Re: [HACKERS] [GENERAL] Memory Errors...

Your patch has been added to the PostgreSQL unapplied patches list at:

    http://candle.pha.pa.us/cgi-bin/pgpatches

I will try to apply it within the next 48 hours.

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Nigel J. Andrews wrote:
> On Thu, 19 Sep 2002, Tom Lane wrote:
>
> > "Ian Harding" <ianh@tpchd.org> writes:
> > > It is pltcl [not plpgsql]
> >
> > Ah.  I don't think we've done much of any work on plugging leaks in
> > pltcl :-(.
> >
> > > It hurts when I do this:
> >
> > > drop function memleak();
> > > create function memleak() returns int as '
> > > for {set counter 1} {$counter < 100000} {incr counter} {
> > >         set sql "select ''foo''"
> > >         spi_exec "$sql"
> > > }
> > > ' language 'pltcl';
> > > select memleak();
> >
> > Yeah, I see very quick memory exhaustion also :-(.  Looks like the
> > spi_exec call is the culprit, but I'm not sure exactly why ...
> > anyone have time to look at this?
>
> Attached is a patch that frees the SPI_tuptable in all post SPI_exec
> non-elog paths in both pltcl_SPI_exec() and pltcl_SPI_execp().
>
> The fault as triggered by the above code has been fixed by this patch but
> please read my assumptions below to ensure they are correct.
>
> I have assumed that Tom's comment about this only being required in non-elog
> paths is correct, which seems a reasonable assumption to me.
>
> I have also assumed, rather than verified, that freeing the tuptable does
> indeed free the tuples as well. Tests with the above function show that the
> process does not increase it's memory footprint during it's operation, although
> if my assumption here is wrong this could be a feature of selecting
> insignificantly sized tuples.
>
> I have not worried about other uses of SPI_exec for selects in pltcl.c on the
> basis that those are not under the control of the function writer and the
> normal function management will release the storage.
>
>
> --
> Nigel J. Andrews

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