From: Tom Lane <tgl@sss.pgh.pa.us>
To: Amit Kapila <amit.kapila16@gmail.com>
cc: Noah Misch <noah@leadboat.com>, Amit Khandekar <amitdkhan.pg@gmail.com>,
        Alvaro Herrera from 2ndQuadrant <alvherre@alvh.no-ip.org>,
        Andres Freund <andres@anarazel.de>,
        =?UTF-8?Q?Juan_Jos=C3=A9_Santamar=C3=ADa_Flecha?=
 <juanjo.santamaria@gmail.com>,
        PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
        Robert Haas <robertmhaas@gmail.com>,
        Thomas Munro <thomas.munro@gmail.com>,
        Tomas Vondra <tomas.vondra@2ndquadrant.com>
Subject: Re: logical decoding : exceeded maxAllocatedDescs for .spill files
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Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Thu, 09 Jan 2020 18:51:41 -0500"
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Date: Thu, 09 Jan 2020 19:40:12 -0500
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I wrote:
>           ReorderBuffer: 223302560 total in 26995 blocks; 7056 free (3 c=
hunks); 223295504 used

> The test case is only inserting 50K fairly-short rows, so this seems
> like an unreasonable amount of memory to be consuming for that; and
> even if you think it's reasonable, it clearly isn't going to scale
> to large production transactions.

> Now, the good news is that v11 and later get through
> 006_logical_decoding.pl just fine under the same restriction.
> So we did something in v11 to fix this excessive memory consumption.
> However, unless we're willing to back-port whatever that was, this
> test case is clearly consuming excessive resources for the v10 branch.

I dug around a little in the git history for backend/replication/logical/,
and while I find several commit messages mentioning memory leaks and
faulty spill logic, they all claim to have been back-patched as far
as 9.4.

It seems reasonably likely to me that this result is telling us about
an actual bug, ie, faulty back-patching of one or more of those fixes
into v10 and perhaps earlier branches.

I don't know this code well enough to take point on looking for the
problem, though.

			regards, tom lane