class_docstr: Shuffle plugin for the scheduler
  This coordinates the individual worker plugins to ensure correctness
  and collects heartbeat messages for the dashboard.
  See Also
  --------
  ShuffleWorkerPlugin
class_docstr_tok: ["Shuffle","plugin","for","the","scheduler","This","coordinates","the","individual","worker","plugins","to","ensure","correctness","and","collects","heartbeat","messages","for","the","dashboard",".","See","Also","--","--","--","--","ShuffleWorkerPlugin"]
code: def _raise_if_barrier_unknown(self, id: ShuffleId) -> None:
      key = barrier_key(id)
      try:
          self.scheduler.tasks[key]
      except KeyError:
          raise RuntimeError(
              f"Barrier task with key {key!r} does not exist. This may be caused by "
              "task fusion during graph generation. Please let us know that you ran "
              "into this by leaving a comment at distributed#7816."
          )
  
imports: from __future__ import annotations
  import contextlib
  import itertools
  import logging
  from collections import defaultdict
  from typing import TYPE_CHECKING, Any
  from dask.typing import Key
  from distributed.diagnostics.plugin import SchedulerPlugin
  from distributed.metrics import time
  from distributed.protocol.pickle import dumps
  from distributed.protocol.serialize import ToPickle
  from distributed.shuffle._core import SchedulerShuffleState, ShuffleId, ShuffleRunSpec, ShuffleSpec, barrier_key, id_from_key
  from distributed.shuffle._worker_plugin import ShuffleWorkerPlugin
  from distributed.utils import log_errors
label_desc: Use image node_id 7 for calling the ShuffleSchedulerPlugin obj's underlying member method code with example usage: obj._raise_if_barrier_unknown(id) without return types