| PT-KILL(1p) | User Contributed Perl Documentation | PT-KILL(1p) |
pt-kill - Kill MySQL queries that match certain criteria.
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
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:
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.
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'
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.
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.
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.
Read this comma-separated list of config files; if specified, this must be the first option on the command line.
This option causes the table specified by "--log-dsn" to be created with the default structure shown in the documentation for that option.
The database to use for the connection.
Only read mysql options from the given file. You must give an absolute pathname.
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).
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.
Connect to host.
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".
Print all output to this file when daemonized.
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 to use when connecting. If password contains commas they must be escaped with a backslash: "exam\,ple"
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 number to use for connection.
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.
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.
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".
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.
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 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 file to use for connection.
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.
Remove SQL comments from queries in the Info column of the PROCESSLIST.
User for login if not current user.
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>.
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:
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 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 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.
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)".
See also "GROUP, MATCH AND KILL".
Match queries that have been running for longer than this time. The queries must be in Command=Query status. This matches a query's Time value as reported by SHOW PROCESSLIST.
Match queries that have been idle/sleeping for longer than this time. The queries must be in Command=Sleep status. This matches a query's Time value as reported by SHOW PROCESSLIST.
Ignore queries whose Command matches this Perl regex.
See "--match-command".
Ignore queries whose db (database) matches this Perl regex.
See "--match-db".
Ignore queries whose Host matches this Perl regex.
See "--match-host".
Ignore queries whose Info (query) matches this Perl regex.
See "--match-info".
Don't kill pt-kill's own connection.
Ignore queries whose State matches this Perl regex. The default is to keep threads from being killed if they are locked waiting for another thread.
See "--match-state".
Ignore queries whose user matches this Perl regex.
See "--match-user".
Match all queries that are not ignored. If no ignore options are specified, then every query matches (except replication threads, unless "--replication-threads" is also specified). This option allows you to specify negative matches, i.e. "match every query except..." where the exceptions are defined by specifying various "--ignore" options.
This option is not the same as "--victims" "all". This option matches all queries within a class, whereas "--victims" "all" specifies that all matching queries in a class (however they matched) will be killed. Normally, however, the two are used together because if, for example, you specify "--victims" "oldest", then although all queries may match, only the oldest will be killed.
Match only queries whose Command matches this Perl regex.
Common Command values are:
Query
Sleep
Binlog Dump
Connect
Delayed insert
Execute
Fetch
Init DB
Kill
Prepare
Processlist
Quit
Reset stmt
Table Dump
See <http://dev.mysql.com/doc/refman/5.1/en/thread-commands.html> for a full list and description of Command values.
Match only queries whose db (database) matches this Perl regex.
Match only queries whose Host matches this Perl regex.
The Host value often time includes the port like "host:port".
Match only queries whose Info (query) matches this Perl regex.
The Info column of the processlist shows the query that is being executed or NULL if no query is being executed.
Match only queries whose State matches this Perl regex.
Common State values are:
Locked
login
copy to tmp table
Copying to tmp table
Copying to tmp table on disk
Creating tmp table
executing
Reading from net
Sending data
Sorting for order
Sorting result
Table lock
Updating
See <http://dev.mysql.com/doc/refman/5.1/en/general-thread-states.html> for a full list and description of State values.
Match only queries whose User matches this Perl regex.
Allow matching and killing replication threads.
By default, matches do not apply to replication threads; i.e. replication threads are completely ignored. Specifying this option allows matches to match (and potentially kill) replication threads on masters and slaves.
Files with processlist snapshots to test matching options against. Since the matching options can be complex, you can save snapshots of processlist in files, then test matching options against queries in those files.
This option disables "--run-time", "--interval", and "--[no]ignore-self".
These matches apply to entire query classes. Classes are created by specifying the "--group-by" option, else all queries are members of a single, default class.
See also "GROUP, MATCH AND KILL".
Match query class if any query has been running for longer than this time. "Longer than" means that if you specify 10, for example, the class will only match if there's at least one query that has been running for greater than 10 seconds.
See "--each-busy-time" for more details.
Match query class if each query has been running for longer than this time. "Longer than" means that if you specify 10, for example, the class will only match if each and every query has been running for greater than 10 seconds.
See also "--any-busy-time" (to match a class if ANY query has been running longer than the specified time) and "--busy-time".
Match query class if it has at least this many queries. When queries are grouped into classes by specifying "--group-by", this option causes matches to apply only to classes with at least this many queries. If "--group-by" is not specified then this option causes matches to apply only if there are at least this many queries in the entire SHOW PROCESSLIST.
Print information to STDOUT about what is being done.
These actions are taken for every matching query from all classes. The actions are taken in this order: "--print", "--execute-command", "--kill" / "--kill-query". This order allows "--execute-command" to see the output of "--print" and the query before "--kill" / "--kill-query". This may be helpful because pt-kill does not pass any information to "--execute-command".
See also "GROUP, MATCH AND KILL".
Execute this command when a query matches.
After the command is executed, pt-kill has no control over it, so the command is responsible for its own info gathering, logging, interval, etc. The command is executed each time a query matches, so be careful that the command behaves well when multiple instances are ran. No information from pt-kill is passed to the command.
See also "--wait-before-kill".
Kill the connection for matching queries.
This option makes pt-kill kill the connections (a.k.a. processes, threads) that have matching queries. Use "--kill-query" if you only want to kill individual queries and not their connections.
Unless "--print" is also given, no other information is printed that shows that pt-kill matched and killed a query.
See also "--wait-before-kill" and "--wait-after-kill".
group: Actions
Comma sepatated list of commands that will be watched/killed if they ran for more than "--busy-time" seconds. Default: "Query"
By default, "--busy-time" kills only "Query" commands but in some cases, it is needed to make "--busy-time" to watch and kill other commands. For example, a prepared statement execution command is "Execute" instead of "Query". In this case, specifying "--kill-busy-commands=Query,Execute" will also kill the prepared stamente execution.
Kill matching queries.
This option makes pt-kill kill matching queries. This requires MySQL 5.0 or newer. Unlike "--kill" which kills the connection for matching queries, this option only kills the query, not its connection.
Print a KILL statement for matching queries; does not actually kill queries.
If you just want to see which queries match and would be killed without actually killing them, specify "--print". To both kill and print matching queries, specify both "--kill" and "--print".
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. If password contains commas they must be escaped with a backslash: "exam\,ple"
dsn: port; copy: yes
Port number to use for connection.
dsn: mysql_socket; copy: yes
Socket file to use for connection.
dsn: user; copy: yes
User for login if not current user.
Table to log actions in, if passed through --log-dsn.
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.
You need Perl, DBI, DBD::mysql, and some core packages that ought to be installed in any reasonably new version of Perl.
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:
If possible, include debugging output by running the tool with "PTDEBUG"; see "ENVIRONMENT".
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.
Baron Schwartz and Daniel Nichter
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.
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.
pt-kill 3.2.1
Hey! The above document had some coding errors, which are explained below:
| 2020-08-30 | perl v5.30.3 |