From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
cc: Jeff Janes <jeff.janes@gmail.com>, Matthias Otterbach <mo@otterbach.eu>,
        pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #15700: PG 10 vs. 11: Large increase in memory usage when
 selecting BYTEA data (maybe memory leak)
In-reply-to: <20190318215710.f6balpny456kink2@alap3.anarazel.de>
References: <15700-8c408321a87d56bb@postgresql.org>
 <16717.1552926811@sss.pgh.pa.us>
 <4ef5f38d5710c4d5c289537c588c7335@otterbach.eu>
 <CAMkU=1wW32K8n4ut_7zz+6HH1J068tFtpv5os=eeAgvjiQH8ZQ@mail.gmail.com>
 <CAMkU=1x_XySqXZ-1gCyoaipKLzefQSr1BuaHL12vy_9WKFnjYQ@mail.gmail.com>
 <13467.1552942521@sss.pgh.pa.us>
 <20190318215710.f6balpny456kink2@alap3.anarazel.de>
Comments: In-reply-to Andres Freund <andres@anarazel.de>
	message dated "Mon, 18 Mar 2019 14:57:10 -0700"
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Date: Mon, 18 Mar 2019 18:03:40 -0400
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Andres Freund <andres@anarazel.de> writes:
> But are we actually prepared to assume that nothing ever leaks in
> receivers? That's, as far as I can tell, not a documented
> assumption.

There's a lot that's not documented there :-(

> We're also assuming that we don't leak into MessageContext over such
> cycles, which seems wrong. At the very least things like
> errdetail_params() are happy to leak into MessageContext.

This leak isn't in MessageContext; if it were, there likely wouldn't
have been a noticeable problem.  It's leaking in the executor's
context over repeat ExecutorRun cycles in the same execution state.
We do have an expectation that there won't be per-row leakage in
the ExecutorState.

			regards, tom lane