question on write transaction

Hi list, recently I wrote app on LMDB, found that for every write , lmdb lock a global lock when transaction is created , and release this lock in mdb_txn_commit, on Ubuntu, this lock is implemented by pthread_mutext_t. in my app, I create write transaction in a thread, then commit this write transaction in another thread, since lmdb use pthread_mutex_unlock to release this lock, according to manual , attempting to unlock the mutex if it was not locked by the calling thread results in undefined behavior, then my app cannot create write transaction . So does this issue known to community or is there any way to work around?

Cheers, xinxin