAwaiter().GetResult() or Result . I think that, or some kind of locking internal to Npgsql itself is your problem, because it's freezing up on a call to NpgsqlCommand.ExecuteReaderAsync() . The async and await keywords were introduced in C# to make asynchronous programming on the .NET platform easier. It is not required to be async all the . This can also lead to deadlocks in certain situations, though probably not in this case. Note that this will only work if the asynchronous code can be run on a thread pool thread (i.e., is not dependent on a UI or ASP.NET context). Doing so can cause deadlocks and unexpected blocking of context threads. In this case you can use the GetAwaiter().GetResult() which, . @linkinshi yes, Task.Wait, GetAwaiter ().GetResult (), Task.Result can all dead lock and they can all starve the thread pool. Using ConfigureAwait(false) to avoid deadlocks is a dangerous practice. In my experience all of these caused deadlocks. In the property（Unable to use async） or function,use sync is dead. Blocking (e.g., GetAwaiter().GetResult()). When you see the debugger's execution point stuck on any of the above, there's a big chance you have a deadlock. It completely depends on what you're calling. One of the common approaches to testing ASP.NET Core applications is to use the integration testing available via the Microsoft.AspNetCore.TestHost package. You invoke this method and synchronously block waiting for it to complete, such as by using .Wait() or .Result or .GetAwaiter().GetResult() off of the returned Task object. It wasn't created to frustrate developers with deadlocks. First, this is an OK thing to do. In your situation the deadlock occurred because you run Demo.Raise() from the UI Thread and (because of the mentioned above) this thread becomes blocked until all event handlers are executed. A normal unit test will pass, but the same code will deadlock if called from a UI or ASP.NET context. Running the code on a thread pool thread (e.g., Task.Run(..).GetAwaiter().GetResult()). Avoiding deadlocks. I'm in the process of updating a library that has an API surface that was built in .NET 3.5. ).GetAwaiter().GetResult() can be used as a workaround to run async code and wait on it synchronously, it will not result in an async deadlock, whereas ().GetAwaiter().GetResult() could.And then you could check if the result is null. Within that async code awaits an incomplete task that does not use .ConfigureAwait (false), or temporarily removes the context. As such, it is subject to the same old deadlock problems as Wait and Result. Here the UnWrap + GetAwaiter do the magic for us to be able to handle the exception normally. An awaiter instance. Deadlock might also be cause by other sort of blocking code, waiting for semaphore, acquiring as lock. However, all three methods cause the potential for deadlock issues and should be avoided in favor of async/await. GetResult is a helper method that does .Wait(), ensures the completion status of the task did not fail or was cancelled and then simply retrieves .Result. imperugo/StackExchange.Redis.Extensions. If you use .Result, .Wait (), .GetAwaiter ().GetResult () you have done a dangerous thing, and you should be prepared to guard against naughty awaiters (you may not even control). GUI applications have a SynchronizationContext that permits only one chunk of code to run at a time. This blocks the thread, and on subsequent token requests, causes a deadlock. They can easily cause deadlocks, especially when called from the UI Thread. In order to avoid deadlocks the async operation is passed to an other Task, that is where TaskFactory.StartNew comes into play. Using ConfigureAwait(false) to avoid deadlock is at best just a hack). What is GetAwaiter? There are a few hacks that can make this better by using GetAwaiter().GetResult() and a number of others, but ultimately these workarounds just reduce the probability of a failure marginally, and the problem of deadlocks is still an issue. As I describe on my blog, GetAwaiter ().GetResult () can deadlock when it's used in a one-thread-at-a-time context. Another context where this might be used is within an NUnit test that are run synchronously and may be calling asynchronous methods to determine test assertions. Task.GetAwaiter().GetResult() is preferred over Task.Wait and Task.Result because it propagates exceptions rather than wrapping them in an AggregateException. Using ConfigureAwait (false) to avoid deadlocks is a dangerous practice. Calling async methods from non-async code. The Short: Deadlocks Threadpool Starvation The Long Here the UnWrap + GetAwaiter do the magic for us to be able to handle the exception normally. To do that, we use the GetAwaiter ().GetResult () pattern to safely block on the async call. One possible solution is to wrap the call using the JoinableTaskFactory, in the following way: var jtf = new JoinableTaskFactory(new JoinableTaskContext()); var result = jtf.Run<DataResult>(() => _myClass.GetDataAsync()); As to why that synchronous wait causes a deadlock, the mystery is in how await does things. In the property（Unable to use async） or function,use sync is dead. Task.GetAwaiter().GetResult() is preferred over Task.Wait and Task.Result because it propagates exceptions rather than wrapping them in an AggregateException.However, all three methods cause the potential for deadlock issues and should be avoided in favor of async/await.. This is most commonly seen when called on the UI thread or in an ASP.NET context (for pre-Core ASP.NET). How would I run an async Task<T> method synchronously? Again, this is synchronous; no execution will take place on the current thread until GetResult returns with the data returned by the operation (the requested string data in this example). 「GetAwaiter（）。GetResult（）」は同じことをします」-いいえ、それはawaitと「同じですが同期的に」行いません：GetResult（）を呼び出すスレッドはスレッドプールにそれ自体を譲りません：スレッド代わりにブロックされます。 Dai 2021-02-26 09:35:45 Remarks. By default, when an incomplete Task is awaited, the current "context" is captured and . They're each waiting for the other, causing a deadlock. The appropriate fix is to use await, and make the calling code asynchronous. As we can see, the helper class basically creates, configure and starts an async task on-the-fly, then unwraps it and synchronously wait for its result: just like the await method above, this approach will prevent deadlocks and could be used within a try/catch . But, sometimes ".GetAwaiter ().GetResult ()" is presented as a good way to replace ".Result" and ".Wait ()" when we can't use async/await. These keywords have fundamentally changed how code is written in most of the C# . However when I call GetAwaiterGetResultOnTask it does not. It can be called using: customerList = AsyncHelpers.RunSync<List<Customer>> ( () => GetCustomers ()); Code is from here. GetResult (); } } Calling the function GetAwaiterGetResultOnFunction will result in a deadlock. Need extra configuration? When used on a faulted Task, GetResult() will propagate the original exception (this is how " await task; " gets its behavior). Events in Discord.Net. What about .ConfigureAwait(false)? In order to avoid deadlocks the async operation is passed to an other Task, that is where TaskFactory.StartNew comes into play. This is the first time that I have experienced a deadlock. What is the key difference between those to functions? While async/await has made this much easier than before . Consider a library method that uses await on the result of some network download. 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