Complete asyncio Learning Path

1. Introduction to asyncio

• What is it? A built-in Python library (since Python 3.4) that lets you write asynchronous code.

• Why use it?

  • To handle I/O-bound operations (like networking, files, databases).
  • Improve performance instead of waiting for blocking operations.
  • It’s the foundation of web frameworks (like FastAPI and Aiohttp).

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2. Core Concepts

• Synchronous vs Asynchronous

  • Synchronous: each operation waits for the previous one.
  • Asynchronous: operations run concurrently (interleaved).

• Coroutines Functions defined with async def.

• Event Loop The “heart” that runs coroutines.

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3. Main Tools in asyncio

1. async / await

   • async def: define a coroutine.
   • await: wait for a coroutine or task.

   import asyncio
   
   async def hello():
       print("Hello")
       await asyncio.sleep(1)
       print("World")
   
   asyncio.run(hello())

2. Tasks

   • Run coroutines concurrently.

   async def main():
       task1 = asyncio.create_task(hello())
       task2 = asyncio.create_task(hello())
       await task1
       await task2
   asyncio.run(main())

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4. Managing Tasks

• asyncio.gather() → run multiple coroutines together.
• asyncio.wait_for() → set a timeout.
• asyncio.shield() → protect a task from cancellation.

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5. Working with I/O

• asyncio.sleep(): simulate delay.
• asyncio streams: handle TCP/UDP sockets.
• aiohttp: HTTP client/server built on asyncio.

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6. Concurrency Control

• Semaphore / Lock: prevent race conditions.
• Queue: manage task communication between coroutines.

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7. Advanced Topics

• Subprocesses with asyncio.
• Cancellation & Exception handling.
• Async context managers (async with).
• Async iterators (async for).
• Integration with other libraries (FastAPI, SQLAlchemy async).

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8. Hands-on Projects

1. Simple scraper with aiohttp.
2. Small chat server using asyncio.
3. Combine asyncio with FastAPI.
4. Build a small task scheduler.