NAME
dbdeadlock - Detect deadlocks and abort lock requests SYNOPSIS
dbdeadlock [-Vv] [-a e | m | n | o | W | w | y ] [-h home] [-L file]
[-t sec.usec] DESCRIPTION The dbdeadlock 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 e When lock or transaction timeouts have been specified, abort any lock request that has timed out. Note that this option does not perform the entire deadlock detection algorithm, but instead only checks for timeouts.
-h home Specify a home directory for the database environment; by default, the current working directory is used.
-L file Log the execution of the dbdeadlock utility to the specified
file in the following format, where ### is the process ID, and the date is the time the utility was started.
dbdeadlock: ### Wed Jun 15 01:23:45 EDT 1995 This file will be removed if the dbdeadlock utility exits gracefully.
-t sec.usec 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, dbdeadlock will run once and exit. The dbdeadlock utility uses a Berkeley DB environment (as described
for the -h option, the environment variable DBHOME, 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, dbdeadlock should always be given the chance to detach from the environment and exit gracefully. To cause dbdeadlock to release all environment resources and exit cleanly, send it an interrupt signal (SIGINT). The dbdeadlock 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 dbdeadlock utility should be started.
The DBENV->lockdetect method is the underlying method used by the dbdeadlock utility. See the dbdeadlock utility source code for an
example of using DBENV->lockdetect in a IEEE/ANSI Std 1003.1 (POSIX) environment. EXIT STATUS The dbdeadlock utility exits 0 on success, and >0 if an error occurs. ENVIRONMENT DBHOME
If the -h option is not specified and the environment variable DBHOME is set, it is used as the path of the database home, as
described in DBENV->open. SEE ALSO dbarchive(1) dbcheckpoint(1) dbdump(1) dbhotbackup(1) dblogver‐ ify(1) dbload(1) dbprintlog(1) dbrecover(1) dbreplicate(1) dbstat(1) dbtuner(1) dbupgrade(1) dbverify(1) BerkeleyDB 5.3.21 06 December 2016 DBDEADLOCK(1)