On 2020-Oct-29, Stephen Frost wrote:
> > It's hard to do better than that, because on most platforms there's
> > no way to get a signal on parent-process death, so the only way to
> > notice would be to poll the postmaster-death pipe constantly; which
> > would be hugely expensive in comparison to the value.
>
> I agree that 'constantly' wouldn't be great, but with some periodicity
> that's more frequent than 'not until a few hours later when we finally
> finish vacuuming this relation' would be nice. At least with autovauum
> we may be periodically sleeping anyway so it doesn't seem like polling
> at that point would really be terrible, though it'd be nice to check
> every once in a while even if we aren't sleeping.
vacuum_delay_point seems an obvious candidate, as soon as we've
determined that the sleep interval is > 0; since we're going to sleep,
the cost of a syscall seems negligible. I'm not sure what to suggest
for vacuums that don't have vacuum costing active, though.