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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Dilip Kumar <dilipbalaut@gmail.com>
Cc: Thomas Munro <thomas.munro@enterprisedb.com>
Cc: Jakub Glapa <jakub.glapa@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: ERROR: too many dynamic shared memory segments
Date: Fri, 02 Feb 2018 15:01:15 -0500
Message-ID: <3647.1517601675@sss.pgh.pa.us> (raw)
In-Reply-To: <CA+Tgmob8LFw55DzH1QEREpBEA9RJ_W_amhBFCVZ6WMwUhVpOqg@mail.gmail.com>
References: <CAJk1zg1LpAAQ3w2bekWd7cbNppBrcgO2baa4zm+Fp=nwQ=MaUg@mail.gmail.com>
	<CAEepm=1C6rXmUpUtj0pNmS4AEEFTOcJOXXF1BLA1SMmSwZX9Yw@mail.gmail.com>
	<CAJk1zg2XqYa1Dx14z9X3qkUgWH6kpoNbvSGT_=NtzDPnMhfFHg@mail.gmail.com>
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	<CA+Tgmob8LFw55DzH1QEREpBEA9RJ_W_amhBFCVZ6WMwUhVpOqg@mail.gmail.com>

Robert Haas <robertmhaas@gmail.com> writes:
> That turned out to produce more than one problem.  I find that the
> select_parallel test then fails like this:
> ERROR:  could not find key 18446744073709486082 in shm TOC at 0x10be98040
> The fix for that problem seems to be:

>      /* Recreate error queues. */
>      error_queue_space =
> -        shm_toc_lookup(pcxt->toc, PARALLEL_KEY_ERROR_QUEUE, false);
> +        shm_toc_lookup(pcxt->toc, PARALLEL_KEY_ERROR_QUEUE, true);
> +    Assert(pcxt->nworkers == 0 || error_queue_space != NULL);

I happened across this patch while preparing the release notes, and
I'm quite distressed by it, because it completely breaks the point
of what I'd done in commit d46633506 (to wit, to not just blindly
assume, nor just Assert, that shm_toc_lookup always succeeds).
Do you mind if I change that Assert to a run-time test?

			regards, tom lane




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  Cc: tgl@sss.pgh.pa.us, robertmhaas@gmail.com, dilipbalaut@gmail.com, thomas.munro@enterprisedb.com, jakub.glapa@gmail.com
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