You fail to mention precisely how its failing ? What version of (Perl, DBI, DBD::ODBC) you're using, and on what platform/OS ?

I don't see anything in your code regarding threads (i.e., no threads->new(), threads::shared, lock(), etc), so I don't see what makes this "thread-safe" ?

That said, have you considered DBIx::Threaded ? It might further simplify the thread-safety issue.