How to stop chrome launched by selenium remote driver?

Question

First, I'm using Django, and I'm building an API. For example, I've route like api/get-some-element.

browser_url = cache.get('user_%d.browser_url' % user_id)
is_browser_queued = cache.get('user_%d.browser_queued' % user_id)
browser_session_id = cache.get('user_%d.browser_session_id' % user_id) # session id of the main chrome

if browser_url:
    capabilities = DesiredCapabilities.CHROME.copy()
    driver = webdriver.Remote(
        command_executor=browser_url,
        desired_capabilities=capabilities,
        options=options,
    )
    driver.session_id = browser_session_id

    return driver

if not is_browser_queued:
    run_browser.delay(user_id) # launch main chrome
    cache.set('user_%d.browser_queued' % user_id, True, None)

On the first access to that route, it will send a task to Celery to launch Selenium Headless Chrome (main chrome). Why I'm using Celery? Because I need to make Chrome always running. (Idk better way, this is what I know).

Then, for the next access on that route, it will response with Waiting chrome to launched., until the Celery task got executed (chrome launched properly).

After main chrome is launched, then it will launch Selenium Headless Remote Driver immediately (without Celery), the purpose of this remote driver is to access the main chrome. Then, it just grab some element from a website.

But, after finish, the Remote Driver is still running. How to stop that?

I know the command such as driver.quit() or driver.close(). But, as far as I know, it's send the command to the main chrome, not to the chrome launched by remote driver. And that's not what I want. I don't want to quit the main chrome, just quit the chrome launched by remote driver.

Answer 1

driver.close(), driver.quit() , driver.close closes the current window and driver.quit closes all the windows , also I highly recommend you don’t use selenium , it is very slow and the same thing can be achieved with requests

Answer 2

The problem is with driver.quit() method only for Chrome. The driver quit didnt work properly it didnt kill all processes of chrome (including child processes). what you can do is change Selenium jar codes to fix this.

or you can make use of finally block.

System.setProperty("webdriver.chrome.driver","/<path to chrome driver>/chromedriver");
    ChromeOptions options = new ChromeOptions();
    options.setBinary(new File("/<path to chrome >/google-chrome"));
    driver = new ChromeDriver(options);
    try
    {
        //automated steps
    }
    finally
    {
        driver.quit();
    }

Answer 3

Are you using multiple Chrome windows?

driver.close should work, because it closes only the focused window. Maybe you should try:

driver.switch_to.window(driver.window_handles[1])
driver.close()

In this case, you should find the certain window to switch for. Please, let me know if that works

Answer 4

You are starting an external process and want to stop it from another (not the one that started it) python process. For this you can save process pid or name and kill it with os.kill(pid, signal.SIGKILL) or with similar alternatives.

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You can also start chromedriver as a service:

service = Service('/path/to/chromedriver')
service.start()
...
service.stop()

which uses subprocess.Popen at the back. As you might be starting from one python process / celery worker and later stopping from another - save service.pid in cache / database / queue / etc and send signals to process pid directly, rather than doing service.stop().

One possible downside of killing process directly - it may not perform all clean-up tasks correctly (i.e. close opened sockets), it may hang, you may need more logic to control its status etc.

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Alternatives to control another process - are to rely on external service manager, like systemd or docker. This separates all process control logic in their configuration (service file or Dockerfile), makes easier to control that only one instance is run and much more.

• launch chromedriver as system service with systemd as a service. You can control from python with i.e. pystemd
• or if you are working with docker - launch chromedriver as docker container with docker-python

With these options you are telling external managers to start / stop service, not trying to control it from your app.

In distributed environment you may want to make sure chromedriver is launched only on specific node - i.e. make only celery worker on it to listen to broker queue with chromedriver launch tasks or connect to docker engine on target node or use node_id / tag in swarm / k8s ...