#!/usr/bin/python

import subprocess
import threading
import time
import signal

spawnLock = threading.Lock()

class Spawner(threading.Thread):
	def __init__(self, number):
		self.spin = True
		self.number = number
		threading.Thread.__init__(self)

	def run(self):
		child = None
		count = 0
		prefix = str(self.number) + '-'
		while self.spin == True:
			# if access to Popen is not serialized for entire process, the empty python 
			# process will regularly be blocked until the sleeping process exits
			#spawnLock.acquire() 
			try:
				start = time.time()
				proc = (['python', '-c', 'import time;time.sleep(2)'], 1) if self.number % 2 == 1 else (['python', '-c', ''], 2)
				child = subprocess.Popen(proc[0])
			finally:
				#spawnLock.release()
				pass
			child.wait()
			diff = time.time() - start
			if proc[1] == 2 and diff > 1: print 'command took too long: ' + str(diff)
			count = count + 1

spawned = []
subprocess._cleanup = lambda: None
for i in range(3):
	th = Spawner(i)
	th.start()
	spawned.append(th)

try:
	signal.pause()
except:
	pass

for th in spawned:
	th.spin = False
	th.join()