#include <db.h> int DB_ENV->set_mp_mtxcount(DB_ENV *dbenv, u_int32_t mtxcount);
The DB_ENV->set_mp_mtxcount()
method
overrides the default number of mutexes for the hash table in each
memory pool cache. The defualt is one mutex per hash bucket.
Setting it to a lower number decreases the number of mutexes used
and the amount of memory needed to store them at the expense of
concurrency in the memory pool. This can also improve startup
time. Setting a number greater than the number size of the hash
table will waste mutexes and space.
You must call this method only before the environment is opened.