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From: hubert depesz lubaczewski <[email protected]>
To: Pavel Stehule <[email protected]>
Cc: Adrian Klaver <[email protected]>
Cc: PostgreSQL General <[email protected]>
Cc: Chris Wilson <[email protected]>
Subject: Re: Streaming replica hangs periodically for ~ 1 second - how to diagnose/debug
Date: Fri, 22 Aug 2025 17:19:33 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAFj8pRBg_C6M-VzchbRitfZ8DiJRXjJYNgozmEKi6HiBXRNFcQ@mail.gmail.com>
References: <[email protected]>
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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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