What are Async and Await ( .NET 4.5 Interview question with answers)?
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- เผยแพร่เมื่อ 28 ก.ย. 2024
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Async and await are markers which mark code positions from where control should resume after a task (thread) completes.
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Well explained, thank you very much. This is unlike some other videos where speakers are very slow to explain, don't explain the meat of the matter, and leaves the watcher confused.
I Initially thought I could use Async and Await in a method that is not running on thread or task, and my application was hanging, but this video of yours explained it beautifully.
I'll be subscribing on your videos and watch the other ones, really grateful.
Asynchronous programming is used to prevent blocking UI for long execution tasks or I/O operations hence it keeps the UI responsive to the user. The same thing can be achieved by using thread also, but have to write a bit complicated coding. The async just simplifies it for easy writing and reading.
very clear with easy simple English.so that I can understand very easy.thanks a lot. Excellent pa.continue .continue
your explanations are pure gold
very nice explanation but my question is instead of using the await keyword can we use synchronous programming. because await also blocks the control and resume when subtask is completed .
yes right. at 3.08. instead of using tpl to invoke the long task. one could have just made a synchronous call to long task.
did you get an answer to this ?
Well explained, thank you very much.
this is to avoid breaking processes of uncertain duration... like sending an amail programatically via smtp...etc...
Wow ,so clearly explained. 👍
Great short and sweet
Thank you sir, very well explain.
very clear and nice ezey
It's really useful thanks.
What if LongTask has parameters i.e. public static void LongTask( string a , string b){ // do something with a ,b }
Good Explanation
good explanation.
thank you !
good
where to use this? can you please explain...real time usage...
Mohanraj Periasamy suppose you are creating a application where a large CSV files data save into DB, so it's take lots of time to validate data and save. so you can use this.
Wherever you would use TPL or threading. It clears up the code.
Thank you so much :)
Hey Shiv, in this case sequential programming serves the purpose. Why should we go for Task and make it wait until completed ?
very true...scrolled down if anyone had asked the same, yes u have asked im waiting for the reply too
this can be achieved without these keywords by calling method directly right
I have a question
Why not just call the LongTask methods as it is,
public void Method()
{
LongTask() ; //No parallel processing
Console.WriteLine(""Do something");
}
public static void LongTask()
{
Thread.sleep(20000);
}
If i can make it wait like this, then why should I go for the async and await?
It will use only main Thread. It is not good approach to wait the main Thread.
when i used in webapplication it is not working, why is that ?
Spelling of async is incorrect at 0:12. Great content.
You skipped over the main usage of async/await which is to achieve responsiveness for UI or scalability for Web (and NOT asynchrony). The threads yields control back to caller when it encounters await.
correctly pointed out...watch kudvenkat sir's video
Tasks can be executed with lambda like Await Task.Run(() => LongTask());
Shorter than New Action
Contd from earlier comment.... Use of Async and Await keywords helps the programmer to get rid of writing spaghetti code (interlinked code) with callbacks making it simple.
Short, clear and straighforward. Thank you Sir.
How many await can be used
Pronunciation of "async" is /eɪˈsɪŋk/
p.s. Good code example :)
Good video. It is worth mentioning that Async and Await keywords are used in asynchronous programming. Earlier the programmers were required to write a callback method for each async function and then if they wanted some block of code to be executed after the aync operation is over, that block of code was required to be written in the callback method. Writing callback method for each async function could become very clumsy and hard to read and understand...contd.
hi, what to do if i want "main thread" to be executed after the new thread?
Thanks for good information I use await and async but now i clear about that
What an explanation, simple to understand and apply, thanks. thumbs up
Very Good Explained Sir... easily understand anyone., Thank You So much for describing in details Sir,,
Excellent description, now I understand. Everything else I looked at, I could not understand. Thank You.
Venkat's teaching is the same as Virat Kholi hitting a six even in difficult situations
we should not release the main thread until all sub-threads are completed otherwise there is no way to catch exceptions if any occurs in sub-threads
Nice video.
But you are missing something significant here about async & await..
No one can explain .Net better than Shiv sir❤. Thanks for the video sir.
Really super explanation sir.within less words ..🙏
Very good explanation..thanks
can you give us a download link for this program ..
thank you
I got epiphany when you said "The main thread did not wait, guys".
Excelent! but why always console mode ...
What I don't understand is - aren't things already like that in C# even without async and await keywords??? I mean, doesn't code go step by step anyway?
Is it because the Task.Run() itself is ignoring the order of execution?
Without using any of these jargons in a simple program we can execute one statement after another, right? That happens in a single thread or the main thread.
What Task.Run() does is it does the work in a different thread (actually, it is from a thread pool and they are slightly different, but nvm let's consider thread). So the main program is running on one thread and the Task.Run() runs on a different thread. It runs simultaneously.
And to make it run step by step way using many threads, we use async and await. Hope this helps :)
Perfectly clear! That's what I call an explanation ;)
Thank you very much! :)
simple words,
while the pointer is in await Task.Run...
The UI (Form) will be perfectly active, you can move, click do everything,
but in normal program running line by line, your UI is frozen completely during that 20,000 ms [20 seconds],
NOW THATS THE CATCH :)
Love u sir ji.. very simplified each n every tough topics..Awesome way to explain..
superb explanation!!! thanks sir, keep it up
Code not workinh Now?
Nice explained!
Great thanks!
Clear and simple explanation...tnx
Thanks a lot for this information
Thank you so much, that was very helpful. God bless.
yes very good explanation. very clear.
ClearlyI
Excellent
Good Video, Thank you
Hi thanks for the video...but what is the difference between await vs wait()..
In this example, Wait() should have been used.
Task.Run returns a Task which is an 'awaitable', hence we can 'await' it, but we can wait simply by calling Task.Wait() method. Typically, async/await should be used for naturally asynchronous operations/methods - HTTP calls, for example.
Thanks.
Brief and complete explanation. Thank you!
What if the longTask method is made async will it wait at your debugger ?
Excellent explaination
Thank you
Good Video..thanks!
However, I believe there should be a correction in the statement made @ around 3:57 mins where the author says that aync & await should be used in pairs.
AFAIK if any method uses "await", it is mandatory to mark that method as "async" but the vice versa is not true. A method could be marked as "async" with having any "await" keyword inside it. In this case, it will be treated as a synchronous method.
Secondly, as per the naming convention standards, an async method methodname should always me suffixed by "async" word; e.g. PrintAsync()
Hope, this helps to the viewers.
Thanks!
Vinay Pugalia yes u r correct
binson eldhose my question is instead of using the await keyword can we use synchronous programming. because await also blocks the control and resume when subtask is completed .
Praveen Shukla I think that is incorrect. As mentioned in the end of the video, the thread from the Main method executed (ie. ran asynchronously), the only thing that waits is the line of code after await WITHIN the Async method.. ie.
OUTPUT ->
Main Thread
New Thread
In Synchronous, the entire thread would await..
OUTPUT ->
New Thread
Main Thread
Synchronous blocks entire thread,
Task blocks nothing,
Async blocks (rather forces to wait) only content within the ASYNC method.
+Praveen Shukla - Hi Its not possible
Brilliant Video !
Excellent