Prevent Jenkins hang with unresponsive web servers

[rhayes-cida]

Existing code can stall the build if it encounters an unresponsive web server (one that allows a connection, but stalls rather than producing a response). We've had to restart Jenkins to clear the stalled builds.

This proposed change does a couple of things to prevent this problem:

• Add a read timeout to the URL connection
• Run the URL check in a separate thread, with a timeout when getting the response

[buildhive]

Jenkins » sitemonitor-plugin #14 FAILURE
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[jenkinsadmin]

Thank you for a pull request! Please check this document for how the Jenkins project handles pull requests

[buildhive]

Jenkins » sitemonitor-plugin #15 FAILURE
Looks like there's a problem with this pull request
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[buildhive]

Jenkins » sitemonitor-plugin #16 SUCCESS
This pull request looks good
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[medington]

What is the status of this pull request? I'm running into a situation that would seem will be fixed by this. If there is something wrong with the pull request I'll be more than happy to fix it.

[JENKINS-13358] appears to be an existing issue that would relate to this pull request.

[medington]

Update: I ran into an issue with this pull request. After running the project one time, I would get an error attempting to save the project configuration after changing a setting. Restarting Jenkins seemed to work around the error but I believe there is some sort of a serialization incompatibility with this change.

I also found that patching the existing master branch with just the change to call connection.setReadTimeout also fixes the issue without restoring to using async validation of the URL.