How does asyncio manage asynchronous I/O in Python?

How does asyncio work under the hood?

Asynchronous I/O is a technique that allows multiple operations to run concurrently on a single thread. This can be achieved by using a technique called coroutines, which are functions that can be paused and resumed as needed.

In Python, coroutines are defined using the async def keyword. When a coroutine function is called, it returns a coroutine object. This object can be awaited, which will cause the coroutine to be resumed.

When a coroutine is awaited, the interpreter will check to see if the coroutine is ready to run. If the coroutine is not ready, such as because it is waiting for I/O to complete, the interpreter will pause the coroutine and return control to the event loop.

The event loop is a central component of asyncio. It is responsible for running coroutines and scheduling callbacks. The event loop will continue running until there are no more coroutines to run.

When an I/O operation is ready to complete, such as when a socket has received data, the event loop will call the appropriate callback function. This callback function will then resume the coroutine that was waiting for the I/O operation to complete.

By using coroutines and the event loop, asyncio can achieve asynchronous I/O without blocking the thread. This allows multiple operations to run concurrently, even on a single thread.

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