Support Multiple GPU Testing?

[dyhBUPT]

Hi, thanks for your excellent work!

I wonder if multi-gpu testing is supported? I've tried to set -b 8 -d 8 while evaluating: python3 tools/track.py -f exps/example/dancetrack/yolox_x.py -c xxx/xxx.pth.tar -b 8 -d 8 --fp16 --fuse but got an error:

2022-07-19 10:51:23 | ERROR    | yolox.core.launch:219 - An error has been caught in function '_distributed_worker', process 'MainProcess' (26659), thread 'MainThread' (139709987980224)
...
...
RuntimeError: tensors.size() > 0 INTERNAL ASSERT FAILED at "../torch/csrc/distributed/c10d/reducer.cpp":1929, please report a bug to PyTorch.