Here's another interesting story about type of problems we've to deal at Browserling and Testling. This story is about how we implemented Windows user session cycling for Testling.
Here's what it is.
We run JavaScript tests on Windows for days straight and Windows sessions become really unstable after a while. When that happens we start getting errors such as Internet Explorer timing out randomly although everything is fine:
Internet Explorer cannot display the website
Or remote desktop connection gets messed up and I'm no longer able to get into the server:
Remote Desktop can't connect to the remote computer
Or Chrome starts to randomly crash:
Aww snap
None of these errors happen when the Windows session is fresh, so to work around these issues we implemented a Windows session cycler that simply logs out the user that runs tests, and logs it back in again every 6 hours. The implementation is pretty straight forward and just uses the standard Windows command line tools for managing users, such as users.exe and logoff.exe, as well as rdesktop.exe.
The user cycler is about a 100 line program but here's how it basically works:
user_id = find user id of testling user using users.exe call <logout.exe user_id> wait until user has been logged off login testling user again using rdesktop.exe
The testling user's startup script initializes the testing environment and tests continue running after a short interruption.
A better solution would be to boot a clean Windows instance for every test but we're not there yet. Until next time.