class_docstr: A training engine hybrid pipeline, data, and model parallel training.
  
  This engine is created by ``deepspeed.initialize()`` when a :class:`PipelineModule`
  is provided.
class_docstr_tok: ["A","training","engine","hybrid","pipeline",",","data",",","and","model","parallel","training",".","This","engine","is","created","by","``","deepspeed.initialize","(",")","``","when","a",":","class",":","`","PipelineModule","`","is","provided","."]
code: def _exec_schedule(self, pipe_schedule):
      # Reserve and reset buffers.
      self._reserve_pipe_buffers(pipe_schedule.num_pipe_buffers())
      self.fwd_outputs = []
  
      # For each step in the schedule
      for step_cmds in pipe_schedule:
          # For each instruction in the step
          for cmd in step_cmds:
              if type(cmd) not in self._INSTRUCTION_MAP:
                  raise RuntimeError(
                      f"{self.__class__.__name__} does not understand instruction {repr(cmd)}"
                  )
  
              # Equivalent to: self._exec_forward_pass(buffer_id=0)
              self._exec_instr = MethodType(
                  self._INSTRUCTION_MAP[type(cmd)], self
              )
              self._exec_instr(**cmd.kwargs)
  
imports: from types import MethodType
  import torch
  from deepspeed import comm
  from deepspeed.utils import logger
  from deepspeed.utils.timer import ThroughputTimer
  from deepspeed.accelerator import get_accelerator
  from deepspeed.runtime.bf16_optimizer import BF16_Optimizer
  from ..engine import DeepSpeedEngine, MEMORY_OPT_ALLREDUCE_SIZE
  from deepspeed.utils.timer import FORWARD_MICRO_TIMER, FORWARD_GLOBAL_TIMER, BACKWARD_MICRO_TIMER, BACKWARD_GLOBAL_TIMER, BACKWARD_INNER_MICRO_TIMER, BACKWARD_INNER_GLOBAL_TIMER, BACKWARD_REDUCE_MICRO_TIMER, BACKWARD_REDUCE_GLOBAL_TIMER, STEP_MICRO_TIMER, STEP_GLOBAL_TIMER
  from ..utils import PartitionedTensor
  from ..dataloader import RepeatingLoader
  from ..zero.config import ZeroStageEnum
  from ..activation_checkpointing import checkpointing
  from .module import PipelineModule, PipelineError
  from .None import p2p
  from .None import schedule
label_desc: Use image node_id 43 for calling the PipelineEngine obj's underlying member method code with example usage: obj._exec_schedule(pipe_schedule) without return types