Horton

Re: Probable memory leak with ECPG and AIX

Noah Misch <noah@leadboat.com>

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From: Noah Misch <noah@leadboat.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Benoit Lobréau <benoit.lobreau@gmail.com>, Guillaume Lelarge <guillaume@lelarge.info>, PostgreSQL Developers <pgsql-hackers@postgresql.org>, "Dr. Michael Meskes" <michael.meskes@credativ.com>
Date: 2022-01-02T00:07:50Z
Lists: pgsql-hackers 
On Sat, Jan 01, 2022 at 11:35:02AM -0500, Tom Lane wrote:
> Noah Misch <noah@leadboat.com> writes:
> > I get the same results.  The leak arises because AIX freelocale() doesn't free
> > all memory allocated in newlocale().  The following program uses trivial
> > memory on GNU/Linux, but it leaks like you're seeing on AIX:
> 
> Bleah.
> 
> > If you have access to file an AIX bug, I recommend doing so.  If we want
> > PostgreSQL to work around this, one idea is to have ECPG do this newlocale()
> > less often.  For example, do it once per process or once per connection
> > instead of once per ecpg_do_prologue().
> 
> It's worse than that: see also ECPGget_desc().  Seems like a case
> could be made for doing something about this just on the basis
> of cycles expended, never mind freelocale() bugs.

Agreed.  Once per process seems best.  I only hesitated before since it means
nothing will free this storage, which could be annoying in the context of
Valgrind and similar.  However, ECPG already has bits of never-freed memory in
the form of pthread_key_create() calls having no pthread_key_delete(), so I
don't mind adding a bit more.

Commits

  1. Fix previous commit's ecpg_clocale for ppc Darwin.

  2. ecpglib: call newlocale() once per process.