Re: DBD::ODBC Destroy bug?

On 24/03/15 18:04, Joel Plotkin wrote:
> Hi,
>
> A few notes:
>
> 1) the final "return;" at the end of Main was a typo... I was trying to clean up the example and had consolidated an additional sub-routine into one big main() function.... even w/ this typo, I still get the original error as described previously.

I guessed as much.

> 2) I (just) tried to get the latest version from git, but I just see
>
> $DBD::ODBC::VERSION = '1.51_4';
>
> from ODBC.pm

  
> I can't seem to find version 1.53_3 at git... I'm not a git expert, so I'll ask my staff for help to see if they can find 1.53_3 for me.

sorry, typo from me - that is the version I am using.

> 3) *** I'm using perl 5.10.1  ... maybe this is the issue.  I'll upgrade to perl 5.19.10 and see if the issue goes away.
>
> I'll keep you posted,
>
> Joel

I've since tried on a load of perlbrews and I still cannot duplicate your issue.

Martin

>
>
>
>
>
>
>
> On Tue, Mar 24, 2015 at 12:24 PM, Martin J. Evans <[email protected] <mailto:[email protected]>> wrote:
>
>     On 24/03/15 15:45, Joel Plotkin wrote:
>
>         Hi,
>
>         I have recently ported a large (1.4M line) perl application from:
>
>         Centos 6.6
>         DBI version 1.6.09
>         DBD::ODBC version 1.23
>
>         To:
>
>         Centos 6.6
>         DBI version 1.6.33
>         DBD::ODBC version 1.50 (and same issue with 1.50_4)
>
>         The error doesn't occur in the 1.23 version, only the later 1.50* versions.
>
>         This error occurs using MS SQL Server 2005, but I don't think it's db server dependent.
>
>         The specific error occurs when one creates a statement handle in a subroutine and returns the statement handle via a return value.  Specific test program attached.  Sample code that generates error below:
>
>         ******************************__******
>         #!/usr/bin/perl
>
>         use strict;
>
>         select((select(STDOUT), $|=1)[$[]);
>
>         package main;
>         BEGIN {
>               # Standard modules
>               use Carp;
>               use DBI;
>         };
>
>         my $dbh;
>
>         MAIN: {
>               # open data connection
>               my $attr = {};
>               my $odbc = "DBI:ODBC:XXXX_odbc";
>               my $db_nm="XXXXX";
>               my $db_user_nm="XXXXX";
>               my $db_user_passwd="XXXXX";
>
>               carp "opening new db connection\n";
>               $dbh = DBI->connect($odbc, $db_user_nm, $db_user_passwd, $attr) ||
>         carp "Error opening database";
>               my $trace_filename = "/tmp/dbi_trace.dat";
>               $dbh->trace(2, $trace_filename);
>
>               # run query
>               my $sql = "SELECT Name FROM Person WHERE p_id = 123";
>         *    my ($sth) = &do_pexect($sql);*
>               my $rowcache = $sth->fetchall_arrayref();
>
>               #pop off all rows. destroys $rowcache structure.
>               while (my $row = shift @$rowcache) {
>                   my ($last_nm) = @$row;
>               }
>               $sth->finish();
>
>               #
>               # Run same sql a 2nd time
>               #
>         #    undef $sth;
>         *    ($sth) = &do_pexect($sql);*
>               carp "This is a test 3\n";
>               $rowcache = $sth->fetchall_arrayref();
>               carp "This is a test 4\n";
>
>               #pop off all rows. destroys $rowcache structure
>               while (my $row = shift @$rowcache) {
>                   my ($last_nm) = @$row;
>               }
>               $sth->finish();
>
>               undef $sth;
>               return;
>         }
>
>         sub do_pexect {
>
>               # input parameters
>               my($sql) = @_;
>
>               my $out;
>
>               $out = $dbh->prepare($sql) ||
>         carp "prepare ($sql): ".$dbh->errstr;
>               $out->execute() ||
>         carp "execute ($sql): ".$dbh->errstr;
>
>               return($out);
>         }
>
>         ******************************__******
>
>         Basic trace error:
>
>             -> prepare for DBD::ODBC::db (DBI::db=HASH(0x13c8928)~__0x1668428 '
>                    SELECT name FROM Person WHERE p_id = 123') thr#139f010
>               <- prepare= DBI::st=HASH(0x156c370) at test12.pl <http://test12.pl> <http://test12.pl> line 92
>               -> execute for DBD::ODBC::st (DBI::st=HASH(0x156c370)~__0x16e8898) thr#139f010
>               <- execute= -1 at test12.pl <http://test12.pl> <http://test12.pl> line 95
>               -> DESTROY for DBD::ODBC::st (DBI::st=HASH(0x13c8c28)~__INNER) thr#139f010
>               !! ERROR: 1 '    Unable to fetch information about the error' (err#1)
>               <- DESTROY= undef at test12.pl <http://test12.pl> <http://test12.pl> line 70
>         DBD::ODBC::st DESTROY failed:     Unable to fetch information about the error at test12.pl <http://test12.pl> <http://test12.pl> line 70.
>         This is a test 3
>            at test12.pl <http://test12.pl> <http://test12.pl> line 70.
>         main::joel_init() called at test12.pl <http://test12.pl> <http://test12.pl> line 36
>               !! The ERROR '1' was CLEARED by call to fetchall_arrayref method
>
>
>         ***********************
>
>         The basic error is that when the handle is created the 2nd time in the sub-routine, DBD destroys the original $sth attached to the $dbh.  Then, when the sub-routine finishes, perl auto-trash compactor tries to destroy $sth a 2nd time as it's the left hand value of the equate statement:  ($sth) = &do_pexec($sql);  but this doesn't work as the $sth has already been destroyed in the subroutine.
>
>         This trace/error didn't occur in the earlier versions of DBD but now do... I can get rid of the error by doing:  undef $sth; before the 2nd use of the variable but this should not be necessary.
>
>         Has anyone else experienced this issue with the newer versions of DBD?
>
>         Thanks for any insight,
>
>         Joel
>
>
>     Sorry Joel, I forgot about your email but in any case this list is a good place to send your issue. When I run your script as it stands (with edits below) I get:
>
>     opening new db connection
>       at mje/joel.pl <http://joel.pl> line 23.
>     This is a test 3
>       at mje/joel.pl <http://joel.pl> line 45.
>     This is a test 4
>       at mje/joel.pl <http://joel.pl> line 47.
>     Can't return outside a subroutine at mje/joel.pl <http://joel.pl> line 56.
>
>     perl 5.19.10
>     DBI 1.631
>     DBD::ODBC 1.53_3 (which is latest git)
>
>     I'm going to SQL Server enterprise edition via the Easysoft SQL Server driver.
>
>     Obviously I changed the logon details and the SQL.
>
>     BTW, I don't think you need those calls to finish (see finish in DBI docs).
>
>     Martin
>
>