Berkeley DB in multithreaded applications

What is the best way to use berkeley DB (bdb) handles in a multi-threaded app开发者_如何学Golication?

1. Is it better to have each thread open its own handle; or,

2. is it better to open a single handle and have each thread do txn_begin { } txn->commit()?

Which one scales better? I am using Transactional Data Store with DB_THREAD flag.

Thanks