Python tricks: Demystifying async, await, and asyncio
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- Опубликовано: 8 фев 2025
- (For more, visit pythontutorial... !) In this video, I show how to write a simple asynchronous program in Python, using the async and await keywords, and the asyncio module. Link to Jupyter notebook: osf.io/w8u26/
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This is one of the best asyncio explanations if come across so far. Kudos!
This is _the best_ asyncio tutorial I've yet encountered.
Succinct while not dumming the explanations down!
This is by far the best simplistic explanation i've seen! Major props and thank you for the video.
man who are you ? why I didn't knew you before !
Never seen such way of explanation in the way you did. AMAZING, Thank you !
Probably the clearest example of all I saw trying to figure out the way async/await works. Combined with some theory from PyCon presenters (on matters like "what is event loop for") this one completes the puzzle. Thank you so much for your efforts!
You are sooooooo underrated man, I don't know what's wrong with the RUclips algorithm not showing your videos to people....
This video is certainly the most helpful about this subject by far
You know yours is by far the best explaination of Async I have seen on the internet over the past two days trying to learn how async works.
Oh man, thanks for that. I am yet to understand the details yet, but after watching your video I understood the "concept" of asynchrony and the role of the event loop. GREAT explanation!
You sir have cleared such deep rooted doubts that I had for parallelism in Python for years and years! Thanks a lot!
I have tried reading around async all over RUclips,
even if you were a IT teacher at junior schools, 10 year olds kids would understand you because of how you simplify it. Thank you Sebastiaan
Your teaching capabilities are beyond everything i've encountered.
I have been trying to understand this concept from past 1 month.. Now I feel much better watching this video.. Thanks Sebastiaan
Very great explanations. Not only I know how to use asyncio, but also how it works. Thanks!
This is hands down the best explanation about asyncio.
In case anyone is interested - to determine if a number is prime you only need to check if it has a prime factor smaller than or equal to its square root. Because C=AB must have factor A
First, an excellent presentation and explanation. My sincerest thanks. Second, when I first saw the "talking" head in the corner I was like, "What the...?" But as the video went on it was like I was sitting in a coffee shop looking over his shoulder as he explained what was going on. So, I am sold on this. Great job Sebastiaan.
Loved this short tutorial. You are real guru. Salute.
Great explanation with the live coding, really helps to get the concept, but as you said, I/O operations like network, file access and other stuff that depends on "outside code" is what really makes it shine
Thanks brother! can't find anything simple than this in terms of explanation basic concepts.
Crystal clear, Thank you!
Man, this is the best explanation ever, thank you
you did a much better job explaining this compared to the top 4 articles returned by google on the subject. Thank you. I like your gradual approach to implementing it... really helped a lot. I'm a lot more familiar with asynchronous javascript, which this is a bit different from... but I think I like it. I certainly like Python over JavaScript in general.
I agree. I have been banging my head against my desk the past few days trying to figure this out from the garbage google links. Just watching this on break at work and i think I can figure out the issue I'm dealing with tonight no problem. thank you!
Totally agreed, by far the best explanation
Clear and concise, easy to follow. Excellent!
Finally i understand this better now. People need to do what you did which is explain why you use the keywords and how that works!
Glad you found it useful!
I would like to thank you because it is very difficult to find such a simple example on the net at this time...
At the same time, to teach how to make your code async incrementally is just wonderfull.
Amazing video!
Highly recommended for beginners in async stuff like me!
Awesome explanation. This was a really great video explaining the concept clearly and in a step by step thought process manner!! Really loved the video. Great job!
The best explanation I've come by so far. Thank you so much for this video.
Very comprehensive... Very well explained. Thanks mate.
explanation skills at peak
These glasses are fundamental, mate. Thanks for the lesson. btw, could you please explain the practical difference between async, threading, processes etc.?
Thanks! The difference between threading, multiprocessing, and async is a video on its own, but here's the quick summary: With *multiprocessing you* simply start your program twice; so you have two separate instances, each with their own variables, etc. As you can image, communication between processes is difficult. With *threading*, you start two threads of code that run in parallel within a single process (so they share variables, et.c). Unlike with async, the operating system decides which thread runs when. And *async*, as explained here, is in a sense a way to simulate threading in a more controlled way that gives you (almost) complete control over how functions suspend and resume.
Any real life examples when this is applicable?
+Михаил Нинин the stereotypical use case would be network communication, in which you often need to wait for data to come in. But I've used coroutines also to implement asynchronous display control and collection of keyboard input.
Any situation where you need to do multiple things at once, but your code is not CPU bound. In such a situation, threads buy you nothing but complications, whereas coroutines are much simpler to deal with.
ruclips.net/video/9zinZmE3Ogk/видео.html - watch this, very good explanation of their core differences
Brilliant explanation. Next level teaching.
This tutorial is so on point, the best one on python asyncio
Thanks for the video well explained. For the is_prime function you can do the division check to and including the square root only no need to go past that.
Hele duidelijke tutorial, dankjewel!
Graag gedaan!
The best aSYNCIO explanation video thank you.
Subscribed shortly after the video started.
This is the best coroutines tutorial on the internet.
Note that asyncio is not just a standard Python event loop, it is the standard Python event loop API. There are already plenty of event loops around--in particular, every GUI toolkit already provides one. Rather than try to force everybody to adopt the asyncio event loop (which would never work anyway), what you need to do is wrap these other event loops in an asyncio-compatible layer. Then it becomes possible to write “event-loop-agnostic” code, which is something I don’t think any language has achieved before.
For example, GTK has its own event loop, provided by GLib. Here github.com/ldo/glibcoro is an asyncio-compatible wrapper for it, implemented in a little over 400 lines of code. This makes it possible to use the GLib event loop interchangeably with the default asyncio one in non-GUI apps. In GUI apps that are built on GTK, it becomes possible to use Python coroutines to run large parts of the application logic, instead of the more usual event callbacks. Both scenarios are demonstrated here: github.com/ldo/glibcoro_examples
You are the coolest programmer I have seen :)
That was brilliant! The best explanation I've seen! Well done mate! ;)
I am trying to wrap my head around async/await, threading and multiprocessing in Python. This demo and some of your statements you made were very helpful. I need a few clarifications:
1) For the example that was discussed, because there was an asynchronous sleep, while that was "in progress", it gave up control to the underlying event loop, which in turn switched to the next call, which after doing some quick CPU load (of running the loop) again went to asynchronous sleep, and so on. This meant that "most" of the time, all three sleeps were in progress simultaneously, thus giving the illusion of parallelism. If instead of the asynchronous sleep, if I chose to run a compute intensive calculation (like increment i to a billion), that would be blocking, and would no longer be async, correct?
2) So the await HAS to be on a load that is OUTSIDE the CPU - sleep, network, read disk, etc., correct?
3) Is there a way for me to write my own code which can simulate an async load outside the current thread/process? Like I really do want to increment from 1 to a large number then return, but should happen parallely over multiple coroutines (if that is the right word). Maybe call an external Python script which does that (which will be another process perhaps, I am not sure).
Top ! a very clear explanation. Well done and thank you.
i don't know why people would dislike this video!!
You're the hero we got, but didn't deserve.
Watched two times And now I think I understand it well.
This guy is a freakin ROCKSTAR! Keep going man
one-liner for is_prime function at 5:25 is just so nice ! :D
Finally understandable explanation! Thank you!
Sebastain, Great Video, I have one doubt, what if => await asyncio.sleep() is not used inside asyc code. Right now I am dealing with some async code. Here code is using async because we have to wait to get some json data from server but I have not seen anywhere , we have used something like await asyncio.sleep(). So does our code is fully asynchronous or do we get benefit by introducing await asyncio.sleep() in our async code
Nice shades and so clear!
This was extremely useful and well explained. There's a lot of docs on this subject, but none of them tell how the transition of execution to the loop occurs. Or maybe it's just me who couldn't understand?
Awesome. Thanks for posting this. The example was great.
Excellent video! Very clear and understandable. Thanks for sharing your knowledge.
so underrated! amazing
Excellent! Explains why I can't use requests directly in code with coroutines (they block). Subscribing.
Very well explained!! Hats Off :)
This is a great explanation! Thanks!
Very informative and beautifully presented. Thank you so much!
The best explanation so far! Nice style!
man ! u r the best ! thanks a lot for this best explanation .
Great explanation fellow Dutchman!
Great explanation. You got my subscription and like for this video. Thanks Sebastiaan!
Short and concise. What else do you need? Dank je well!
Amazing explanation. Thank you Sir. :)
Beautiful. Thank you man!
Now this guy is on my wavelength
Excellent ! Understood very well from your video. Keep on the good work.
Very well explained, love your explanation using code :)
Thanks for the great explanation.
Only human friendly explanation that I able to find over internet
great video thanks also those are some cool glasses
very nice explanation with live coding
Thanks, Dude! that help me a lot! A really great explanation!
Thanks for the video man, Loved it
Best asyncio explanation 👍👍👍👍👍
Excellent explanation!! Congrats and thank you very much!
very good explanation. One thing I wanted to ask. The time that you give in asyncio.wait function, is that even useful? I mean, we know that it's a point where the function is suspended and another functions might be called. But once another function is called, we cannot really be sure that the function will suspend and get back to the original function in the specified time?
this is a great explanation.
@Sebastiaan
if we move `await asyncio.sleep(0.01)` above the for loop, loop execution will be happen asynchronously, right ?
async def highest_prime_below(x):
print('Highest prime below %d' % x)
await asyncio.sleep(0.01)
for y in range(x-1, 0, -1):
if is_prime(y):
print('→ Highest prime below %d is %d' % (x, y))
return y
return None
thank you. You are the best. really the best
Great video!
Great video! On the spot. Thank you.
8:00 The asyncio library is pure Python. That means that anything the event loop can do, your own Python code can do. You can implement your own event loop!
well explained, took it as a refresher. Would be awesome to have advanced look at Future in a follow up.
This is a great explanation, thank you for this video and the code
Thanks so much for that explanation!
Lets say the function return values need to be passed to the subsequent functions. Would it be possible to make them parallel too?
HI Sebastiaan, thanks for amazing explanation. BTW, I have a way of determining of primariness of number. I would like you to take a look at it.
def is_prime(x):
return not any (not x % i for i in range(2, int(x ** 0.5)))
Hey bro, really good stuff. Keep the shades on.
nice lesson; please continue to make some!
Thanks, great video!
Very clear. Excellent. Thank you SM.
Great example, and a well-paced video, not over-complicated, but still detailed enough!
And btw, it's `x%i == 0`, not `x//i == x/i` ;)
Excellent explanation!!
Excellent explanation.
Thanks, that was a great explanation
Is there still a way to run socket functions with asyncio?
Anyone know how he generates that little arrow in his string? Does it have a function, or is it just for readability?
Hey loved your explanation, but one thing is when there are multiple CPU intensive functions which need to be run in async, even after adding async.sleep , it is still slow. Any explanations/workaround for this?
really nice - thanks!