Python多线程：thread、threading、queue

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Python多线程：thread、threading、queue

2018年10月06日 ⁄ 综合 ⁄ 共 2079字 ⁄ 字号小中大 ⁄ 评论关闭

一、名字解释

Python虚拟机：也叫解释器主循环，控制Python代码的执行。

多线程：类似单CPU系统中运行多个进程。任意时刻，只能有一个线程在解释器中运行。

全局解释器锁（GIL）：保证同一个时刻只有一个线程在运行。

二、thread

#!/usr/bin/env python

#import thread
from time import sleep, ctime

def loop0():
        print "start loop 0 at:", ctime()
        sleep(4)
        print "end loop 0 at:", ctime()

def loop1():
        print "start loop 1 at:", ctime()
        sleep(2)
        print "end loop 1 at:",ctime()

def main():
        print "starting at:", ctime()
        loop0()
        loop1()
        #thread.start_new_thread(loop0,())
        #thread.start_new_thread(loop1,())
        #sleep(6)
        print "ending at:", ctime();

if __name__ == "__main__":
        main()

没有thread：共耗时4+2=6秒

有thread，无锁：并发执行，共耗时4秒，需要主线程中手动sleep

#!/usr/bin/env python

import thread
from time import sleep, ctime

secs = [4,2]

def loop(nloop, nsec, lock):
        print "start loop ", nloop," at:", ctime()
        sleep(nsec)
        print "end loop ", nloop, " at:", ctime()
        lock.release()

def main():
        print "starting at:", ctime()
        nsecs = range(len(secs))
        locks = []
        for i in nsecs:
                lock = thread.allocate_lock()
                lock.acquire()
                locks.append(lock)

        for i in nsecs:
                thread.start_new_thread(loop, (i, secs[i], locks[i]))

        for i in nsecs:
                while locks[i].locked(): pass
        print "ending at:", ctime();

if __name__ == "__main__":
        main()

有thread，有锁：共耗时4秒，主线程无需等待

三、threading

3种创建线程方法

1. 创建一个Thread的实例，传给它一个函数

2. 创建一个Thread的实例，传给它一个可调用的类对象

3. 从Thread派生出一个子类，创建一个这个子类的实例

#!/usr/bin/env python

import threading
from time import sleep, ctime

secs = [4,2]

#class ThreadFunc(object):
#       def __init__(self, func, args, name=''):
#               self.name = name
#               self.func = func
#               self.args = args
#
#       def __call__(self):
#               apply(self.func, self.args)

def loop(nloop, nsec):
        print "start loop ", nloop, " at:", ctime()
        sleep(nsec)
        print "end loop ", nloop," at:", ctime()

def main():
        print "starting at:", ctime()
        nsecs = range(len(secs))
        threads = []
        for i in nsecs:
                #t = threading.Thread(target=ThreadFunc(loop, (i, secs[i]), loop.__name__))
                t = threading.Thread(target=loop,args=(i,secs[i]))
                threads.append(t)

        for i in nsecs:
                threads[i].start()

        for i in nsecs:
                threads[i].join()
        print "ending at:", ctime();

if __name__ == "__main__":
        main()

上述代码是2种创建线程方法：执行结果一样，都是耗时4秒，主线程无需等待