fixed bug where tuner would not tune lr if also tuning batch_size

[Palzer]

What does this PR do?

current_step should be set to the global_step instead of global_step + 1. This fixes that issue which was causing the tuner to not tune the learning rate if also tuning batch_size. The comment on the line also implies that this change should have already been made.

Fixes #4616

Before submitting

• Was this discussed/approved via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure your PR does only one thing, instead of bundling different changes together? Otherwise, we ask you to create a separate PR for every change.
• Did you make sure to update the documentation with your changes?
• Did you write any new necessary tests?
• Did you verify new and existing tests pass locally with your changes?
• If you made a notable change (that affects users), did you update the CHANGELOG?

PR review

Anyone in the community is free to review the PR once the tests have passed.
Before you start reviewing make sure you have read Review guidelines. In in short, see following bullet-list:

• Is this pull request ready for review? (if not, please submit in draft mode)
• Check that all items from Before submitting are resolved
• Make sure the title is self explanatory and the description concisely explains the PR
• Add labels and milestones (and optionally projects) to the PR so it can be classified; Bugfixes should be including in bug-fix release milestones (m.f.X) and features should be included in (m.X.b) releases.

Did you have fun?

Make sure you had fun coding 🙃

[pep8speaks]

Hello @Palzer! Thanks for updating this PR.

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2021-03-09 00:00:55 UTC

[codecov]

Codecov Report

Merging #4688 (ebc17f1) into master (9eded7f) will decrease coverage by 2%.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master   #4688    +/-   ##
=======================================
- Coverage      94%     92%    -2%     
=======================================
  Files         161     161            
  Lines       11497   11497            
=======================================
- Hits        10753   10529   -224     
- Misses        744     968   +224     

[Palzer]

Not sure about the failing timing test.

[SkafteNicki]

@Palzer the failing test seems to be unrelated to the change. Could you add some sort of test that shows the issue is solved?

[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 7 days if no further activity occurs. If you need further help see our docs: https://pytorch-lightning.readthedocs.io/en/latest/CONTRIBUTING.html#pull-request or ask the assistance of a core contributor here or on Slack. Thank you for your contributions.

[Borda]

lgtm, mind add some test got this case? :]

[tchaton]

Great catch ! Mind adding a test ?

[Palzer]

My laptop died a week or so ago. New one should be arriving Monday and then I can take care of tests. Sorry for the delay!

[Borda]

@Palzer there won't be any more releases in 1.1.x so I have changed your destination branch to feat 1.2
pls, there is no need to close this PR, just rebase on the target branch, or maybe easier just cherry-pick the commit (@kaushikb11 will help you if needed)

[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 7 days if no further activity occurs. If you need further help see our docs: https://pytorch-lightning.readthedocs.io/en/latest/generated/CONTRIBUTING.html#pull-request or ask the assistance of a core contributor here or on Slack. Thank you for your contributions.

[carmocca]

LGTM

self.beta**(current_step + 1) avoids division by 0

IMO we don't really need a test for this