Python Async Programming

Marking a function as async turns it into a coroutine function
Unlike a normal function calling a coroutine function does not run the function
Calling a coroutine function returns a coroutine which is a lightweight task

asyncio.run() is used to run/ start a coroutine function. The main coroutine function of the application can be started using this function. This function creates a event loop which is used to schedule and run and async functions.

NOTE

This function optimally take debug=True as a parameter which makes things slower but provides much better error information

await keyword is used to tell Python to wait till the coroutine function is completed
To await multiple coroutine functions together we need to create tasks, this is done using the asyncio.tasks() function. This function takes coroutine function as input and turns it into a task that is scheduled to run in the event loop without awaiting it

await asyncio.wait() is used to wait for all the tasks that are scheduled on the event loop await asyncio.gather() can be also used to await scheduled tasks, additionally gather also allows to schedule coroutines directly (it will automatically turn them into tasks) If there any exception occurs in a task it will get reraised when we access the result of the task

IMPORTANT

• Unlike multi threading and multi processing asyncio uses only the main process/ thread to achieve parallelism (new threads/ processes are not created)
• For asyncio to have any effect all the libraries that are used in the async part of the code should support asynchronous programming (For making HTTP requests the requests library cannot be used as it does not support asyncio instead a library like httpx needs to be used)

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