docstr: Close the chunk. Any tensor can't be appended to a closed chunk later.
docstr_tok: ["Close","the","chunk",".","Any","tensor","ca","n't","be","appended","to","a","closed","chunk","later","."]
code: def close_chunk(self):
      """Close the chunk. Any tensor can't be appended to a closed chunk later."""
      # sanity check
      assert self.chunk_temp is not None
  
      # calculate the valid end for each shard
      if self.utilized_size <= self.shard_begin:
          self.valid_end = 0
      elif self.utilized_size < self.shard_end:
          self.valid_end = self.utilized_size - self.shard_begin
  
      if self.chunk_temp.device.type == "cpu":
          self.cuda_global_chunk = self.chunk_temp.to(
              get_current_device()
          )
          self.__update_tensors_ptr()
      else:
          self.cuda_global_chunk = self.chunk_temp
      self.chunk_temp = None
  
      self.__scatter()
      # gathered chunk never have shard attribute
      if self.keep_gathered:
          return
  
      if self.pin_memory or self.shard_device.type == "cpu":
          self.cpu_shard = torch.empty(
              self.shard_size,
              dtype=self.dtype,
              pin_memory=self.pin_memory,
          )
          self.cpu_shard.copy_(self.cuda_shard)
          self.cpu_vis_flag = True  # cpu_shard has been visited
  
      if self.shard_device.type == "cpu":
          self.cuda_shard = None
  
imports: from dataclasses import dataclass
  from enum import Enum
  from typing import Dict, List, Optional
  import torch
  import torch.distributed
  from torch.distributed import ProcessGroup
  from colossalai.utils import get_current_device
  from colossalai.utils.device import IS_NPU_AVAILABLE
label_desc: Use image node_id 12 for calling the Chunk obj's underlying member method code with example usage: obj.close_chunk() without return types