An event loop is an asynchronous programming technique that allows us to handle multiple events in a single thread, improving the performance of your Python code. In this tutorial, we will cover the basics of event loops, how to create and manage them, and how to use them to build asynchronous applications. So, let's dive in and explore the exciting world of event loops in Python.

Table of Contents :

  • What is Python Event Loop
  • How the Event Loop Works in Python

What is Python Event Loop :

  • Python event loop is a mechanism that allows Python to handle asynchronous programming.
  • It is implemented in modules such as  asyncio  and  curio .
  • The event loop is responsible for scheduling and executing asynchronous tasks in a cooperative multitasking manner, enabling high-performance I/O operations in Python.

How the Event Loop Works in Python :

  • The event loop works by running an infinite loop that listens for and dispatches events as they occur.
  • An event can be any I/O operation such as network I/O, file I/O, or user input.
  • When an event occurs, the event loop wakes up and schedules the corresponding co-routine to run.
  • The co-routine executes until it gets blocked on an I/O operation, at which point the event loop switches to another co-routine and runs it until it gets blocked.
  • This process continues, allowing multiple co routines to run concurrently.
  • Code sample : 

import asyncio

async def hello():
   await asyncio.sleep(1)

async def main():
   await asyncio.gather( hello(), hello(), hello() )

  • In the above example, we define two asynchronous functions  hello()  and  main() .
    •  hello()  function prints  "Hello" , then sleeps for one second, then prints  "World!" .
    •  main()  function creates three co routines for  hello()  function and waits for them to complete using the  gather()  method.
  • The  method is used to run the  main()  coroutine and start the event loop.
  • When we run this program, it will output  "Hello"  three times, then wait for one second, and finally output   "World!"  three times.

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