At 15:19 -0700 on 07/11/2011, Bill McQuillan wrote about Comments on:
draft-melnikov-smtp-priority-02:
Section 5.1:
Since the vast majority of messages will either be marked as
"PRIORITY 0" or presumed to be priority 0, is there any mechanism
to prevent starvation for those messages marked at a negative
priority? Note that for a high volume MTA there would likely
always be SOME priority 0 messages in the queue which would
preclude sending ANY messages at a lower priority.
Many queuing systems that I have seen reward items that have a low
priority and thus have sat on the queue and never processed [due to
there always being higher priority items on the queue that prevent
their being selected] by periodically bumping their priority. In this
type of system, you would, for example, designate that a low priority
item gets its priority bumped one priority notch after it has been
unprocessed for x minutes (until it gets to priority 0/normal). Thus
if the bump interval is 15 minutes, a priority -3 will go normal
after no longer than 45 minutes (and thus be sent as it gets to the
top of the priority 0 queue [which I assume will be FIFO within
priority] either due to FIFO on queue or submission timestamp [which
would make the delayed and bumped item the highest priority 0 item]).