docstr: A helper method that records a straggler metric
  for the given key. A user should call this when
  the last gradient for the param location is received.
  Args:
      key (str): unique id for metric within a group
docstr_tok: ["A","helper","method","that","records","a","straggler","metric","for","the","given","key",".","A","user","should","call","this","when","the","last","gradient","for","the","param","location","is","received",".","Args",":","key","(","str",")",":","unique","id","for","metric","within","a","group"]
code: def record_straggler_end(self, key):
      r"""
      A helper method that records a straggler metric
      for the given key. A user should call this when
      the last gradient for the param location is received.
      Args:
          key (str): unique id for metric within a group
      """
      self.__metrics_logger.record_end(
          self.PARAMETER_SERVER_STRAGGLER_METRIC, key
      )
  
imports: import functools
  import threading
  import time
  from abc import ABC, abstractmethod
  import torch
  import torch.distributed.rpc
  from metrics.MetricsLogger import MetricsLogger
  from utils import sparse_rpc_format_to_tensor, sparse_tensor_to_rpc_format
label_desc: Use image node_id 8 for calling the ParameterServerBase obj's underlying member method code with example usage: obj.record_straggler_end(key) without return types