1DB_DEADLOCK(1) BerkeleyDB Utilities DB_DEADLOCK(1)
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6 db_deadlock - Detect deadlocks and abort lock requests
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9 db_deadlock [-Vv] [-a e | m | n | o | W | w | y ] [-h home] [-L file]
10 [-t sec.usec]
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13 The db_deadlock utility traverses the database environment lock region,
14 and aborts a lock request each time it detects a deadlock or a lock
15 request that has timed out. By default, in the case of a deadlock, a
16 random lock request is chosen to be aborted.
17 This utility should be run as a background daemon, or the underlying
19 Berkeley DB deadlock detection interfaces should be called in some
20 other way, whenever there are multiple threads or processes accessing a
21 database and at least one of them is modifying it.
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24 -a When a deadlock is detected, abort the locker:
25 m with the most locks
27 n with the fewest locks
29 o with the oldest lock
31 W with the most write locks
33 w with the fewest write locks
35 y with the youngest lock
37 e When lock or transaction timeouts have been specified,
39 abort any lock request that has timed out. Note that this
40 option does not perform the entire deadlock detection
41 algorithm, but instead only checks for timeouts.
42 -h home
44 Specify a home directory for the database environment; by
45 default, the current working directory is used.
46 -L file
48 Log the execution of the db_deadlock utility to the specified
49 file in the following format, where ### is the process ID, and
50 the date is the time the utility was started.
51 db_deadlock: ### Wed Jun 15 01:23:45 EDT 1995
53 This file will be removed if the db_deadlock utility exits
55 gracefully.
56 -t sec.usec
58 Check the database environment every sec seconds plus usec
59 microseconds to see if a process has been forced to wait for a
60 lock; if one has, review the database environment lock struc‐
61 tures.
62 -V Write the library version number to the standard output, and
64 exit.
65 -v Run in verbose mode, generating messages each time the detector
67 runs.
68 If the -t option is not specified, db_deadlock will run once and exit.
70 The db_deadlock utility uses a Berkeley DB environment (as described
72 for the -h option, the environment variable DB_HOME, or because the
73 utility was run in a directory containing a Berkeley DB environment).
74 In order to avoid environment corruption when using a Berkeley DB envi‐
75 ronment, db_deadlock should always be given the chance to detach from
76 the environment and exit gracefully. To cause db_deadlock to release
77 all environment resources and exit cleanly, send it an interrupt signal
78 (SIGINT).
79 The db_deadlock utility does not attempt to create the Berkeley DB
81 shared memory regions if they do not already exist. The application
82 which creates the region should be started first, and then, once the
83 region is created, the db_deadlock utility should be started.
84 The DB_ENV->lock_detect method is the underlying method used by the
86 db_deadlock utility. See the db_deadlock utility source code for an
87 example of using DB_ENV->lock_detect in a IEEE/ANSI Std 1003.1 (POSIX)
88 environment.
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91 The db_deadlock utility exits 0 on success, and >0 if an error occurs.
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94 DB_HOME
95 If the -h option is not specified and the environment variable
96 DB_HOME is set, it is used as the path of the database home, as
97 described in DB_ENV->open.
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100 db_archive(1) db_checkpoint(1) db_dump(1) db_hotbackup(1) db_log_ver‐
101 ify(1) db_load(1) db_printlog(1) db_recover(1) db_replicate(1)
102 db_stat(1) db_tuner(1) db_upgrade(1) db_verify(1)
103BerkeleyDB 5.3.21 06 December 2016 DB_DEADLOCK(1)