#include <db.h> int DB_ENV->failchk(DB_ENV *dbenv, u_int32_t flags);
         The DB_ENV->failchk() method checks for threads of control (either a
         true thread or a process) that have exited while manipulating Berkeley
         DB library data structures, while holding a logical database lock, or
         with an unresolved transaction (that is, a transaction that was never
         aborted or committed).  For more information, see 
         Architecting Data Store and 
         Concurrent Data Store applications, and 
         Architecting Transactional 
             Data Store applications, both in the
         Berkeley DB Programmer's Reference Guide.
    
         The DB_ENV->failchk() method is 
         used in conjunction with the 
         DB_ENV->set_thread_count(),
         DB_ENV->set_isalive() and
         DB_ENV->set_thread_id()
         methods.  Before calling the failchk()method, applications must:
     
Configure their database using the DB_ENV->set_thread_count() method.
                 Establish an is_alive() function and
                 invoke
                 DB_ENV->set_isalive() 
                 with that function as the is_alive parameter.
             
                 Establish a thread_id function and
                 invoke
                DB_ENV->set_thread_id()
                with that function as the thread_id
                parameter.
             
         If any of these methods are omitted, a program may be unable to
         allocate a thread control block. This is true of the standalone
         Berkeley DB utility programs. To avoid problems when using the
         standalone Berkeley DB utility programs with environments
         configured for failure checking, incorporate the utility's
         functionality directly in the application, or call the
         DB_ENV->failchk() method along with its 
         associated methods before running the utility.
     
         If DB_ENV->failchk() determines a thread of control exited while
         holding database read locks, it will release those locks.  If
         DB_ENV->failchk() determines a thread of control exited with an
         unresolved transaction, the transaction will be aborted.  In either of
         these cases, DB_ENV->failchk() will return 0 and the application may
         continue to use the database environment.
    
         In either of these cases, the DB_ENV->failchk() method will also
         report the process and thread IDs associated with any released locks
         or aborted transactions.  The information is printed to a specified
         output channel (see the 
         DB_ENV->set_msgfile() 
         method for more information), or passed to an application callback
         function (see the 
         DB_ENV->set_msgcall() 
         method for more information).
    
         If DB_ENV->failchk() determines a thread of control has exited such
         that database environment recovery is required, it will return 
         DB_RUNRECOVERY.
         In this case, the application should not continue to use the database
         environment.  For a further description as to the actions the
         application should take when this failure occurs, see 
         Handling failure in Data Store and 
         Concurrent Data Store applications, and 
         Handling failure in Transactional Data
             Store applications, both in the
         Berkeley DB Programmer's Reference Guide.
    
	In multiprocess applications, it is recommended that the DB_ENV handle 
        used to invoke the DB_ENV->failchk() method not be shared and therefore
	not free-threaded.  
    
             The DB_ENV->failchk() method may not be called by the 
	     application before the DB_ENV->open()  
	     method is called.
    
         The DB_ENV->failchk() 
            
                  method returns a non-zero error value on failure and 0 on success.
            
            
        
    
                         The DB_ENV->failchk() 
            
                 method may fail and return one of the following non-zero errors: