Python。 多处理

Question

最后一次尝试得到答案。

我需要在不同线程上无限循环运行 4 个函数。

错误是只有第一个线程运行。 随意问为什么这些功能是这样的。

import time
import threading
import requests
from bs4 import BeautifulSoup

headers = {'user-agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.111 Safari/537.36'}

def carrigaline(): #Get the first Ad's link
    while True:

        try:
            page = requests.get(
                'https://www.daft.ie/property-for-sale/carrigaline-and-surrounds-cork?salePrice_from=200000&salePrice_to=300000',
                headers=headers).text
            soup = BeautifulSoup(page, 'html.parser')
            divs = soup.findAll('a', attrs={'class': None})
            cur_carri = 'https://www.daft.ie' + divs[0].get('href')
            return cur_carri
        except Exception as e:
            print(e)
            pass

def crosshaven():
    while True:
        try:
            page = requests.get(
                'https://www.daft.ie/property-for-sale/crosshaven-cork?salePrice_from=200000&salePrice_to=300000',
                headers=headers).text
            soup = BeautifulSoup(page, 'html.parser')
            divs = soup.findAll('a', attrs={'class': None})
            cur_haven = 'https://www.daft.ie' + divs[0].get('href')
            return cur_haven
        except Exception as e:
            print(e)
            pass

def minane():
    while True:
        try:
            page = requests.get(
                'https://www.daft.ie/property-for-sale/minane-bridge-cork?salePrice_from=200000&salePrice_to=300000',
                headers=headers).text
            soup = BeautifulSoup(page, 'html.parser')
            divs = soup.findAll('a', attrs={'class': None})
            cur_min = 'https://www.daft.ie' + divs[0].get('href')
            return cur_min
        except Exception as e:
            print(e)
            pass
def ballygarvan():
    while True:
        try:
            page = requests.get(
                'https://www.daft.ie/property-for-sale/ballygarvan-cork?salePrice_from=200000&salePrice_to=300000',
                headers=headers).text
            soup = BeautifulSoup(page, 'html.parser')
            divs = soup.findAll('a', attrs={'class': None})
            cur_bally = 'https://www.daft.ie' + divs[0].get('href')
            return cur_bally
        except Exception as e:
            print(e)
            pass



first_run = True

while True:
    print("Starting 1st thread")
    time.sleep(6) #Sleep 5 minutes
    bally = ballygarvan()
    first_run = False
    new_bally = ballygarvan()
    print(new_bally)
    if not first_run:
        if new_bally != bally:
            print("New Ad")
            continue

while True:
    print("starting second")
    time.sleep(5) #Sleep 5 minutes
    min_a = minane()
    first_run = False
    new_mina = minane()
    print(new_mina)
    if not first_run:
        if new_mina != min_a:
            print("New Ad")
            continue
while True:
    print("starting third")
    time.sleep(7) #Sleep 5 minutes
    carr = carrigaline()
    first_run = False
    new_carr = carrigaline()
    print(new_carr)
    if not first_run:
        if new_carr != carr:
            print("New Ad")
            continue

while True:
    print("starting fourth")
    time.sleep(9) #Sleep 5 minutes
    cross = crosshaven()
    first_run = False
    new_cross = crosshaven()
    print((new_cross))
    if not first_run:
        if new_cross != cross:
            print("New Ad")
            continue


if __name__ == "__main__":
    t1 = threading.Thread(target=carrigaline, name='t1')
    t1.start()
    t2 = threading.Thread(target=minane, name='t2')
    t2.start()
    t3 = threading.Thread(target=crosshaven, name='t3')
    t3.start()
    t4 = threading.Thread(target=ballygarvan, name='t4')
    t4.start()

Answer 1

我想你希望你的代码从

if __name__ == "__main__":
    t1 = threading.Thread(target=carrigaline, name='t1')

但它实际上首先进入了这个while循环：

first_run = True

while True:
    print("Starting 1st thread")
    time.sleep(6) #Sleep 5 minutes
    bally = ballygarvan()
    first_run = False
    new_bally = ballygarvan()
    print(new_bally)
    if not first_run:
        if new_bally != bally:
            print("New Ad")
            continue

并且由于它是一个无限循环，因此代码被卡在那里。

发生这种情况是因为循环不在任何 function 内。 所以主 function 永远不会被调用，你的线程也没有启动。