#include <db.h> int DB_ENV->mutex_set_increment(DB_ENV *dbenv, u_int32_t increment);
Configure the number of additional mutexes to allocate.
         If an application will allocate mutexes for its own use, 
         the DB_ENV->mutex_set_increment() method is used to add a
         number of mutexes to the default allocation.
    
         Calling the DB_ENV->mutex_set_increment() method discards any value
         previously set using the DB_ENV->mutex_set_max() method.
    
The database environment's number of additional mutexes may also be configured using the environment's DB_CONFIG file. The syntax of the entry in that file is a single line with the string "mutex_set_increment", one or more whitespace characters, and the number of additional mutexes. Because the DB_CONFIG file is read when the database environment is opened, it will silently overrule configuration done before that time.
         The DB_ENV->mutex_set_increment() method configures a database
         environment, not only operations performed using the specified 
         DB_ENV  handle.
    
         The DB_ENV->mutex_set_increment() method may not be called after the
         DB_ENV->open()  method is
         called. If the database environment already exists when 
         DB_ENV->open()  is called, the
         information specified to DB_ENV->mutex_set_increment() will be
         ignored.
    
         The DB_ENV->mutex_set_increment() 
            
                  method returns a non-zero error value on failure and 0 on success.
            
            
        
    
                         The DB_ENV->mutex_set_increment() 
            
                 method may fail and return one of the following non-zero errors:
            
            
        
                    
If the method was called after DB_ENV->open() was called; or if an invalid flag value or parameter was specified.