[BUG] Logging does not work again with pennylane

Expected behavior

Similar to this issue, I was expecting writing logs into a log file by setting:

logging.basicConfig(
      format='%(asctime)s - %(levelname)s: %(message)s',
      filename='log.txt',
      filemode='w'
)

Actual behavior

However, the logger still outputs everything to stdout. I guess that PennyLane may overwrite my logging setting.

Additional information

No response

Source code

# Some qml functions I used
qml.BasisStatePreparation
qml.StronglyEntanglingLayers
qml.AngleEmbedding
qml.StronglyEntanglingLayers
qml.expval
qml.PauliZ
qml.StronglyEntanglingLayers.shape
qml.device
qml.QNode
qml.qnn.TorchLayer

Tracebacks

No response

System information

Name: PennyLane
Version: 0.19.1
Summary: PennyLane is a Python quantum machine learning library by Xanadu Inc.
Home-page: https://github.com/XanaduAI/pennylane
Author: None
Author-email: None
License: Apache License 2.0
Location: /home/qlan3/miniconda3/lib/python3.9/site-packages
Requires: scipy, semantic-version, autograd, pennylane-lightning, cachetools, networkx, autoray, toml, numpy, appdirs
Required-by: PennyLane-Lightning
Platform info:           Linux-5.8.0-44-generic-x86_64-with-glibc2.31
Python version:          3.9.5
Numpy version:           1.20.3
Scipy version:           1.7.1
Installed devices:
- default.gaussian (PennyLane-0.19.1)
- default.mixed (PennyLane-0.19.1)
- default.qubit (PennyLane-0.19.1)
- default.qubit.autograd (PennyLane-0.19.1)
- default.qubit.jax (PennyLane-0.19.1)
- default.qubit.tf (PennyLane-0.19.1)
- default.qubit.torch (PennyLane-0.19.1)
- default.tensor (PennyLane-0.19.1)
- default.tensor.tf (PennyLane-0.19.1)
- lightning.qubit (PennyLane-Lightning-0.19.0)

• I have searched existing GitHub issues to make sure the issue does not already exist.

[Jaybsoni]

So as a closing comment I would like summarize:

When using logging and PennyLane, one should make sure to import and setup logging first BEFORE importing PL to ensure the logger settings are not ignored.

import logging
logging.basicConfig(filename='mylogfile.txt', level=logging.INFO)
logging.info('A log entry.')

import pennylane as qml

@josh146, after looking into this, it seems that the logging we currently do is not used anywhere else in the codebase. In fact, we don’t log to file at all. It might be worth removing completely. Let me know what you think.

[Jaybsoni]

@raghavven and @qlan3,

I just want to confirm if there are any action items here? From the above thread it seems you were able to get your loggers working by swapping the order of the imports and/or removing the line from configuration.py which called the logger in the first place?

Thanks again for pointing this out! Let me know if you are seeing any additional issues around this bug and I can address this it in a bug fix PR, otherwise if it was just a matter of keeping an eye on which order the logger is being imported then we can close the issue here 👍🏼

Cheers,