Unclean exit from ipython on MacOS

Describe the bug

Hi, I have installed the qsharp package as described here: https://docs.microsoft.com/en-us/quantum/install-guide/python?view=qsharp-preview and have successfully run the Python examples given on my machine in an IPython environment. Hoewever, on exit I receive the following traceback:

Exception ignored in: <function Socket.__del__ at 0x1041b4290>
Traceback (most recent call last):
  File "/Users/mlxd/qstmp/qs_conda/envs/qs_env/lib/python3.7/site-packages/zmq/sugar/socket.py", line 67, in __del__
  File "/Users/mlxd/qstmp/qs_conda/envs/qs_env/lib/python3.7/site-packages/zmq/sugar/socket.py", line 105, in close
  File "/Users/mlxd/qstmp/qs_conda/envs/qs_env/lib/python3.7/site-packages/zmq/sugar/context.py", line 153, in _rm_socket
TypeError: 'NoneType' object is not callable
Exception ignored in: <function Socket.__del__ at 0x1041b4290>
Traceback (most recent call last):
  File "/Users/mlxd/qstmp/qs_conda/envs/qs_env/lib/python3.7/site-packages/zmq/sugar/socket.py", line 67, in __del__
  File "/Users/mlxd/qstmp/qs_conda/envs/qs_env/lib/python3.7/site-packages/zmq/sugar/socket.py", line 105, in close
  File "/Users/mlxd/qstmp/qs_conda/envs/qs_env/lib/python3.7/site-packages/zmq/sugar/context.py", line 153, in _rm_socket
TypeError: 'NoneType' object is not callable
Exception ignored in: <function Socket.__del__ at 0x1041b4290>
Traceback (most recent call last):
  File "/Users/mlxd/qstmp/qs_conda/envs/qs_env/lib/python3.7/site-packages/zmq/sugar/socket.py", line 67, in __del__
  File "/Users/mlxd/qstmp/qs_conda/envs/qs_env/lib/python3.7/site-packages/zmq/sugar/socket.py", line 105, in close
  File "/Users/mlxd/qstmp/qs_conda/envs/qs_env/lib/python3.7/site-packages/zmq/sugar/context.py", line 153, in _rm_socket
TypeError: 'NoneType' object is not callable

To Reproduce To attempt to rule out my python environment, I set up a clean miniconda build and ran the example from there:

cd ~ && mkdir qstmp && cd qstmp
wget https://repo.anaconda.com/miniconda/Miniconda3-latest-MacOSX-x86_64.sh
chmod +x ./Miniconda3-latest-MacOSX-x86_64.sh
./Miniconda3-latest-MacOSX-x86_64.sh -b -p ./qs_conda
source ./qs_conda/bin/activate ;
conda create -n qs_env -y python
conda activate qs_env
dotnet tool install -g Microsoft.Quantum.IQSharp
dotnet iqsharp install
dotnet iqsharp --version
dotnet tool update -g Microsoft.Quantum.IQSharp
pip install qsharp --upgrade
conda install ipython -y
ipython -c "import qsharp"

The result was as listed above. Running ipython -c "import zmq" gave no output.

Expected behavior There should be no output/traceback from importing the qsharp module and exiting.

System information

• OS: MacOS 10.14.6
• iqsharp: 0.9.1908.2906
• Jupyter Core: 1.1.14623.0

If I can give any more input, feel free to let me know.

Thanks, Lee.

[bromeg]

Thank you for reporting this! We’re having some trouble reproducing this reliably on our end, but we are investigating what might be causing this bug.

[rmshaffer]

This appears to be a garbage collection issue in the pyzmq project, tracked by https://github.com/zeromq/pyzmq/issues/1356. It is harmless, since it’s just a failure during garbage collection of something that had already been released.

According to the PR https://github.com/zeromq/pyzmq/pull/1367, it is fixed in version 19.0.1 of pyzmq. I verified this by running pip install pyzmq==19.0.1 and noting that these errors on shutdown stopped occurring.

Closing this issue since it’s external, benign, and is already fixed in the upstream package. Thank you to everyone who reported this!