3 ms·

so the process that fails releases the lock marking the job undone which causes another process to lock it?

• xyzzy_plugh 7y ago
  It means another process could grab it, yes. In the parent post's model, the "scheduler" operates in a "at least once" model", as unless the transaction is committed, a premature failure would result in the message will be picked up again by a scheduler, which could result in some duplicate work. The parent post's model also tracks "attempts", but this only captures known or acknowledged failures -- unacknowledged failures (i.e. crashes) will not be recorded, so a task which explodes the process would be re-run ad infinitum. An alternative method could be to record an attempt in a separate transaction, so that the next scheduler execution can detect that the job/message was serviced before, even if the message itself appears fresh.