Occasional 'unable to obtain stable firefox connection' Error

[travis-fillmore-ck]

When attempting to run selenium webdriver tests with the headless gem (v1.0.1) on CentOS, we are seeing tests fail with the following message around ~5% of the time on our CI server:
unable to obtain stable firefox connection in 60 seconds

This seems very similar to the issue detailed in this closed ticket, and the more recent comments indicate that other people are seeing this problem as well. #33

When running with debug output we also see this error occur before the firefox timeout:
The application 'firefox' lost its connection to the display :1785.0; most likely the X server was shut down or you killed/destroyed the application.

Our tests should not be doing anything that would stop or restart the X server directly, as they are only accessing Xvfb through the headless gem. We are out of ideas to debug this issue, any information you might be able to provide would be greatly appreciated.

Full debug output can be seen here:
https://gist.github.com/tfillmore-ck/fcb534384752193ad4bd

[ZirconCode]

Ran into this error too. This problem only seems to occur when I ask the webdriver to start from a profile.

# Causes problem
headless = Headless.new
headless.start
profile = Selenium::WebDriver::Firefox::Profile.new
profile["media.volume_scale"] = 0.0
d = Selenium::WebDriver.for :firefox, :profile => profile

# Does not cause problem
headless = Headless.new
headless.start
d = Selenium::WebDriver.for :firefox

[leonid-shevtsov]

Closing this for old age (and sorry for not looking into it earlier!) - please reopen if you have any current issues.