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ps-top

ps-top - a top-like program for MySQL

ps-top is a program which collects information from MySQL 5.6+'s performance_schema database and uses this information to display server load in real-time. Data is shown by table or filename and the metrics also show how this is split between select, insert, update or delete activity. User activity is now shown showing the number of different hosts that connect with the same username and the activity of those users. There are also statistics on mutex and sql stage timings.

Installation

Install each binary by doing: $ go install github.com/sjmudd/ps-top@latest

Check the version of go you are using as older versions of GO may not work.

The sources will be downloaded together with the dependencies and the binary will be built and installed into $GOPATH/bin/. If this path is in your PATH setting then the program can be run directly without having to specify any specific path.

Configuration

Sometimes you may want to combine different tables together and show the combined output. A typical example might be if you have lots of similarly named tables. Should you want to do this you can use the following configuration file ~/.pstoprc to hole the configuration information:

[munge]
<regexp_match> = <replacement_string>
_[0-9]{8}$ = _YYYYMMDD
_[0-9]{6}$ = _YYYYMM

MySQL Access

Access to MySQL can be made by one of the following methods:

The user if not specified will default to the contents of $USER. The port if not specified will default to 3306.

An example setting could be to use TLS which is not fully supported at the moment with command line parameters:

$ export MYSQL_DSN='user:pass@tcp(host:3306)/performance_schema?tls=skip-verify&allowCleartextPasswords=1'
$ ps-top

MySQL/MariaDB configuration

The performance_schema database MUST be enabled for ps-top to work. By default on MySQL this is enabled, but on MariaDB >= 10.0.12 it is disabled. So please check your settings. Simply configure in /etc/my.cnf:

performance_schema = 1

If you change this setting you'll need to restart MariaDB for it to take effect.

Grants

ps-top needs SELECT grants to access performance_schema tables. They will not run if access to the required tables is not available.

setup_instruments: To view mutex_latency or stages_latency ps-top will try to change the configuration if needed and if you have grants to do this. If the server is --read-only or you do not have sufficient grants to change these tables these views may be empty. Pior to stopping ps-top will restore the setup_instruments configuration back to its original settings if it had successfully updated the table when starting up.

Views

ps-top can show 7 different views of data, the views are updated every second by default. The views are named:

You can change the polling interval and switch between modes (see below).

[1] See Grants above. These views may appear empty if setup_instruments is not configured correctly.

Keys

When in ps-top mode the following keys allow you to navigate around the different ps-top displays or to change it's behaviour.

See also

See also:

Incompatible Changes

As of v1.0.7 ps-stats has been removed. I never used it and it is simpler to remove unused functionality.

As of v0.5.0 the original utility was renamed from pstop which could work in stdout or top mode into two utilities named ps-top and ps-stats. This change of name was triggered to avoid the name conflict with the Oracle command pstop(1). See https://docs.oracle.com/cd/E19683-01/816-0210/6m6nb7mii/index.html. While the two commands are not related it was felt better to avoid the name overload, and while ps-top is reasonably young this change should not yet cause too much trouble.

Contributing

This program was started as a simple project to allow me to learn go, which I'd been following for a while, but hadn't used in earnest. This probably shows in the code so suggestions on improvement are most welcome.

Licensing

BSD 2-Clause License

Feedback

Feedback and patches welcome. I am especially interested in hearing from you if you are using ps-top, or if you have ideas of how I can better use other information from the performance_schema tables to provide a more complete vision of what MySQL is doing or where it's busy. The tool has been used by myself and colleagues and helped quickly identify bottlenecks and problems in several systems.

Simon J Mudd sjmudd@pobox.com

Code Documenton

godoc.org/github.com/sjmudd/ps-top