In this article, I pick a asynchronous programming concept from python which is launched in python 3.4. It provides infrastructure for writing single-threading concurrent code using coroutines and it is totally based on event loop.
The basic terminology used-
- Coroutine :-
This is a sequence of instruction or a simply function which is used for specific task but difference between simple function and coroutine is that coroutine can pause and resume that’s why coroutine can be used for non-primitive multi-tasking.
In python, Coroutine like generator but difference between coroutine and generator is that generator produce data but coroutine consume data.
coroutine is define in two way -
A. Using async def which is given in 3.5 -
B. By using
@asyncio.coroutine decorator (generator based)-
We have to use this decorator @asyncio.coroutine to define coroutine.
2. Task -
It is scheduler for coroutine. A Task is a subclass of Future that wraps a coroutine and Future is an object that is supposed to have a result in the future.
3. Event loop -
something like -
Simple use case :-
- web scraping -
Web scraping automatically extracts data and presents it in a format you can access easily.
Key Points to remember-
- Firstly, You should check website’s terms and condition before scrape.
- Do not hit more request simultaneously because this may break the website. Below my example show only basic use, You can use asyncio for hit multiple website together.
- The layout of a website may change from time to time, so make sure to revisit the site and rewrite your code as needed.
Note:- This is only example how to use asyncio. you should not be used data for commercial purposes.
2. In django project -
Let suppose you want to send mail/bulk send then you never want toend users to have to wait unnecessarily. In this case we can use asyncio-