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- Fixed exception handler in the asyncio test runner not properly handling a context
that does not contain the ``exception`` key


- Fixed ``TypeError`` in ``get_current_task()`` on asyncio when using a custom ``Task`` factory
- Updated type annotations on ``run_process()`` and ``open_process()``:

* ``command`` now accepts accepts bytes and sequences of bytes
* ``stdin``, ``stdout`` and ``stderr`` now accept file-like objects
(PR by John T. Wodder II)
- Changed the pytest plugin to run both the setup and teardown phases of asynchronous
generator fixtures within a single task to enable use cases such as cancel scopes and
task groups where a context manager straddles the ``yield``


- Added ``start_new_session`` keyword argument to ``run_process()`` and ``open_process()``
(PR by Jordan Speicher)
- Fixed deadlock in synchronization primitives on asyncio which can happen if a task acquiring a
primitive is hit with a native (not AnyIO) cancellation with just the right timing, leaving the
next acquiring task waiting forever (`398 <>`_)
- Added workaround for bpo-46313_ to enable compatibility with OpenSSL 3.0

.. _bpo-46313:


- Added context propagation to/from worker threads in ``to_thread.run_sync()``,
```` and ``from_thread.run_sync()``
(`363 <>`_; partially based on a PR by Sebastián

**NOTE**: Requires Python 3.7 to work properly on asyncio!
- Fixed race condition in ``Lock`` and ``Semaphore`` classes when a task waiting on ``acquire()``
is cancelled while another task is waiting to acquire the same primitive
(`387 <>`_)
- Fixed async context manager's ``__aexit__()`` method not being called in
``BlockingPortal.wrap_async_context_manager()`` if the host task is cancelled
(`381 <>`_; PR by Jonathan Slenders)
- Fixed worker threads being marked as being event loop threads in sniffio
- Fixed task parent ID not getting set to the correct value on asyncio
- Enabled the test suite to run without IPv6 support, trio or pytest plugin autoloading


- 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


- 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


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


- Added missing documentation for the ``ExceptionGroup.exceptions`` attribute
- Changed the asyncio test runner not to use uvloop by default (to match the behavior of
- 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


- 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``
- 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


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


- 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
- 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


- 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
- 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)


- 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.


- Curio support has been dropped (see the :doc:`FAQ <faq>` as for why)
- API changes:

* **BACKWARDS INCOMPATIBLE** Submodules under ```` have been made private (use only
```` 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()`` →
* ``open_cancel_scope()`` → ``anyio.CancelScope()``
* ``run_sync_in_worker_thread()`` → ``anyio.to_thread.run_sync()``
* ``run_async_from_thread()`` → ````
* ``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 ```` instead now)
* **BACKWARDS INCOMPATIBLE** The ``SocketStream`` and ``SocketListener`` classes were made
* Made all non-frozen dataclasses hashable with ``eq=False``
* Removed ``__slots__`` from ``BlockingPortal``

See the :doc:`migration documentation <migration>` for instructions on how to deal with these
- 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()``
* 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
- Added the ``RunVar`` class for scoping variables to the running event loop


- 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
- 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


- 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 ````
- 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


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


- 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
- Fixed ``wait_all_tasks_blocked()`` raising ``AttributeError`` on asyncio if a native task is
waiting on an async generator's ``asend()`` method


- 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 ```` 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
- **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
- ``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
- ``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)

.. _IDNA 2008:


- 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


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


- 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


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


- 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


- 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()``


- Added the possibility to parametrize regular pytest test functions against the selected list of
- 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 ```` 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


- 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


- 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

.. _pathlib2:


- 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)

.. _Hypothesis:


- 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