Resolves the duplicate logs issue

[qizhuli]

Motivation

The console handler present in the root logger leads to duplicate messages being printed on the console, creating unnecessary clutter. This has also been discussed here. This PR fixes this issue, and resolves #1000.

Modification

In mmcv.utils.get_logger(), all StreamHandler present in the root logger are set to log at the ERROR level, instead of NOTSET which is the default.

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[zhouzaida]

hi @qizhuli ,please fix the CI

[qizhuli]

@zhouzaida Hi there. I have revised my PR to satisfy the tests. Now it sets any StreamHandler associated with the root logger to log at the ERROR level (instead of NOTSET by default).

Over the past few days, I did a little more searching on this matter, and it seems to me that the cleanest solution would be to do logger.propagate = False right after calling logger = logging.getLogger(name), which would stop messages from being sent to the root logger completely. Coincidentally, that's exactly the approach adopted by Detectron2. Unfortunately, this approach is problematic with the caplog fixture in mmcv's tests, as killing child-to-parent propagation would cut off the LogCaptureHandler too, on which caplog depends. People have been talking about it at lengths in eisensheng/pytest-catchlog#44 and pytest-dev/pytest#3697, but there seems to be no official fix after more than 5 years...

[codecov]

Codecov Report

Merging #1164 (b203441) into master (b035fe9) will decrease coverage by 0.03%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master    #1164      +/-   ##
==========================================
- Coverage   68.01%   67.98%   -0.04%     
==========================================
  Files         159      159              
  Lines       10421    10429       +8     
  Branches     1895     1899       +4     
==========================================
+ Hits         7088     7090       +2     
- Misses       2966     2969       +3     
- Partials      367      370       +3     

Flag	Coverage Δ
unittests	67.98% <33.33%> (-0.04%)	⬇️

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Impacted Files	Coverage Δ
mmcv/utils/logging.py	95.23% <33.33%> (-4.77%)	⬇️
mmcv/ops/saconv.py	83.58% <0.00%> (-5.13%)	⬇️

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[ZwwWayne]

Can be merged after verification in downstream repos like MMSeg/MMDet