The eval check around $dbh->ping is pointless, DBD::Oracle does it's own eval internally. That subroutine seems weird anyhow, because you first check for definedness of $dbh, then try to call disconnect on it regardless of whether it was defined or not, then return 1 regardless of whether the disconnect was successful or not.

Not sure that any of this will help with your actual problem, but I thought I'd point it out.