pt-pmp - Aggregate GDB stack traces for a selected program.
pt-pmp [OPTIONS] [FILES]
pt-pmp is a poor man’s profiler, inspired by http://poormansprofiler.org. It can create and summarize full stack traces of processes on Linux. Summaries of stack traces can be an invaluable tool for diagnosing what a process is waiting for.
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
pt-pmp performs two tasks: it gets a stack trace, and it summarizes the stack trace. If a file is given on the command line, the tool skips the first step and just aggregates the file.
To summarize the stack trace, the tool extracts the function name (symbol) from each level of the stack, and combines them with commas. It does this for each thread in the output. Afterwards, it sorts similar threads together and counts how many of each one there are, then sorts them most-frequent first.
pt-pmp is a read-only tool. However, collecting GDB stacktraces is achieved by attaching GDB to the program and printing stack traces from all threads. This will freeze the program for some period of time, ranging from a second or so to much longer on very busy systems with a lot of memory and many threads in the program. In the tool’s default usage as a MySQL profiling tool, this means that MySQL will be unresponsive while the tool runs, although if you are using the tool to diagnose an unresponsive server, there is really no reason not to do this. In addition to freezing the server, there is also some risk of the server crashing or performing badly after GDB detaches from it.
short form: -b; type: string; default: mysqld
Which binary to trace.
Show help and exit.
short form: -i; type: int; default: 1
How many traces to gather and aggregate.
short form: -l; type: int; default: 0
Aggregate only first specified number of many functions; 0=infinity.
short form: -k; type: string
Keep the raw traces in this file after aggregation.
Show version and exit.
This tool does not use any environment variables.
This tool requires Bash v3 or newer. If no backtrace files are given, then gdb is also required to create backtraces for the process specified on the command line.
For a list of known bugs, see https://jira.percona.com/projects/PT/issues.
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
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
Using <PTDEBUG> might expose passwords. When debug is enabled, all command line parameters are shown in the output.
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:
TOOL with the name of any tool.
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 2011-2021 Percona LLC and/or its affiliates, 2010-2011 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.