Python server programming: Asynchronous programming using coroutines

Python has become a widely used programming language, and Python server programming is becoming increasingly popular. In Python server programming, especially in the field of web development, asynchronous programming has become an increasingly popular programming method. This article will introduce how to use coroutines to implement asynchronous programming.

1. Advantages of asynchronous programming

In server programming, asynchronous programming has the following advantages:

1.1 Improved performance

In traditional In the synchronous blocking method, you have to wait for the return value of the function before continuing to perform the next operation, while asynchronous programming allows the program to perform other tasks while waiting for an operation to complete. This approach can avoid context switching between threads or processes, thereby reducing resource consumption, improving concurrency, and thus improving program performance.

1.2 Improve response speed

Because asynchronous programming allows the program to perform other tasks while waiting for an operation to complete, asynchronous programming has a faster response than traditional synchronous methods when handling concurrent requests. speed. This is especially important for applications such as web servers that need to handle a large number of requests.

2. Introduction to coroutines

Coroutines are very lightweight threads. Coroutine switching is more portable and efficient than thread switching, so it is suitable for asynchronous applications. used in programming.

Coroutines are a concurrency technology in user space. They are cheaper than thread switching and have high execution efficiency. For applications with intensive IO operations, using coroutines can better utilize the computer's performance. Coroutines handle requests in an event-driven manner and use the event loop mechanism to implement asynchronous operations.

In Python, the way to use coroutines is to use the asyncio standard library. Asyncio contains many modules and classes for implementing asynchronous programming, such as:

• asyncio.AbstractEventLoop
• asyncio.Protocol
• asyncio.StreamReader
• asyncio.SubprocessProtocol etc.

3. Sample code

The following is a simple sample code that shows how to use the asyncio library and coroutines to implement asynchronous programming.

import asyncio

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

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

asyncio.run(main())

In this example, we define a coroutine function hello_world() to output "Hello World" and "Hello Again", and wait for 1 second after outputting "Hello World".

In the coroutine function, the await keyword is used to suspend asynchronous tasks so that the event loop can handle other tasks. In the main program, we use an asynchronous method to execute multiple hello_world() functions at the same time, using the asyncio.gather() method.

Use the asyncio.gather() method to execute multiple coroutine functions concurrently. The program will not exit until all coroutine functions are completed.

4. Summary

In Python server programming, using coroutines to implement asynchronous programming can provide better performance and response speed. Coroutines are lightweight threads that can reduce context switching between threads or processes and improve the concurrency capabilities of the system. Python's asyncio standard library provides a wealth of modules and classes to implement coroutines, making asynchronous programming easier.

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