国产一级a片免费看高清,亚洲熟女中文字幕在线视频,黄三级高清在线播放,免费黄色视频在线看

一．多進(jìn)程：

當(dāng)計(jì)算機(jī)運(yùn)行程序時(shí)，就會(huì)創(chuàng)建包含代碼和狀態(tài)的進(jìn)程。這些進(jìn)程會(huì)通過計(jì)算機(jī)的一個(gè)或多個(gè)CPU執(zhí)行。不過，同一時(shí)刻每個(gè)CPU只會(huì)執(zhí)行一個(gè)進(jìn)程，然后不同進(jìn)程間快速切換，給我們一種錯(cuò)覺，感覺好像多個(gè)程序在同時(shí)進(jìn)行。例如：有一個(gè)大型工廠，該工廠負(fù)責(zé)生產(chǎn)電腦，工廠有很多的車間用來生產(chǎn)不同的電腦部件。每個(gè)車間又有很多工人互相合作共享資源來生產(chǎn)某個(gè)電腦部件。這里的工廠相當(dāng)于一個(gè)爬蟲工程，每個(gè)車間相當(dāng)于一個(gè)進(jìn)程，每個(gè)工人就相當(dāng)于線程。線程是CPU調(diào)度的基本單元。

需要注意的是單核CPU系統(tǒng)中，真正的并發(fā)是不可能的．

１．順序執(zhí)行 

２．多進(jìn)程并發(fā) 注意除了時(shí)間的加速意外也要看看函數(shù)返回值的寫法，帶有多進(jìn)程的map,是返回一個(gè)列表

import requests
import re
import time
from multiprocessing import Pool
from multiprocessing.dummy import Pool as ThreadPool
def spyder(url):
    # res = []
    res = {'init:':'hello'}
    print('hahah:{}'.format(url))
    time.sleep(1)
    # res.append(url)
    res.update({'entr:'+url:url})
    return res
def use_process():
    urls = ["https://www.qiushibaike.com/text/page/{}/".format(str(i)) for i in range(0, 4)]
    start_1 = time.time()
    #獲取函數(shù)返回結(jié)果
    res1 = []
    for url in urls:
        res_ = spyder(url)
        res1.append(res_)
    end_1 = time.time()
    print("單進(jìn)程：", end_1 - start_1)
    print('res1:', res1)
    # 獲取函數(shù)返回結(jié)果
    # 　進(jìn)程池
    start_2 = time.time()
    pool = Pool(processes=2)
    res2 = pool.map(spyder, urls)
    pool.close()
    pool.join()
    print('res2:', res2)
    end_2 = time.time()
    print("2進(jìn)程：", end_2 - start_2)
    # 獲取函數(shù)返回結(jié)果
    # 進(jìn)程池
    start_3 = time.time()
    pool = Pool(processes=4)
    res3 = pool.map(spyder, urls)
    pool.close()
    pool.join()
    print('res2:', res3)
    end_3 = time.time()
    print("4進(jìn)程：", end_3 - start_3)
if __name__ == "__main__":
    use_process()

2.多線程

2.1 thread多線程

import time
import _thread
from threading import Thread
# 使用線程鎖，防止線程死鎖
mutex = _thread.allocate_lock()
def test(d_num):
    d_num.append(89)
    print("test: %s"% str(d_num))
def test1(d_num):
    print("test1: %s"% str(d_num))
def main():
    d_num = [100, 58]
    t1 = Thread(target=test, args=(d_num,))
    t2 = Thread(target=test1, args=(d_num,))
    t1.start()
    time.sleep(1)
    t2.start()
    time.sleep(1)
if __name__ == '__main__':
    main()

2.2 多線程隊(duì)列版

import time
import _thread
from threading import Thread
import queue
# 使用線程鎖，防止線程死鎖
mutex = _thread.allocate_lock()
frame_queue = queue.Queue()
def test(d_num):
    print("test: %s" % str(d_num))
    for i in range(d_num):
        frame_queue.put(i)
def test1():
    while 1:
        if frame_queue.empty() != True:
            # 從隊(duì)列中取出圖片
            value = frame_queue.get()
            print('==value:', value)
            time.sleep(1)
        else:
            break
def main():
    d_num = 10
    t1 = Thread(target=test, args=(d_num,))
    t1.start()
    t2 = Thread(target=test1)
    t2.start()
if __name__ == '__main__':
    main()

2.3 注意傳參與多進(jìn)程的區(qū)別,線程池

from functools import partial
from itertools import repeat
from multiprocessing import Pool, freeze_support
def func(a, b):
    return a + b
def main():
    a_args = [1, 2, 3]
    second_arg = 1
    with Pool() as pool:
        L = pool.starmap(func, [(1, 1), (2, 1), (3, 1)])
        print('L:', L)
        M = pool.starmap(func, zip(a_args, repeat(second_arg)))
        print('M:', M)
        N = pool.map(partial(func, b=second_arg), a_args)
        print('N:', N)
main()

import requests
import re
import time
from multiprocessing import Pool
from multiprocessing.dummy import Pool as ThreadPool
def spyder(url):
    # res = []
    res = {'init:':'hello'}
    print('hahah:{}'.format(url))
    time.sleep(1)
    # res.append(url)
    res.update({'entr:'+url:url})
    return res
def use_process():
    urls = ["https://www.qiushibaike.com/text/page/{}/".format(str(i)) for i in range(0, 4)]
    start_1 = time.time()
    #獲取函數(shù)返回結(jié)果
    res1 = []
    for url in urls:
        res_ = spyder(url)
        res1.append(res_)
    end_1 = time.time()
    print("單進(jìn)程：", end_1 - start_1)
    print('res1:', res1)
    # 獲取函數(shù)返回結(jié)果
    # 　進(jìn)程池
    start_2 = time.time()
    pool = Pool(processes=2)
    res2 = pool.map(spyder, urls)
    pool.close()
    pool.join()
    print('res2:', res2)
    end_2 = time.time()
    print("2進(jìn)程：", end_2 - start_2)
    # 獲取函數(shù)返回結(jié)果
    # 進(jìn)程池
    start_3 = time.time()
    pool = Pool(processes=4)
    res3 = pool.map(spyder, urls)
    pool.close()
    pool.join()
    print('res2:', res3)
    end_3 = time.time()
    print("4進(jìn)程：", end_3 - start_3)
def use_threadpool():
    urls = [["https://www.qiushibaike.com/text/page/{}/".format(str(i))] for i in range(0, 4)]
    print('urls:', urls)
    # 線程池
    start = time.time()
    pool = ThreadPool(processes=4)
    res = pool.starmap(spyder, urls)
    pool.close()
    pool.join()
    end = time.time()
    print('res:', res)
    print("4線程：", end - start)
if __name__ == "__main__":
    # use_process()
    use_threadpool()

實(shí)際應(yīng)用將圖片路徑和名字傳入，用zip方式打包傳參

import os
import cv2
import time
import itertools
from multiprocessing.dummy import Pool as ThreadPool
SIZE = (75,75)
SAVE_DIRECTORY='thumbs'
def save_img(filename,save_path):
    save_path+= filename.split('/')[-1]
    im = cv2.imread(filename)
    im=cv2.resize(im,SIZE)
    cv2.imwrite(save_path,im)
if __name__ == '__main__':
    path='./data/testlabel'
    print(path)
    output_path='./data/thumbs/'
    if not os.path.exists(output_path):
        os.mkdir(output_path)
    print(output_path)
    imgs_list_path=[os.path.join(path,i) for i in os.listdir(path)]
    print(len(imgs_list_path))
    start_time=time.time()
    pool = ThreadPool(processes=8)
    print(list(zip(imgs_list_path,[output_path]*len(imgs_list_path))))
    pool.starmap(save_img,zip(imgs_list_path,[output_path]*len(imgs_list_path)))
    pool.close()
    pool.join()
    end_time=time.time()
    print('use time=',end_time-start_time)