detectron2报错解决方案 RuntimeError: Default process group has not been initialized, please make sure to c

问题：RuntimeError: Default process group has not been initialized, please make sure to call init_process_group.
解决： github503问题，解决方案，windows环境使用detectron2 # 503

 cuda_num = os.environ['CUDA_VISIBLE_DEVICES']
 cuda_num_list = list(cuda_num.split(","))
	if len(cuda_num_list) == 1:
        import torch.distributed as dist
   
        dist.init_process_group(backend='nccl', init_method='tcp://localhost:23456', rank=0, world_size=1)
    出现报错 RuntimeError: Distributed package doesn't have NCCL built in
    原因分析： windows不支持NCCL backend
    解决方案： 在dist.init_process_group语句之前添加backend=‘gloo’，也就是在windows中使用GLOO替代NCCL