| From: | hubert depesz lubaczewski <depesz(at)depesz(dot)com> |
|---|---|
| To: | Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> |
| Cc: | Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com>, PostgreSQL General <pgsql-general(at)lists(dot)postgresql(dot)org>, Chris Wilson <chris+google(at)qwirx(dot)com> |
| Subject: | Re: Streaming replica hangs periodically for ~ 1 second - how to diagnose/debug |
| Date: | 2025-08-22 15:19:33 |
| Message-ID: | aKiKhUQHTNnLDqqb@depesz.com |
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| Lists: | pgsql-general |
On Fri, Aug 22, 2025 at 05:07:09PM +0200, Pavel Stehule wrote:
> > Any idea on what could it be?
> Few years ago I had a similar experience - some sec mystic lags - the
> problem was in virtualization.
While I can't discount this idea, after all it is aws ec2, so virtual
boxes, what makes me wonder is:
in case of this slow situation there is futex call, which takes
a second. But there are no futex calls in any other query processing
logs.
So, while it is obvious that futex "wasted" this time, the question is:
why would pg run futex() for this one query at all?
Best regards,
depesz
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