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Date: Thu, 12 Jul 2018 12:15:42 +0300
From: Marina Polyakova <m.polyakova@postgrespro.ru>
To: Fabien COELHO <coelho@cri.ensmp.fr>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>, pgsql-hackers@postgresql.org,
 Ildus Kurbangaliev <i.kurbangaliev@postgrespro.ru>, Teodor Sigaev
 <teodor@sigaev.ru>
Subject: Re: [HACKERS] WIP Patch: Pgbench Serialization and deadlock errors
Organization: Postgres Professional
In-Reply-To: <alpine.DEB.2.21.1807112124210.27883@lancre>
References: <20180508193621.dphlgwrd5yz67o2z@alvherre.pgsql>
 <0569c5309cf536a839e2a3a1433bd113@postgrespro.ru>
 <alpine.DEB.2.21.1807091451520.17811@lancre>
 <a6299efa310e1d106144f761259f4fd6@postgrespro.ru>
 <alpine.DEB.2.21.1807111435250.27883@lancre>
 <976a25a46420c93866ada4051976b1be@postgrespro.ru>
 <alpine.DEB.2.21.1807112124210.27883@lancre>
Message-ID: <f153ffd55f481d714ee44afc99ecc67e@postgrespro.ru>
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On 11-07-2018 22:34, Fabien COELHO wrote:
>> can we try something like this?
>> 
>> PGBENCH_ERROR_START(DEBUG_FAIL)
>> {
>> 	PGBENCH_ERROR("client %d repeats the failed transaction (try %d",
> 
> Argh, no? I was thinking of something much more trivial:
> 
>    pgbench_error(DEBUG, "message format %d %s...", 12, "hello world");
> 
> If you really need some complex dynamic buffer, and I would prefer
> that you avoid that, then the fallback is:
> 
>    if (level >= DEBUG)
>    {
>       initPQstuff(&msg);
>       ...
>       pgbench_error(DEBUG, "fixed message... %s\n", msg);
>       freePQstuff(&msg);
>    }
> 
> The point is to avoid building the message with dynamic allocation and 
> so
> if in the end it is not used.

Ok! About avoidance - I'm afraid there's one more piece of debugging 
code with the same problem:

else if (command->type == META_COMMAND)
{
...
	initPQExpBuffer(&errmsg_buf);
	printfPQExpBuffer(&errmsg_buf, "client %d executing \\%s",
					  st->id, argv[0]);
	for (i = 1; i < argc; i++)
		appendPQExpBuffer(&errmsg_buf, " %s", argv[i]);
	appendPQExpBufferChar(&errmsg_buf, '\n');
	ereport(ELEVEL_DEBUG, (errmsg("%s", errmsg_buf.data)));
	termPQExpBuffer(&errmsg_buf);

-- 
Marina Polyakova
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company