From: Tom Lane <tgl@sss.pgh.pa.us>
To: Peter Geoghegan <pg@bowt.ie>
cc: Thomas Munro <thomas.munro@gmail.com>,
 Dmitry Astapov <dastapov@gmail.com>,
        pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #17619: AllocSizeIsValid violation in parallel hash join
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Comments: In-reply-to Peter Geoghegan <pg@bowt.ie>
	message dated "Tue, 27 Sep 2022 09:40:05 -0700"
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Date: Tue, 27 Sep 2022 12:44:40 -0400
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Peter Geoghegan <pg@bowt.ie> writes:
> On Tue, Sep 27, 2022 at 9:24 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I think I'd personally prefer to treat such memory more like we
>> treat palloc'd memory, ie there's *not* a guarantee of zero
>> initialization and indeed testing builds intentionally clobber it.

> Isn't that already how it works? The problem is that it's not
> particularly clear that that's how it works right now. And that the
> dynamic shared memory stuff isn't tested via the same techniques that
> we use for palloc.

Right, the missing piece is the intentional clobber.  Thomas indicated
he'd made such a test locally, but I think it needs full support with
the same options that mcxt.c has (CLOBBER_FREED_MEMORY and so on
--- although unmapping the memory is equally good for that, if we
always do it).

			regards, tom lane