Flamboyant Flamegraphs
In this article, I am showing you how to make a flamegraph, a new feature in Xdebug 3.3.
Flamegraphs are an interesting way of showing where an application spends a lot of time.
To show you the functionality, I will be using Xdebug’s own website, which I run locally at port 9874.
First of all, we need to configure Xdebug to make our flamegraphs. We do that in a configuration file. With php --ini I find out which file to use:
Configuration File (php.ini) Path: /usr/local/php/8.2dev/lib Loaded Configuration File: /usr/local/php/8.2dev/lib/php.ini Scan for additional .ini files in: /usr/local/php/8.2dev/lib/conf.d Additional .ini files parsed: /usr/local/php/8.2dev/lib/conf.d/20-mongodb.ini, /usr/local/php/8.2dev/lib/conf.d/zzz-xdebug.ini
If you are running Apache or Nginx, I would suggest you use phpinfo() output in the browser to find the same information instead.
I have a specific Xdebug INI file called zzz-xdebug.ini. Its contents are currently:
zend_extension=xdebug.so xdebug.mode=develop,debug
Flamegraphs are part of Xdebug’s tracing functionality, which we need to enable by changing the xdebug.mode line to:
xdebug.mode=develop,debug,trace
The tracing functionality supports multiple formats. The flamegraph is number three, so we need to set that as well by adding:
xdebug.trace_format=3
By default, Xdebug Tracer will put files into the /tmp directory, and use a hash of the current working directory to create a trace file name. We want distinct flamegraphs for each URL, so we need to change that by setting:
xdebug.trace_output_name=xdebug.%R
We start all files with trace., and then we use %R to configure to use the URI. Xdebug also supports many other formatting specifiers.
By default, all file names will also be postfixed by .xt.gz.
After making INI changes, you need to restart the web server.
To initiate the tracer, I use an Xdebug Helper browser extension available for Chrome, Firefox, and other browsers.
I click on the debug icon and then on trace:
After requesting the home page, and documentation page, Xdebug’s tracer created the following files in the /tmp directory:
derick@gargleblaster:~$ ls -l /tmp/trace.* -rw-r--r-- 1 derick derick 123 Sep 26 03:31 /tmp/trace..05d7ef.xt.gz -rw-r--r-- 1 derick derick 2560 Sep 25 16:55 /tmp/trace._core2_css.xt.gz -rw-r--r-- 1 derick derick 3550 Sep 25 16:55 /tmp/trace._docs_.xt.gz -rw-r--r-- 1 derick derick 2419 Sep 25 16:55 /tmp/trace._fonts_IBMPlexSans-RegularItalic-Latin1_woff2.xt.gz -rw-r--r-- 1 derick derick 2474 Sep 25 16:55 /tmp/trace._images_logos_11com7_svg.xt.gz -rw-r--r-- 1 derick derick 2507 Sep 25 16:55 /tmp/trace._images_logos_io_svg.xt.gz -rw-r--r-- 1 derick derick 2530 Sep 25 16:55 /tmp/trace._images_logos_private-packagist_svg.xt.gz -rw-r--r-- 1 derick derick 2455 Sep 25 16:55 /tmp/trace._images_logos_typo3_svg.xt.gz -rw-r--r-- 1 derick derick 2523 Sep 25 16:55 /tmp/trace._images_logos_xdebug-cloud_svg.xt.gz -rw-r--r-- 1 derick derick 6165 Sep 25 16:55 /tmp/trace._.xt.gz
Because we go through our PHP router process, there are also files for images and fonts.
The important ones are:
-rw-r--r-- 1 derick derick 3550 Sep 25 16:55 /tmp/trace._docs_.xt.gz -rw-r--r-- 1 derick derick 6165 Sep 25 16:55 /tmp/trace._.xt.gz
The contents of these files look like:
{main};require_once;require_once 3046
{main};require_once;ComposerAutoloaderInit7d176ec022516f68e20dcb88554529a8::getLoader;require 7043
{main};require_once;ComposerAutoloaderInit7d176ec022516f68e20dcb88554529a8::getLoader;spl_autoload_register 9408
{main};require_once;ComposerAutoloaderInit7d176ec022516f68e20dcb88554529a8::getLoader;ComposerAutoloaderInit7d176ec022516f68e20dcb88554529a8::loadClassLoader;require 3176
{main};require_once;ComposerAutoloaderInit7d176ec022516f68e20dcb88554529a8::getLoader;ComposerAutoloaderInit7d176ec022516f68e20dcb88554529a8::loadClassLoader 41368
{main};require_once;ComposerAutoloaderInit7d176ec022516f68e20dcb88554529a8::getLoader;dirname 6061
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