Tensorflow logging messages do not appear

Question

I use tensorflow 1.2.0 installed with pip install.

When I run samples that include

import logging
tf.logging.set_verbosity(tf.logging.INFO)

the logging messages of the form

logging.info('TEST')

do not appear in the terminal output, even with the flag --tostderr.

According to this answer I also tried

os.environ['TF_CPP_MIN_LOG_LEVEL'] = '0'

but still the problem persists. Any ideas?

Answer 1

TF Logging Basics:

So there is a lot of confusion around tensorflow logging, and it is really not well documented. I landed here a few times in my searches, so it seems to be a good place to post an answer.

After some research and experimentation with Ubuntu and Windows (more than I had planned), this is what I got:

There are two flags, similarly named, but with somewhat different semantics:

• TF_CPP_MIN_LOG_LEVEL - which has 3 or 4 basic levels - low numbers = more messages.
  • 0 outputs Information, Warning, Error, and Fatals (default)
  • 1 outputs Warning, and above
  • 2 outputs Errors and above.
  • etc... I didn't check edge cases
• TF_CPP_MIN_VLOG_LEVEL - which causes very very many extra Information errors - really for debugging only - low numbers = less messages.
  • 3 Outputs lots and lots of stuff
  • 2 Outputs less
  • 1 Outputs even less
  • 0 Outputs nothing extra (default)

Additional Notes:

• Since all the VLOG messages are Informational, then LOG needs to be set at 0 for you to see them. Fortunately that is the default.
• These errors go to the standard error so you can redirect them with something like:
  • python tf-program.py &>mylog.log
• These are supposed to be picked up by the os module so you should be able to set them in the environment
• Without the VLOG and with no GPU there are not that many information messages, so you can think logging is not working when it really is.

Windows:

• Except python's os module did not pick them up under Windows. Python never loved Windows...
  • this code sequence works for me in Windows (and would surely work in Linux):
    • import os
    • os.environ['TF_CPP_MIN_LOG_LEVEL'] = '0'
    • os.environ['TF_CPP_MIN_VLOG_LEVEL'] = '3'
    • import tensorflow as tf

Linux:

• Under Linux (bash) you can specify these conveniently on the command line, so with something like:
  • TF_CPP_MIN_VLOG_LEVEL=3 python tf-program.py

FWIW, I tested on TensorFlow 1.7 with this tutorial:

https://github.com/tensorflow/models/tree/master/tutorials/image/mnist

And this is what it looks like: