Release history

trio-asyncio 0.13.0 (2023-12-01)


  • Exiting an async with trio_asyncio.open_loop(): block now cancels any asyncio tasks that are still running in the background, like does, so that they have a chance to clean up resources by running async context managers and finally blocks. Previously such tasks would simply be abandoned to the garbage collector, resulting in potential deadlocks and stderr spew. Note that, like, we do still abandon any tasks that are started during this finalization phase and outlive the existing tasks. (#91)


  • A deadlock will no longer occur if trio_asyncio.open_loop() is cancelled before its first checkpoint. We also now cancel and wait on all asyncio tasks even if open_loop() terminates due to an exception that was raised within the async with block. (#115)

  • Uncaught exceptions from asyncio tasks will now propagate out of the trio_asyncio.open_loop() call. This has always been the documented behavior, but didn’t actually work before. (#121)

  • Use of loop.add_reader() or loop.add_writer() with a socket object (rather than a file descriptor) will no longer potentially produce spurious uncaught exceptions if the socket is closed in the reader/writer callback. (#121)


  • trio-asyncio now requires Trio 0.22 and does not produce deprecation warnings. Python 3.12 is now supported. Python 3.6 and 3.7 are no longer supported. (#121)

  • trio-asyncio now indicates its presence to sniffio using the sniffio.thread_local interface that is preferred since sniffio v1.3.0. This should be less likely than the previous approach to cause sniffio.current_async_library() to return incorrect results due to unintended inheritance of contextvars. (#123)

trio-asyncio 0.12.0 (2021-01-07)


  • trio-asyncio now cancels any Trio tasks that were started inside a trio-asyncio loop (using e.g. trio_as_aio()) before it allows the trio-asyncio loop to close. This should resolve some cases of deadlocks and “RuntimeError: Event loop is closed” when an async with open_loop(): block is cancelled. (#89)

  • asyncio.get_running_loop() will now return the trio-asyncio event loop (if running), instead of failing with RuntimeError. (#99)

  • On Python versions with native contextvars support (3.7+), a Trio task started from asyncio context (using trio_as_aio(), trio_as_future(), etc) will now properly inherit the contextvars of its caller. Also, if the entire trio-asyncio loop is cancelled, such tasks will no longer let trio.Cancelled exceptions leak into their asyncio caller. (#76)

  • Previously, cancelling the context surrounding an open_loop() block might cause a deadlock in some cases. The ordering of operations during loop teardown has been improved, so this shouldn’t happen anymore. (#81)

Deprecations and Removals

A number of functions deprecated since 0.10.0 are now removed:



wrap_generator(proc, *args)








run_future TrioEventLoop.run_future


run_coroutine TrioEventLoop.run_coroutine




TrioEventLoop.run_trio(proc, *args)


run_asyncio(proc, *args)



  • trio-asyncio now requires Trio 0.15. Support for Python < 3.6 has been removed. (#82)

  • No more TrioDeprecationWarning about trio.hazmat. (#82)

trio-asyncio 0.11.0 (2020-03-09)


  • Substantially reorganize monkeypatching for asyncio event loop and event loop policy accessors, fixing support for Python 3.8. Also, stop using features deprecated in Trio 0.12. (#66)


  • Calling loop.stop manually no longer causes a deadlock when exiting the context of trio_asyncio.open_loop (#58)

  • now properly returns whatever was returned by the async function it ran, like does. (#57)

  • Replace uses of deprecated trio.open_cancel_scope() with trio.CancelScope.

Deprecations and Removals

  • The non-underscore-prefixed names of trio-asyncio submodules (trio_asyncio.loop, trio_asyncio.adapter, etc) have been deprecated; public names should be imported from trio_asyncio directly.

    trio_asyncio.current_policy, trio_asyncio.TrioChildWatcher, and trio_asyncio.TrioPolicy have been deprecated with no replacement. current_policy is no longer used at all, and the other two are singletons that can’t be customized so there’s no reason to make them publicly visible.

    A number of functions which were already documented as deprecated now raise the new TrioAsyncioDeprecationWarning where previously they provided either no runtime warning or a generic DeprecationWarning. (#64)

trio-asyncio 0.10.0 (2018-12-09)


  • Replace deprecated trio.Queue with new channels, requiring Trio 0.9 or later. (#49)

trio-asyncio 0.9.1 (2018-09-06)


  • Defer creating an asyncio coroutine until asyncio mode is actually entered. (#40)

trio-asyncio 0.9.0 (2018-08-31)


Deprecations and Removals

  • run_asyncio() is deprecated: replace with a aio_as_trio() wrapper.

    trio2aio() is deprecated: replace with aio_as_trio().

    run_future() and TrioEventLoop.run_future() are deprecated: replace with run_aio_future().

    run_coroutine() and TrioEventLoop.run_coroutine() are deprecated: replace with run_aio_coroutine().

    TrioEventLoop.wrap_generator() is deprecated: replace with a aio_as_trio() wrapper.

    TrioEventLoop.run_iterator() is deprecated: replace with aio_as_trio(). (#36)

trio-asyncio 0.8.2 (2018-08-25)


trio-asyncio 0.8.1 (2018-08-25)


  • trio_asyncio now contains an allow_asyncio() wrapper which allows you to seamlessly mix asyncio and trio semantics:

    import asyncio
    import trio
    from trio_asyncio import run, allow_asyncio
    async def main():
        print("Sleeping 1")
        await asyncio.sleep(1)
        print("Sleeping 2")
        await trio.sleep(1)
    run(allow_asyncio, main)

    The problem with this solution is that Trio’s cancellations will no longer be converted to asyncio’s CancelledError within asyncio code. This may or may not be an issue for your code. (#30)

  • While the test suite still requires Python 3.6, trio_asyncio itself now works on Python 3.5.3 and later. (#33)

  • TrioEventLoop.run_asyncio() now supports wrapping async iterators and async context managers, in addition to its existing support for async functions.

trio-asyncio 0.8.0 (2018-08-03)

  • Add TrioEventLoop.run_iterator() as an alias for run_generator().

  • Add support for Python 3.7 via a monkey-patch to asyncio.set_event_loop_policy(). (#23)

  • Deprecate the use of “compatibility mode” / “sync event loops”, except as a tool for running the test suites of existing asyncio projects.

trio-asyncio 0.7.5 (2018-07-23)

  • Use a contextvar to represent the current trio-asyncio loop, rather than the deprecated trio.TaskLocal.

  • Use the outcome library rather than the deprecated trio.hazmat.Result.

  • Better handle errors in wrapped async generators.

trio-asyncio 0.7.0 (2018-03-27)

  • The @trio2aio and @aio2trio decorators now can be used to decorate both async generator functions and async functions that take keyword arguments.

  • open_loop() now takes an optional queue_len= parameter to specify the length of the internal callback queue (for performance tuning).

  • Add BaseTrioEventLoop.synchronize().

  • Monkey-patch asyncio.get_event_loop_policy() and asyncio.get_event_loop() so trio-asyncio works correctly in multithreaded programs that use a different asyncio event loop in other threads.

  • Add wrap_generator() and run_generator() which adapt an asyncio-flavored async generator to be used from Trio code.

trio-asyncio 0.5.0 (2018-02-20)

  • Support contextvars on Python 3.7 and later.

  • Support waiting for child processes even though Trio doesn’t (yet).

trio-asyncio 0.4.2 (2018-02-12)

  • Add

  • Fix a deadlock in SyncTrioEventLoop. Encourage people to use the async TrioEventLoop instead.

trio-asyncio 0.4.1 (2018-02-08)

  • Add TrioEventLoop.run_task() as an entry point for running Trio code in a context that allows asyncio calls, for use when neither a Trio nor an asyncio event loop is running.

trio-asyncio 0.4.0 (2018-02-07)

  • Add support for async loops (open_loop()) and encourage their use. Numerous functions renamed.

trio-asyncio 0.3.0 (2017-10-17)

  • Initial release.