PT-KILL(1p) User Contributed Perl Documentation PT-KILL(1p)
NAME
pt-kill - Kill MySQL queries that match certain criteria.
SYNOPSIS
Usage: pt-kill [OPTIONS]
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
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-kill kills queries if you use the "--kill" option, so it can disrupt your database's users, of course. You should test with the
<"--print"> option, which is safe, if you're unsure what the tool will do.
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-kill <http://www.percona.com/bugs/pt-
kill>.
See also "BUGS" for more information on filing bugs and getting help.
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.
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.
--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.
--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.
--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.
--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.
--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".
--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.
--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.
--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)".
See also "GROUP, MATCH AND KILL".
--busy-time
type: time; group: Query Matches
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.
--idle-time
type: time; group: Query Matches
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-command
type: string; group: Query Matches
Ignore queries whose Command matches this Perl regex.
See "--match-command".
--ignore-db
type: string; group: Query Matches
Ignore queries whose db (database) matches this Perl regex.
See "--match-db".
--ignore-host
type: string; group: Query Matches
Ignore queries whose Host matches this Perl regex.
See "--match-host".
--ignore-info
type: string; group: Query Matches
Ignore queries whose Info (query) matches this Perl regex.
See "--match-info".
--[no]ignore-self
default: yes; group: Query Matches
Don't kill pt-kill's own connection.
--ignore-state
type: string; group: Query Matches; default: Locked
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-user
type: string; group: Query Matches
Ignore queries whose user matches this Perl regex.
See "--match-user".
--match-all
group: Query Matches
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-command
type: string; group: Query Matches
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 <http://dev.mysql.com/doc/refman/5.1/en/thread-commands.html> for a
full list and description of Command values.
--match-db
type: string; group: Query Matches
Match only queries whose db (database) matches this Perl regex.
--match-host
type: string; group: Query Matches
Match only queries whose Host matches this Perl regex.
The Host value often time includes the port like "host:port".
--match-info
type: string; group: Query Matches
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-state
type: string; group: Query Matches
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 <http://dev.mysql.com/doc/refman/5.1/en/general-thread-
states.html> for a full list and description of State values.
--match-user
type: string; group: Query Matches
Match only queries whose User matches this Perl regex.
--replication-threads
group: Query Matches
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.
--test-matching
type: array; group: Query Matches
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".
CLASS MATCHES
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".
--any-busy-time
type: time; group: Class Matches
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.
--each-busy-time
type: time; group: Class Matches
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".
--query-count
type: int; group: Class Matches
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.
--verbose
short form: -v
Print information to STDOUT about what is being done.
ACTIONS
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-command
type: string; group: Actions
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
group: Actions
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".
--kill-query
group: Actions
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
group: Actions
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".
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.
o A
dsn: charset; copy: yes
Default character set.
o D
dsn: database; copy: yes
Default database.
o F
dsn: mysql_read_default_file; copy: yes
Only read default options from the given file
o h
dsn: host; copy: yes
Connect to host.
o p
dsn: password; copy: yes
Password to use when connecting.
o P
dsn: port; copy: yes
Port number to use for connection.
o S
dsn: mysql_socket; copy: yes
Socket file to use for connection.
o u
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-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 <http://www.percona.com/bugs/pt-kill>.
Please report bugs at https://bugs.launchpad.net/percona-toolkit <https://bugs.launchpad.net/percona-toolkit>. Include the following
information in your bug report:
o Complete command-line used to run the tool
o Tool "--version"
o MySQL version of all servers involved
o Output from the tool including STDERR
o 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/ <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 developed by Percona for MySQL support and consulting.
Percona Toolkit was forked from two projects in June, 2011: Maatkit and Aspersa. Those projects were created by Baron Schwartz and
developed primarily by him and Daniel Nichter, both of whom are employed by Percona. Visit <http://www.percona.com/software/> for more
software developed by Percona.
COPYRIGHT, LICENSE, AND WARRANTY
This program is copyright 2009-2011 Baron Schwartz, 2011-2012 Percona Inc. Feedback and improvements are welcome.
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 2.1.2
perl v5.14.2 2012-06-15 PT-KILL(1p)