pt-pmp

NAME

pt-pmp - Aggregate GDB stack traces for a selected program.

SYNOPSIS

Usage

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.

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-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.

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-pmp.

See also “BUGS” for more information on filing bugs and getting help.

DESCRIPTION

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.

OPTIONS

Options must precede files on the command line.

-b BINARY Which binary to trace (default mysqld)
-i ITERATIONS How many traces to gather and aggregate (default 1)
-k KEEPFILE Keep the raw traces in this file after aggregation
-l NUMBER Aggregate only first NUMBER functions; 0=infinity (default 0)
-p PID Process ID of the process to trace; overrides -b
-s SLEEPTIME Number of seconds to sleep between iterations (default 0)

ENVIRONMENT

This tool does not use any environment variables.

SYSTEM REQUIREMENTS

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.

BUGS

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

Please report bugs at https://bugs.launchpad.net/percona-toolkit. 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, based on a script by Domas Mituzas (http://poormansprofiler.org/)

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.

VERSION

pt-pmp 2.1.9

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