db_deadlock(1) General Commands Manual db_deadlock(1)
db_deadlock [-Vv] [-a e | m | n | o | w | y] [-h home] [-L file]
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