pt-deadlock-logger
NAME
pt-deadlock-logger - Extract and log MySQL deadlock information.
SYNOPSIS
Usage
pt-deadlock-logger [OPTION...] SOURCE_DSN
pt-deadlock-logger extracts and saves information about the most recent deadlock
in a MySQL server.
Print deadlocks on SOURCE_DSN:
pt-deadlock-logger SOURCE_DSN
Store deadlock information from SOURCE_DSN in test.deadlocks table on SOURCE_DSN
(source and destination are the same host):
pt-deadlock-logger SOURCE_DSN --dest D=test,t=deadlocks
Store deadlock information from SOURCE_DSN in test.deadlocks table on DEST_DSN
(source and destination are different hosts):
pt-deadlock-logger SOURCE_DSN --dest DEST_DSN,D=test,t=deadlocks
Daemonize and check for deadlocks on SOURCE_DSN every 30 seconds for 4 hours:
pt-deadlock-logger SOURCE_DSN --dest D=test,t=deadlocks --daemonize --run-time 4h --interval 30s
RISKS
The following section is included to inform users about the potential risks,
whether known or unknown, of using this tool. The two main categories of risks
are those created by the nature of the tool (e.g. read-only tools vs. read-write
tools) and those created by bugs.
pt-deadlock-logger is a read-only tool unless you specify a --dest table.
In some cases polling SHOW INNODB STATUS too rapidly can cause extra load on the
server. If you’re using it on a production server under very heavy load, you
might want to set --interval to 30 seconds or more.
At the time of this release, we know of no bugs that could cause serious harm to
users.
The authoritative source for updated information is always the online issue
tracking system. Issues that affect this tool will be marked as such. You can
see a list of such issues at the following URL:
http://www.percona.com/bugs/pt-deadlock-logger.
See also “BUGS” for more information on filing bugs and getting help.
DESCRIPTION
pt-deadlock-logger extracts deadlock data from a MySQL server. Currently only
InnoDB deadlock information is available. You can print the information to
standard output, store it in a database table, or both. If neither
--print nor --dest are given, then the deadlock information is
printed by default. If only --dest is given, then the deadlock
information is only stored. If both options are given, then the deadlock
information is printed and stored.
The source host can be specified using one of two methods. The first method is
to use at least one of the standard connection-related command line options:
--defaults-file, --password, --host, --port, --socket
or --user. These options only apply to the source host; they cannot be
used to specify the destination host.
The second method to specify the source host, or the optional destination host
using --dest, is a DSN. A DSN is a special syntax that can be either just
a hostname (like server.domain.com or 1.2.3.4), or a
key=value,key=value string. Keys are a single letter:
KEY MEANING
=== =======
h Connect to host
P Port number to use for connection
S Socket file to use for connection
u User for login if not current user
p Password to use when connecting
F Only read default options from the given file
If you omit any values from the destination host DSN, they are filled in with
values from the source host, so you don’t need to specify them in both places.
pt-deadlock-logger reads all normal MySQL option files, such as ~/.my.cnf, so
you may not need to specify username, password and other common options at all.
OUTPUT
You can choose which columns are output and/or saved to --dest with the
--columns argument. The default columns are as follows:
server
The (source) server on which the deadlock occurred. This might be useful if
you’re tracking deadlocks on many servers.
ts
The date and time of the last detected deadlock.
thread
The MySQL thread number, which is the same as the connection ID in SHOW FULL
PROCESSLIST.
txn_id
The InnoDB transaction ID, which InnoDB expresses as two unsigned integers. I
have multiplied them out to be one number.
txn_time
How long the transaction was active when the deadlock happened.
user
The connection’s database username.
hostname
The connection’s host.
ip
The connection’s IP address. If you specify
--numeric-ip, this is
converted to an unsigned integer.
db
The database in which the deadlock occurred.
tbl
The table on which the deadlock occurred.
idx
The index on which the deadlock occurred.
lock_type
The lock type the transaction held on the lock that caused the deadlock.
lock_mode
The lock mode of the lock that caused the deadlock.
wait_hold
Whether the transaction was waiting for the lock or holding the lock. Usually
you will see the two waited-for locks.
victim
Whether the transaction was selected as the deadlock victim and rolled back.
query
The query that caused the deadlock.
INNODB CAVEATS AND DETAILS
InnoDB’s output is hard to parse and sometimes there’s no way to do it right.
Sometimes not all information (for example, username or IP address) is included
in the deadlock information. In this case there’s nothing for the script to put
in those columns. It may also be the case that the deadlock output is so long
(because there were a lot of locks) that the whole thing is truncated.
Though there are usually two transactions involved in a deadlock, there are more
locks than that; at a minimum, one more lock than transactions is necessary to
create a cycle in the waits-for graph. pt-deadlock-logger prints the
transactions (always two in the InnoDB output, even when there are more
transactions in the waits-for graph than that) and fills in locks. It prefers
waited-for over held when choosing lock information to output, but you can
figure out the rest with a moment’s thought. If you see one wait-for and one
held lock, you’re looking at the same lock, so of course you’d prefer to see
both wait-for locks and get more information. If the two waited-for locks are
not on the same table, more than two transactions were involved in the deadlock.
Finally, keep in mind that, because usernames with spaces are not quoted by
InnoDB, the tool will generally misreport the second word of these usernames
as the hostname.
OPTIONS
This tool accepts additional command-line arguments. Refer to the
“SYNOPSIS” and usage information for details.
-
--ask-pass
Prompt for a password when connecting to MySQL.
-
--charset
short form: -A; type: string
Default character set. If the value is utf8, sets Perl’s binmode on
STDOUT to utf8, passes the mysql_enable_utf8 option to DBD::mysql, and runs SET
NAMES UTF8 after connecting to MySQL. Any other value sets binmode on STDOUT
without the utf8 layer, and runs SET NAMES after connecting to MySQL.
-
--clear-deadlocks
type: string
Use this table to create a small deadlock. This usually has the effect of
clearing out a huge deadlock, which otherwise consumes the entire output of
SHOW INNODB STATUS. The table must not exist. pt-deadlock-logger will
create it with the following MAGIC_clear_deadlocks structure:
CREATE TABLE test.deadlock_maker(a INT PRIMARY KEY) ENGINE=InnoDB;
After creating the table and causing a small deadlock, the tool will drop the
table again.
-
--[no]collapse
Collapse whitespace in queries to a single space. This might make it easier to
inspect on the command line or in a query. By default, whitespace is collapsed
when printing with --print, but not modified when storing to --dest.
(That is, the default is different for each action).
-
--columns
type: hash
Output only this comma-separated list of columns. See “OUTPUT” for more
details on columns.
-
--config
type: Array
Read this comma-separated list of config files; if specified, this must be the
first option on the command line.
-
--create-dest-table
Create the table specified by --dest.
Normally the --dest table is expected to exist already. This option
causes pt-deadlock-logger to create the table automatically using the suggested
table structure.
-
--daemonize
Fork to the background and detach from the shell. POSIX operating systems only.
-
--defaults-file
short form: -F; type: string
Only read mysql options from the given file. You must give an absolute
pathname.
-
--dest
type: DSN
DSN for where to store deadlocks; specify at least a database (D) and table (t).
Missing values are filled in with the same values from the source host, so you
can usually omit most parts of this argument if you’re storing deadlocks on the
same server on which they happen.
By default, whitespace in the query column is left intact;
use --[no]collapse if you want whitespace collapsed.
The following MAGIC_dest_table is suggested if you want to store all the
information pt-deadlock-logger can extract about deadlocks:
CREATE TABLE deadlocks (
server char(20) NOT NULL,
ts datetime NOT NULL,
thread int unsigned NOT NULL,
txn_id bigint unsigned NOT NULL,
txn_time smallint unsigned NOT NULL,
user char(16) NOT NULL,
hostname char(20) NOT NULL,
ip char(15) NOT NULL, -- alternatively, ip int unsigned NOT NULL
db char(64) NOT NULL,
tbl char(64) NOT NULL,
idx char(64) NOT NULL,
lock_type char(16) NOT NULL,
lock_mode char(1) NOT NULL,
wait_hold char(1) NOT NULL,
victim tinyint unsigned NOT NULL,
query text NOT NULL,
PRIMARY KEY (server,ts,thread)
) ENGINE=InnoDB
If you use --columns, you can omit whichever columns you don’t want to
store.
-
--help
Show help and exit.
-
--host
short form: -h; type: string
Connect to host.
-
--interval
type: time
How often to check for deadlocks. If no --run-time is specified,
pt-deadlock-logger runs forever, checking for deadlocks at every interval.
See also --run-time.
-
--log
type: string
Print all output to this file when daemonized.
-
--numeric-ip
Express IP addresses as integers.
-
--password
short form: -p; type: string
Password to use when connecting.
-
--pid
type: string
Create the given PID file when daemonized. The file contains the process ID of
the daemonized instance. The PID file is removed when the daemonized instance
exits. The program checks for the existence of the PID file when starting; if
it exists and the process with the matching PID exists, the program exits.
-
--port
short form: -P; type: int
Port number to use for connection.
-
--print
Print results on standard output. See “OUTPUT” for more. By default,
enables --[no]collapse unless you explicitly disable it.
If --interval or --run-time is specified, only new deadlocks are
printed at each interval. A fingerprint for each deadlock is created using
--columns server, ts and thread (even if those columns were not specified
by --columns) and if the current deadlock’s fingerprint is different from
the last deadlock’s fingerprint, then it is printed.
-
--run-time
type: time
How long to run before exiting. By default pt-deadlock-logger runs once,
checks for deadlocks, and exits. If --run-time is specified but
no --interval is specified, a default 1 second interval will be used.
-
--set-vars
type: string; default: wait_timeout=10000
Set these MySQL variables. Immediately after connecting to MySQL, this string
will be appended to SET and executed.
-
--socket
short form: -S; type: string
Socket file to use for connection.
-
--tab
Print tab-separated columns, instead of aligned.
-
--user
short form: -u; type: string
User for login if not current user.
-
--version
Show version and exit.
-
--version-check
type: string; default: off
Send program versions to Percona and print suggested upgrades and problems.
Possible values for –version-check:
https, http, auto, off
auto first tries using https, and resorts to http if that fails.
Keep in mind that https might not be available if
IO::Socket::SSL is not installed on your system, although
--version-check http should work everywhere.
The version check feature causes the tool to send and receive data from
Percona over the web. The data contains program versions from the local
machine. Percona uses the data to focus development on the most widely
used versions of programs, and to suggest to customers possible upgrades
and known bad versions of programs.
For more information, visit http://www.percona.com/version-check.
DSN OPTIONS
These DSN options are used to create a DSN. Each option is given like
option=value. The options are case-sensitive, so P and p are not the
same option. There cannot be whitespace before or after the = and
if the value contains whitespace it must be quoted. DSN options are
comma-separated. See the percona-toolkit manpage for full details.
dsn: charset; copy: yes
Default character set.
dsn: database; copy: yes
Default database.
dsn: mysql_read_default_file; copy: yes
Only read default options from the given file
dsn: host; copy: yes
Connect to host.
dsn: password; copy: yes
Password to use when connecting.
dsn: port; copy: yes
Port number to use for connection.
dsn: mysql_socket; copy: yes
Socket file to use for connection.
Table in which to store deadlock information.
dsn: user; copy: yes
User for login if not current user.
ENVIRONMENT
The environment variable PTDEBUG enables verbose debugging output to STDERR.
To enable debugging and capture all output to a file, run the tool like:
PTDEBUG=1 pt-deadlock-logger ... > FILE 2>&1
Be careful: debugging output is voluminous and can generate several megabytes
of output.
SYSTEM REQUIREMENTS
You need Perl, DBI, DBD::mysql, and some core packages that ought to be
installed in any reasonably new version of Perl.
DOWNLOADING
Visit http://www.percona.com/software/percona-toolkit/ to download the
latest release of Percona Toolkit. Or, get the latest release from the
command line:
wget percona.com/get/percona-toolkit.tar.gz
wget percona.com/get/percona-toolkit.rpm
wget percona.com/get/percona-toolkit.deb
You can also get individual tools from the latest release:
wget percona.com/get/TOOL
Replace TOOL with the name of any tool.
COPYRIGHT, LICENSE, AND WARRANTY
This program is copyright 2011-2013 Percona Ireland Ltd,
2007-2011 Baron Schwartz.
THIS PROGRAM IS PROVIDED “AS IS” AND WITHOUT ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation, version 2; OR the Perl Artistic License. On UNIX and similar
systems, you can issue `man perlgpl’ or `man perlartistic’ to read these
licenses.
You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place, Suite 330, Boston, MA 02111-1307 USA.
VERSION
pt-deadlock-logger 2.1.9
