18.5. asyncio — 异步 I/O、事件循环、协程及任务 ¶

This module provides infrastructure for writing single-threaded concurrent code using coroutines, multiplexing I/O access over sockets and other resources, running network clients and servers, and other related primitives. Here is a more detailed list of the package contents:

• a pluggable 事件循环 with various system-specific implementations;
• transport and protocol abstractions (similar to those in Twisted );
• concrete support for TCP, UDP, SSL, subprocess pipes, delayed calls, and others (some may be system-dependent);
• a Future class that mimics the one in the concurrent.futures module, but adapted for use with the event loop;
• coroutines and tasks based on yield from ( PEP 380 ), to help write concurrent code in a sequential fashion;
• cancellation support for Future s and coroutines;
• 同步原语 for use between coroutines in a single thread, mimicking those in the threading 模块；
• an interface for passing work off to a threadpool, for times when you absolutely, positively have to use a library that makes blocking I/O calls.

Asynchronous programming is more complex than classical “sequential” programming: see the Develop with asyncio page which lists common traps and explains how to avoid them. Enable the debug mode during development to detect common issues.

内容表：

• 18.5.1. 基事件循环
  • 18.5.1.1. 运行事件循环
  • 18.5.1.2. 调用
  • 18.5.1.3. 延迟调用
  • 18.5.1.4. Futures
  • 18.5.1.5. 任务
  • 18.5.1.6. 创建连接
  • 18.5.1.7. 创建监听连接
  • 18.5.1.8. Watch file descriptors
  • 18.5.1.9. 低级套接字操作
  • 18.5.1.10. Resolve host name
  • 18.5.1.11. 连接管道
  • 18.5.1.12. UNIX 信号
  • 18.5.1.13. 执行器
  • 18.5.1.14. 错误处理 API
  • 18.5.1.15. 调试模式
  • 18.5.1.16. 服务器
  • 18.5.1.17. Handle
  • 18.5.1.18. 事件循环范例
    • 18.5.1.18.1. Hello World with call_soon()
    • 18.5.1.18.2. Display the current date with call_later()
    • 18.5.1.18.3. Watch a file descriptor for read events
    • 18.5.1.18.4. Set signal handlers for SIGINT and SIGTERM
• 18.5.2. 事件循环
  • 18.5.2.1. 事件循环函数
  • 18.5.2.2. 可用事件循环
  • 18.5.2.3. 平台支持
    • 18.5.2.3.1. Windows
    • 18.5.2.3.2. Mac OS X
  • 18.5.2.4. 事件循环策略和默认策略
  • 18.5.2.5. 事件循环策略接口
  • 18.5.2.6. 访问全局循环策略
• 18.5.3. 任务和协程
  • 18.5.3.1. 协程
    • 18.5.3.1.1. Example: Hello World coroutine
    • 18.5.3.1.2. Example: Coroutine displaying the current date
    • 18.5.3.1.3. Example: Chain coroutines
  • 18.5.3.2. InvalidStateError
  • 18.5.3.3. TimeoutError
  • 18.5.3.4. Future
    • 18.5.3.4.1. Example: Future with run_until_complete()
    • 18.5.3.4.2. Example: Future with run_forever()
  • 18.5.3.5. 任务
    • 18.5.3.5.1. Example: Parallel execution of tasks
  • 18.5.3.6. 任务函数
• 18.5.4. 传输和协议 (基于回调的 API)
  • 18.5.4.1. 传输
    • 18.5.4.1.1. BaseTransport
    • 18.5.4.1.2. ReadTransport
    • 18.5.4.1.3. WriteTransport
    • 18.5.4.1.4. DatagramTransport
    • 18.5.4.1.5. BaseSubprocessTransport
  • 18.5.4.2. 协议
    • 18.5.4.2.1. 协议类
    • 18.5.4.2.2. Connection callbacks
    • 18.5.4.2.3. Streaming protocols
    • 18.5.4.2.4. Datagram protocols
    • 18.5.4.2.5. Flow control callbacks
    • 18.5.4.2.6. Coroutines and protocols
  • 18.5.4.3. 协议范例
    • 18.5.4.3.1. TCP 回显客户端协议
    • 18.5.4.3.2. TCP 回显服务器协议
    • 18.5.4.3.3. UDP 回显客户端协议
    • 18.5.4.3.4. UDP 回显服务器协议
    • 18.5.4.3.5. Register an open socket to wait for data using a protocol
• 18.5.5. 流 (基于协程的 API)
  • 18.5.5.1. Stream functions
  • 18.5.5.2. StreamReader
  • 18.5.5.3. StreamWriter
  • 18.5.5.4. StreamReaderProtocol
  • 18.5.5.5. IncompleteReadError
  • 18.5.5.6. LimitOverrunError
  • 18.5.5.7. 流范例
    • 18.5.5.7.1. TCP echo client using streams
    • 18.5.5.7.2. TCP echo server using streams
    • 18.5.5.7.3. Get HTTP headers
    • 18.5.5.7.4. Register an open socket to wait for data using streams
• 18.5.6. 子进程
  • 18.5.6.1. Windows event loop
  • 18.5.6.2. Create a subprocess: high-level API using Process
  • 18.5.6.3. Create a subprocess: low-level API using subprocess.Popen
  • 18.5.6.4. Constants
  • 18.5.6.5. 进程
  • 18.5.6.6. 子进程和线程
  • 18.5.6.7. 子进程范例
    • 18.5.6.7.1. Subprocess using transport and protocol
    • 18.5.6.7.2. Subprocess using streams
• 18.5.7. 同步原语
  • 18.5.7.1. 锁
    • 18.5.7.1.1. 锁
    • 18.5.7.1.2. 事件
    • 18.5.7.1.3. 条件
  • 18.5.7.2. 信号量
    • 18.5.7.2.1. 信号量
    • 18.5.7.2.2. BoundedSemaphore
• 18.5.8. 队列
  • 18.5.8.1. 队列
  • 18.5.8.2. PriorityQueue
  • 18.5.8.3. LifoQueue
    • 18.5.8.3.1. 异常
• 18.5.9. 采用 asyncio 开发
  • 18.5.9.1. asyncio 的调试模式
  • 18.5.9.2. Cancellation
  • 18.5.9.3. Concurrency and multithreading
  • 18.5.9.4. Handle blocking functions correctly
  • 18.5.9.5. Logging
  • 18.5.9.6. Detect coroutine objects never scheduled
  • 18.5.9.7. Detect exceptions never consumed
  • 18.5.9.8. Chain coroutines correctly
  • 18.5.9.9. Pending task destroyed
  • 18.5.9.10. Close transports and event loops

另请参阅

The asyncio module was designed in PEP 3156 . For a motivational primer on transports and protocols, see PEP 3153 .