code: def gather_host(
      self,
      rank,
      world_size,
      comm,
      cupy_sign_list_packed,
      cupy_recvbuf_sign,
      cupy_worker_scale,
      cupy_recvbuf_scale,
  ):
      # In-place operations are not possible for newly created cupy arrays
      # so we need to return the new buffers
      numpy_recvbuf_sign = np.zeros(
          [world_size, cupy_sign_list_packed[rank].size],
          dtype=cupy_sign_list_packed[0].dtype,
      )
      numpy_recvbuf_scale = np.zeros(
          [world_size, 1], dtype=cupy_worker_scale.dtype
      )
  
      # 1. convert from cupy to numpy
      numpy_sign_list_packed = cupy_sign_list_packed
  
      for idx in range(world_size):
          numpy_sign_list_packed[idx] = cupy.asnumpy(
              cupy_sign_list_packed[idx]
          )
  
      numpy_worker_scale = cupy.asnumpy(cupy_worker_scale)
      numpy_recvbuf_scale = cupy.asnumpy(cupy_recvbuf_scale)
  
      cupy.cuda.get_current_stream().synchronize()
  
      # 2. use numpy buffers for communication
      requests = []
  
      for idx in range(world_size):
          req_sign = self.my_igather(
              rank,
              world_size,
              comm,
              numpy_sign_list_packed[idx],
              numpy_recvbuf_sign,
              root=idx,
          )
          requests += req_sign
  
      for idx in range(world_size):
          req_scale = self.my_igather(
              rank,
              world_size,
              comm,
              numpy_worker_scale,
              numpy_recvbuf_scale,
              root=idx,
          )
          requests += req_scale
  
      MPI.Request.Waitall(requests)
  
      # 3. Convert back from numpy to cupy
      cupy_recvbuf_sign = cupy.asarray(numpy_recvbuf_sign)
      for idx in range(world_size):
          cupy_sign_list_packed[idx] = cupy.asarray(
              numpy_sign_list_packed[idx]
          )
  
      cupy_worker_scale = cupy.asarray(numpy_worker_scale)
      cupy_recvbuf_scale = cupy.asarray(numpy_recvbuf_scale)
      cupy.cuda.get_current_stream().synchronize()
  
      return (
          cupy_sign_list_packed,
          cupy_recvbuf_sign,
          cupy_worker_scale,
          cupy_recvbuf_scale,
      )
  
file_path: H2O/h2o_flexgen/benchmark/third_party/DeepSpeed/deepspeed/runtime/comm/mpi.py
imports: import torch
  import cupy
  import time
  import numpy
  from mpi4py import MPI
  from deepspeed.runtime.compression.cupy import CupyBackend
label_desc: Use image node_id 4 for calling the MpiBackend obj's underlying member method code with example usage: obj.gather_host(rank, world_size, comm, cupy_sign_list_packed, cupy_recvbuf_sign, cupy_worker_scale, cupy_recvbuf_scale) and returns: cupy_sign_list_packed,  cupy_recvbuf_sign,  cupy_worker_scale,  cupy_recvbuf_scale