Python 共享变量加锁、释放详解

import threading
sum = 0
loopSum = 1000000
def myAdd():
  global sum, loopSum
for i in range(1, loopSum):
  sum += 1
def myMinu():
  global sum, loopSum
for i in range(1, loopSum):
  sum -= 1
if __name__ == "__main__":
  print("Dont,,,,,,,{0}".format(sum))
t1 = threading.Thread(target = myAdd, args = ())
t2 = threading.Thread(target = myMinu, args = ())
t1.start()
t2.start()
t1.join()
t2.join()
print("Done,,,,,,{0}".format(sum))

import threading
sum = 0
loopSum = 1000000
lock = threading.Lock()
# 先生成一个锁的实例
def myAdd():
  global sum, loopSum
for i in range(1, loopSum):
  lock.acquire()# 这里申请了一把锁
sum += 1
lock.release()# 注意千万不要忘了释放锁
def myMinu():
  global sum, loopSum
for i in range(1, loopSum):
  lock.acquire()
sum -= 1
lock.release()
if __name__ == "__main__":
  print("Done,,,,,,,{0}".format(sum))
t1 = threading.Thread(target = myAdd, args = ())
t2 = threading.Thread(target = myMinu, args = ())
t1.start()
t2.start()
t1.join()
t2.join()
print("Done,,,,,,{0}".format(sum))