Issue with DistPersonDetector in Person Detection

[dnaveenr]

Hello,

I've tried out the DistPersonDetector in persondetector.py. I get the following error:

Traceback (most recent call last):
  File "person_detection_multi_gpu.py", line 15, in <module>
    detector = DistPersonDetector('rcnn', cfg, weight_det)
  File "/movienet/tools/detector/persondetector.py", line 136, in __init__
    broadcast_buffers=False)
  File "/lib/python3.7/site-packages/torch/nn/parallel/distributed.py", line 255, in __init__
    self.process_group = _get_default_group()
  File "/lib/python3.7/site-packages/torch/distributed/distributed_c10d.py", line 262, in _get_default_group
    raise RuntimeError("Default process group has not been initialized, "
RuntimeError: Default process group has not been initialized, please make sure to call init_process_group.

Any inputs on how we can get this working and the correct way to initialize init_process_group().