| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Andres Freund <andres(at)2ndquadrant(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Magnus Hagander <magnus(at)hagander(dot)net>, Simon Riggs <simon(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: WAL Rate Limiting |
| Date: | 2014-01-17 15:10:22 |
| Message-ID: | 3711.1389971422@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Andres Freund <andres(at)2ndquadrant(dot)com> writes:
> On 2014-01-17 09:04:54 -0500, Robert Haas wrote:
>> That having been said, I bet it could be done at the tail of
>> XLogInsert().
> I don't think there are many locations where this would be ok. Sleeping
> while holding exclusive buffer locks? Quite possibly inside a criticial
> section?
More or less by definition, you're always doing both when you call
XLogInsert.
> Surely not.
I agree. It's got to be somewhere further up the call stack.
I'm inclined to think that what we ought to do is reconceptualize
vacuum_delay_point() as something a bit more generic, and sprinkle
calls to it in a few more places than now.
It's also interesting to wonder about the relationship to
CHECK_FOR_INTERRUPTS --- although I think that currently, we assume
that that's *cheap* (1 test and branch) as long as nothing is pending.
I don't want to see a bunch of arithmetic added to it.
regards, tom lane
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