Which do I use, ConfigureAwait True or False? 

One point I forgot to make in the video was around performance. Using ConfigureAwait(false) is performs MUCH better because it's expensive to switch back to the original thread. This becomes especially important when doing async stuff in loops or performing expensive work after returning. Don't force the system to switch back unless you have to. Stick with ConfigureAwait(false) by default. Only set ConfigureAwait(true) if you really must run the continuation task on the original thread.

Thanks for this. I've wondered about this before. Everyone just seems fo say always use ConfigureAwait(false). Now I know what it means and can intelligently decide when to use it.

It is the first time I understand ConfigureAwait Thank you.

Super simple explanation. Thanks a lot. Now I understand it !!! :)

How to close window from view model in WPF app?

Thank you so much ❤❤❤

if you have super complex question. just ask to Brian Lagunas and BOOM.. you will get an answer super easy to understand !!!!! :) Thanks a lot !!

Glad that .Net Core got rid of synchronizaton context and we don't need to do that.

What about Asp.Net? In which cases should we use .ConfugureAwait(false) there?

Question: Do you need CQRS when you have Application Services that can implement commands and queries as application service methods?

I have one doubt is await creating a thread? As you told it is executing in worker thread

Make a playlist on the TPL

nice

Besides UI/Apps.. how does this affect things like APIs? Also.. you should post a working repo of this... I wasn't able to replicate it myself. I had no issues...

ConfigureAwait should have been named RetainThread. Self explanatory this way.

Hey Brian. I noticed that images in xaml create memory leaks. Case: Listbox with images, wait for images to be loaded, then clear collection, memory not releases. Also tried to load images from stream in view model, and then dispose stream, but images still exist in memory. Any ideas please? Also it would be very interesting if you make a video about memory leaks. Thank you

interesting....

ConfigureAwait should default to false but it actually defaults to true. This was a poor design decision by Microsoft to sacrifice performance in order to appease beginner developers. The net result is; if you want your application to be very performant, you have to litter the code with ConfigureAwait(false) after every single effing function call. In practice the only time you ever need to use ConfigureAwait(true) is when you are touching UI elements directly because without it you will get cross-thread execution errors when you try to update UI controls via their properties. (Cross thread errors are yet another arbitrary and poor design decision by Microsoft). If your UI is using databinding (MVVM) OR there is no UI (Windows service, web API, console etc) then there is almost never a need to use ConfigureAwait(true) unless it is manipulating bitmaps or something else that is arbitrarily protected from cross thread manipulation. All ConfigureAwait(true) does is force the function to return back to the UI (or calling) thread but only when that thread is free to continue processing.. So it actually causes a bottlenecks in your application which can result in the UI becoming unresponsive if your async functions do a lot of heavy processing. And yes the function name ConfigureAwait() itself was yet another poor design decision by Microsoft because it does not even remotely describe what the function actually does. How about just calling it ReturnToContext() and just making people call it only when they actually want the function to return to the context it was called from.

This the most clear explanation of ConfigureAwait I've seen. Thank you for sharing!

Incredible! I was struggling with this in a project today and then this video pops up and answers the question! Thanks Brian!

ConfigureAwait is a stupidly named method.

ConfigureAwait has is not directly about threads. It's about SynchronizationContext. WPF and its DispatcherSynchronizationContext or Windows Forms and its WindowsFormsSynchronizationContext happen to be tied to the UI thread, but that's not the case of, for example, the AspNetSynchronizationContext. referencesource.microsoft.com/#mscorlib/system/threading/synchronizationcontext.cs,8b34a86241c7b423,references

So TL;DR, UI = true, Library = false. What happens when Library code is used in a UI?

I think if you make a series on TPL and Async and Await it will be hit :)

When the if condition becomes false, then the task is skipped, but the task should not be skipped until the condition becomes true.

I wonder why they have choosen to use ConfigureAwait(true) as a default, as most (or all of my asp.net core code) should benefit from ConfigureAwait(false). When working with UI code you are probably more aware of the UI thread switching.

Nice and clear explanation. Thank you.

Hah. I have had a question about ConfigureAwait at job interview few days ago. Thanks!

Half of my code is ConfigureAwait(false)... Finally I know why. I do API or library mainly.

what's the default behavior if you don't use ConfigureAwait?

Sir, here is a request video from me and I believe many of us need it. Can you please do a video on XAML/WPF debugging using any tools or any techniques you had developed over years such as finding failures in binding. I know one way to look in output window. Thank you

What an explanation man! I was seriously in a confusion for the difference between the two and almost got headache . But it's very clear now because of your video love you 😍

Brief but accurate and precise explanation. Thanks.

Basically all of the C# code I write is backend stuff, does this have any use case when not implementing a UI?

Great explanation! Thank you. Now I get it. You got a new subscriber ;)

As always.. great vid. I'm trying to brush up on my Prism skills.. so I will see you again very soon. 👍

seems await is not running on other thread , the thread id looks similar. Or I miss something ...?? no idea... sorry did not get the point.. I think here is the answer.. www.skylinetechnologies.com/Blog/Skyline-Blog/December_2018/async-await-configureawait

do these same rules apply for MVC/Blazor web applications?

This is awesome.

Omg thank you

Great video :)

At the risk of being super pedantic, please define "coding on the UI." As in, are you talking about code within a Razor View [page], within a Controller, or...? (Thanks!)

У меня не возникает DeadLock как в конце видео, хотя я сделал всё идентично. Я не понимаю почему он должен возникнуть. Почему .ConfigureAwait(true) вдруг должен ждать какого-то ответа от UI потока? Если мы говорим этим выражением, что хотим продолжать код в UI потоке. По логике второй поток должен выполнить дополнительный процесс, закрыться и передать управление обратно UI потоку. С чего бы второму потоку при await ждать первый?

Thanks Brian, I love these new videos. Your the best

Thanks, really simple video, I finally understood the ConfigureAwait concept.

Thank you for the great explanation! I had a hard time understanding this before

Thanks Brian, I was struggling with the use of ConfigureAwait till now but not anymore. :)

Explanation at its best!! Thanks a lot !

Спасибо!!!

If you have a service that handles all rest get requests that's injected into a viewmodel and called in the viewmodel do you simply add configure await true in the service? Keep in mind the view delegates a command to the viewmodel that ultimately calls the service method. I'm guessing that this is on the UI thread as it all originated from the UI?

How do you handle a cancellable task?

Great video, thank you Brian!

Cooool... Hi Brian, How can i Configure or Add Interface Services for dependency injection in Wpf App? Please :)

These short videos are awesome Brain. Learning a lot.

Vidoe seems to have a small audio/video lag/sync issue, just at the beginning. Not sure if its just me. Thanks for the video

Thank you so much for these videos which are clearing all of our doubts about async and await. Your method of explanation is so much easy to understand, it just feels like child's play. I have one question please, I would like to know what is the right way to write async method which does not have any async method called inside it and has a value to return back. I may not sound clear but hope you understood my question. Thank you.

thanks!!!!!

Hi brian, how can I add a red border on textbox to validation a field? It will be nice has a tooltip to show the validation error. Thank you!

excellent

Hey Brian - great explanation. I have a situation where we have a web page (MVC .NET CORE) and was reading about configureawait(true) vs false for that technology. Would I be right in thinking that for all await calls in the views, we should be using configureawait(true)?

I have a question I have a number of users that may be from 10 to 2000 and i want to send to them sms and for each sms sent to user i need to insert it in database How to implement this without forcing the ui user to wait for all of these 2000 sms to be sent

Again an awesome video. Thanks brian.

Informative as usual sir :)

I wonder why they called it ConfigureAwait instead of something like PreserveContext. It's as if they were planning to have more configuration options and never got around to it.