Ubuntu Manpage: pt-kill - Kill MySQL queries that match certain criteria.

Provided by: percona-toolkit_3.1+dfsg-1.1_all

NAME

       pt-kill - Kill MySQL queries that match certain criteria.

SYNOPSIS

       Usage: pt-kill [OPTIONS] [DSN]

       pt-kill kills MySQL connections.  pt-kill connects to MySQL and gets queries from SHOW PROCESSLIST if no
       FILE is given.  Else, it reads queries from one or more FILE which contains the output of SHOW
       PROCESSLIST.  If FILE is -, pt-kill reads from STDIN.

       Kill queries running longer than 60s:

         pt-kill --busy-time 60 --kill

       Print, do not kill, queries running longer than 60s:

         pt-kill --busy-time 60 --print

       Check for sleeping processes and kill them all every 10s:

         pt-kill --match-command Sleep --kill --victims all --interval 10

       Print all login processes:

         pt-kill --match-state login --print --victims all

       See which queries in the processlist right now would match:

          mysql -e "SHOW PROCESSLIST" > proclist.txt
          pt-kill --test-matching proclist.txt --busy-time 60 --print

RISKS

       Percona Toolkit is mature, proven in the real world, and well tested, but all database tools can pose a
       risk to the system and the database server.  Before using this tool, please:

       •   Read the tool's documentation

       •   Review the tool's known "BUGS"

       •   Test the tool on a non-production server

       •   Backup your production server and verify the backups

DESCRIPTION

pt-kill captures queries from SHOW PROCESSLIST, filters them, and then either kills or prints them. This
is also known as a "slow query sniper" in some circles. The idea is to watch for queries that might be
consuming too many resources, and kill them.

For brevity, we talk about killing queries, but they may just be printed (or some other future action)
depending on what options are given.

Normally pt-kill connects to MySQL to get queries from SHOW PROCESSLIST. Alternatively, it can read SHOW
PROCESSLIST output from files. In this case, pt-kill does not connect to MySQL and "--kill" has no
effect. You should use "--print" instead when reading files. The ability to read a file with
"--test-matching" allows you to capture SHOW PROCESSLIST and test it later with pt-kill to make sure that
your matches kill the proper queries. There are a lot of special rules to follow, such as "don't kill
replication threads," so be careful not to kill something important!

Two important options to know are "--busy-time" and "--victims". First, whereas most match/filter
options match their corresponding value from SHOW PROCESSLIST (e.g. "--match-command" matches a query's
Command value), the Time value is matched by "--busy-time". See also "--interval".

Second, "--victims" controls which matching queries from each class are killed. By default, the matching
query with the highest Time value is killed (the oldest query). See the next section, "GROUP, MATCH AND
KILL", for more details.

Usually you need to specify at least one "--match" option, else no queries will match. Or, you can
specify "--match-all" to match all queries that aren't ignored by an "--ignore" option.

GROUP, MATCH AND KILL

       Queries pass through several steps to determine which exactly will be killed (or printed--whatever action
       is specified).  Understanding these steps will help you match precisely the queries you want.

       The first step is grouping queries into classes.  The "--group-by" option controls grouping.  By default,
       this option has no value so all queries are grouped into one default class.  All types of matching and
       filtering (the next step) are applied per-class.  Therefore, you may need to group queries in order to
       match/filter some classes but not others.

       The second step is matching.  Matching implies filtering since if a query doesn't match some criteria, it
       is removed from its class.  Matching happens for each class.  First, queries are filtered from their
       class by the various "Query Matches" options like "--match-user".  Then, entire classes are filtered by
       the various "Class Matches" options like "--query-count".

       The third step is victim selection, that is, which matching queries in each class to kill.  This is
       controlled by the "--victims" option.  Although many queries in a class may match, you may only want to
       kill the oldest query, or all queries, etc.

       The forth and final step is to take some action on all matching queries from all classes.  The "Actions"
       options specify which actions will be taken.  At this step, there are no more classes, just a single list
       of queries to kill, print, etc.

       pt-kill will kill all the queries matching ANY of the specified criteria (logical OR).  For example,
       using:

         --busy-time 114 --match-command 'Query|Execute'

       will kill all queries having busy-time > 114 "OR" where the command is "Query" or "Execute"

       If you want to kill only the queries where "busy-time " 114> "AND" the command is Query or Execute, you
       need to use "--kill-busy-commands:

         --busy-time 114 --kill-busy-commands 'Query|Execute'

OUTPUT

       If only "--kill" is given, then there is no output.  If only "--print" is given, then a timestamped KILL
       statement if printed for every query that would have been killed, like:

         # 2009-07-15T15:04:01 KILL 8 (Query 42 sec) SELECT * FROM huge_table

       The line shows a timestamp, the query's Id (8), its Time (42 sec) and its Info (usually the query SQL).

       If both "--kill" and "--print" are given, then matching queries are killed and a line for each like the
       one above is printed.

       Any command executed by "--execute-command" is responsible for its own output and logging.  After being
       executed, pt-kill has no control or interaction with the command.

OPTIONS

Specify at least one of "--kill", "--kill-query", "--print", "--execute-command" or "--stop".

"--any-busy-time" and "--each-busy-time" are mutually exclusive.

"--kill" and "--kill-query" are mutually exclusive.

"--daemonize" and "--test-matching" are mutually exclusive.

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.

--config
type: Array

Read this comma-separated list of config files; if specified, this must be the first option on the
command line.

--create-log-table
Create the "--log-dsn" table if it does not exist.

This option causes the table specified by "--log-dsn" to be created with the default structure shown
in the documentation for that option.

--daemonize
Fork to the background and detach from the shell. POSIX operating systems only.

--database
short form: -D; type: string

The database to use for the connection.

--defaults-file
short form: -F; type: string

Only read mysql options from the given file. You must give an absolute pathname.

--filter
type: string

Discard events for which this Perl code doesn't return true.

This option is a string of Perl code or a file containing Perl code that gets compiled into a
subroutine with one argument: $event. This is a hashref. If the given value is a readable file,
then pt-kill reads the entire file and uses its contents as the code. The file should not contain a
shebang (#!/usr/bin/perl) line.

If the code returns true, the chain of callbacks continues; otherwise it ends. The code is the last
statement in the subroutine other than "return $event". The subroutine template is:

sub { $event = shift; filter && return $event; }

Filters given on the command line are wrapped inside parentheses like like "( filter )". For
complex, multi-line filters, you must put the code inside a file so it will not be wrapped inside
parentheses. Either way, the filter must produce syntactically valid code given the template. For
example, an if-else branch given on the command line would not be valid:

--filter 'if () { } else { }' # WRONG

Since it's given on the command line, the if-else branch would be wrapped inside parentheses which is
not syntactically valid. So to accomplish something more complex like this would require putting the
code in a file, for example filter.txt:

my $event_ok; if (...) { $event_ok=1; } else { $event_ok=0; } $event_ok

Then specify "--filter filter.txt" to read the code from filter.txt.

If the filter code won't compile, pt-kill will die with an error. If the filter code does compile,
an error may still occur at runtime if the code tries to do something wrong (like pattern match an
undefined value). pt-kill does not provide any safeguards so code carefully!

It is permissible for the code to have side effects (to alter $event).

--group-by
type: string

Apply matches to each class of queries grouped by this SHOW PROCESSLIST column. In addition to the
basic columns of SHOW PROCESSLIST (user, host, command, state, etc.), queries can be matched by
"fingerprint" which abstracts the SQL query in the "Info" column.

By default, queries are not grouped, so matches and actions apply to all queries. Grouping allows
matches and actions to apply to classes of similar queries, if any queries in the class match.

For example, detecting cache stampedes (see "all-but-oldest" under "--victims" for an explanation of
that term) requires that queries are grouped by the "arg" attribute. This creates classes of
identical queries (stripped of comments). So queries "SELECT c FROM t WHERE id=1" and "SELECT c FROM
t WHERE id=1" are grouped into the same class, but query c<"SELECT c FROM t WHERE id=3"> is not
identical to the first two queries so it is grouped into another class. Then when "--victims"
"all-but-oldest" is specified, all but the oldest query in each class is killed for each class of
queries that matches the match criteria.

--help
Show help and exit.

--host
short form: -h; type: string; default: localhost

Connect to host.

--interval
type: time

How often to check for queries to kill. If "--busy-time" is not given, then the default interval is
30 seconds. Else the default is half as often as "--busy-time". If both "--interval" and
"--busy-time" are given, then the explicit "--interval" value is used.

See also "--run-time".

--log
type: string

Print all output to this file when daemonized.

--log-dsn
type: DSN

Store each query killed in this DSN.

The argument specifies a table to store all killed queries. The DSN passed in must have the database
(D) and table (t) options. The table must have at least the following columns. You can add more
columns for your own special purposes, but they won't be used by pt-kill. The following CREATE TABLE
definition is also used for "--create-log-table". MAGIC_create_log_table:

CREATE TABLE kill_log (
kill_id int(10) unsigned NOT NULL AUTO_INCREMENT,
server_id bigint(4) NOT NULL DEFAULT '0',
timestamp DATETIME,
reason TEXT,
kill_error TEXT,
Id bigint(4) NOT NULL DEFAULT '0',
User varchar(16) NOT NULL DEFAULT '',
Host varchar(64) NOT NULL DEFAULT '',
db varchar(64) DEFAULT NULL,
Command varchar(16) NOT NULL DEFAULT '',
Time int(7) NOT NULL DEFAULT '0',
State varchar(64) DEFAULT NULL,
Info longtext,
Time_ms bigint(21) DEFAULT '0', # NOTE, TODO: currently not used
PRIMARY KEY (kill_id)
) DEFAULT CHARSET=utf8

--password
short form: -p; type: string

Password to use when connecting. If password contains commas they must be escaped with a backslash:
"exam\,ple"

--pid
type: string

Create the given PID file. The tool won't start if the PID file already exists and the PID it
contains is different than the current PID. However, if the PID file exists and the PID it contains
is no longer running, the tool will overwrite the PID file with the current PID. The PID file is
removed automatically when the tool exits.

--port
short form: -P; type: int

Port number to use for connection.

--query-id
Prints an ID of the query that was just killed. This is equivalent to the "ID" output of pt-query-
digest. This allows cross-referencing the output of both tools.

Example:

Query ID 0xE9800998ECF8427E

Note that this is a digest (or hash) of the query's "fingerprint", so queries of the same form but
with different values will have the same ID. See pt-query-digest for more information.

--rds
Denotes the instance in question is on Amazon RDS. By default pt-kill runs the MySQL command "kill"
for "--kill" and "kill query" "--kill-query". On RDS these two commands are not available and are
replaced by function calls. This option modifies "--kill" to use "CALL mysql.rds_kill(thread-id)"
instead and "--kill-query" to use "CALL mysql.rds_kill_query(thread-id)"

--run-time
type: time

How long to run before exiting. By default pt-kill runs forever, or until its process is killed or
stopped by the creation of a "--sentinel" file. If this option is specified, pt-kill runs for the
specified amount of time and sleeps "--interval" seconds between each check of the PROCESSLIST.

--sentinel
type: string; default: /tmp/pt-kill-sentinel

Exit if this file exists.

The presence of the file specified by "--sentinel" will cause all running instances of pt-kill to
exit. You might find this handy to stop cron jobs gracefully if necessary. See also "--stop".

--slave-user
type: string

Sets the user to be used to connect to the slaves. This parameter allows you to have a different
user with less privileges on the slaves but that user must exist on all slaves.

--slave-password
type: string

Sets the password to be used to connect to the slaves. It can be used with --slave-user and the
password for the user must be the same on all slaves.

--set-vars
type: Array

Set the MySQL variables in this comma-separated list of "variable=value" pairs.

By default, the tool sets:

wait_timeout=10000

Variables specified on the command line override these defaults. For example, specifying "--set-vars
wait_timeout=500" overrides the defaultvalue of 10000.

The tool prints a warning and continues if a variable cannot be set.

--socket
short form: -S; type: string

Socket file to use for connection.

--stop
Stop running instances by creating the "--sentinel" file.

Causes pt-kill to create the sentinel file specified by "--sentinel" and exit. This should have the
effect of stopping all running instances which are watching the same sentinel file.

--[no]strip-comments
default: yes

Remove SQL comments from queries in the Info column of the PROCESSLIST.

--user
short form: -u; type: string

User for login if not current user.

--version
Show version and exit.

--[no]version-check
default: yes

Check for the latest version of Percona Toolkit, MySQL, and other programs.

This is a standard "check for updates automatically" feature, with two additional features. First,
the tool checks its own version and also the versions of the following software: operating system,
Percona Monitoring and Management (PMM), MySQL, Perl, MySQL driver for Perl (DBD::mysql), and Percona
Toolkit. Second, it checks for and warns about versions with known problems. For example, MySQL
5.5.25 had a critical bug and was re-released as 5.5.25a.

A secure connection to Percona’s Version Check database server is done to perform these checks. Each
request is logged by the server, including software version numbers and unique ID of the checked
system. The ID is generated by the Percona Toolkit installation script or when the Version Check
database call is done for the first time.

Any updates or known problems are printed to STDOUT before the tool's normal output. This feature
should never interfere with the normal operation of the tool.

For more information, visit <https://www.percona.com/doc/percona-toolkit/LATEST/version-check.html>.

--victims
type: string; default: oldest

Which of the matching queries in each class will be killed. After classes have been
matched/filtered, this option specifies which of the matching queries in each class will be killed
(or printed, etc.). The following values are possible:

oldest
Only kill the single oldest query. This is to prevent killing queries that aren't really long-
running, they're just long-waiting. This sorts matching queries by Time and kills the one with
the highest Time value.

all Kill all queries in the class.

all-but-oldest
Kill all but the oldest query. This is the inverse of the "oldest" value.

This value can be used to prevent "cache stampedes", the condition where several identical
queries are executed and create a backlog while the first query attempts to finish. Since all
queries are identical, all but the first query are killed so that it can complete and populate
the cache.

--wait-after-kill
type: time

Wait after killing a query, before looking for more to kill. The purpose of this is to give blocked
queries a chance to execute, so we don't kill a query that's blocking a bunch of others, and then
kill the others immediately afterwards.

--wait-before-kill
type: time

Wait before killing a query. The purpose of this is to give "--execute-command" a chance to see the
matching query and gather other MySQL or system information before it's killed.

QUERY MATCHES
These options filter queries from their classes. If a query does not match, it is removed from its
class. The "--ignore" options take precedence. The matches for command, db, host, etc. correspond to
the columns returned by SHOW PROCESSLIST: Command, db, Host, etc. All pattern matches are case-sensitive
by default, but they can be made case-insensitive by specifying a regex pattern like "(?i-xsm:select)".

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.

       •   A

           dsn: charset; copy: yes

           Default character set.

       •   D

           dsn: database; copy: yes

           Default database.

       •   F

           dsn: mysql_read_default_file; copy: yes

           Only read default options from the given file

       •   h

           dsn: host; copy: yes

           Connect to host.

       •   p

           dsn: password; copy: yes

           Password to use when connecting.  If password contains commas they must be escaped with a backslash:
           "exam\,ple"

       •   P

           dsn: port; copy: yes

           Port number to use for connection.

       •   S

           dsn: mysql_socket; copy: yes

           Socket file to use for connection.

       •   u

           dsn: user; copy: yes

           User for login if not current user.

       •   t

           Table to log actions in, if passed through --log-dsn.

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-kill ... > 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.

BUGS

       For a list of known bugs, see <http://www.percona.com/bugs/pt-kill>.

       Please report bugs at <https://jira.percona.com/projects/PT>.  Include the following information in your
       bug report:

       •   Complete command-line used to run the tool

       •   Tool "--version"

       •   MySQL version of all servers involved

       •   Output from the tool including STDERR

       •   Input files (log/dump/config files, etc.)

       If possible, include debugging output by running the tool with "PTDEBUG"; see "ENVIRONMENT".

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.

AUTHORS

       Baron Schwartz and Daniel Nichter

ABOUT PERCONA TOOLKIT

       This tool is part of Percona Toolkit, a collection of advanced command-line tools for MySQL developed by
       Percona.  Percona Toolkit was forked from two projects in June, 2011: Maatkit and Aspersa.  Those
       projects were created by Baron Schwartz and primarily developed by him and Daniel Nichter.  Visit
       <http://www.percona.com/software/> to learn about other free, open-source software from Percona.

COPYRIGHT, LICENSE, AND WARRANTY

       This program is copyright 2011-2018 Percona LLC and/or its affiliates, 2009-2011 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-kill 3.1.0

POD ERRORS

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