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From: Laurenz Albe <[email protected]>
To: James Pang <[email protected]>
To: [email protected]
Subject: Re: lwlock:LockManager wait_events
Date: Fri, 25 Oct 2024 10:36:45 +0300
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAHgTRfesRFm1BuG_5guvdSCof2qoHGZvaa1YEkim97EMALaWgQ@mail.gmail.com>
References: <CAHgTRfesRFm1BuG_5guvdSCof2qoHGZvaa1YEkim97EMALaWgQ@mail.gmail.com>

On Fri, 2024-10-25 at 14:36 +0800, James Pang wrote:
> we faced into a lot of  lwlock:LockManager wait-events , all of these queries are "select ..." ,
> there are other several session are doing DML, insert/update/delete on same table.
> Did these DML transactions holding "transactionid" and "tuple" lock blocking "select" on lwlock:LockManager ?

This is not about waiting for a lock.  Rather, it means that very many sessions are trying
to take a lock.  They have to grab the lock manager to take a lock, and the competition for
that resource is the bottleneck.

It is hard to say what is the root cause without further analysis, but very often the
cause is that you have too many connections to the database.  Using an effective connection
pool *might* solve that particular problem.

Yours,
Laurenz Albe

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