[bugfix] Accumulated_gradient and TensoBoard

[tchaton]

What does this PR do?

This PR tries to improve the logging display on TensorBoard when using accumulated_grad_batches > 1.
It also introduces log_epoch_metrics_on_step parameter within the trainer.

log_epoch_metrics_on_step idea was dropped !

Fixes #4304

log_epoch_metrics_on_step = True

log_epoch_metrics_on_step = False

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[pep8speaks]

Hello @tchaton! Thanks for updating this PR.

• In the file pytorch_lightning/trainer/connectors/logger_connector/logger_connector.py:

Line 193:121: E501 line too long (122 > 120 characters)
Line 194:121: E501 line too long (134 > 120 characters)

Comment last updated at 2020-11-25 12:01:40 UTC

[codecov]

Codecov Report

Merging #4738 (f5cb188) into master (d24a267) will increase coverage by 0%.
The diff coverage is 100%.

@@          Coverage Diff           @@
##           master   #4738   +/-   ##
======================================
  Coverage      93%     93%           
======================================
  Files         118     118           
  Lines        9031    9033    +2     
======================================
+ Hits         8403    8405    +2     
  Misses        628     628           

[tchaton]

@tchaton can we split this to 2 PRs?

Hey @edenlightning, I removed the parameters as you suggested. This PR contains only the fix for tensorboard logging in case of accumulated_gradient > 1

[Borda]

sure about the APPI, and pls update docs

[SkafteNicki]

LGTM

[tchaton]

Hey @williamFalcon , can you review this one ?