"""Test GIL mechanism speed.

Adjust CheckInterval, keeping it small so GIL unlocks/locks/blocks
take a majority of a thread's time.
"""

import sys, threading, time, random

ThreadCount = 4
CheckInterval = 1
WorkIterations = (500, 1000)
RunsPerThread = 100
Seed = 123456

# --

ThreadsDone = threading.Semaphore(0)
RateSum = 0.0

def WorkerThread(Iterations):
  global RateSum
  
  RunNum = RunsPerThread
  clock = time.clock
  sleep = time.sleep
  
  try:
    TimeTotal = clock()
    
    while RunNum:

      Iter = Iterations

      while Iter:
        Iter -= 1
        
      RunNum -= 1

    TimeTotal = clock() - TimeTotal
    TimeTotal /= RunsPerThread * Iterations
    RateSum += TimeTotal
  
  finally:
    ThreadsDone.release()


def Run():
  global RateSum
  IterMin, IterMax = WorkIterations
  IterScale = IterMax - IterMin
  
  sys.setcheckinterval(CheckInterval)
  random.seed(Seed)

  if ThreadCount == 1:
    WorkerThread(int(IterMin + random.random()*IterScale))
  else:
    for N in xrange(ThreadCount):
      IterN = int(IterMin + random.random()*IterScale)
      T = threading.Thread(target=WorkerThread, args=(IterN,))
      T.setDaemon(False)
      T.start()

    Done = 0
    
    while 1:
      ThreadsDone.acquire()
      Done += 1
      sys.stdout.write(".")
      sys.stdout.flush()
      if Done == ThreadCount:
        break

    
  print
  RateSum /= float(ThreadCount)
  Nsec = RateSum*1000.0*1000.0*1000.0 # nanoseconds
  
  print "%07.03f ns/iter" % Nsec
  

if __name__ == "__main__":
  Run()