スレッドセーフじゃない例

gistfile1.txt

#! /usr/bin/env python
import time
from threading import Thread

count = 0


class CountUpThread(Thread):
    def run(self):
        global count
        for ii in range(1000):
            value = count
            time.sleep(0.001)
            value += 1
            count = value

children = [CountUpThread() for ii in range(100)]
for child in children:
    child.start()

for child in children:
    child.join()

print(count)