This lists the root job UUIDs (the jobs with no dependants).
Currently only implemented by fsjobqueue. The function for
dbjobqueue currently returns nil.
Related: RHEL-60120
Fixes the special case that if no worker is available and we
generate an internal timeout and cancel the depsolve including all
followup jobs, no error was propagated.
If a job is unresponsive the worker has most likely crashed or been shut
down and the in-progress job been lost.
Instead of failing these jobs, requeue them up to two times. Once a job is lost
a third time it fails. This avoids infinite loops.
This is implemented by extending FinishJob to RequeuOrFinish job. It takes a
max number of requeues as an argument, and if that is 0, it has the same
behavior as FinishJob used to have.
If the maximum number of requeues has not yet been reached, then the running
job is returned to pending state to be picked up again.
