import os

def foo1():

print('Process (%s) start...' % os.getpid())

# only work on Unix/Linux/Mac

pid = os.fork()

if pid == 0:

print('i am child process (%s) and my parent is %s.' % (os.getpid(), os.getppid()))

else:

print('i (%S) just create a child process(%s).' % (os.getpid, pid))

return True

import time, threading

# 假定这是你的银行存款:

balance = 0

def change_it(n):

# 先存后取，结果应该为0:

global balance

balance = balance + n

balance = balance - n

def run_thread(n):

for i in range(100000):

change_it(n)

# t1 = threading.Thread(target=run_thread, args=(5,))

# t2 = threading.Thread(target=run_thread, args=(8,))

# t1.start()

# t2.start()

# t1.join()

# t2.join()

# print(balance)

balance = 0

lock = threading.Lock()

def runthread(n):

for i in range(100000):

# lock

lock.acquire()

try:

change_it(n)

finally:

lock.release()

if __name__ == '__main__':

t1 = threading.Thread(target=runthread, args=(5,))

t2 = threading.Thread(target=runthread, args=(8,))

t1.start()

t2.start()

t1.join()

t2.join()

print(balance)