Thread: PATCH: Memory leaks on start-up
Guys, attached is a patch to fix two memory leaks on start-up. The first is when freeaddrinfo has been used to free memory allocated by getaddrinfo2 (so freeaddrinfo2 should be used). The second is 2 leaks when creating the lock (PostgreSQL and socket) files. The diff is against last night's CVS HEAD. L.
Lee Kindness <lkindness@csl.co.uk> writes:
> Guys, attached is a patch to fix two memory leaks on start-up.
I do not like the changes to miscinit.c. In the first place, it is not
a "memory leak" to do a one-time allocation of state for a proc_exit
function. A bigger complaint is that your proposed change introduces
fragile coupling between CreateLockFile and its callers, in order to
save no resources worth mentioning. More, it introduces an assumption
that the globals directoryLockFile and socketLockFile don't change while
the postmaster is running. UnlinkLockFile should unlink the file that
it was originally told to unlink, regardless of what happens to those
globals.
If you are intent on spending code to free stuff just before the
postmaster exits, a better fix would be for UnlinkLockFile to free its
string argument after using it.
regards, tom lane
Tom, happier with the attached patch?
I'd have to disagree with regards to the memory leaks not being worth
a mention - any such leak can cause problems when the PostgreSQL
installation is either unattended, long-living andor has very high
connection levels. Half a kilobyte on start-up isn't negligible in
this light.
Regards, Lee.
Tom Lane writes:
> Lee Kindness <lkindness@csl.co.uk> writes:
> > Guys, attached is a patch to fix two memory leaks on start-up.
>
> I do not like the changes to miscinit.c. In the first place, it is not
> a "memory leak" to do a one-time allocation of state for a proc_exit
> function. A bigger complaint is that your proposed change introduces
> fragile coupling between CreateLockFile and its callers, in order to
> save no resources worth mentioning. More, it introduces an assumption
> that the globals directoryLockFile and socketLockFile don't change while
> the postmaster is running. UnlinkLockFile should unlink the file that
> it was originally told to unlink, regardless of what happens to those
> globals.
>
> If you are intent on spending code to free stuff just before the
> postmaster exits, a better fix would be for UnlinkLockFile to free its
> string argument after using it.
Index: src/backend/libpq/pqcomm.c
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/backend/libpq/pqcomm.c,v
retrieving revision 1.157
diff -u -r1.157 pqcomm.c
--- src/backend/libpq/pqcomm.c 12 Jun 2003 07:36:51 -0000 1.157
+++ src/backend/libpq/pqcomm.c 22 Jul 2003 14:16:46 -0000
@@ -363,7 +363,7 @@
added++;
}
- freeaddrinfo(addrs);
+ freeaddrinfo2(family, addrs);
if (!added)
{
Index: src/backend/utils/init/miscinit.c
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/backend/utils/init/miscinit.c,v
retrieving revision 1.104
diff -u -r1.104 miscinit.c
--- src/backend/utils/init/miscinit.c 27 Jun 2003 19:08:37 -0000 1.104
+++ src/backend/utils/init/miscinit.c 22 Jul 2003 14:16:46 -0000
@@ -673,8 +673,15 @@
static void
UnlinkLockFile(int status, Datum filename)
{
- unlink((char *) DatumGetPointer(filename));
- /* Should we complain if the unlink fails? */
+ char *fname = (char *)DatumGetPointer(filename);
+ if( fname != NULL )
+ {
+ if( unlink(fname) != 0 )
+ {
+ /* Should we complain if the unlink fails? */
+ }
+ free(fname);
+ }
}
/*
Lee Kindness <lkindness@csl.co.uk> writes:
> I'd have to disagree with regards to the memory leaks not being worth
> a mention - any such leak can cause problems when the PostgreSQL
> installation is either unattended, long-living andor has very high
> connection levels.
I don't see how. We are talking about two strings, no more, no less,
that live for exactly the duration of the postmaster run. Explain to me
how any of your above conditions will affect this code in the slightest?
If UnlinkLockFile ever got invoked before postmaster exit, then this
would be worth doing, and I'll accept the change as a matter of
future-proofing that routine against such use. But on the argument of
preventing resource leakage today, this is just a waste of code space.
regards, tom lane
Tom Lane writes:> Lee Kindness <lkindness@csl.co.uk> writes:> > I'd have to disagree with regards to the memory leaks notbeing worth> > a mention - any such leak can cause problems when the PostgreSQL> > installation is either unattended,long-living andor has very high> > connection levels.> I don't see how. We are talking about two strings, nomore, no less,> that live for exactly the duration of the postmaster run. Explain to me> how any of your above conditionswill affect this code in the slightest? For the lock file leak yeah - it's just 2 strings once in a blue moon. However in the more general case of freeaddrinfo and the eniron wizardry (which is also leaking, and is done every new instance, yeah?) it does build up. Anyway, it's no reason to be lazy/messy, is it? L.
Your patch has been added to the PostgreSQL unapplied patches list at:
http://momjian.postgresql.org/cgi-bin/pgpatches
I will try to apply it within the next 48 hours.
---------------------------------------------------------------------------
Lee Kindness wrote:
Content-Description: message body text
> Tom, happier with the attached patch?
>
> I'd have to disagree with regards to the memory leaks not being worth
> a mention - any such leak can cause problems when the PostgreSQL
> installation is either unattended, long-living andor has very high
> connection levels. Half a kilobyte on start-up isn't negligible in
> this light.
>
> Regards, Lee.
>
> Tom Lane writes:
> > Lee Kindness <lkindness@csl.co.uk> writes:
> > > Guys, attached is a patch to fix two memory leaks on start-up.
> >
> > I do not like the changes to miscinit.c. In the first place, it is not
> > a "memory leak" to do a one-time allocation of state for a proc_exit
> > function. A bigger complaint is that your proposed change introduces
> > fragile coupling between CreateLockFile and its callers, in order to
> > save no resources worth mentioning. More, it introduces an assumption
> > that the globals directoryLockFile and socketLockFile don't change while
> > the postmaster is running. UnlinkLockFile should unlink the file that
> > it was originally told to unlink, regardless of what happens to those
> > globals.
> >
> > If you are intent on spending code to free stuff just before the
> > postmaster exits, a better fix would be for UnlinkLockFile to free its
> > string argument after using it.
>
> Index: src/backend/libpq/pqcomm.c
> ===================================================================
> RCS file: /projects/cvsroot/pgsql-server/src/backend/libpq/pqcomm.c,v
> retrieving revision 1.157
> diff -u -r1.157 pqcomm.c
> --- src/backend/libpq/pqcomm.c 12 Jun 2003 07:36:51 -0000 1.157
> +++ src/backend/libpq/pqcomm.c 22 Jul 2003 14:16:46 -0000
> @@ -363,7 +363,7 @@
> added++;
> }
>
> - freeaddrinfo(addrs);
> + freeaddrinfo2(family, addrs);
>
> if (!added)
> {
> Index: src/backend/utils/init/miscinit.c
> ===================================================================
> RCS file: /projects/cvsroot/pgsql-server/src/backend/utils/init/miscinit.c,v
> retrieving revision 1.104
> diff -u -r1.104 miscinit.c
> --- src/backend/utils/init/miscinit.c 27 Jun 2003 19:08:37 -0000 1.104
> +++ src/backend/utils/init/miscinit.c 22 Jul 2003 14:16:46 -0000
> @@ -673,8 +673,15 @@
> static void
> UnlinkLockFile(int status, Datum filename)
> {
> - unlink((char *) DatumGetPointer(filename));
> - /* Should we complain if the unlink fails? */
> + char *fname = (char *)DatumGetPointer(filename);
> + if( fname != NULL )
> + {
> + if( unlink(fname) != 0 )
> + {
> + /* Should we complain if the unlink fails? */
> + }
> + free(fname);
> + }
> }
>
> /*
>
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--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073
This patch no longer applies cleanly. The call is now:
freeaddrinfo_all(hint.ai_family, addrs);
Would you please submit a new patch, or is it no longer required? There
were two fixed in your patch.
Thanks.
---------------------------------------------------------------------------
Lee Kindness wrote:
Content-Description: message body text
> Tom, happier with the attached patch?
>
> I'd have to disagree with regards to the memory leaks not being worth
> a mention - any such leak can cause problems when the PostgreSQL
> installation is either unattended, long-living andor has very high
> connection levels. Half a kilobyte on start-up isn't negligible in
> this light.
>
> Regards, Lee.
>
> Tom Lane writes:
> > Lee Kindness <lkindness@csl.co.uk> writes:
> > > Guys, attached is a patch to fix two memory leaks on start-up.
> >
> > I do not like the changes to miscinit.c. In the first place, it is not
> > a "memory leak" to do a one-time allocation of state for a proc_exit
> > function. A bigger complaint is that your proposed change introduces
> > fragile coupling between CreateLockFile and its callers, in order to
> > save no resources worth mentioning. More, it introduces an assumption
> > that the globals directoryLockFile and socketLockFile don't change while
> > the postmaster is running. UnlinkLockFile should unlink the file that
> > it was originally told to unlink, regardless of what happens to those
> > globals.
> >
> > If you are intent on spending code to free stuff just before the
> > postmaster exits, a better fix would be for UnlinkLockFile to free its
> > string argument after using it.
>
> Index: src/backend/libpq/pqcomm.c
> ===================================================================
> RCS file: /projects/cvsroot/pgsql-server/src/backend/libpq/pqcomm.c,v
> retrieving revision 1.157
> diff -u -r1.157 pqcomm.c
> --- src/backend/libpq/pqcomm.c 12 Jun 2003 07:36:51 -0000 1.157
> +++ src/backend/libpq/pqcomm.c 22 Jul 2003 14:16:46 -0000
> @@ -363,7 +363,7 @@
> added++;
> }
>
> - freeaddrinfo(addrs);
> + freeaddrinfo2(family, addrs);
>
> if (!added)
> {
> Index: src/backend/utils/init/miscinit.c
> ===================================================================
> RCS file: /projects/cvsroot/pgsql-server/src/backend/utils/init/miscinit.c,v
> retrieving revision 1.104
> diff -u -r1.104 miscinit.c
> --- src/backend/utils/init/miscinit.c 27 Jun 2003 19:08:37 -0000 1.104
> +++ src/backend/utils/init/miscinit.c 22 Jul 2003 14:16:46 -0000
> @@ -673,8 +673,15 @@
> static void
> UnlinkLockFile(int status, Datum filename)
> {
> - unlink((char *) DatumGetPointer(filename));
> - /* Should we complain if the unlink fails? */
> + char *fname = (char *)DatumGetPointer(filename);
> + if( fname != NULL )
> + {
> + if( unlink(fname) != 0 )
> + {
> + /* Should we complain if the unlink fails? */
> + }
> + free(fname);
> + }
> }
>
> /*
>
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> TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073
Bruce Momjian <pgman@candle.pha.pa.us> writes:
> This patch no longer applies cleanly. The call is now:
> freeaddrinfo_all(hint.ai_family, addrs);
> Would you please submit a new patch, or is it no longer required?
That part of the patch is not needed (it is the same as what I changed,
except that while I was at it I renamed freeaddrinfo2 to the hopefully
more mnemonic freeaddrinfo_all). The change in miscinit should still
work though.
regards, tom lane
miscinit.c part of patch applied. Thanks.
The other part Tom already addressed.
---------------------------------------------------------------------------
Lee Kindness wrote:
Content-Description: message body text
> Tom, happier with the attached patch?
>
> I'd have to disagree with regards to the memory leaks not being worth
> a mention - any such leak can cause problems when the PostgreSQL
> installation is either unattended, long-living andor has very high
> connection levels. Half a kilobyte on start-up isn't negligible in
> this light.
>
> Regards, Lee.
>
> Tom Lane writes:
> > Lee Kindness <lkindness@csl.co.uk> writes:
> > > Guys, attached is a patch to fix two memory leaks on start-up.
> >
> > I do not like the changes to miscinit.c. In the first place, it is not
> > a "memory leak" to do a one-time allocation of state for a proc_exit
> > function. A bigger complaint is that your proposed change introduces
> > fragile coupling between CreateLockFile and its callers, in order to
> > save no resources worth mentioning. More, it introduces an assumption
> > that the globals directoryLockFile and socketLockFile don't change while
> > the postmaster is running. UnlinkLockFile should unlink the file that
> > it was originally told to unlink, regardless of what happens to those
> > globals.
> >
> > If you are intent on spending code to free stuff just before the
> > postmaster exits, a better fix would be for UnlinkLockFile to free its
> > string argument after using it.
>
> Index: src/backend/libpq/pqcomm.c
> ===================================================================
> RCS file: /projects/cvsroot/pgsql-server/src/backend/libpq/pqcomm.c,v
> retrieving revision 1.157
> diff -u -r1.157 pqcomm.c
> --- src/backend/libpq/pqcomm.c 12 Jun 2003 07:36:51 -0000 1.157
> +++ src/backend/libpq/pqcomm.c 22 Jul 2003 14:16:46 -0000
> @@ -363,7 +363,7 @@
> added++;
> }
>
> - freeaddrinfo(addrs);
> + freeaddrinfo2(family, addrs);
>
> if (!added)
> {
> Index: src/backend/utils/init/miscinit.c
> ===================================================================
> RCS file: /projects/cvsroot/pgsql-server/src/backend/utils/init/miscinit.c,v
> retrieving revision 1.104
> diff -u -r1.104 miscinit.c
> --- src/backend/utils/init/miscinit.c 27 Jun 2003 19:08:37 -0000 1.104
> +++ src/backend/utils/init/miscinit.c 22 Jul 2003 14:16:46 -0000
> @@ -673,8 +673,15 @@
> static void
> UnlinkLockFile(int status, Datum filename)
> {
> - unlink((char *) DatumGetPointer(filename));
> - /* Should we complain if the unlink fails? */
> + char *fname = (char *)DatumGetPointer(filename);
> + if( fname != NULL )
> + {
> + if( unlink(fname) != 0 )
> + {
> + /* Should we complain if the unlink fails? */
> + }
> + free(fname);
> + }
> }
>
> /*
>
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--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073