def init_process_group(self, backend):
        """
        Initializes the default PyTorch distributed process group.
        """
        # of not printing logger.info messages on processes with rank > 0
        logger.warning('trying to initialize process group ...')
        torch.distributed.init_process_group(backend=backend,
                                             init_method=self.init_method_url,
                                             world_size=self.world_size,
                                             rank=self.rank)
        logger.warning('process group initialized')

        Initializes the default PyTorch distributed process group.
        
trainer/utils/mpi_adapter.py