MicroPython中文社区

来自：https://superfastpython.com/python-asyncio/

Asyncio允许我们在Python中使用基于coroutine并发的异步编程。

尽管Asyncio在Python中已经存在很多年了，但它仍然是Python中最有趣但也是最令人沮丧的领域之一。

对于新的开发者来说，要开始使用asyncio简直是难上加难。

本指南对Python中的asyncio进行了详细而全面的回顾，包括如何定义、创建和运行cououtines，什么是异步编程，什么是非阻塞io，与cououtines一起使用的并发原语，常见问题，以及最佳实践。

这是一个巨大的29000多字的指南。你可能想把它收藏起来，这样你就可以在开发并发程序时参考它。让我们深入了解一下。

• What is Asynchronous Programming
  • Asynchronous Tasks
  • Asynchronous Programming
  • Asynchronous Programming in Python
• What is Asyncio
  • Changes to Python to add Support for Coroutines
  • The asyncio Module
• When to Use Asyncio
  • Reasons to Use Asyncio in Python
  • Other Reasons to Use Asyncio
  • When to Not Use Asyncio
• Coroutines in Python
  • What is a Coroutine
  • Coroutine vs Routine and Subroutine
  • Coroutine vs Generator
  • Coroutine vs Task
  • Coroutine vs Thread
  • Coroutine vs Process
  • When Were Coroutines Added to Python
• Define, Create and Run Coroutines
  • How to Define a Coroutine
  • How to Create a Coroutine
  • How to Run a Coroutine From Python
• What is the Event Loop
  • What is the Asyncio Event Loop
  • How To Start and Get An Event Loop
  • What is an Event Loop Object
  • Why Get Access to The Event Loop
• Create and Run Asyncio Tasks
  • What is an Asyncio Task
  • How to Create a Task
  • When Does a Task Run?
• Work With and Query Tasks
  • Task Life-Cycle
  • How to Check Task Status
  • How to Get Task Result
  • How to Get Task Exception
  • How to Cancel a Task
  • How to Use Callback With a Task
  • How to Set the Task Name
• Current and Running Tasks
  • How to Get the Current Task
  • How to Get All Tasks
• Run Many Coroutines Concurrently
  • What is Asyncio gather()
  • How to use Asyncio gather()
  • Example of gather() For Many Coroutines in a List
• Wait for A Collection of Tasks
  • What is asyncio.wait()
  • How to Use asyncio.wait()
  • Example of Waiting for All Tasks
• Wait for a Coroutine with a Time Limit
  • What is Asyncio wait_for()
  • How to Use Asyncio wait_for()
  • Example of Asyncio wait_for() With a Timeout
• Shield Tasks from Cancellation
  • What is Asyncio shield()
  • How to Use Asyncio shield()
  • Example of Asyncio shield() for a Task
• Run a Blocking Task in Asyncio
  • Need to Run Blocking Tasks in Asyncio
  • How to Run Blocking Tasks
  • Example of Running I/O-Bound Task in Asyncio with to_thread()
• Asynchronous Iterators
  • What Are Asynchronous Iterators
  • What is the “async for” loop?
  • How to Use Asynchronous Iterators
  • Example of an Asynchronous Iterator
• Asynchronous Generators
  • What Are Asynchronous Generators
  • How to Use an Asynchronous Generator
  • Example of an Asynchronous Generator
• Asynchronous Context Managers
  • What is an Asynchronous Context Manager
  • How to Use Asynchronous Context Managers
  • Example of an Asynchronous Context Manager and “async with”
• Asynchronous Comprehensions
  • What are Asynchronous Comprehensions
  • Comprehensions
  • Asynchronous Comprehensions
  • Await Comprehensions
• Run Commands in Non-Blocking Subprocesses
  • What is asyncio.subprocess.Process
  • How to Run a Command Directly
  • How to Run a Command Via the Shell
• Non-Blocking Streams
  • Asyncio Streams
  • How to Open a Connection
  • How to Start a Server
  • How to Write Data with the StreamWriter
  • How to Read Data with the StreamReader
  • How to Close Connection
• Example of Checking Website Status
  • How to Check HTTP Status with Asyncio
  • Open HTTP Connection
  • Write HTTP Request
  • Read HTTP Response
  • Close HTTP Connection
  • Example of Checking HTTP Status Sequentially
  • Example of Checking Website Status Concurrently
• Python Asyncio Common Errors
  • Error 1: Trying to Run Coroutines by Calling Them
  • Error 2: Not Letting Coroutines Run in the Event Loop
  • Error 3: Using the Low-Level Asyncio API
  • Error 4: Exiting the Main Coroutine Too Early
  • Error 5: Assuming Race Conditions and Deadlocks are Impossible
• Python Asyncio Common Questions
  • How to Stop a Task?
  • How to Wait for a Task To Finish?
  • How to Get a Return Value from a Task?
  • How to Run a Task in the Background?
  • How to Wait for All Background Tasks?
  • Does a Running Task Stop the Event Loop from Exiting?
  • How to Show Progress of Running Tasks?
  • How to Run a Task After a Delay?
  • How to Run a Follow-Up Task?
  • How to Execute a Blocking I/O or CPU-bound Function in Asyncio?
• Common Objections to Using Asyncio
  • What About the Global Interpreter Lock (GIL)?
  • Are Python Coroutines “Real“?
  • Isn’t Python Concurrency Buggy?
  • Isn’t Python a Bad Choice for Concurrency?
  • Why Not Use Threads Instead?
• Further Reading
  • Python Asyncio Books
  • Other Books
  • APIs
  • References
• Conclusions