#!/usr/bin/python
# -*- coding: utf-8 -*-

import os
import sys
import time

from multiprocessing import Process, cpu_count

#-----------------------------------------------------------------------
def log(msg):
  print "[%s %d] %s" % (time.asctime(), os.getpid(), msg)

#-----------------------------------------------------------------------
def dummy_process():
  import random
  t = random.randint(0, 2)
  log("Sleeping %d second(s)..." % t)
  time.sleep(t)
  log("Done, bye")

#-----------------------------------------------------------------------
def process_manager(total_procs, target, wait_time=0.2):
  """ Always maintain a total of @total_procs running @target and
      waiting for each thread to finish @wait_time second(s). """
  procs = []
  log("Maximum number of processes in pool is %d" % total_procs)
  while 1:
    if len(procs) < total_procs:
      log("Starting process %d" % (len(procs)+1))
      p = Process(target=target)
      p.start()
      procs.append(p)
      log("Total of %d process(es) started" % len(procs))
    else:
      i = 0
      for p in list(procs):
        p.join(wait_time)
        if not p.is_alive():
          log("Process finished, deleting and starting a new one...")
          del procs[i]
          continue
        i += 1

if __name__ == "__main__":
  total_procs = cpu_count()*5
  manage_pool(total_procs, dummy_process)