Python. Multi-procressing

Question

Last attempt to get an answer.

I need to run 4 functions in an infinite loop on different threads.

The error is that only the first thread runs. Feel free to ask why the functions are like what they are.

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

I think you expect your code to start at

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

But it actually enters this while loop first :

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

and since it is an infinite loop the code is stuck there.

This happens because the loop is not inside any function. So main function is never called and your threads are not started.