yunfeiz / learn_asyncio

Learn Asyncio

these notes are collected from python concurrency with asyncio book.

Coroutines

couroutines are like a regular python functions but with the superpower that it can pause its execution when it encounters an operations that could take a while to complete.

async keywords will let us define a coroutines.

await keywords will let us pause our coroutines when we have a long-running operation.

create coroutines

import asyncio

async def my_coroutines():
    await asyncio.sleep(4)
    print("this is my coroutine")

mudoles

• asyncio.run()

  • create a event-loop and run couroutine in event loop

• asyncio.sleep(4)

  • awaitable sleep with asyncio

• asyncio.get_running_loop()

  • get current running event loop

• asyncio.new_event_loop()

  • create new event loop

decorator for timing coroutines

import functools
import time 
from typing import Callable, Any

def async_timed():
    def wrapper(func: Callable) -> Callable:
        @functools.wraps(func)
        async def wrapped(*args, **kwargs) -> Any:
            print(f"starting {func} ")
            start = time.time()
            try:
                return await func(*args, **kwargs)
            finally:
                end = time.time()
                total = end-start

                print(f"finished {func} in {total:.4f} seconds")
            return wrapped
        
        return wrapper