PYTHON機器學習自學/自修 整理[00028] ~ PYTHON – 100天从新手到大师(13.进程和线程.md)

01.多行程(multiprocess)

from multiprocessing import Process
from os import getpid
from random import randint
from time import time, sleep


def download_task(filename):
    print('启动下载进程，进程号[%d].' % getpid())
    print('开始下载%s...' % filename)
    time_to_download = randint(5, 10)
    sleep(time_to_download)
    print('%s下载完成! 耗费了%d秒' % (filename, time_to_download))


def main():
    start = time()#運算時間計時
    p1 = Process(target=download_task, args=('Python从入门到住院.pdf',))
    p2 = Process(target=download_task, args=('Peking Hot.avi',))
    #Process对象的start方法用来启动进程
    p1.start()
    p2.start()
    #join方法表示等待进程执行结束
    p1.join()
    p2.join()
    end = time()#運算時間計時
    print('总共耗费了%.2f秒.' % (end - start))


if __name__ == '__main__':
    main()

02.多 執行序/線程(multithread)-(基本範例)

from random import randint
from threading import Thread
from time import time, sleep


def download(filename):
    print('开始下载%s...' % filename)
    time_to_download = randint(5, 10)
    sleep(time_to_download)
    print('%s下载完成! 耗费了%d秒' % (filename, time_to_download))


def main():
    start = time()
    t1 = Thread(target=download, args=('Python从入门到住院.pdf',))
    t2 = Thread(target=download, args=('Peking Hot.avi',))
    t1.start()
    t2.start()
    t1.join()
    t2.join()
    end = time()
    print('总共耗费了%.3f秒' % (end - start))


if __name__ == '__main__':
    main()

03.多 執行序/線程(multithread)-(建立繼承執行序的類別)

from random import randint
from threading import Thread
from time import time, sleep


class DownloadTask(Thread):
	#建立繼承執行序的類別
	
    def __init__(self, filename):
        super().__init__()
        self._filename = filename

    def run(self):
        print('开始下载%s...' % self._filename)
        time_to_download = randint(5, 10)
        sleep(time_to_download)
        print('%s下载完成! 耗费了%d秒' % (self._filename, time_to_download))


def main():
    start = time()
    t1 = DownloadTask('Python从入门到住院.pdf')
    t2 = DownloadTask('Peking Hot.avi')
    t1.start()    
    t2.start()
    t1.join()
    t2.join()
    end = time()
    print('总共耗费了%.2f秒.' % (end - start))


if __name__ == '__main__':
    main()

04.多 執行序/線程(multithread)-(執行序配合鎖功能達到共享變數存取)

from time import sleep
from threading import Thread, Lock


class Account(object):

    def __init__(self):
        self._balance = 0
        self._lock = Lock()

    def deposit(self, money):
        # 先获取锁才能执行后续的代码
        self._lock.acquire()
        try:
            new_balance = self._balance + money
            sleep(0.01)
            self._balance = new_balance
        finally:
            # 在finally中执行释放锁的操作保证正常异常锁都能释放
            self._lock.release()

    @property
    def balance(self):
        return self._balance


class AddMoneyThread(Thread):

    def __init__(self, account, money):
        super().__init__()
        self._account = account
        self._money = money

    def run(self):
        self._account.deposit(self._money)


def main():
    account = Account()
    threads = []
    i=0
    for _ in range(100):
        i+=1;
        t = AddMoneyThread(account, i)
        threads.append(t)
        t.start()
    for t in threads:
        t.join()
    print('账户余额为: ￥%d元' % account.balance)


if __name__ == '__main__':
    main()