gil.pyx

cdef extern from "unistd.h":
  cdef void sleep(int time)

def lock(time):
  print "starting to block"
  sleep(10)
  print "stop blocking"

test.py

import pyximport; pyximport.install()
import time
import gil
import threading


class Test(threading.Thread):

  def run(self):
    num = 0
    while True:
      print num
      num += 1


def main():
  tt = Test()
  tt.daemon = True
  tt.start()
  time.sleep(0.1)
  gil.lock(4)


if __name__ == '__main__':
  main()