#include <db_cxx.h> int DbEnv::set_mp_mtxcount(u_int32_t mtxcount);
         The DbEnv::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.