Re: Memory Errors...

[ Previous version removed from patches queue..]

Thanks for doing both interfaces.

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:
>
> Ok, below is the original email I sent, which I can not remember seeing come
> across the patches list. Please do read the assumptions since they might throw
> up problems with what I have done.
>
> I have attached the pltcl patch again, just in case. For the sake of clarity
> let's say this patch superscedes the previous one.
>
> I have also attached a patch addressing the similar memory leak problem in
> plpython. This includes a slight adjustment of the tests in the source
> directory. The patch also includes a cosmetic change to remove a compiler
> warning although I think the change makes the code look worse though.
>
> Once again, please read my text below and also take a quick look at the comment
> I've added in the plpython patch since it may well show that that
> particular change is complete rubbish.
>
> BTW, by my reckoning the memory leak would occur with prepared plans and
> without. If that is not the case then I've been barking up the wrong tree.
>
> Of further note, I have not tested for the memory leak in plpython but the
> build passes the normal and big checks. However, I have tried testing using the
> test.sh script in src/pl/plpython. This seems to be generating errors where
> before there were warnings. Can anyone comment on the correctness of this?
> Reversing my changes doesn't really help matters so I presume it is something
> else that is causing the different behaviour.
>
>
> --
> Nigel J. Andrews
>
>
> On Fri, 20 Sep 2002, Nigel J. Andrews wrote:
>
> > On Thu, 19 Sep 2002, Tom Lane wrote:
> >
> > > "Ian Harding" <ianh(at)tpchd(dot)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.
>

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