remote_worker.py

   1 #!/usr/bin/env python3
   2
   3 """A simple utility to unpickle some code, run it, and pickle the
   4 results.
   5 """
   6
   7 import logging
   8 import os
   9 import signal
  10 import threading
  11 import sys
  12 import time
  13 from typing import Optional
  14
  15 import cloudpickle  # type: ignore
  16 import psutil  # type: ignore
  17
  18 import argparse_utils
  19 import bootstrap
  20 import config
  21 from stopwatch import Timer
  22 from thread_utils import background_thread
  23
  24
  25 logger = logging.getLogger(__file__)
  26
  27 cfg = config.add_commandline_args(
  28     f"Remote Worker ({__file__})",
  29     "Helper to run pickled code remotely and return results",
  30 )
  31 cfg.add_argument(
  32     '--code_file',
  33     type=str,
  34     required=True,
  35     metavar='FILENAME',
  36     help='The location of the bundle of code to execute.',
  37 )
  38 cfg.add_argument(
  39     '--result_file',
  40     type=str,
  41     required=True,
  42     metavar='FILENAME',
  43     help='The location where we should write the computation results.',
  44 )
  45 cfg.add_argument(
  46     '--watch_for_cancel',
  47     action=argparse_utils.ActionNoYes,
  48     default=True,
  49     help='Should we watch for the cancellation of our parent ssh process?',
  50 )
  51
  52
  53 @background_thread
  54 def watch_for_cancel(terminate_event: threading.Event) -> None:
  55     logger.debug('Starting up background thread...')
  56     p = psutil.Process(os.getpid())
  57     while True:
  58         saw_sshd = False
  59         ancestors = p.parents()
  60         for ancestor in ancestors:
  61             name = ancestor.name()
  62             pid = ancestor.pid
  63             logger.debug(f'Ancestor process {name} (pid={pid})')
  64             if 'ssh' in name.lower():
  65                 saw_sshd = True
  66                 break
  67         if not saw_sshd:
  68             logger.error(
  69                 'Did not see sshd in our ancestors list?!  Committing suicide.'
  70             )
  71             os.system('pstree')
  72             os.kill(os.getpid(), signal.SIGTERM)
  73             time.sleep(5.0)
  74             os.kill(os.getpid(), signal.SIGKILL)
  75             sys.exit(-1)
  76         if terminate_event.is_set():
  77             return
  78         time.sleep(1.0)
  79
  80
  81 def cleanup_and_exit(
  82     thread: Optional[threading.Thread],
  83     stop_thread: Optional[threading.Event],
  84     exit_code: int,
  85 ) -> None:
  86     if stop_thread is not None:
  87         stop_thread.set()
  88         assert thread is not None
  89         thread.join()
  90     sys.exit(exit_code)
  91
  92
  93 @bootstrap.initialize
  94 def main() -> None:
  95     in_file = config.config['code_file']
  96     out_file = config.config['result_file']
  97
  98     thread = None
  99     stop_thread = None
 100     if config.config['watch_for_cancel']:
 101         (thread, stop_thread) = watch_for_cancel()
 102
 103     logger.debug(f'Reading {in_file}.')
 104     try:
 105         with open(in_file, 'rb') as rb:
 106             serialized = rb.read()
 107     except Exception as e:
 108         logger.exception(e)
 109         logger.critical(f'Problem reading {in_file}.  Aborting.')
 110         cleanup_and_exit(thread, stop_thread, 1)
 111
 112     logger.debug(f'Deserializing {in_file}.')
 113     try:
 114         fun, args, kwargs = cloudpickle.loads(serialized)
 115     except Exception as e:
 116         logger.exception(e)
 117         logger.critical(f'Problem deserializing {in_file}.  Aborting.')
 118         cleanup_and_exit(thread, stop_thread, 2)
 119
 120     logger.debug('Invoking user code...')
 121     with Timer() as t:
 122         ret = fun(*args, **kwargs)
 123     logger.debug(f'User code took {t():.1f}s')
 124
 125     logger.debug('Serializing results')
 126     try:
 127         serialized = cloudpickle.dumps(ret)
 128     except Exception as e:
 129         logger.exception(e)
 130         logger.critical(f'Could not serialize result ({type(ret)}).  Aborting.')
 131         cleanup_and_exit(thread, stop_thread, 3)
 132
 133     logger.debug(f'Writing {out_file}.')
 134     try:
 135         with open(out_file, 'wb') as wb:
 136             wb.write(serialized)
 137     except Exception as e:
 138         logger.exception(e)
 139         logger.critical(f'Error writing {out_file}.  Aborting.')
 140         cleanup_and_exit(thread, stop_thread, 4)
 141     cleanup_and_exit(thread, stop_thread, 0)
 142
 143
 144 if __name__ == '__main__':
 145     main()