Chrome crashes after several hours while multiprocessing using Selenium through Python

问题

This is the error traceback after several hours of scraping:

The process started from chrome location /usr/bin/google-chrome is no longer running, so ChromeDriver is assuming that Chrome has crashed.

This is my setup of selenium python:

#scrape.py
from selenium.common.exceptions import *
from selenium.webdriver.common.by import By
from selenium.webdriver.support import expected_conditions as EC
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.chrome.options import Options

def run_scrape(link):
    chrome_options = Options()
    chrome_options.add_argument('--no-sandbox')
    chrome_options.add_argument("--headless")
    chrome_options.add_argument('--disable-dev-shm-usage')
    chrome_options.add_argument("--lang=en")
    chrome_options.add_argument("--start-maximized")
    chrome_options.add_experimental_option("excludeSwitches", ["enable-automation"])
    chrome_options.add_experimental_option('useAutomationExtension', False)
    chrome_options.add_argument("user-agent=Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.181 Safari/537.36")
    chrome_options.binary_location = "/usr/bin/google-chrome"
    browser = webdriver.Chrome(executable_path=r'/usr/local/bin/chromedriver', options=chrome_options)
    browser.get(<link passed here>)
    try:
        #scrape process
    except:
        #other stuffs
    browser.quit()

#multiprocess.py
import time,
from multiprocessing import Pool
from scrape import *

if __name__ == '__main__':
    start_time = time.time()
    #links = list of links to be scraped
    pool = Pool(20)
    results = pool.map(run_scrape, links)
    pool.close()
    print("Total Time Processed: "+"--- %s seconds ---" % (time.time() - start_time))

Chrome, ChromeDriver Setup, Selenium Version

ChromeDriver 79.0.3945.36 (3582db32b33893869b8c1339e8f4d9ed1816f143-refs/branch-heads/3945@{#614})
Google Chrome 79.0.3945.79
Selenium Version: 4.0.0a3

Im wondering why is the chrome is closing but other processes are working?

回答1:

I took your code, modified it a bit to suit to my Test Environment and here is the execution results:

Code Block:

multiprocess.py:

import time
from multiprocessing import Pool
from multiprocessingPool.scrape import run_scrape

if __name__ == '__main__':
    start_time = time.time()
    links = ["https://selenium.dev/downloads/", "https://selenium.dev/documentation/en/"] 
    pool = Pool(2)
    results = pool.map(run_scrape, links)
    pool.close()
    print("Total Time Processed: "+"--- %s seconds ---" % (time.time() - start_time))

scrape.py:

from selenium import webdriver
from selenium.common.exceptions import NoSuchElementException, TimeoutException
from selenium.webdriver.common.by import By
from selenium.webdriver.chrome.options import Options

def run_scrape(link):
    chrome_options = Options()
    chrome_options.add_argument('--no-sandbox')
    chrome_options.add_argument("--headless")
    chrome_options.add_argument('--disable-dev-shm-usage')
    chrome_options.add_argument("--lang=en")
    chrome_options.add_argument("--start-maximized")
    chrome_options.add_experimental_option("excludeSwitches", ["enable-automation"])
    chrome_options.add_experimental_option('useAutomationExtension', False)
    chrome_options.add_argument("user-agent=Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.181 Safari/537.36")
    chrome_options.binary_location=r'C:\Program Files (x86)\Google\Chrome\Application\chrome.exe'
    browser = webdriver.Chrome(executable_path=r'C:\Utility\BrowserDrivers\chromedriver.exe', options=chrome_options)
    browser.get(link)
    try:
        print(browser.title)
    except (NoSuchElementException, TimeoutException):
        print("Error")
    browser.quit()

Console Output:

Downloads
The Selenium Browser Automation Project :: Documentation for Selenium
Total Time Processed: --- 10.248600006103516 seconds ---

Conclusion

It is pretty much evident your program is logically flawless and just perfect.

This usecase

As you mentioned this error surfaces after several hours of scraping, I suspect this due to the fact that WebDriver is not thread-safe. Having said that, if you can serialize access to the underlying driver instance, you can share a reference in more than one thread. This is not advisable. But you can always instantiate one WebDriver instance for each thread.

Ideally the issue of thread-safety isn't in your code but in the actual browser bindings. They all assume there will only be one command at a time (e.g. like a real user). But on the other hand you can always instantiate one WebDriver instance for each thread which will launch multiple browsing tabs/windows. Till this point it seems your program is perfect.

Now, different threads can be run on same Webdriver, but then the results of the tests would not be what you expect. The reason behind is, when you use multi-threading to run different tests on different tabs/windows a little bit of thread safety coding is required or else the actions you will perform like click() or send_keys() will go to the opened tab/window that is currently having the focus regardless of the thread you expect to be running. Which essentially means all the test will run simultaneously on the same tab/window that has focus but not on the intended tab/window.

回答2:

Right now im using this threading module to instantiate one Webdriver each thread

import threading
threadLocal = threading.local()

def get_driver():
    browser = getattr(threadLocal, 'browser', None)
    if browser is None:
        chrome_options = Options()
        chrome_options.add_argument('--no-sandbox')
        chrome_options.add_argument("--headless")
        chrome_options.add_argument('--disable-dev-shm-usage')
        chrome_options.add_argument("--lang=en")
        chrome_options.add_argument("--start-maximized")
        chrome_options.add_experimental_option("excludeSwitches", ["enable-automation"])
        chrome_options.add_experimental_option('useAutomationExtension', False)
        chrome_options.add_argument("user-agent=Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.181 Safari/537.36")
        chrome_options.binary_location = "/usr/bin/google-chrome"
        browser = webdriver.Chrome(executable_path=r'/usr/local/bin/chromedriver', options=chrome_options)
        setattr(threadLocal, 'browser', browser)
    return browser

and it really helps me to scrape faster than executing one driver at a time.

来源：https://stackoverflow.com/questions/60181613/chrome-crashes-after-several-hours-while-multiprocessing-using-selenium-through

标签

python

selenium

google-chrome

multiprocessing

selenium-chromedriver