Python Selenium: Extracting the PID of Chrome and Firefox browser

Question

How do you get the process ID (PID) of the Chrome/Chromium or Firefox browser launched by Selenium? I'm looking for a solution that also works when the browser is launched in a Selenium Grid.

Using driver.service.process.pid is not possible with Selenium Grid.

Answer 1

To retrieve the process ID (PID) of the Chrome/Firefox browsers launched by Selenium you can use the following solutions:

Firefox

• Code Block:

  from selenium import webdriver
  
  driver = webdriver.Firefox(executable_path=r'C:\WebDrivers\geckodriver.exe')
  my_dict = driver.capabilities
  print("PID of the browser process is: " + str(my_dict['moz:processID']))
  

• Console Output:

  PID of the browser process is: 2172
  

Chrome

• Code Block:

  from selenium import webdriver
  from contextlib import suppress
  import psutil
  
  driver = webdriver.Chrome(executable_path=r'C:\WebDrivers\chromedriver.exe')
  driver.get('https://www.google.com/')
  for process in psutil.process_iter():
    if process.name() == 'chrome.exe' and '--test-type=webdriver' in process.cmdline():
            with suppress(psutil.NoSuchProcess):
                print(process.pid)
  driver.quit()
  

• Console Output:

  12384
  13656
  13800
  

---

References

You can find a couple of relevant detailed discussions in:

• Get PID of Browser launched by selenium

Answer 2

When launching a browser with Selenium, it creates a new temporary directory for the profile settings (unless otherwise specified). We can use this to identify the specific process(es) that the browser uses:

In [470]: driver.capabilities
Out[470]: 
{'acceptInsecureCerts': False,
 'browserName': 'chrome',
 'browserVersion': '86.0.4240.198',
 'chrome': {'chromedriverVersion': '85.0.4183.87 (cd6713ebf92fa1cacc0f1a598df280093af0c5d7-refs/branch-heads/4183@{#1689})',
  'userDataDir': '/tmp/.com.google.Chrome.nW2W6p'},
 'goog:chromeOptions': {'debuggerAddress': 'localhost:44047'},
...}

This approach works for both Firefox and Chrome, even if you have multiple instances of a browser running, and also if the browsers are launched through Selenium Grid (if the code is run on the node server).

You will need to install psutil:

pip install psutil

import psutil
import re
from typing import List


def pgrep(term, regex=False, full=True) -> List[psutil.Process]:
    """
    If `full`, then `term` is matched against the command line
    the process has been called with,
    else it is only matched against the process name.
    """
    procs = []
    for proc in psutil.process_iter(['pid', 'name', 'username', 'cmdline']):
        if full:
            name = ' '.join(proc.cmdline())
        else:
            name = proc.name()
        try:
            if regex and re.search(term, name):
                procs.append(proc)
            elif term in name:
                procs.append(proc)
        except psutil.NoSuchProcess:
            pass
    return procs


def browser_procs(driver) -> List[psutil.Process]:
    """
    Return the Processes associated with the browser
    (excluding geckodriver/chromedriver)
    """
    if driver.capabilities['browserName'] == 'firefox':
        directory = driver.capabilities['moz:profile']
    else:
        directory = driver.capabilities['chrome']['userDataDir']
    procs = pgrep(directory, full=True)
    procs.sort(key=lambda p: p.pid)
    return procs


def browser_proc(driver) -> psutil.Process:
    """
    Return the main Process of the browser
    (excluding geckodriver/chromedriver)
    """
    procs = browser_procs(driver)
    for proc in procs:
        name = proc.parent().name()
        if 'chromedriver' in name or 'geckodriver' in name:
            return proc
    raise ValueError



def driver_proc(driver) -> psutil.Process:
    """
    Return the Process of the geckodriver/chromedriver
    """
    return browser_proc(driver).parent()

Let's see it in action:

In [436]: driver = Chrome()

In [451]: browser_procs(driver)
Out[468]: 
[psutil.Process(pid=38453, name='chrome', status='sleeping', started='18:45:51'),
 psutil.Process(pid=38462, name='chrome', status='sleeping', started='18:45:51'),
 psutil.Process(pid=38463, name='chrome', status='sleeping', started='18:45:51'),
 psutil.Process(pid=38467, name='chrome', status='sleeping', started='18:45:51'),
 psutil.Process(pid=38486, name='chrome', status='sleeping', started='18:45:52'),
 psutil.Process(pid=38489, name='chrome', status='sleeping', started='18:45:52'),
 psutil.Process(pid=38521, name='chrome', status='sleeping', started='18:45:52'),
 psutil.Process(pid=38522, name='chrome', status='sleeping', started='18:45:52')]

In [471]: p = browser_proc(driver)
In [472]: p.pid
Out[472]: 38453

If you want the PID of the chromedriver or geckodriver, then you can get that process through browser_proc(driver).parent()