Selenium: "Unable to find session with ID" after a few minutes of idling-CodePudding

I started a Docker container with: docker run -d --shm-size="4g" --hostname selenium_firefox selenium/standalone-firefox

In another container with Python:

...
>>> driver = webdriver.Remote(command_executor="http://"  selenium_host ":4444/w
d/hub", desired_capabilities=DesiredCapabilities.FIREFOX, keep_alive=True)      
                                                                             
>>> driver.title                                                                
''                                                                              
>>> driver.title                                                                
Traceback (most recent call last):                                              
  File "<stdin>", line 1, in <module>                                           
  File "/usr/local/lib/python3.10/site-packages/selenium/webdriver/remote/webdri
ver.py", line 447, in title                                                     
    resp = self.execute(Command.GET_TITLE)                                      
  File "/usr/local/lib/python3.10/site-packages/selenium/webdriver/remote/webdri
ver.py", line 424, in execute                                                   
    self.error_handler.check_response(response)                                 
  File "/usr/local/lib/python3.10/site-packages/selenium/webdriver/remote/errorh
andler.py", line 247, in check_response                                         
    raise exception_class(message, screen, stacktrace)                          
selenium.common.exceptions.WebDriverException: Message: Unable to execute reques
t for an existing session: Unable to find session with ID: 5c619451-8361-4ec9-9b
7e-58b7afac15ff                                                                 
Build info: version: '4.1.1', revision: 'e8fcc2cecf'                            
System info: host: 'selenium_firefox', ip: '172.17.0.3', os.name: 'Linux', os.ar
ch: 'amd64', os.version: '5.4.0-89-generic', java.version: '11.0.13'            
Driver info: driver.version: unknown

The first driver.title I ran it immediately after creating the remote webdriver.

Then I waited for some time (around 15 minutes) and ran driver.title again, and it seem that the Python console has lost connection to the corresponding browser.

Why does this happen and how do I avoid it? It doesn't happen if I don't use a remote webdriver.

CodePudding user response：

Option 1: Override Docker Selenium Grid default session timeout

From docker/selenium documentation:

Grid has a default session timeout of 300 seconds, where the session can be on a stale state until it is killed. You can use SE_NODE_SESSION_TIMEOUT to overwrite that value in seconds.

docker run -d -e SE_NODE_SESSION_TIMEOUT=1000 --shm-size="4g" --hostname selenium_firefox selenium/standalone-firefox

Option 2: Ping your session once in 60 (any < 300) seconds

You may execute some driver command in a loop during the idle time

for x in range(15):
    time.sleep(60)
    driver.current_url

Reference

https://github.com/SeleniumHQ/docker-selenium#grid-url-and-session-timeout