Webdriver randomly produces 'chrome not reachable' on Linux tests

Question

Our CI tests fail randomly with 'chrome not reachable' error. Initially they were quite rare, but as our test base grows, it has become intolerable. There are several other questions / bug reports about this, but none of these seem to relate to our case.

The tests are written with Cucumber + Ruby + Watir-Webdriver + Selenium-Webdriver (latest versions of each gem). We're running the tests on Ubuntu Linux 12.04 in headless mode using xvfb on physical hardware (no virtualization). I can reproduce it quite reliably on my laptop running Linux Mint 16. We're running the tests in parallel for speeding up things.

I've tried using both Chromium 18.0.1025.151~r130497-0ubuntu1 and Google Chrome 34.0.1847.116, with ChromeDriver v2.9.248304. The same problem has occurred with older versions of the browser and ChromeDriver as well.

Typically several tests fail in a row due to the same error and then is starts working again on a later test during the same run.

The stack trace is:

  chrome not reachable
    (Session info: chrome=34.0.1847.116)
    (Driver info: chromedriver=2.9.248304,platform=Linux 3.2.0-60-generic x86_64) (Selenium::WebDriver::Error::WebDriverError)
  /home/weller/jenkins/workspace/TEST_CHROME_C/server/cucumber/support/step_support/browsers.rb:14:in `goto'
  /home/weller/jenkins/workspace/TEST_CHROME_C/server/cucumber/support/step_support/browsers.rb:35:in `blank_page'
  /home/weller/jenkins/workspace/TEST_CHROME_C/server/cucumber/support/step_support/browsers.rb:44:in `add_cookie'
  ./features/support/mocking.rb:11:in `mock'
  ./features/support/time_steps.rb:5:in `/^the current time zone is "(.*?)"$/'
  features/trackers/mood/mood_data_entry.feature:7:in `And the current time zone is "GMT+4"'

Update: The problem seems to be related to the parallelism. When one of the tests exit, there's a chance that another one will start failing with 'chrome not reachable'. If I add a delay to the end of the tests, so that all tests have finished before any Chrome windows are closed, the tests run without problem. I reported a bug against ChromeDriver about the issue.

Answer 1

I had the same problem, in my case it was because user-data-dir, which is randomly created by chromedriver, in some cases was the same for several tests. I solved it by synchronizing webdriver creation (performance is not affected by this)