there is a $dbh (just to test, I called it $dbg) in a main thread and another $dbh for each thread, both $dbg and $dbh are declared "my". (so 1 main + 3 threads = 4 independent DB connections). Each threads calls the method "hitMe" every time they end processing the data from the DB, and I need to process about 70.000 rows in the DB, but I can only process 3 at a time, so that's why I thought of threading it.