One of our CI builds is bound by labels to run either on Slave 10 (Mac) or on Slave 8 (Win). They are not supposed to run on our Master.

Nevertheless, from time to time you can observe that one of the jobs gets stuck in the assignment phase where it looks like that it is bound to the Master but the job is sitting on one of the Slaves. (See attachment)

If you leave the job untouched it somehow finishes after 28min even though the task just needs 4sec. (see attachment). That means a job which would need 4sec does nothing for 27min until it solved its assignment issue.

However, if you "stop" the job in the weird assignment phase then this job is bound forever to nothing. That means if you want to run this job again you need to reboot the entire farm the get rid of the zombie-job.