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DB5.3_DEADLOCK(1)                      General Commands Manual                     DB5.3_DEADLOCK(1)



NAME
       db5.3_deadlock - Detect and abort deadlocks

SYNOPSIS
       db5.3_deadlock [-Vv] [-a e | m | n | o | W | w | y] [-h home] [-L file] [-t sec.usec]

DESCRIPTION
       The  db5.3_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 de‐
       tection 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.

OPTIONS
       -a     When a deadlock is detected, abort the locker:

              m      with the most locks

              n      with the fewest locks

              o      with the oldest lock

              W      with the most write locks

              w      with the fewest write locks

              y      with the youngest lock

              When lock or transaction timeouts have been specified:

              e      abort any lock request that has timed out

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

       -L     Log the execution of the db5.3_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 db5.3_deadlock utility exits gracefully.

       -t      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  environ‐
               ment lock structures.

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

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

       If the -t option is not specified, db5.3_deadlock will run once and exit.

       The  db5.3_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, db5.3_deadlock should always be given the chance to detach from the  environment
       and  exit  gracefully.  To cause db5.3_deadlock to release all environment resources and exit
       cleanly, send it an interrupt signal (SIGINT).

       The db5.3_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 db5.3_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 db5.3_deadlock utility exits 0 on success, and >0 if an error occurs.

ENVIRONMENT
       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.

AUTHORS
       Sleepycat  Software,  Inc.  This  manual page was created based on the HTML documentation for
       db_deadlock from Sleepycat, by Thijs Kinkhorst <thijs AT kinkhorst.com>, for the  Debian  system
       (but may be used by others).



                                           28 January 2005                         DB5.3_DEADLOCK(1)