db_deadlock(1)               General Commands Manual              db_deadlock(1)


     db_deadlock [-Vv] [-a e | m | n | o | w | y] [-h home] [-L file]
                 [-t sec.usec]

     The db_deadlock utility traverses the database environment lock region, and
     aborts a lock request each time it detects a deadlock or a lock request
     that has timed out. By default, in the case of a deadlock, a random lock
     request is chosen to be aborted.

     This utility should be run as a background daemon, or the underlying
     Berkeley DB deadlock detection interfaces should be called in some other
     way, whenever there are multiple threads or processes accessing a database
     and at least one of them is modifying it.

     The options are as follows:

       When a deadlock is detected, abort the locker:

         with the greatest number of locks

         with the fewest number of locks

         with the oldest locker ID

         with the fewest number of write locks

         with the youngest locker ID

       When lock or transaction timeouts have been specified:

         abort any lock request that has timed out

       Specify a home directory for the database environment; by default, the
       current working directory is used.

       Log the execution of the db_deadlock utility to the specified file in the
       following format, where ### is the process ID, and the date is the time
       the utility was started.

             db_deadlock: ### Wed Jun 15 01:23:45 EDT 1995

       This file will be removed if the db_deadlock utility exits gracefully.

       Check the database environment every sec seconds plus usec microseconds
       to see if a process has been forced to wait for a lock; if one has,
       review the database environment lock structures.

       Write the library version number to the standard output, and exit.

       Run in verbose mode, generating messages each time the detector runs.

     If the -t option is not specified, db_deadlock will run once and exit.

     The db_deadlock utility uses a Berkeley DB environment (as described for
     the -h option, the environment variable DB_HOME, or because the utility was
     run in a directory containing a Berkeley DB environment). In order to avoid
     environment corruption when using a Berkeley DB environment, db_deadlock
     should always be given the chance to detach from the environment and exit
     gracefully. To cause db_deadlock to release all environment resources and
     exit cleanly, send it an interrupt signal (SIGINT).

     The db_deadlock utility does not attempt to create the Berkeley DB shared
     memory regions if they do not already exist. The application which creates
     the region should be started first, and then, once the region is created,
     the db_deadlock utility should be started.

     The DB_ENV->lock_detect method is the underlying method used by the
     db_deadlock utility. See the db_deadlock utility source code for an example
     of using DB_ENV->lock_detect in a IEEE/ANSI Std 1003.1 (POSIX) environment.

     The db_deadlock utility exits 0 on success, and >0 if an error occurs.

     DB_HOME  If the -h option is not specified and the environment variable
              DB_HOME is set, it is used as the path of the database home, as
              described in DB_ENV->open.

     db_archive(1), db_checkpoint(1), db_dump(1), db_load(1), db_printlog(1),
     db_recover(1), db_stat(1), db_upgrade(1), db_verify(1)

Darwin                          December 3, 2003                          Darwin