Re: Fwd: [BUG]: the walsender does not update its IO statistics until it exits
| От | Xuneng Zhou |
|---|---|
| Тема | Re: Fwd: [BUG]: the walsender does not update its IO statistics until it exits |
| Дата | |
| Msg-id | CABPTF7XT=txv4-6SnpZGkx-CreWQ3UsOq2WCat1i64TNnuO=Cw@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Fwd: [BUG]: the walsender does not update its IO statistics until it exits (Bertrand Drouvot <bertranddrouvot.pg@gmail.com>) |
| Ответы |
Re: Fwd: [BUG]: the walsender does not update its IO statistics until it exits
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| Список | pgsql-hackers |
Hi,
I performed some tests using elog(no so sure whether this is the proper way to do it) to monitor the new method. Here are the findings:
• With PGSTAT_MIN_INTERVAL set to 1000ms, the number of flush reports was reduced to approximately 40–50 during the installcheck test suite.
• With PGSTAT_IDLE_INTERVAL set to 10000ms, the reports dropped to fewer than 5.
• In contrast, the previous approach—flushing after every WalSndKeepaliveIfNecessary()—resulted in roughly 50,000 flushes.
This reduction is significant, so the overhead from the flush reports is no longer a concern. However, we still need to determine whether this frequency is sufficient to capture the system’s state during periods of high WAL activity. Based on my tests, using PGSTAT_MIN_INTERVAL seems to provide a better balance than PGSTAT_IDLE_INTERVAL.
> > 1. maybe relying on PGSTAT_IDLE_INTERVAL would make more sense? In both
> > case
> > PGSTAT_MIN_INTERVAL or PGSTAT_MIN_INTERVAL, I'm not sure there is a need to
> > update the related doc.
> >
> >
> PGSTAT_IDLE_INTERVAL seems to reduce the frequency even more.
Yeah, I think that PGSTAT_MIN_INTERVAL is the one to use (that's why that's the
one the patch is using). I just mentioned PGSTAT_IDLE_INTERVAL as an open door
for conversation in case one prefers a "larger" frequency.
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