validation_epoch_end with DDP
What is your question?
I am trying to implement a metric which needs access to whole data. So instead of updating the metric in *_step() methods, I am trying to collect the outputs in the *_epoch_end() methods. However, the outputs contain only the output of the partition of the data each device gets.  Basically if there are n devices, then each device is getting 1/n of the total outputs.
Stackoverflow Post
What's your environment?

OS: ubuntu
Packaging: conda
Version [1.0.4
Pytorch: 1.6.0