test_write_timeout(trio) is failing on python3.14 #3686

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1. augustogoulart commented on Oct 10, 2025

   

   augustogoulart

   on Oct 10, 2025

   More actions

   I can see this in python3.13.3 already.

   =============================================================================================== test session starts ================================================================================================
   platform darwin -- Python 3.13.3, pytest-8.4.1, pluggy-1.6.0
   rootdir: /Users/augustogoulart/Workspace/httpx
   configfile: pyproject.toml
   plugins: anyio-4.11.0
   collected 2 items
   
   tests/test_timeouts.py .F                                                                                                                                                                                    [100%]
   
   ===================================================================================================== FAILURES =====================================================================================================
   _____________________________________________________________________________________________ test_write_timeout[trio] _____________________________________________________________________________________________
   
   agen = <async_generator object ByteStream.__aiter__ at 0x108b8d840>
   
       @_core.enable_ki_protection
       def finalizer(agen: AsyncGeneratorType[object, NoReturn]) -> None:
           try:
               self.foreign.remove(id(agen))
           except KeyError:
               is_ours = True
           else:
               is_ours = False
   
           agen_name = name_asyncgen(agen)
           if is_ours:
               runner.entry_queue.run_sync_soon(
                   finalize_in_trio_context,
                   agen,
                   agen_name,
               )
   
               # Do this last, because it might raise an exception
               # depending on the user's warnings filter. (That
               # exception will be printed to the terminal and
               # ignored, since we're running in GC context.)
   >           warnings.warn(
                   f"Async generator {agen_name!r} was garbage collected before it "
                   "had been exhausted. Surround its use in 'async with "
                   "aclosing(...):' to ensure that it gets cleaned up as soon as "
                   "you're done using it.",
                   ResourceWarning,
                   stacklevel=2,
                   source=agen,
               )
   E           ResourceWarning: Async generator 'httpx._content.ByteStream.__aiter__' was garbage collected before it had been exhausted. Surround its use in 'async with aclosing(...):' to ensure that it gets cleaned up as soon as you're done using it.
   
   venv/lib/python3.13/site-packages/trio/_core/_asyncgens.py:122: ResourceWarning

   👍React with 👍1Reacted by Aarni Koskela
2. augustogoulart commented on Oct 10, 2025

   

   augustogoulart

   on Oct 10, 2025

   Last edited by augustogoulart

   More actions

   AFAIK asyncio is more lenient (although providing shutdown_asyncgens() for such cases) and doesn't monitor async generators for resource leaks, while Trio does.

   If an async generator gets garbage collected before being exhausted, asyncio will do nothing while Trio will raise the ResourceWarning shown above.

   In the patch below you can see that if we replace the generator returned by ByteStream.__aiter__ with an async iterator (ByteStreamAsyncIterator), Trio will have nothing to watch for and the tests will pass.

   Not saying this is a solution (maybe?) but it helps illustrating the issue.

   diff --git a/httpx/_content.py b/httpx/_content.py
   index 6f479a0..ae64717 100644
   --- a/httpx/_content.py
   +++ b/httpx/_content.py
   @@ -28,6 +28,24 @@ from ._utils import peek_filelike_length, primitive_value_to_str
    __all__ = ["ByteStream"]
    
    
   +class ByteStreamAsyncIterator:
   +    def __init__(self, stream: bytes) -> None:
   +        self._stream = stream
   +        self._yielded = False
   +
   +    def __aiter__(self) -> AsyncIterator[bytes]:
   +        return self
   +
   +    async def __anext__(self) -> bytes:
   +        if self._yielded:
   +            raise StopAsyncIteration
   +        self._yielded = True
   +        return self._stream
   +
   +    async def aclose(self) -> None:
   +        pass
   +
   +
    class ByteStream(AsyncByteStream, SyncByteStream):
        def __init__(self, stream: bytes) -> None:
            self._stream = stream
   @@ -35,8 +53,8 @@ class ByteStream(AsyncByteStream, SyncByteStream):
        def __iter__(self) -> Iterator[bytes]:
            yield self._stream
    
   -    async def __aiter__(self) -> AsyncIterator[bytes]:
   -        yield self._stream
   +    def __aiter__(self) -> AsyncIterator[bytes]:
   +        return ByteStreamAsyncIterator(self._stream)
    
    
    class IteratorByteStream(SyncByteStream):
3. joao-faria-dev

   added a commit that references this issue on Oct 29, 2025

   fix: resolve async stream resource leak on timeout

   ...

   This issue will close once commit 8216567 is merged into the 'master' branch.

   8216567
4. akx

   added a commit that references this issue on Feb 24, 2026

   Add real async iterator for ByteStreams

   ...

   This issue will close once commit 357b42f is merged into the 'master' branch.

   357b42f