ModuleNotFoundError: No module named 'anyio._backends._curio'

[maingoh]

The sample from the documentation does not seem to work with curio.
I get the following stacktrace:

**Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/anyio/_core/_eventloop.py", line 153, in get_asynclib
    return sys.modules[modulename]
KeyError: 'anyio._backends._curio'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<stdin>", line 3, in main
  File "/usr/local/lib/python3.8/site-packages/httpx/_client.py", line 1729, in get
    return await self.request(
  File "/usr/local/lib/python3.8/site-packages/httpx/_client.py", line 1506, in request
    return await self.send(request, auth=auth, follow_redirects=follow_redirects)
  File "/usr/local/lib/python3.8/site-packages/httpx/_client.py", line 1593, in send
    response = await self._send_handling_auth(
  File "/usr/local/lib/python3.8/site-packages/httpx/_client.py", line 1621, in _send_handling_auth
    response = await self._send_handling_redirects(
  File "/usr/local/lib/python3.8/site-packages/httpx/_client.py", line 1658, in _send_handling_redirects
    response = await self._send_single_request(request)
  File "/usr/local/lib/python3.8/site-packages/httpx/_client.py", line 1695, in _send_single_request
    response = await transport.handle_async_request(request)
  File "/usr/local/lib/python3.8/site-packages/httpx/_transports/default.py", line 353, in handle_async_request
    resp = await self._pool.handle_async_request(req)
  File "/usr/local/lib/python3.8/site-packages/httpcore/_async/connection_pool.py", line 216, in handle_async_request
    status = RequestStatus(request)
  File "/usr/local/lib/python3.8/site-packages/httpcore/_async/connection_pool.py", line 19, in __init__
    self._connection_acquired = AsyncEvent()
  File "/usr/local/lib/python3.8/site-packages/httpcore/_synchronization.py", line 29, in __init__
    self._event = anyio.Event()
  File "/usr/local/lib/python3.8/site-packages/anyio/_core/_synchronization.py", line 78, in __new__
    return get_asynclib().Event()
  File "/usr/local/lib/python3.8/site-packages/anyio/_core/_eventloop.py", line 155, in get_asynclib
    return import_module(modulename)
  File "/usr/local/lib/python3.8/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 973, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'anyio._backends._curio'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/anyio/_core/_eventloop.py", line 153, in get_asynclib
    return sys.modules[modulename]
KeyError: 'anyio._backends._curio'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.8/site-packages/curio/kernel.py", line 822, in run
    return kernel.run(corofunc, *args)
  File "/usr/local/lib/python3.8/site-packages/curio/kernel.py", line 172, in run
    raise ret_exc
  File "/usr/local/lib/python3.8/site-packages/curio/kernel.py", line 736, in kernel_run
    trap = current.send(current._trap_result)
  File "/usr/local/lib/python3.8/site-packages/curio/task.py", line 167, in send
    return self._send(value)
  File "/usr/local/lib/python3.8/site-packages/curio/task.py", line 171, in _task_runner
    return await coro
  File "<stdin>", line 4, in main
  File "/usr/local/lib/python3.8/site-packages/httpx/_client.py", line 1975, in __aexit__
    await self._transport.__aexit__(exc_type, exc_value, traceback)
  File "/usr/local/lib/python3.8/site-packages/httpx/_transports/default.py", line 332, in __aexit__
    await self._pool.__aexit__(exc_type, exc_value, traceback)
  File "/usr/local/lib/python3.8/site-packages/httpcore/_async/connection_pool.py", line 326, in __aexit__
    await self.aclose()
  File "/usr/local/lib/python3.8/site-packages/httpcore/_async/connection_pool.py", line 303, in aclose
    async with self._pool_lock:
  File "/usr/local/lib/python3.8/site-packages/httpcore/_synchronization.py", line 15, in __aenter__
    await self._lock.acquire()
  File "/usr/local/lib/python3.8/site-packages/anyio/_core/_synchronization.py", line 121, in acquire
    await checkpoint_if_cancelled()
  File "/usr/local/lib/python3.8/site-packages/anyio/lowlevel.py", line 42, in checkpoint_if_cancelled
    await get_asynclib().checkpoint_if_cancelled()
  File "/usr/local/lib/python3.8/site-packages/anyio/_core/_eventloop.py", line 155, in get_asynclib
    return import_module(modulename)
  File "/usr/local/lib/python3.8/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 973, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'anyio._backends._curio'

It might be because httpx use anyio which does not support curio anymore ?

Can httpx support curio without using anyio ?

[florimondmanca]

@maingoh Hi, I moved this to a Q&A discussion while we assess if there's something to address on the HTTPX side.

It turns out curio support was dropped from HTTPCore in version 0.14.0, released in November 2021: https://github.com/encode/httpcore/blob/master/CHANGELOG.md#0140-november-11th-2021

Note that curio support is not currently available in 0.14.0. If you're using httpcore with curio please get in touch, so we can assess if we ought to prioritize it as a feature or not.

This was reflected in HTTPX 0.21.0: https://github.com/encode/httpx/blob/master/CHANGELOG.md#0210-15th-november-2021

Removed

• Curio support is no longer currently included. Please get in touch if you require this, so that we can assess priorities.

Curio support can be discussed, although, right now it does seem like curio is incorrectly mentioned in docs.

[maingoh]

Sorry, I realized there is a discussion about this #1953. You may want to close this discussion..

[florimondmanca]

I opened issue #2233 for dropping curio from the docs. Looks like discussion can continue on #1953. :) Feel free to mark a comment as answer to mark this discussion as resolved.

[maingoh]

I don't strictly need curio for now, I was mainly trying to benchmark httpx using either asyncio or curio to see if it could speed up my script.