class_docstr: A class that listens for exceptions in children processes and propagates
  the tracebacks to the parent process.
docstr: signal handler
docstr_tok: ["signal","handler"]
code: def signal_handler(self, signalnum, stackframe):
      """signal handler"""
      for pid in self.children_pids:
          os.kill(pid, signal.SIGINT)  # kill children processes
      (rank, original_trace) = self.error_queue.get()
      msg = """\n\n-- Tracebacks above this line can probably
                   be ignored --\n\n"""
      msg += original_trace
      raise Exception(msg)
  
imports: import os
  import signal
  import math
  import pickle
  import torch.distributed
  from datetime import timedelta
  from onmt.translate.translator import build_translator
  from onmt.transforms import get_transforms_cls
  from onmt.constants import CorpusTask
  from onmt.utils.logging import init_logger, logger
  from onmt.inputters.dynamic_iterator import build_dynamic_dataset_iter
label_desc: Use image node_id 4 for calling the ErrorHandler obj's underlying member method code with example usage: obj.signal_handler(signalnum, stackframe) without return types