Feedback-ID: i0fe9450f:Fastmail
Date: Wed, 6 Aug 2025 17:40:33 +0900
From: Michael Paquier <michael@paquier.xyz>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Thomas Munro <thomas.munro@gmail.com>,
	Xuneng Zhou <xunengzhou@gmail.com>, exclusion@gmail.com,
	pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #19006: Assert(BufferIsPinned) in BufferGetBlockNumber() is
 triggered for forwarded buffer
Message-ID: <aJMVAbYRcdImR3-V@paquier.xyz>
References: <19006-80fcaaf69000377e@postgresql.org>
 <CABPTF7VaW0Hw2-KXoiYFTH40LeUgr06gE5q09sq9LXQPH-vjPA@mail.gmail.com>
 <CA+hUKGK5x5Yekufz7a+Jr1neahwE9cLZn9xt3gSzSZgE=Spjpw@mail.gmail.com>
 <CA+hUKGJyqwQs_kQFB1J=bx4pHMrMcPF8_PgNKyeNFEo+yNvyiQ@mail.gmail.com>
 <992760.1754368986@sss.pgh.pa.us>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
	protocol="application/pgp-signature"; boundary="MUZm0cX0eHbte1PH"
Content-Disposition: inline
In-Reply-To: <992760.1754368986@sss.pgh.pa.us>
Archived-At: 
 <https://www.postgresql.org/message-id/aJMVAbYRcdImR3-V%40paquier.xyz>
Precedence: bulk


--MUZm0cX0eHbte1PH
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Tue, Aug 05, 2025 at 12:43:06AM -0400, Tom Lane wrote:
> I've not looked at the issue actually being fixed, but a drive-by
> comment: these loops
>=20
> +	for (int i =3D 0; i < stream->forwarded_buffers; ++i)
> +		Assert(BufferGetBlockNumber(stream->buffers[stream->next_buffer_index =
+ i]) =3D=3D
> +			   stream->pending_read_blocknum + i);
>=20
> should be wrapped in "#ifdef USE_ASSERT_CHECKING".  Maybe the
> compiler is smart enough to throw away the useless looping logic
> in a production build, or maybe it isn't.

I'd bet it is usually not that smart..  Embedding these in an extra
#ifdef is a sound defense IMO.
--
Michael

--MUZm0cX0eHbte1PH
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----
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=NDi4
-----END PGP SIGNATURE-----

--MUZm0cX0eHbte1PH--