It helps to reference Que's schema [1] and source code to explain this further. But I'm also going from memory so it's possible I will miss some details :)
* If the entire worker process dies, then it will lose its Postgres connection which is holding an advisory lock on the jobs being worked. This releases those jobs to be worked by another worker. I don't recall how the built-in retry & back-off mechanisms work in this scenario. This advisory lock is indeed held for the entire time the jobs are being worked on, but only from a single supervisor connection (rather than one connection per job).
* If the job thread crashes, the worker supervisor catches this and the job is marked for a retry at a later time.
* If the entire worker process dies, then it will lose its Postgres connection which is holding an advisory lock on the jobs being worked. This releases those jobs to be worked by another worker. I don't recall how the built-in retry & back-off mechanisms work in this scenario. This advisory lock is indeed held for the entire time the jobs are being worked on, but only from a single supervisor connection (rather than one connection per job).
* If the job thread crashes, the worker supervisor catches this and the job is marked for a retry at a later time.
[1]: https://github.com/que-rb/que/blob/master/lib/que/migrations...