Make INFO-level logs not red in PyCharm

Description & Motivation

In PyCharm, informational messages from Lightning are printed in red, which doesn’t look great and obscures real errors.

This is because the logger is printing to stderr and PyCharm by default makes that red.

Pitch

You can fix this by tweaking your root logger to print to stdout for INFO and below, and stderr for everything else. All the other loggers will inherit from this

In pytorch_lightning/__init__.py:

_logger = logging.getLogger(__name__)
_logger.setLevel(logging.INFO)

# log lower levels to stdout
stdout_handler = logging.StreamHandler(stream=sys.stdout)
stdout_handler.addFilter(lambda rec: rec.levelno <= logging.INFO)
_logger.addHandler(stdout_handler)

# log higher levels to stderr (red)
stderr_handler = logging.StreamHandler(stream=sys.stderr)
stderr_handler.addFilter(lambda rec: rec.levelno > logging.INFO)
_logger.addHandler(stderr_handler)

Which then prints like so:

Alternatives

No response

Additional context

No response

cc @borda @justusschock

[carmocca]

Logging to stderr is usually on purpose for libraries/frameworks. The main benefit is that it uses a different stream than the regular prints/logs that are generated from the user code.

This decision is mainly a “stylistic standard” but changing it would be an unavoidable breaking change.

For example, I’ve written PL scripts where I print results relevant to my experiment (to stdout) and pipe the command into a text file (python script.py > out.txt). Doing this change would break such workflow and would make it difficult to separate user logs from library logs.

The same can be said for colored logs. Many terminals do not support rendering so adding them can add intentionally annoying lines in between the valuable messages for the color output. Maybe this is fine as long as we adhere to the requirements in https://no-color.org. Still, a too-colorful choice can be distracting so I would ask for examples of how some experiment logs would show first.

[carmocca]

It’s probably more involved than that, because in the wild people use really different terminals. I suggest looking at the rich.Console implementation as a reference. If you cmd+F for “color” in the file, you’ll see several interesting details.

If you are feeling brave, feel free to open a PR for color support specifically and we can discuss details there.