Option to redirect log messages to console

[jburos]

When fitting long-running models, it can be helpful to see error messages / warnings produced by stancache in the console.

It would be nice to add this option to the config file so that messages are broadcast more widely, particularly when they involve being unable to save to disk.

[jburos]

I'm pretty sure @tavinathanson set this up by default for cohorts, will likely borrow his implementation

[maximz]

Here's a way to print to the console from which jupyter notebook is running, rather than to a notebook itself:

import sys
print("stdout -- visible only in jupyter notebook", file=sys.stdout)
print("stderr -- visible only in jupyter notebook", file=sys.stderr)
alt_stdout = open('/dev/stdout', 'w')
print("this only shows up in the console", file=alt_stdout)

[jburos]

I was thinking of adding something like this snippet of code to add a second output stream handler to the logger, depending on the user's preferences.

    if logger.handlers:
        logger.handlers = []
    stdout_handler = logging.StreamHandler(sys.stdout)
    logger.addHandler(stdout_handler)
    logger.setLevel(logging.INFO)

You can do this now with logging, in a notebook, yourself. I was going to add a convenience so that this can be set in the config files. It looks like you would want to replace the sys.stdout with your alt_stdout above.

Putting these pieces together, it would look something like the following:

    alt_stdout = open('/dev/stdout', 'w')
    stdout_handler = logging.StreamHandler(alt_stdout)
    logger.addHandler(stdout_handler)

or,

    stdout_handler = logging.FileHandler('/dev/stdout')
    logger.addHandler(stdout_handler)