python-多线程
进程：是程序的一次执行，有独立的内存地址空间。
线程：是进程的分支，用于完成和实现进程的功能，线程之间共享内存地址空间
1：单线程，一次只能做一件事情，比如看电影和听音乐，只有它们中的一个结束了，才能继续下一件事情：
ODW [:/srv/scratch/python-scripts] 1024$ cat music-movie.py
from time import sleep,ctime //导入时间相关的模块方法
def music(args): //定义for循环打印输出2次，每次间隔1s
for i in range(2):
print ("i am listening the music--%s at%s"%(args,ctime()))
sleep(1)
def movie(args): //同上
for t in range(2):
print ("i am watching the movies --%s at%s"%(args,ctime()))
sleep(5)
if __name__=="__main__": //判断该脚本文件时候是直接执行还是被调用 ，直接执行就会调用music和movie函数，
music("rolling in the deep")
movie("the iron-wolf")
print ("all over %s"%ctime())
ODW [:/srv/scratch/python-scripts] 1023$ python3 music-movie.py
i am listening the music--rolling in the deep at Tue Aug 1 17:31:49 2017 //由时间可以看出是一件一件按部就班的执行的
i am listening the music--rolling in the deep at Tue Aug 1 17:31:50 2017
i am watching the movies--the iron-wolf at Tue Aug 1 17:31:51 2017
i am watching the movies--the iron-wolf at Tue Aug 1 17:31:56 2017
all over Tue Aug 1 17:32:01 2017
2：多线程，同一时刻可以有多个线程同时执行：
ODW [:/srv/scratch/python-scripts] 1054$ cat music-movie1.py
import threading
from time import sleep,ctime
def music(args):
for i in range(2):
print ("i am listening the music--%s at %s"%(args,ctime()))
sleep(1)
def movie(args):
for t in range(2):
print ("i am watching the movies--%s at %s"%(args,ctime()))
sleep(5)
threads=[] //定义一个列表用来放置线程对象
t1=threading.Thread(target=music,args=("rolling in the deep",)) //创建对象，指定引用函数和参数，要注意args=(,)中的逗号，当传入一个参数，不加逗号报错
threads.append(t1) //向列表中添加数据对象t1,t2
t2=threading.Thread(target=movie,args=("the iron-wolf",))
threads.append(t2)
if __name__=="__main__":
for t in threads:
t.setDaemon(True) //setDaemon属性的设置必须在线程启动之前，（默认这个属性为False,主进程会等待守护子进程运行结束。）
t.start() //当设置为True时声明为守护线程,该线程不重要，主线程运行完成，不管子线程是否运行结束，都随主线程强制结束。
print ("all over %s"%ctime())
ODW [:/srv/scratch/python-scripts] 1053$ python3 music-movie1.py
i am listening the music--rolling in the deep at Tue Aug 1 17:57:39 2017 //由函数定义可知线程需要有等待时间和打印的次数，但是输出并没有显示，说明子线程并没有运行
i am watching the movies--the iron-wolf at Tue Aug 1 17:57:39 2017 // 结束而被强制终止，
all over Tue Aug 1 17:57:39 2017
3.只更改setDaemon的属性值为默认值False查看输出：
ODW [:/srv/scratch/python-scripts] 1056$ python3 music-movie1.py
i am listening the music--rolling in the deep at Tue Aug 1 18:18:19 2017
i am watching the movies--the iron-wolf at Tue Aug 1 18:18:19 2017
all over Tue Aug 1 18:18:19 2017 //由输出可知，主线程和子线程同时启动，并且主线程会守护子线程的输出直至结束
i am listening the music--rolling in the deep at Tue Aug 1 18:18:20 2017
i am watching the movies--the iron-wolf at Tue Aug 1 18:18:24 2017
4在第2个脚本的基础上加jion方法： //此时setDeamon=True, join()方法的位置是在for循环外的，也就是说必须等待for循环里的两个线程都
ODW [:/srv/scratch/python-scripts] 1063$ python3 music-movie1.py //结束了才执行主线程
i am listening the music--rolling in the deep at Tue Aug 1 18:37:422017 // join用于等待线程终止的作用是在子线程完成运行之前，这个子线程的父线程将
i am watching the movies--the iron-wolf at Tue Aug 1 18:37:42 2017 //一直被阻塞
i am listening the music--rolling in the deep at Tue Aug 1 18:37:43 2017 //join方法用于等待线程终止
i am watching the movies--the iron-wolf at Tue Aug 1 18:37:47 2017
all over Tue Aug 1 18:37:52 2017
5僵尸进程：
cat music-movie1.py
import threading
from time import sleep,ctime
def music(args):
for i in range(2):
print ("i am listening the music--%s at %s"%(args,ctime()))
sleep(5)
def movie(args):
for t in range(2):
print ("i am watching the movies--%s at %s"%(args,ctime()))
sleep(2)
threads=[]
t1=threading.Thread(target=music,args=("rolling in the deep",))
threads.append(t1)
t2=threading.Thread(target=movie,args=("the iron-wolf",))
threads.append(t2)
if __name__=="__main__":
for t in threads:
t.setDaemon(True)
t.start()
t.join()
print ("all over %s"%ctime())
ODW [:/srv/scratch/python-scripts] 1067$ python3 music-movie1.py //仅仅只是修改2个函数的sleep时间
i am listening the music--rolling in the deep at Tue Aug 1 18:52:51 2017 //2个线程同时启动，主线程和movie线程都结束了，但是music这个线程没有结束，
i am watching the movies--the iron-wolf at Tue Aug 1 18:52:51 2017 //
i am watching the movies--the iron-wolf at Tue Aug 1 18:52:53 2017
all over Tue Aug 1 18:52:55 2017