code: def __init__(
      self,
      subtask: Subtask,
      session_api: SessionAPI,
      storage_api: StorageAPI,
      meta_api: MetaAPI,
      worker_meta_api: WorkerMetaAPI,
      band: BandType,
      supervisor_address: str,
      engines: List[str] = None,
  ):
      self.subtask = subtask
      self._session_id = self.subtask.session_id
      self._chunk_graph = subtask.chunk_graph
      self._actual_chunk_count = len(
          [
              chunk
              for chunk in subtask.chunk_graph
              if not isinstance(chunk.op, (Fetch, FetchShuffle))
          ]
      )
      self._band = band
      self._supervisor_address = supervisor_address
      self._engines = (
          engines
          if engines is not None
          else task_options.runtime_engines
      )
  
      # result
      self.result = SubtaskResult(
          subtask_id=subtask.subtask_id,
          session_id=subtask.session_id,
          task_id=subtask.task_id,
          stage_id=subtask.stage_id,
          status=SubtaskStatus.pending,
          bands=[self._band],
          progress=0.0,
          execution_start_time=time.time(),
      )
      self.is_done = asyncio.Event()
  
      # status and intermediate states
      # operand progress, from op key to progress
      self._op_progress: Dict[str, float] = defaultdict(lambda: 0.0)
      # temp data store that holds chunk data during computation
      self._processor_context = ProcessorContext()
      # chunk key to real data keys
      self._chunk_key_to_data_keys = dict()
  
      # other service APIs
      self._session_api = session_api
      self._storage_api = storage_api
      self._meta_api = meta_api
      self._worker_meta_api = worker_meta_api
  
      # add metrics
      self._subtask_execution_time = Metrics.gauge(
          "mars.subtask_execution_time_secs",
          "Time consuming in seconds to execute a subtask",
          ("session_id", "subtask_id"),
      )
  
imports: import asyncio
  import logging
  import sys
  import time
  from collections import defaultdict
  from typing import Any, Dict, List, Optional, Set, Type, Tuple
  from ....None import oscar
  from ....core import ChunkGraph, OperandType, enter_mode, ExecutionError
  from ....core.context import get_context
  from ....core.operand import Fetch, FetchShuffle, execute
  from ....lib.aio import alru_cache
  from ....metrics import Metrics
  from ....optimization.physical import optimize
  from ....serialization import AioSerializer
  from ....typing import BandType, ChunkType
  from ....utils import calc_data_size, get_chunk_key_to_data_keys, get_node_ip_address, lazy_import
  from ...context import ThreadedServiceContext
  from ...meta.api import MetaAPI, WorkerMetaAPI
  from ...session import SessionAPI
  from ...storage import StorageAPI
  from ...task import TaskAPI, task_options
  from ..core import Subtask, SubtaskStatus, SubtaskResult
  from ..utils import iter_input_data_keys, iter_output_data, get_mapper_data_keys
label_desc: Use image node_id 1 to create a new SubtaskProcessor object  with example: obj = SubtaskProcessor(subtask, session_api, storage_api, meta_api, worker_meta_api, band, supervisor_address, engines)