pt-pmpp - Online in the Cloud

PROGRAM:

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

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

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.

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.

OPTIONS

--binary
short form: -b; type: string; default: mysqld

Which binary to trace.

--help
Show help and exit.

--interval
short form: -s; type: int; default: 0

Number of seconds to sleep between "--iterations".

--iterations
short form: -i; type: int; default: 1

How many traces to gather and aggregate.

--lines
short form: -l; type: int; default: 0

Aggregate only first specified number of many functions; 0=infinity.

--pid
short form: -p; type: int

Process ID of the process to trace; overrides "--binary".

--save-samples
short form: -k; type: string

Keep the raw traces in this file after aggregation.

--version
Show version and exit.

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.

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