Thanks for explain. I bind statement into connection object, also make sure all statement reseted before quit lexical scope. Transaction always execute in one thread, and in one lexical scope. One more question related to this design: The task is initiated by main event loop, pass to worker thread by message. after work done notify main event loop thread by message. (check libuv worker docuement) My question is from the worker thread, is it safe to read/write main event loop task object direct ? (the task object will never access by event loop thread before worker done message)