asyncio

asyncio_demo.py

import asyncio

# 1: Coroutines:
"""
Coroutines are functions that can pause and resume their execution. 
They are defined using the async def syntax. To call a coroutine, you use await.
"""

async def my_coroutine():
    print("Hello")
    await asyncio.sleep(1)
    print("World")

# 2: Event Loop:
"""
The event loop is the core of the asyncio module. It runs in the background, executing tasks and handling I/O events. 
You can get the event loop using asyncio.get_event_loop() and run it using loop.run_until_complete().
"""

loop = asyncio.get_event_loop()
loop.run_until_complete(my_coroutine())


# 3: Tasks:
"""
Tasks are used to schedule coroutines concurrently.
When you create a task, it gets scheduled by the event loop and runs as soon as possible.
"""
async def my_task():
    print("Task started")
    await asyncio.sleep(2)
    print("Task finished")

asyncio.run(my_task())

# 4: Futures:
"""
A Future is an object that represents a result of an operation that hasn’t 
completed yet. It is used lower-level in the asyncio module.
"""

# 5: Async/Await Syntax:
"""
async defines a coroutine, and await is used to pause the coroutine until the awaited task is complete.
"""

async def say_hello():
    await asyncio.sleep(1)
    print("Hello")

asyncio.run(say_hello())

# 6: Running Multiple Coroutines:
"""
You can run multiple coroutines concurrently using asyncio.gather() or asyncio.create_task().
"""

async def task1():
    await asyncio.sleep(1)
    print("Task 1 complete")

async def task2():
    await asyncio.sleep(2)
    print("Task 2 complete")

asyncio.run(asyncio.gather(task1(), task2()))


# 7: Example: Fetching Data Asynchronously
"""
Here’s an example of using asyncio to fetch data from multiple URLs concurrently:
"""
import asyncio
import aiohttp

async def fetch_url(session, url):
    async with session.get(url) as response:
        return await response.text()

async def main():
    urls = ['http://example.com', 'http://example.org', 'http://example.net']
    async with aiohttp.ClientSession() as session:
        tasks = [fetch_url(session, url) for url in urls]
        results = await asyncio.gather(*tasks)
        for result in results:
            print(result)

asyncio.run(main())