Re: Potential dbi memory leak.

[Steve Cookson - gmail]

Hi Tim,

Oh yes for (1..500) does exactly that.  Thank you.  No memory leak at all!

Regards

Steve.

On 26/05/15 10:13, Tim Bunce wrote:

I've added this as a note:

     Note that the ChildHandles array holds weak references and that 'from
     time to time' the old slots get freed up. This isn't a leak, it just
     appears to be if you're not familiar with the caching that DBI does
     internally. You can rest assured that if the DBI did have a real leak
     a) a great many people would be affected and b) it would get fixed very 
quickly.

I think 'from time to time' is every 120 or so newly created child handles.

Tim.

On Tue, May 26, 2015 at 07:57:53AM -0300, Steve Cookson - gmail wrote:

It seems to be further documented here, together with a solution:

http://stackoverflow.com/questions/13338308/perl-dbi-memory-leak,

But the solution does not seem to be reliable.  Sometimes it works sometimes
not.

I'll update you when I know more.

Regards,

Steve.

On 26/05/15 07:07, Steve Cookson - gmail wrote:

Hi Guys,

You may have seen part of this post on PerlMonks.  If so apologies for the
duplication.  This started off as a general search for leaks in my code,
and resulted in a few hits, one of which was attached to every database
access.

A simple "select ATT_RECORD_NAME_TXT from TBL_TEST; " results in the leak
of one scalar value.  It seems to be attached to the ->prepare statement.

At first I assumed it was down to my Firebird driver, which is relatively
new, so I switched the driver to ODBC::Firebird, with the same result.
Finally I changed to mysql and again got a memory leak.  The only thing I
can assume is that either my code is generically wrong (and I hope this is
the case), or there is a leak in dbi, which I would be surprised by.

I would appreciate some advice.

Test code follows.  Please install Devel::Leak to pick up leaked scalars
and update the dsn to the dsn of your choice.

Thanks for your help.

Regards,

Steve.

#! /usr/bin/perl

package main;
use strict;
use warnings;
use DBI;
#use DBD::Firebird;
use DBD::ODBC;
use Devel::Leak;
    my $handle;
    my $count_start;
    my $count_stop;
    my $gl_dbh;

    # Just do this 5 times to make sure there is no contribution to
$handle count from Devel::Leak
    for (1..10){
    print "Handle init: ", Devel::Leak::NoteSV($Launch::handle),"\n";
    }
#my $loc_dsn = <<DSN;
#dbi:ODBC:Driver=Firebird;Dbname=/home/image/Documents/Endoscopia/DB/newEndo.fdb;

#ib_dialect=3;
#DSN
my $loc_dsn = <<DSN;
DBI:mysql:database=new_schema_test;
host=localhost;
port=3306";
DSN
    $Launch::gl_dbh=DBI->connect($loc_dsn,"root","password", {
        PrintError => 1,                    # Report errors via warn
        RaiseError => 1                    # Report errors via Die
    }
    ) or die;

    my @loc_sql_string =();
    $loc_sql_string[0]="CREATE TABLE TBL_TEST_LEAK ( ATTR_RECORD_ID_TXT
VARCHAR(10) NOT NULL, ATT_RECORD_NAME_TXT VARCHAR(255), CONSTRAINT
PK_TBL_TEST_LEAK PRIMARY KEY (ATTR_RECORD_ID_TXT) ); ";
    $loc_sql_string[1]="GRANT DELETE, INSERT, REFERENCES, SELECT, UPDATE
ON TBL_TEST_LEAK TO  SYSDBA WITH GRANT OPTION";
    $loc_sql_string[2]="INSERT INTO TBL_TEST_LEAK (ATTR_RECORD_ID_TXT,
ATT_RECORD_NAME_TXT) VALUES ('206', 'Delay Test 1' )";
    $loc_sql_string[3]="select ATT_RECORD_NAME_TXT from TBL_TEST_LEAK; ";
    $loc_sql_string[4]= $loc_sql_string[3];
    $loc_sql_string[5]= $loc_sql_string[3];
    $loc_sql_string[6]= $loc_sql_string[3];
    $loc_sql_string[7]= $loc_sql_string[3];
    $loc_sql_string[8]= $loc_sql_string[3];
    $loc_sql_string[9]="drop table TBL_TEST_LEAK; ";

    for (my $i=1;$i<=9;$i++){
    $count_start=Devel::Leak::NoteSV($Launch::handle);
    print "DBD start: ", $count_start,"\n";
    print $loc_sql_string[$i], "\n";
    dbd_select($loc_sql_string[$i]);
    # You can use
    #$count_stop=Devel::Leak::CheckSV($Launch::handle);
    $count_stop=Devel::Leak::NoteSV($Launch::handle);
    print "Handle stop: ", $count_stop,"\n";
    print "Count difference: ", $count_stop-$count_start,"\n";
    }
    $Launch::gl_dbh->disconnect;

sub dbd_select{
    my $loc_sql_string=shift;
    my $loc_sth=$Launch::gl_dbh->prepare($loc_sql_string) or die;
    #$loc_sth->execute() or die;
    #$loc_sth->finish();
    return;
}

1;