Version history

This library adheres to Semantic Versioning 2.0.


  • Added the lock parameter to anyio.create_condition() (PR by Matthias Urlichs)

  • Added async iteration for queues (PR by Matthias Urlichs)

  • Added capacity limiters

  • Added the possibility of using capacity limiters for limiting the maximum number of threads

  • Fixed compatibility with trio v0.12

  • Fixed IPv6 support in create_tcp_server(), connect_tcp() and create_udp_socket()

  • Fixed mishandling of task cancellation while the task is running a worker thread on asyncio and curio


  • Fixed pathlib2 compatibility with anyio.aopen()

  • Fixed timeouts not propagating from nested scopes on asyncio and curio (PR by Matthias Urlichs)

  • Fixed incorrect call order in socket close notifications on asyncio (mostly affecting Windows)

  • Prefixed backend module names with an underscore to better indicate privateness


  • Fixed some corner cases of cancellation where behavior on asyncio and curio did not match with that of trio. Thanks to Joshua Oreman for help with this.

  • Fixed current_effective_deadline() not taking shielded cancellation scopes into account on asyncio and curio

  • Fixed task cancellation not happening right away on asyncio and curio when a cancel scope is entered when the deadline has already passed

  • Fixed exception group containing only cancellation exceptions not being swallowed by a timed out cancel scope on asyncio and curio

  • Added the current_time() function

  • Replaced CancelledError with get_cancelled_exc_class()

  • Added support for Hypothesis

  • Added support for PEP 561

  • Use uvloop for the asyncio backend by default when available (but only on CPython)


  • Fixed setsockopt() passing options to the underlying method in the wrong manner

  • Fixed cancellation propagation from nested task groups

  • Fixed get_running_tasks() returning tasks from other event loops

  • Added the parent_id attribute to anyio.TaskInfo

  • Added the get_current_task() function

  • Added guards to protect against concurrent read/write from/to sockets by multiple tasks

  • Added the notify_socket_close() function


  • Added introspection of running tasks via anyio.get_running_tasks()

  • Added the getsockopt() and setsockopt() methods to the SocketStream API

  • Fixed mishandling of large buffers by BaseSocket.sendall()

  • Fixed compatibility with (and upgraded minimum required version to) trio v0.11


  • Initial release