Disable multiple queued items attribute

@odinserj

https://gist.github.com/odinserj/a8332a3f486773baa009 this is your gist with that attribute and it’s extremely useful for a lot of people I believe.

Two questions about it.

If job is performed but will be retried, the lock is released, so if another job comes at that time it’s possible to have 2 running at the same time, right?
Would a fix be to move adding fingerprint from OnCreating to OnPerforming method so fingerprint is live only when job is performing?
It’s not optimal because it’s possible to queue a ton of jobs that will only fail on execution so they take workers time for nothing. But at least you avoid 2 same jobs at the same time which is much more severe issue for some systems.

Field value is 100 chars max, so if a job has DateTime parameter and a bit longer name it’s easy to go over that limit. Maybe update gist with using hash of fingerprint so it’s constant length. It was a pain to debug this when it happened to us