High workload issue "partially initialized module 'anyio._backends._asyncio' has no attribute 'checkpoint_if_cancelled'"

Hey,

I notice some error are thrown sporadically with no reason

 core.error_handler:log_error:18 - <class 'AttributeError'> - AttributeError("partially initialized module 'anyio._backends._asyncio' has no attribute 'checkpoint_if_cancelled' (most likely due to a circular import)") 

Full stack trace

File "/usr/local/lib/python3.9/site-packages/httpx/_client.py", line 1568, in send
 response = await self._send_handling_auth(
File "/usr/local/lib/python3.9/site-packages/httpx/_client.py", line 1604, in _send_handling_auth
 response = await self._send_handling_redirects(
File "/usr/local/lib/python3.9/site-packages/httpx/_client.py", line 1640, in _send_handling_redirects
 response = await self._send_single_request(request, timeout)
File "/usr/local/lib/python3.9/site-packages/httpx/_client.py", line 1681, in _send_single_request
 ) = await transport.handle_async_request(
File "/usr/local/lib/python3.9/site-packages/httpx_socks/_async_transport.py", line 60, in handle_async_request
 response = await connection.handle_async_request(
File "/usr/local/lib/python3.9/site-packages/httpcore/_async/connection.py", line 128, in handle_async_request
 async with self.request_lock:
File "/usr/local/lib/python3.9/site-packages/httpcore/_backends/base.py", line 76, in __aenter__
 await self.acquire()
File "/usr/local/lib/python3.9/site-packages/httpcore/_backends/anyio.py", line 104, in acquire
 await self._lock.acquire()
File "/usr/local/lib/python3.9/site-packages/anyio/_core/_synchronization.py", line 117, in acquire
 await checkpoint_if_cancelled()
File "/usr/local/lib/python3.9/site-packages/anyio/lowlevel.py", line 42, in checkpoint_if_cancelled
 await get_asynclib().checkpoint_if_cancelled()

Env: Linux : 5.4.0-80-generic - Running in k8s Python interpreter : Python 3.9.5

Dependencies :

hpack==4.0.0
httpcore==0.13.6
httptools==0.2.0
httpx==0.18.2
httpx-socks==0.4.1
hyperframe==6.0.1
h11==0.12.0
h2==4.0.0

Did someone already experience the same issue ? My project is using asyncio package as async lib, so nothing exoctic here. The send method is called in a multi threaded app.

Thanks, will continue to dig on my side what happened

[2-X]

@tomchristie lol that solves my issue, thanks! i was just going by the docs which only use AsyncClient as an example and that misled me a bit

[tomchristie]

Since my application requires http/2, I need to make an async client with httpx (since that’s the only one that supports http/2)

You can use HTTP/2 with a regular client…

client = httpx.Client(http2=True)

(Doesn’t need to be async)