进程和线程

• 进程：一个程序 一个进程，操作系统分配资源（内存、线程）
• 线程：cpu运算调度的最小单位

创建

方法一

from threading import Thread


def thread_func(name):
    for i in range(10):
        print(name, i)
# 主线程中创建了3个子线程
if __name__ == '__main__':
    thread1 = Thread(target=thread_func, args=('张三',)) # 参数是元组
    thread2 = Thread(target=thread_func, args=('李四',)) # 参数是元组
    thread3 = Thread(target=thread_func, args=('王五',)) # 参数是元组
    thread1.start()
    thread2.start()
    thread3.start()
    print("主线程")

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方法二

续承Thread类

from threading import Thread

class ThreadFunc(Thread):
    def __init__(self, name):
        super(ThreadFunc, self).__init__()
        self.name = name
    # 重写run函数
    def run(self):
        for i in range(10):
            print(self.name, i, sep="---")
# 主线程中创建了3个子线程
if __name__ == '__main__':
    thread1 = ThreadFunc('张三')
    thread2 = ThreadFunc('李四')
    thread3 = ThreadFunc('王五')
    thread1.start()
    thread2.start()
    thread3.start()
    print("主线程")

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线程池

无返回值

from concurrent.futures import ThreadPoolExecutor

def work_thread(name):
    for i in range(8):
        print(name)
if __name__ == '__main__':
    with ThreadPoolExecutor(8) as thread_pool:
        for i in range(5):
            thread_pool.submit(work_thread, f"岳王{i}")
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有返回值

• 返回值的顺序不确定，谁执行完，先返回谁

import time
from concurrent.futures import ThreadPoolExecutor

def work_thread(name, t):
    time.sleep(t)
    # print("you can call me ", name)
    return name
def func_return(outcome):
    print(outcome.result())
if __name__ == '__main__':
    with ThreadPoolExecutor(8) as thread_pool:
        # 分别睡3秒、1秒、2秒
        thread_pool.submit(work_thread, "岳王",3).add_done_callback(func_return)
        thread_pool.submit(work_thread, "张飞",1).add_done_callback(func_return)
        thread_pool.submit(work_thread, "刘备",2).add_done_callback(func_return)
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• 返回值的顺序不确定。map返回值是生成器，按任务分发的顺序进行返回

import time
from concurrent.futures import ThreadPoolExecutor

def work_thread(name, t):
    time.sleep(t)
    # print("you can call me ", name)
    return name
def func_return(outcome):
    print(outcome.result())
if __name__ == '__main__':
    with ThreadPoolExecutor(8) as thread_pool:
        # 分别睡3秒、1秒、2秒
        res = thread_pool.map(work_thread, ['岳王', '张飞', '刘备'], [3, 1, 2])
        for i in res:
            print(i)
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线程实例

from concurrent.futures import ThreadPoolExecutor
import requests
from lxml import etree
def get_data(page):
    data = {
        'limit': '20',
        'current': page,
        'pubDateStartTime':'',
        'pubDateEndTime':'',
        'prodPcatid': '1189',
        'prodCatid':'',
        'prodName':'',
    }
    url = '仅做格式http://www.xinfadi.com.cn/getPriceData.html未曾试用'
    res = requests.post(url, data=data).json()
    for i in res['list']:
        # print(i)
        one_row = i['prodCat']+','+i['prodPcat']+','+i['prodName']+','+i['lowPrice']+','+i['avgPrice']+','+i['highPrice']+','+i['specInfo']+','+i['place']+','+i['unitInfo']+','+i['pubDate']
        f.write(one_row)
        f.write('\n')
f = open('price.csv', 'w', encoding='utf-8')
if __name__ == '__main__':
    with ThreadPoolExecutor(8) as thread_pool:
        for page in range(1, 8):
            thread_pool.submit(get_data, page)

    # print(res['list'])

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