Invalid usage of torch.no_grad Context manager

[8greg8]

🐛 Bug

Using no_grad context manager in the following line https://github.com/PyTorchLightning/pytorch-lightning/blob/127454ade2b851dd267b7f0b4d973bdefd0329e5/pytorch_lightning/utilities/distributed.py#L210
is incorrect as the context manager is callable. Parentheses are missing.

The line should be: with torch.no_grad():

Please reproduce using the BoringModel and post here

https://colab.research.google.com/drive/1snyzXx4G6QCatbs6bN2GCsTFIMdItvmm?usp=sharing

To Reproduce

Expected behavior

• No AttributeError enter
• gathered_loss == loss in BoringModel

Environment

Note: Bugs with code are solved faster ! Colab Notebook should be made public !

• IDE: Please, use our python bug_report_model.py template.

• Colab Notebook: Please copy and paste the output from our environment collection script (or fill out the checklist below manually).

You can get the script and run it with:

wget https://raw.githubusercontent.com/PyTorchLightning/pytorch-lightning/master/tests/collect_env_details.py
# For security purposes, please check the contents of collect_env_details.py before running it.
python collect_env_details.py

• CUDA:
  • GPU:
    • Tesla P100-PCIE-16GB
  • available: True
  • version: 10.1
• Packages:
  • numpy: 1.18.5
  • pyTorch_debug: True
  • pyTorch_version: 1.7.0+cu101
  • pytorch-lightning: 1.1.0
  • tqdm: 4.41.1
• System:
  • OS: Linux
  • architecture:
    • 64bit
  • processor: x86_64
  • python: 3.6.9
  • version: Proposal for help #1 SMP Thu Jul 23 08:00:38 PDT 2020

Additional context

Training using "ddp" accelerator with arbitrary number of gpus.

[github-actions]

Hi! thanks for your contribution!, great first issue!