docstr: Repair offload strategy.
  It attempts to convert asynchronous prefetch into synchronous upload operations and selects the best one.
  The repair process does not end until peak memory is reduced or there is no asynchronous prefetch operation.
docstr_tok: ["Repair","offload","strategy",".","It","attempts","to","convert","asynchronous","prefetch","into","synchronous","upload","operations","and","selects","the","best","one",".","The","repair","process","does","not","end","until","peak","memory","is","reduced","or","there","is","no","asynchronous","prefetch","operation","."]
code: def _repair_strategy(self):
      """
      Repair offload strategy.
      It attempts to convert asynchronous prefetch into synchronous upload operations and selects the best one.
      The repair process does not end until peak memory is reduced or there is no asynchronous prefetch operation.
      """
      print("repair strategy ......")
  
      peak_mem_saving = 0
      while len(self.region_to_region_map) and peak_mem_saving <= 0:
          max_profit = (0,)
          best_ts = None
          undo_host_region = None
          undo_offload_region = None
  
          for (
              offload_region_id,
              host_region,
          ) in self.region_to_region_map.items():
              offload_region = self.region_list[offload_region_id]
              assert host_region.bwd_prefetch_region == offload_region
              assert offload_region.need_offload
              assert not offload_region.is_syn
  
              ts, profit = self._try_convert_to_syn_upload(
                  host_region, offload_region
              )
  
              if self._compare_profit(profit, max_profit):
                  undo_host_region = host_region
                  undo_offload_region = offload_region
                  max_profit = profit
                  best_ts = ts
  
          if best_ts is None:
              raise NotImplementedError("repair error!")
  
          assert not undo_offload_region.is_syn
          undo_offload_region.is_syn = True
          undo_host_region.bwd_prefetch_region = None
  
          peak_mem_saving = self.best_ts.peak_mem - best_ts.peak_mem
  
          self._update_state(best_ts)
          self.region_to_region_map.pop(undo_offload_region.r_id)
  
      return best_ts
  
imports: import time
  from abc import ABC, abstractmethod
  from typing import Dict, List, Type
  import torch
  from torch.fx.node import Node
  from colossalai.utils.device import get_current_device
  from .region import Region
  from .training_simulator import AsynTrainingSimulator, SynTrainingSimulator, TrainingSimulator
  from .util import NodeInfo, NvDevicePower
label_desc: Use image node_id 6 for calling the AsynGreedySolver obj's underlying member method code with example usage: obj._repair_strategy() and returns: best_ts