Version history

This library adheres to Semantic Versioning 2.0.

3.3.4

Fixed BrokenResourceError instead of EndOfStream being raised in TLSStream when the peer abruptly closes the connection while TLSStream is receiving data with standard_compatible=False set

3.3.3

Fixed UNIX socket listener not setting accepted sockets to non-blocking mode on asyncio
Changed unconnected UDP sockets to be always bound to a local port (on “any” interface) to avoid errors on asyncio + Windows

3.3.2

Fixed cancellation problem on asyncio where level-triggered cancellation for all parent cancel scopes would not resume after exiting a shielded nested scope (#370)

3.3.1

Added missing documentation for the ExceptionGroup.exceptions attribute
Changed the asyncio test runner not to use uvloop by default (to match the behavior of anyio.run())
Fixed RuntimeError on asyncio when a CancelledError is raised from a task spawned through a BlockingPortal (#357)
Fixed asyncio warning about a Future with an exception that was never retrieved which happened when a socket was already written to but the peer abruptly closed the connection

3.3.0

Added asynchronous Path class
Added the wrap_file() function for wrapping existing files as asynchronous file objects
Relaxed the type of the path initializer argument to FileReadStream and FileWriteStream so they accept any path-like object (including the new asynchronous Path class)
Dropped unnecessary dependency on the async_generator library
Changed the generics in AsyncFile so that the methods correctly return either str or bytes based on the argument to open_file()
Fixed an asyncio bug where under certain circumstances, a stopping worker thread would still accept new assignments, leading to a hang

3.2.1

Fixed idle thread pruning on asyncio sometimes causing an expired worker thread to be assigned a task

3.2.0

Added Python 3.10 compatibility
Added the ability to close memory object streams synchronously (including support for use as a synchronous context manager)
Changed the default value of the use_uvloop asyncio backend option to False to prevent unsafe event loop policy changes in different threads
Fixed to_thread.run_sync() hanging on the second call on asyncio when used with loop.run_until_complete()
Fixed to_thread.run_sync() prematurely marking a worker thread inactive when a task await on the result is cancelled
Fixed ResourceWarning about an unclosed socket when UNIX socket connect fails on asyncio
Fixed the type annotation of open_signal_receiver() as a synchronous context manager
Fixed the type annotation of DeprecatedAwaitable(|List|Float).__await__ to match the typing.Awaitable protocol

3.1.0

Added env and cwd keyword arguments to run_process() and open_process.
Added support for mutation of CancelScope.shield (PR by John Belmonte)
Added the sleep_forever() and sleep_until() functions
Changed asyncio task groups so that if the host and child tasks have only raised CancelledErrors, just one CancelledError will now be raised instead of an ExceptionGroup, allowing asyncio to ignore it when it propagates out of the task
Changed task names to be converted to str early on asyncio (PR by Thomas Grainger)
Fixed sniffio._impl.AsyncLibraryNotFoundError: unknown async library, or not in async context on asyncio and Python 3.6 when to_thread.run_sync() is used from loop.run_until_complete()
Fixed odd ExceptionGroup: 0 exceptions were raised in the task group appearing under certain circumstances on asyncio
Fixed wait_all_tasks_blocked() returning prematurely on asyncio when a previously blocked task is cancelled (PR by Thomas Grainger)
Fixed declared return type of TaskGroup.start() (it was declared as None, but anything can be returned from it)
Fixed TextStream.extra_attributes raising AttributeError (PR by Thomas Grainger)
Fixed await maybe_async(current_task()) returning None (PR by Thomas Grainger)
Fixed: pickle.dumps(current_task()) now correctly raises TypeError instead of pickling to None (PR by Thomas Grainger)
Fixed return type annotation of Event.wait() (bool → None) (PR by Thomas Grainger)
Fixed return type annotation of RunVar.get() to return either the type of the default value or the type of the contained value (PR by Thomas Grainger)
Fixed a deprecation warning message to refer to maybe_async() and not maybe_awaitable() (PR by Thomas Grainger)
Filled in argument and return types for all functions and methods previously missing them (PR by Thomas Grainger)

3.0.1

Fixed to_thread.run_sync() raising RuntimeError on asyncio when no “root” task could be found for setting up a cleanup callback. This was a problem at least on Tornado and possibly also Twisted in asyncio compatibility mode. The life of worker threads is now bound to the the host task of the topmost cancel scope hierarchy starting from the current one, or if no cancel scope is active, the current task.

3.0.0

Curio support has been dropped (see the FAQ as for why)
API changes:
- BACKWARDS INCOMPATIBLE Submodules under anyio.abc. have been made private (use only anyio.abc from now on).
- BACKWARDS INCOMPATIBLE The following method was previously a coroutine method and has been converted into a synchronous one:
  - MemoryObjectReceiveStream.receive_nowait()
- The following functions and methods are no longer asynchronous but can still be awaited on (doing so will emit a deprecation warning):
  - current_time()
  - current_effective_deadline()
  - get_current_task()
  - get_running_tasks()
  - CancelScope.cancel()
  - CapacityLimiter.acquire_nowait()
  - CapacityLimiter.acquire_on_behalf_of_nowait()
  - Condition.release()
  - Event.set()
  - Lock.release()
  - MemoryObjectSendStream.send_nowait()
  - Semaphore.release()
- The following functions now return synchronous context managers instead of asynchronous context managers (and emit deprecation warnings if used as async context managers):
  - fail_after()
  - move_on_after()
  - open_cancel_scope() (now just CancelScope(); see below)
  - open_signal_receiver()
- The following functions and methods have been renamed/moved (will now emit deprecation warnings when you use them by their old names):
  - create_blocking_portal() → anyio.from_thread.BlockingPortal()
  - create_capacity_limiter() → anyio.CapacityLimiter()
  - create_event() → anyio.Event()
  - create_lock() → anyio.Lock()
  - create_condition() → anyio.Condition()
  - create_semaphore() → anyio.Semaphore()
  - current_default_worker_thread_limiter() → anyio.to_thread.current_default_thread_limiter()
  - open_cancel_scope() → anyio.CancelScope()
  - run_sync_in_worker_thread() → anyio.to_thread.run_sync()
  - run_async_from_thread() → anyio.from_thread.run()
  - run_sync_from_thread() → anyio.from_thread.run_sync()
  - BlockingPortal.spawn_task → BlockingPortal.start_task_soon
  - CapacityLimiter.set_total_tokens() → limiter.total_tokens = ...
  - TaskGroup.spawn() → TaskGroup.start_soon()
- BACKWARDS INCOMPATIBLE start_blocking_portal() must now be used as a context manager (it no longer returns a BlockingPortal, but a context manager that yields one)
- BACKWARDS INCOMPATIBLE The BlockingPortal.stop_from_external_thread() method (use portal.call(portal.stop) instead now)
- BACKWARDS INCOMPATIBLE The SocketStream and SocketListener classes were made non-generic
- Made all non-frozen dataclasses hashable with eq=False
- Removed __slots__ from BlockingPortal
See the migration documentation for instructions on how to deal with these changes.
Improvements to running synchronous code:
- Added the run_sync_from_thread() function
- Added the run_sync_in_process() function for running code in worker processes (big thanks to Richard Sheridan for his help on this one!)
Improvements to sockets and streaming:
- Added the UNIXSocketStream class which is capable of sending and receiving file descriptors
- Added the FileReadStream and FileWriteStream classes
- create_unix_listener() now removes any existing socket at the given path before proceeding (instead of raising OSError: Address already in use)
Improvements to task groups and cancellation:
- Added the TaskGroup.start() method and a corresponding BlockingPortal.start_task() method
- Added the name argument to BlockingPortal.start_task_soon() (renamed from BlockingPortal.spawn_task())
- Changed CancelScope.deadline to be writable
- Added the following functions in the anyio.lowlevel module:
  - checkpoint()
  - checkpoint_if_cancelled()
  - cancel_shielded_checkpoint()
Improvements and changes to synchronization primitives:
- Added the Lock.acquire_nowait(), Condition.acquire_nowait() and Semaphore.acquire_nowait() methods
- Added the statistics() method to Event, Lock, Condition, Semaphore, CapacityLimiter, MemoryObjectReceiveStream and MemoryObjectSendStream
- Lock and Condition can now only be released by the task that acquired them. This behavior is now consistent on all backends whereas previously only Trio enforced this.
- The CapacityLimiter.total_tokens property is now writable and CapacityLimiter.set_total_tokens() has been deprecated
- Added the max_value property to Semaphore
Asyncio specific improvements (big thanks to Thomas Grainger for his effort on most of these!):
- Cancel scopes are now properly enforced with native asyncio coroutine functions (without any explicit AnyIO checkpoints)
- Changed the asyncio CancelScope to raise a RuntimeError if a cancel scope is being exited before it was even entered
- Changed the asyncio test runner to capture unhandled exceptions from asynchronous callbacks and unbound native tasks which are then raised after the test function (or async fixture setup or teardown) completes
- Changed the asyncio TaskGroup.start_soon() (formerly spawn()) method to call the target function immediately before starting the task, for consistency across backends
- Changed the asyncio TaskGroup.start_soon() (formerly spawn()) method to avoid the use of a coroutine wrapper on Python 3.8+ and added a hint for hiding the wrapper in tracebacks on earlier Pythons (supported by Pytest, Sentry etc.)
- Changed the default thread limiter on asyncio to use a RunVar so it is scoped to the current event loop, thus avoiding potential conflict among multiple running event loops
- Thread pooling is now used on asyncio with run_sync_in_worker_thread()
- Fixed current_effective_deadline() raising KeyError on asyncio when no cancel scope is active
Added the RunVar class for scoping variables to the running event loop

2.2.0

Added the maybe_async() and maybe_async_cm() functions to facilitate forward compatibility with AnyIO 3
Fixed socket stream bug on asyncio where receiving a half-close from the peer would shut down the entire connection
Fixed native task names not being set on asyncio on Python 3.8+
Fixed TLSStream.send_eof() raising ValueError instead of the expected NotImplementedError
Fixed open_signal_receiver() on asyncio and curio hanging if the cancel scope was cancelled before the function could run
Fixed Trio test runner causing unwarranted test errors on BaseException (PR by Matthias Urlichs)
Fixed formatted output of ExceptionGroup containing too many newlines

2.1.0

Added the spawn_task() and wrap_async_context_manager() methods to BlockingPortal
Added the handshake_timeout and error_handler parameters to TLSListener
Fixed Event objects on the trio backend not inheriting from anyio.abc.Event
Fixed run_sync_in_worker_thread() raising UnboundLocalError on asyncio when cancelled
Fixed send() on socket streams not raising any exception on asyncio, and an unwrapped BrokenPipeError on trio and curio when the peer has disconnected
Fixed MemoryObjectSendStream.send() raising BrokenResourceError when the last receiver is closed right after receiving the item
Fixed ValueError: Invalid file descriptor: -1 when closing a SocketListener on asyncio

2.0.2

Fixed one more case of AttributeError: 'async_generator_asend' object has no attribute 'cr_await' on asyncio

2.0.1

Fixed broken MultiListener.extra() (PR by daa)
Fixed TLSStream returning an empty bytes object instead of raising EndOfStream when trying to receive from the stream after a closing handshake
Fixed AttributeError when cancelling a task group’s scope inside an async test fixture on asyncio
Fixed wait_all_tasks_blocked() raising AttributeError on asyncio if a native task is waiting on an async generator’s asend() method

2.0.0

General new features:
- Added support for subprocesses
- Added support for “blocking portals” which allow running functions in the event loop thread from external threads
- Added the anyio.aclose_forcefully() function for closing asynchronous resources as quickly as possible
General changes/fixes:
- BACKWARDS INCOMPATIBLE Some functions have been renamed or removed (see further below for socket/fileio API changes):
  - finalize() → (removed; use contextlib.aclosing() instead)
  - receive_signals() → open_signal_receiver()
  - run_in_thread() → run_sync_in_worker_thread()
  - current_default_thread_limiter() → current_default_worker_thread_limiter()
  - ResourceBusyError → BusyResourceError
- BACKWARDS INCOMPATIBLE Exception classes were moved to the top level package
- Dropped support for Python 3.5
- Bumped minimum versions of trio and curio to v0.16 and v1.4, respectively
- Changed the repr() of ExceptionGroup to match trio’s MultiError
Backend specific changes and fixes:
- asyncio: Added support for ProactorEventLoop. This allows asyncio applications to use AnyIO on Windows even without using AnyIO as the entry point.
- asyncio: The asyncio backend now uses asyncio.run() behind the scenes which properly shuts down async generators and cancels any leftover native tasks
- curio: Worked around the limitation where a task can only be cancelled twice (any cancellations beyond that were ignored)
- asyncio + curio: a cancellation check now calls sleep(0), allowing the scheduler to switch to a different task
- asyncio + curio: Host name resolution now uses IDNA 2008 (with UTS 46 compatibility mapping, just like trio)
- asyncio + curio: Fixed a bug where a task group would abandon its subtasks if its own cancel scope was cancelled while it was waiting for subtasks to finish
- asyncio + curio: Fixed recursive tracebacks when a single exception from an inner task group is reraised in an outer task group
Socket/stream changes:
- BACKWARDS INCOMPATIBLE The stream class structure was completely overhauled. There are now separate abstract base classes for receive and send streams, byte streams and reliable and unreliable object streams. Stream wrappers are much better supported by this new ABC structure and a new “typed extra attribute” system that lets you query the wrapper chain for the attributes you want via .extra(...).
- BACKWARDS INCOMPATIBLE Socket server functionality has been refactored into a network-agnostic listener system
- BACKWARDS INCOMPATIBLE TLS functionality has been split off from SocketStream and can now work over any bidirectional bytes-based stream – you can now establish a TLS encrypted communications pathway over UNIX sockets or even memory object streams. The TLSRequired exception has also been removed as it is no longer necessary.
- BACKWARDS INCOMPATIBLE Buffering functionality (receive_until() and receive_exactly()) was split off from SocketStream into a stream wrapper class (anyio.streams.buffered.BufferedByteReceiveStream)
- BACKWARDS INCOMPATIBLE IPv6 addresses are now reported as 2-tuples. If original 4-tuple form contains a nonzero scope ID, it is appended to the address with % as the separator.
- BACKWARDS INCOMPATIBLE Byte streams (including socket streams) now raise EndOfStream instead of returning an empty bytes object when the stream has been closed from the other end
- BACKWARDS INCOMPATIBLE The socket API has changes:
  - create_tcp_server() → create_tcp_listener()
  - create_unix_server() → create_unix_listener()
  - create_udp_socket() had some of its parameters changed:
    - interface → local_address
    - port → local_port
    - reuse_address was replaced with reuse_port (and sets SO_REUSEPORT instead of SO_REUSEADDR)
  - connect_tcp() had some of its parameters changed:
    - address → remote_address
    - port → remote_port
    - bind_host → local_address
    - bind_port → (removed)
    - autostart_tls → tls
    - tls_hostname (new parameter, when you want to match the certificate against against something else than remote_address)
  - connect_tcp() now returns a TLSStream if TLS was enabled
  - notify_socket_closing() was removed, as it is no longer used by AnyIO
  - SocketStream has changes to its methods and attributes:
    address → .extra(SocketAttribute.local_address)
    
    alpn_protocol → .extra(TLSAttribute.alpn_protocol)
    
    close() → aclose()
    
    get_channel_binding → .extra(TLSAttribute.channel_binding_tls_unique)
    
    cipher → .extra(TLSAttribute.cipher)
    
    getpeercert → .extra(SocketAttribute.peer_certificate) or .extra(SocketAttribute.peer_certificate_binary)
    
    getsockopt() → .extra(SocketAttribute.raw_socket).getsockopt(...)
    
    peer_address → .extra(SocketAttribute.remote_address)
    
    receive_chunks() → (removed; use async for on the stream instead)
    
    receive_delimited_chunks() → (removed)
    
    receive_exactly() → BufferedReceiveStream.receive_exactly()
    
    receive_some() → receive()
    
    receive_until() → BufferedReceiveStream.receive_until()
    
    send_all() → send()
    
    setsockopt() → .extra(SocketAttribute.raw_socket).setsockopt(...)
    
    shared_ciphers → .extra(TLSAttribute.shared_ciphers)
    
    server_side → .extra(TLSAttribute.server_side)
    
    start_tls() → stream = TLSStream.wrap(...)
    
    tls_version → .extra(TLSAttribute.tls_version)
  - UDPSocket has changes to its methods and attributes:
    - address → .extra(SocketAttribute.local_address)
    - getsockopt() → .extra(SocketAttribute.raw_socket).getsockopt(...)
    - port → .extra(SocketAttribute.local_port)
    - receive() no longer takes a maximum bytes argument
    - receive_packets() → (removed; use async for on the UDP socket instead)
    - send() → requires a tuple for destination now (address, port), for compatibility with the new UnreliableObjectStream interface. The sendto() method works like the old send() method.
    - setsockopt() → .extra(SocketAttribute.raw_socket).setsockopt(...)
- BACKWARDS INCOMPATIBLE Renamed the max_size parameter to max_bytes wherever it occurred (this was inconsistently named max_bytes in some subclasses before)
- Added memory object streams as a replacement for queues
- Added stream wrappers for encoding/decoding unicode strings
- Support for the SO_REUSEPORT option (allows binding more than one socket to the same address/port combination, as long as they all have this option set) has been added to TCP listeners and UDP sockets
- The send_eof() method was added to all (bidirectional) streams
File I/O changes:
- BACKWARDS INCOMPATIBLE Asynchronous file I/O functionality now uses a common code base (anyio.AsyncFile) instead of backend-native classes
- BACKWARDS INCOMPATIBLE The File I/O API has changes to its functions and methods:
  - aopen() → open_file()
  - AsyncFileclose() → AsyncFileaclose()
Task synchronization changes:
- BACKWARDS INCOMPATIBLE Queues were replaced by memory object streams
- BACKWARDS INCOMPATIBLE Added the acquire() and release() methods to the Lock, Condition and Semaphore classes
- BACKWARDS INCOMPATIBLE Removed the Event.clear() method. You must now replace the event object with a new one rather than clear the old one.
- Fixed Condition.wait() not working on asyncio and curio (PR by Matt Westcott)
Testing changes:
- BACKWARDS INCOMPATIBLE Removed the --anyio-backends command line option for the pytest plugin. Use the -k option to do ad-hoc filtering, and the anyio_backend fixture to control which backends you wish to run the tests by default.
- The pytest plugin was refactored to run the test and all its related async fixtures inside the same event loop, making async fixtures much more useful
- Fixed Hypothesis support in the pytest plugin (it was not actually running the Hypothesis tests at all)

1.4.0

Added async name resolution functions (anyio.getaddrinfo() and anyio.getnameinfo())
Added the family and reuse_address parameters to anyio.create_udp_socket() (Enables multicast support; test contributed by Matthias Urlichs)
Fixed fail.after(0) not raising a timeout error on asyncio and curio
Fixed move_on_after() and fail_after() getting stuck on curio in some circumstances
Fixed socket operations not allowing timeouts to cancel the task
Fixed API documentation on Stream.receive_until() which claimed that the delimiter will be included in the returned data when it really isn’t
Harmonized the default task names across all backends
wait_all_tasks_blocked() no longer considers tasks waiting on sleep(0) to be blocked on asyncio and curio
Fixed the type of the address parameter in UDPSocket.send() to include IPAddress objects (which were already supported by the backing implementation)
Fixed UDPSocket.send() to resolve host names using anyio.getaddrinfo() before calling socket.sendto() to avoid blocking on synchronous name resolution
Switched to using anyio.getaddrinfo() for name lookups

1.3.1

Fixed warnings caused by trio 0.15
Worked around a compatibility issue between uvloop and Python 3.9 (missing shutdown_default_executor() method)

1.3.0

Fixed compatibility with Curio 1.0
Made it possible to assert fine grained control over which AnyIO backends and backend options are being used with each test
Added the address and peer_address properties to the SocketStream interface

1.2.3

Repackaged release (v1.2.2 contained extra files from an experimental branch which broke imports)

1.2.2

Fixed CancelledError leaking from a cancel scope on asyncio if the task previously received a cancellation exception
Fixed AttributeError when cancelling a generator-based task (asyncio)
Fixed wait_all_tasks_blocked() not working with generator-based tasks (asyncio)
Fixed an unnecessary delay in connect_tcp() if an earlier attempt succeeds
Fixed AssertionError in connect_tcp() if multiple connection attempts succeed simultaneously

1.2.1

Fixed cancellation errors leaking from a task group when they are contained in an exception group
Fixed trio v0.13 compatibility on Windows
Fixed inconsistent queue capacity across backends when capacity was defined as 0 (trio = 0, others = infinite)
Fixed socket creation failure crashing connect_tcp()

1.2.0

Added the possibility to parametrize regular pytest test functions against the selected list of backends
Added the set_total_tokens() method to CapacityLimiter
Added the anyio.current_default_thread_limiter() function
Added the cancellable parameter to anyio.run_in_thread()
Implemented the Happy Eyeballs (RFC 6555) algorithm for anyio.connect_tcp()
Fixed KeyError on asyncio and curio where entering and exiting a cancel scope happens in different tasks
Fixed deprecation warnings on Python 3.8 about the loop argument of asyncio.Event()
Forced the use WindowsSelectorEventLoopPolicy in asyncio.run when on Windows and asyncio to keep network functionality working
Worker threads are now spawned with daemon=True on all backends, not just trio
Dropped support for trio v0.11

1.1.0

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

1.0.0

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

1.0.0rc2

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)

1.0.0rc1

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

1.0.0b2

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

1.0.0b1

Initial release