Python 线程同步
以下代码可以直观展示加锁和不加锁时，对数据修改情况。
加锁时
# -*-* encoding:UTF-8 -*-
# author : shoushixiong
# date : 2018/11/22
import threading
import time
list = [0,0,0,0,0,0,0,0,0,0,0,0]
class myThread(threading.Thread):
def __init__(self,threadId,name,counter):
threading.Thread.__init__(self)
self.threadId = threadId
self.name = name
self.counter = counter
def run(self):
print "开始线程:",self.name
# 获得锁，成功获得锁定后返回 True
# 可选的timeout参数不填时将一直阻塞直到获得锁定
# 否则超时后将返回 False
threadLock.acquire()
print_time(self.name,self.counter,list.__len__())
# 释放锁
threadLock.release()
def __del__(self):
print self.name,"线程结束！"
def print_time(threadName,delay,counter):
while counter:
time.sleep(delay)
list[counter-1] += 1
print "[%s] %s 修改第 %d 个值，修改后值为:%d" % (time.ctime(time.time()),threadName,counter,list[counter-1])
counter -= 1
threadLock = threading.Lock()
threads = []
# 创建新线程
thread1 = myThread(1,"Thread-1",1)
thread2 = myThread(2,"Thread-2",2)
# 开启新线程
thread1.start()
thread2.start()
# 添加线程到线程列表
threads.append(thread1)
threads.append(thread2)
# 等待所有线程完成
for t in threads:
t.join()
print "主进程结束！"
输出结果为：
开始线程: Thread-1 开始线程: Thread-2 [Thu Nov 22 16:04:13 2018] Thread-1 修改第 12 个值，修改后值为:1 [Thu Nov 22 16:04:14 2018] Thread-1 修改第 11 个值，修改后值为:1 [Thu Nov 22 16:04:15 2018] Thread-1 修改第 10 个值，修改后值为:1 [Thu Nov 22 16:04:16 2018] Thread-1 修改第 9 个值，修改后值为:1 [Thu Nov 22 16:04:17 2018] Thread-1 修改第 8 个值，修改后值为:1 [Thu Nov 22 16:04:18 2018] Thread-1 修改第 7 个值，修改后值为:1 [Thu Nov 22 16:04:19 2018] Thread-1 修改第 6 个值，修改后值为:1 [Thu Nov 22 16:04:20 2018] Thread-1 修改第 5 个值，修改后值为:1 [Thu Nov 22 16:04:21 2018] Thread-1 修改第 4 个值，修改后值为:1 [Thu Nov 22 16:04:22 2018] Thread-1 修改第 3 个值，修改后值为:1 [Thu Nov 22 16:04:23 2018] Thread-1 修改第 2 个值，修改后值为:1 [Thu Nov 22 16:04:24 2018] Thread-1 修改第 1 个值，修改后值为:1 [Thu Nov 22 16:04:26 2018] Thread-2 修改第 12 个值，修改后值为:2 [Thu Nov 22 16:04:28 2018] Thread-2 修改第 11 个值，修改后值为:2 [Thu Nov 22 16:04:30 2018] Thread-2 修改第 10 个值，修改后值为:2 [Thu Nov 22 16:04:32 2018] Thread-2 修改第 9 个值，修改后值为:2 [Thu Nov 22 16:04:34 2018] Thread-2 修改第 8 个值，修改后值为:2 [Thu Nov 22 16:04:36 2018] Thread-2 修改第 7 个值，修改后值为:2 [Thu Nov 22 16:04:38 2018] Thread-2 修改第 6 个值，修改后值为:2 [Thu Nov 22 16:04:40 2018] Thread-2 修改第 5 个值，修改后值为:2 [Thu Nov 22 16:04:42 2018] Thread-2 修改第 4 个值，修改后值为:2 [Thu Nov 22 16:04:44 2018] Thread-2 修改第 3 个值，修改后值为:2 [Thu Nov 22 16:04:46 2018] Thread-2 修改第 2 个值，修改后值为:2 [Thu Nov 22 16:04:48 2018] Thread-2 修改第 1 个值，修改后值为:2 主进程结束！ Thread-1 线程结束！ Thread-2 线程结束！
不加锁时
同样是上面实例的代码，注释以下两行代码：threadLock.acquire() threadLock.release()
输出结果为：
开始线程: Thread-1 开始线程: Thread-2 [Thu Nov 22 16:09:20 2018] Thread-1 修改第 12 个值，修改后值为:1 [Thu Nov 22 16:09:21 2018] Thread-2 修改第 12 个值，修改后值为:2 [Thu Nov 22 16:09:21 2018] Thread-1 修改第 11 个值，修改后值为:1 [Thu Nov 22 16:09:22 2018] Thread-1 修改第 10 个值，修改后值为:1 [Thu Nov 22 16:09:23 2018] Thread-1 修改第 9 个值，修改后值为:1 [Thu Nov 22 16:09:23 2018] Thread-2 修改第 11 个值，修改后值为:2 [Thu Nov 22 16:09:24 2018] Thread-1 修改第 8 个值，修改后值为:1 [Thu Nov 22 16:09:25 2018] Thread-2 修改第 10 个值，修改后值为:2 [Thu Nov 22 16:09:25 2018] Thread-1 修改第 7 个值，修改后值为:1 [Thu Nov 22 16:09:26 2018] Thread-1 修改第 6 个值，修改后值为:1 [Thu Nov 22 16:09:27 2018] Thread-2 修改第 9 个值，修改后值为:2 [Thu Nov 22 16:09:27 2018] Thread-1 修改第 5 个值，修改后值为:1 [Thu Nov 22 16:09:28 2018] Thread-1 修改第 4 个值，修改后值为:1 [Thu Nov 22 16:09:29 2018] Thread-2 修改第 8 个值，修改后值为:2 [Thu Nov 22 16:09:29 2018] Thread-1 修改第 3 个值，修改后值为:1 [Thu Nov 22 16:09:30 2018] Thread-1 修改第 2 个值，修改后值为:1 [Thu Nov 22 16:09:31 2018] Thread-2 修改第 7 个值，修改后值为:2 [Thu Nov 22 16:09:31 2018] Thread-1 修改第 1 个值，修改后值为:1 [Thu Nov 22 16:09:33 2018] Thread-2 修改第 6 个值，修改后值为:2 [Thu Nov 22 16:09:35 2018] Thread-2 修改第 5 个值，修改后值为:2 [Thu Nov 22 16:09:37 2018] Thread-2 修改第 4 个值，修改后值为:2 [Thu Nov 22 16:09:39 2018] Thread-2 修改第 3 个值，修改后值为:2 [Thu Nov 22 16:09:41 2018] Thread-2 修改第 2 个值，修改后值为:2 [Thu Nov 22 16:09:43 2018] Thread-2 修改第 1 个值，修改后值为:2 主进程结束！ Thread-1 线程结束！ Thread-2 线程结束！
