AnyIO

AnyIO is an asynchronous networking and concurrency library that works on top of either asyncio or trio. It implements trio-like structured concurrency (SC) on top of asyncio and works in harmony with the native SC of trio itself.

Applications and libraries written against AnyIO’s API will run unmodified on either asyncio or trio. AnyIO can also be adopted into a library or application incrementally – bit by bit, no full refactoring necessary. It will blend in with the native libraries of your chosen backend.

Documentation

View full documentation at: https://anyio.readthedocs.io/

Features

AnyIO offers the following functionality:

• Task groups (nurseries in trio terminology)

• High-level networking (TCP, UDP and UNIX sockets)

  • Happy eyeballs algorithm for TCP connections (more robust than that of asyncio on Python 3.8)

  • async/await style UDP sockets (unlike asyncio where you still have to use Transports and Protocols)

• A versatile API for byte streams and object streams

• Inter-task synchronization and communication (locks, conditions, events, semaphores, object streams)

• Worker threads

• Subprocesses

• Asynchronous file I/O (using worker threads)

• Signal handling

AnyIO also comes with its own pytest plugin which also supports asynchronous fixtures. It even works with the popular Hypothesis library.

The manual

• The basics
  • Installation
  • Running async programs
  • Backend specific options
  • Using native async libraries
• Creating and managing tasks
  • Starting and initializing tasks
  • Handling multiple errors in a task group
  • Context propagation
  • Differences with asyncio.TaskGroup
• Cancellation and timeouts
  • Timeouts
  • Shielding
  • Finalization
  • Avoiding cancel scope stack corruption
• Using synchronization primitives
  • Events
  • Semaphores
  • Locks
  • Conditions
  • Capacity limiters
  • Resource guards
  • Queues
• Streams
  • Memory object streams
  • Stapled streams
  • Buffered byte streams
  • Text streams
  • File streams
  • TLS streams
• Using typed attributes
  • Defining your own typed attributes
• Using sockets and streams
  • Working with TCP sockets
  • Working with UNIX sockets
  • Working with UDP sockets
  • Working with UNIX datagram sockets
• Working with threads
  • Running a function in a worker thread
  • Calling asynchronous code from a worker thread
  • Calling synchronous code from a worker thread
  • Calling asynchronous code from an external thread
  • Spawning tasks from worker threads
  • Using asynchronous context managers from worker threads
  • Context propagation
  • Adjusting the default maximum worker thread count
  • Reacting to cancellation in worker threads
  • Sharing a blocking portal on demand
• Using subprocesses
  • Running one-shot commands
  • Working with processes
  • Running functions in worker processes
• Asynchronous file I/O support
  • Asynchronous path operations
• Receiving operating system signals
  • Handling KeyboardInterrupt and SystemExit
• Testing with AnyIO
  • Creating asynchronous tests
  • Specifying the backends to run on
  • Asynchronous fixtures
  • Using async fixtures with higher scopes
  • Technical details
• API reference
  • Event loop
  • Asynchronous resources
  • Typed attributes
  • Timeouts and cancellation
  • Task groups
  • Running code in worker threads
  • Running code in worker processes
  • Running asynchronous code from other threads
  • Async file I/O
  • Streams and stream wrappers
  • Sockets and networking
  • Subprocesses
  • Synchronization
  • Operating system signals
  • Low level operations
  • Testing and debugging
  • Exceptions
• Migrating from AnyIO 3 to AnyIO 4
  • The non-standard exception group class was removed
  • Task groups now wrap single exceptions in groups
  • Syntax for type annotated memory object streams has changed
  • Event loop factories instead of event loop policies
• Migrating from AnyIO 2 to AnyIO 3
  • Asynchronous functions converted to synchronous
  • Starting tasks
  • Blocking portal changes
  • Synchronization primitives
  • Threading functions moved
• Frequently Asked Questions
  • Why is Curio not supported as a backend?
  • Why is Twisted not supported as a backend?
• Getting help
• Reporting bugs
• Contributing to AnyIO
  • Making a pull request on Github
• Version history