37. Asyncio Basics
Asyncio is Python’s built-in library for writing concurrent code using the async/await syntax. It provides a foundation for asynchronous programming by enabling cooperative multitasking, where tasks voluntarily yield control to allow other tasks to run.
Event Loop Concept
The event loop is the core of every asyncio application. It runs asynchronous tasks and callbacks, manages events, and handles IO operations. The loop continuously checks for tasks that are ready to run and executes them.
Coroutines
Coroutines are special functions defined with ‘async def’. They represent asynchronous operations and can be paused and resumed using ‘await’.
Example:
import asyncio
async def greet():
print(“Hello”)
await asyncio.sleep(1)
print(“World”)
asyncio.run(greet())
Tasks
Tasks wrap coroutines and schedule them to run on the event loop. They allow multiple coroutines to run concurrently.
Example:
async def task(name):
print(f”Starting {name}”)
await asyncio.sleep(1)
print(f”Finished {name}”)
async def main():
await asyncio.gather(task(“A”), task(“B”))
asyncio.run(main())
Async/Await Syntax
The ‘async’ keyword defines a coroutine, and ‘await’ is used to pause execution until the awaited coroutine completes. This syntax makes asynchronous code easier to read and write.
Use Cases
– Network applications (e.g., web scraping, chat servers)
– IO-bound operations (e.g., file and database access)
– Real-time data processing
Best Practices
– Use ‘asyncio.run()’ to start the event loop
– Prefer ‘asyncio.gather()’ for running multiple coroutines concurrently
– Avoid blocking calls inside coroutines
– Use timeouts and exception handling for robustness
Common Pitfalls
– Mixing synchronous and asynchronous code improperly
– Forgetting to await coroutines
– Blocking the event loop with long-running synchronous operations