db5.1_deadlock(1)



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

NAME
       db5.1_deadlock - Detect and abort deadlocks

SYNOPSIS
       db5.1_deadlock [-Vv] [-a e | m | n | o | W | w | y] [-h home] [-L file]
       [-t sec.usec]

DESCRIPTION
       The db5.1_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.

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 db5.1_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 db5.1_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 environment  lock  struc-
               tures.

       -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, db5.1_deadlock will run once and
       exit.

       The db5.1_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 envi-
       ronment, db5.1_deadlock should always be given  the  chance  to  detach
       from  the  environment and exit gracefully.  To cause db5.1_deadlock to
       release all environment resources and exit cleanly, send it  an  inter-
       rupt signal (SIGINT).

       The  db5.1_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 db5.1_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  db5.1_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@kinkhorst.com>, for the Debian system (but may be used  by  oth-
       ers).

                                28 January 2005              DB5.1_DEADLOCK(1)

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