#include <db_cxx.h> int DbEnv::set_mp_max_openfd(int maxopenfd);
         The DbEnv::set_mp_max_openfd() method limits the number of file
         descriptors the library will open concurrently when flushing dirty
         pages from the cache.
    
The database environment's limit on open file descriptors to flush dirty pages 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 "set_mp_max_openfd", one or more whitespace characters, and the number of open file descriptors. Because the DB_CONFIG file is read when the database environment is opened, it will silently overrule configuration done before that time.
The DbEnv::set_mp_max_openfd() method configures a database environment, not only operations performed using the specified DbEnv handle.
         The DbEnv::set_mp_max_openfd() 
            
            
                method either returns a non-zero error value or throws an
                exception that encapsulates a non-zero error value on
                failure, and returns 0 on success.
            
        
    
                         The DbEnv::set_mp_max_openfd() 
            
            
                method may fail and throw a DbException 
                exception, encapsulating one of the following non-zero errors, or return one
                of the following non-zero errors: