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Hunting down (possible) memory leak in DBD::Oracle

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Fennell, Brian
December 16, 2017 22:19
Hunting down (possible) memory leak in DBD::Oracle
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Dear DBI people - 

I am trying to port some old perl code to a new box.  (see Details below) Needless to say the original box and code works fine, but the new box (and old code) does not.
Specifically what I am seeing is that when I select slightly over a million records from a specific join of two tables (to be dumped one row at a time into a TSV file) we get strange ORA-NNNNN errors that don't really make any sense in this context.
The Same database and same table works fine on the original box with the large number of records.  2 million records always causes errors but two groups of 1million (divided up by ROWNUM - the EXACT same rows) causes no errors.  I am using a test database with little activity do I am reasonably certain that the queries deal with the same rows.
So I am thinking the problem is data volume and not any specific piece of data (originally I thought it might be an odd string/data related error, but I am starting to think it is a memory leak of some kind).
The error always happens inside of fetchrow_array - and "$dbh->trace( 4 , $filename )" shows that the error originates inside the DBD::Oracle module while reading field 3 of 6.  
Researching the ORA-NNNNNN error gives a perfectly sane description that makes no sense at all in the context of reading a specific field.  

We are going thru an Audit and tightening up security so there are some things (like REAL hostnames and REAL column/table names) that I cannot share - but I will try to share as much as I can.

The Host I am calling "prod" below is the only one NOT exhibiting this issue.

Things I want to try - 

1) recompile the DBD::Oracle module on Host "sandbox" with "perl Makefile.PL -g" and then use Valgrind.  I haven't used Valgrind before, but I guess it is time to learn.
2) Anything else this list suggests. 


Host: prod
OS: Red Hat Enterprise Linux AS release 4 (Nahant Update 4)
Perl: 5.8.8 built for x86_64-linux
DBI: 1.53
DBD::Oracle: 1.19

Host: dev
OS: Red Hat Enterprise Linux Server release 6.5 (Santiago)
Perl: 5.16.1  built for x86_64-linux
DBI: 1.631
DBD::Oracle: 1.74

Host: prodnew
OS: Red Hat Enterprise Linux Server release 6.5 (Santiago)
Perl: 5.16.1  built for x86_64-linux
DBI: 1.631
DBD::Oracle: 1.70

Host: sandbox
OS: CentOS Linux release 7.4.1708 (Core)
Perl: 5.16.3  built for x86_64-linux-thread-multi
DBI: 1.637
DBD::Oracle: 1.74

Brian Fennell, Software Engineer | Radial
O: 610 491 7308 | M: 484 354 1699

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