Thread: Memory leak!!
Hi all,
We've have a supply chain management system running under the following
configuration.
Redhat 7.1
Perl v5.6.0
Postgres 7.3.2
Perl/DBI 1.35
DBD-Pg 1.22
Please note that Postgres 7.3.2, DBI 1.35 and DBD-Pg 1.22 have been
upgraded recently.
I wrote a small script to check for any memory leak. This is what i've
found. Initially, the memory occupied was about 5 MB and then, it started
to grow at the range of 5-10k for every 1-2 minutes. After running the
script for about 40 minutes in a while loop, the memory occupied was 7.4
MB.
Here's the code snippet :
while (1) { print "sql executed and returned :", $Dbh->prepare("select user_id from
users limit 1")->execute, "\n";
}
Pls. note that there were no "lost references" in my script and it's a
very simple one. What could be the problem ?
Please advice me.
TIA.
Regards,
Guru Prasad.
Systems Engineer
bk Systems (P) Ltd.
"P.N.Guru Prasad" <pnguruji@yahoo.com> writes:
> while (1) {
> print "sql executed and returned :", $Dbh->prepare("select user_id from
> users limit 1")->execute, "\n";
> }
I'm not a DBI user, but I'd kinda expect that executing a query would
result in an object holding the results from that query. Don't you need
to do something to close/delete the result objects you're generating?
regards, tom lane
On Wednesday 09 April 2003 06:58, Tom Lane wrote:
> "P.N.Guru Prasad" <pnguruji@yahoo.com> writes:
> > while (1) {
> > print "sql executed and returned :", $Dbh->prepare("select user_id from
> > users limit 1")->execute, "\n";
> > }
>
> I'm not a DBI user, but I'd kinda expect that executing a query would
> result in an object holding the results from that query. Don't you need
> to do something to close/delete the result objects you're generating?
Does
while (1) { my $sth = $Dbh->prepare("select user_id from users limit 1"); print "sql executed and returned :",
$sth->execute,"\n"; $sth->finish();
}
make any difference?
If not try asking the dbi-users list, dbi-users@perl.org
( http://lists.perl.org/showlist.cgi?name=dbi-users )
Ian Barwick
barwick@gmx.net
On Thursday 10 April 2003 16:39, guru prasad wrote: > Hi All, (...) > Also, i wanted to narrow down the problem, ie. whether > the problem is in DBI or DBD::Pg. Could anyone throw > some light on where should i start ? I can go by trial > & error method to find out but at the same time, i > feel there will be many guru's in this list who can > help me out. Unfortunately I'm still waiting for the Academy to send me my Guru Certificate, so I can't help you much more ;-). Seriously, I have no idea off spec and haven't got the time to go into it right now. As I said, do try the dbi-users list, it's fairly low traffic but has a higher concentration of Perl / DBI gurus and other very helpful people who may have much more insight, especially if it is more a DBI than an DBD::Pg problem. > > dbi-users@perl.org > > http://lists.perl.org/showlist.cgi?name=dbi-users Ian Barwick barwick@gmx.net
Hi All,
> while (1) {
> my $sth = $Dbh->prepare("select user_id from users
> limit 1");
> print "sql executed and returned :",
> $sth->execute, "\n";
> $sth->finish();
> }
>
> make any difference?
I tried it. Here's the observation. Initially, the
script didn't eat so much RAM and it just stayed at
6604 MB for some time (atleast for 4 hours). I wanted
the script to run for more than a day. Next day, when
i did a 'top' in my RH Linux box, the mem. occupied
by the script was 8028 MB of RAM. Why the difference ?
May be, my test script wasn't a perfect one to check
for memory leaks in DBI or DBD::Pg. How can i create a
more efficient test script to check for memory leaks ?
Using the script, i should be able to find out any
memory leak, in about say 1 or 2 hours. Any thoughts ?
Also, i wanted to narrow down the problem, ie. whether
the problem is in DBI or DBD::Pg. Could anyone throw
some light on where should i start ? I can go by trial
& error method to find out but at the same time, i
feel there will be many guru's in this list who can
help me out.
Regards,
Guru Prasad.
--- Ian Barwick <barwick@gmx.net> wrote:
> On Wednesday 09 April 2003 06:58, Tom Lane wrote:
> > "P.N.Guru Prasad" <pnguruji@yahoo.com> writes:
> > > while (1) {
> > > print "sql executed and returned :",
> $Dbh->prepare("select user_id from
> > > users limit 1")->execute, "\n";
> > > }
> >
> > I'm not a DBI user, but I'd kinda expect that
> executing a query would
> > result in an object holding the results from that
> query. Don't you need
> > to do something to close/delete the result objects
> you're generating?
>
> Does
>
> while (1) {
> my $sth = $Dbh->prepare("select user_id from users
> limit 1");
> print "sql executed and returned :",
> $sth->execute, "\n";
> $sth->finish();
> }
>
> make any difference?
>
> If not try asking the dbi-users list,
> dbi-users@perl.org
> ( http://lists.perl.org/showlist.cgi?name=dbi-users
> )
>
> Ian Barwick
> barwick@gmx.net
>
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Tom Lane <tgl@sss.pgh.pa.us> writes:
> "P.N.Guru Prasad" <pnguruji@yahoo.com> writes:
> > while (1) {
> > print "sql executed and returned :", $Dbh->prepare("select user_id from
> > users limit 1")->execute, "\n";
> > }
>
> I'm not a DBI user, but I'd kinda expect that executing a query would
> result in an object holding the results from that query. Don't you need
> to do something to close/delete the result objects you're generating?
Perl reference counts these objects so that shouldn't be a problem.
You could be sure by using Devel::LeakTrace or Devel::Leak or something like
that. But I suspect they won't find anything because I suspect the problem is
in the DBD::pg driver or libpq at the C level.
--
greg