Why do I have this error when multithreading a PyQt5 script

Question

When I run the following python code I get the following error. Is there something that I'm missing ?

from bs4 import BeautifulSoup
import sys
import requests
from PyQt5.QtWebEngineWidgets import QWebEnginePage
from PyQt5.QtWidgets import QApplication
from PyQt5.QtCore import QUrl
from threading import Thread

url = "https://www.booking.com/searchresults.fr.html?label=gen173nr-1FCAEoggI46AdIM1gEaE2IAQGYAQ24ARjIAQzYAQHoAQH4AQuIAgGoAgS4Ar3x5ukFwAIB&sid=a454e37209591e054b02e8917d61befe&tmpl=searchresults&checkin_month=8&checkin_monthday=1&checkin_year=2019&checkout_month=8&checkout_monthday=2&checkout_year=2019&class_interval=1&dest_id=-1456928&dest_type=city&dtdisc=0&from_sf=1&group_adults=1&group_children=0&inac=0&index_postcard=0&label_click=undef&no_rooms=1&postcard=0&raw_dest_type=city&room1=A&sb_price_type=total&shw_aparth=1&slp_r_match=0&src_elem=sb&srpvid=14466c78e41800bd&ss=Paris&ss_all=0&ssb=empty&sshis=0&ssne=Paris&ssne_untouched=Paris&order=review_score_and_price"


class Page(QWebEnginePage):
    def __init__(self, url):
        self.app = QApplication(sys.argv)
        QWebEnginePage.__init__(self)
        self.html = ''
        self.loadFinished.connect(self._on_load_finished)
        self.load(QUrl(url))
        self.app.exec_()

    def _on_load_finished(self):
        self.html = self.toHtml(self.Callable)
        print('Load finished')

    def Callable(self, html_str):
        self.html = html_str
        self.app.quit()


class test(Thread):
    def __init__(self, number):
        Thread.__init__(self)
        self.number = number
        print(self.number)

    def run(self):
        """Code à exécuter pendant l'exécution du thread."""
        page = Page(url)
        soup = BeautifulSoup(page.html, 'html.parser')
        print(self.number)
        f = open("test" + self.number + ".html", "w")
        f.write(soup)
        f.close()



thread1 = test("1")
thread2 = test("2")

thread1.start()
thread2.start()

thread1.join()
thread2.join()

1 2 WARNING: QApplication was not created in the main() thread. WARNING: QApplication was not created in the main() thread. Segmentation fault: 11

1) You cannot and should not create a QApplicacion in another thread, 2) You must not create a QWebEnginePage in another thread. In the duplicates that I have provided, one bases what I indicated above and in the other it indicates an alternative to what you are doing. — eyllanesc, Jul 25 '19 at 19:24

score 0 · Answer 1 · answered Jul 25 '19 at 18:44

As the warning states, you are creating the QApplication instance outside the main thread. For any Qt application there is exactly one QApplication object and it must be created before any other Qt objects are created. Try something like this instead:

class Page(QWebEnginePage):
    def __init__(self, url):
        QWebEnginePage.__init__(self)
        self.html = ''
        self.loadFinished.connect(self._on_load_finished)
        self.load(QUrl(url))

...

app = QApplication(sys.argv)

thread1 = test("1")
thread2 = test("2")

thread1.start()
thread2.start()

thread1.join()
thread2.join()

app.exec()

Why do I have this error when multithreading a PyQt5 script

1 Answers1