python 线程冲突问题
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2023-12-31 13:16:52
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线程冲突问题
# !/usr/bin/python
# -*- coding:utf-8 -*-
# ++++++++++++++++++++
# author: FMspider
# time: 2018-5-3 10:15
# function: 线程冲突
import threading
def addnum():
global num
# num -= 1
tem = num
print('ok')
num = tem - 1
num = 100
threading_list = []
# 创建一百个线程,去执行addnum函数,addnum函数是一个-1的动作,按道理说执行结果会是 0
for i in range(100):
t = threading.Thread(target=addnum)
t.start()
threading_list.append(t)
for t in threading_list: # 等待所有线程执行完毕
t.join()
print(num)
运行结果:
解决办法,加一把锁
# !/usr/bin/python
# -*- coding:utf-8 -*-
# ++++++++++++++++++++
# author: FMspider
# time: 2018-5-3 10:15
# function: 线程冲突, 加把锁
import threading
def addnum():
global num
# num -= 1
r.acquire() # 获取锁 这个锁是锁的线程,防止CUP切换过快
tem = num
print('ok')
num = tem - 1
r.release() # 释放锁
num = 100
threading_list = []
r = threading.Lock()
# 创建一百个线程,去执行addnum函数
for i in range(100):
t = threading.Thread(target=addnum)
t.start()
threading_list.append(t)
for t in threading_list: # 等待所有线程执行完毕
t.join()
print(num)