Playing with processes (Helping a brother out)

playing_with_processes.py

import os
import sys
import random
import time
import tempfile
from datetime import datetime
from multiprocessing import Process
from utils import is_number

MAX_TIME_TO_SLEEP = 20

def sub_program():
  pid = str(os.getpid())
  sleep_time = random.randrange(MAX_TIME_TO_SLEEP)
  print("Hello from pid {}\r\nTime {}".format(pid, datetime.now()))
  print("Sleeping for {} seconds".format(sleep_time))
  time.sleep(sleep_time)

if __name__ == '__main__':
  parent_id = os.getpid()
  pidfile = os.path.join(tempfile.gettempdir(),"my_unique_process.pid")
  if(len(sys.argv) <= 1):
    print("Error - Please supply number of processes as an argument. For example {} 3".format(sys.argv[0]))
    sys.exit()

  number_of_processes = sys.argv[1]
  if not is_number(number_of_processes):
    print("Error - Please supply number as the number of processes")
    sys.exit()

  number_of_processes = int(number_of_processes)

  print("Started at time {}".format(datetime.now()))

  # Check if already running
  if os.path.isfile(pidfile):
    print("{} already exists, exiting".format(pidfile))
    sys.exit()

  open(pidfile, "w").write("{}".format(parent_id))

  try:
    processes = []
    for i in range(number_of_processes):
      p = Process(target=sub_program)
      processes.append(p)

    for p in processes:
      p.start()

    success = 0
    failure = 0
    for p in processes:
      p.join()
      if p.exitcode == 0:
          success+=1
      else:
          failure+=1

    print("Success process {}, Failed process {}".format(success,failure))

  finally:
    print("Finished running.\r\nTime {}".format(datetime.now()))
    os.unlink(pidfile)

And here is the utils function that checks for a number:

def is_number(s):
  try:
    float(s)
    return True
  except ValueError:
    pass

  try:
    import unicodedata
    unicodedata.numeric(s)
    return True
  except (TypeError, ValueError):
    pass

  return False