In a recent post from Learncomputer.com, there's a comparison of two PHP profilers - the PHP Quick Profiler and the one included in Xdebug.

Whether you are an experienced developer or just getting started it is important to know how to measure the performance of your scripts and applications so that you can learn to make improvements and optimizations to your code. [...] This article compares two of the most popular [profiling] solutions under free license that you can begin using today to profile your PHP applications.

They describe each of the tools - the Quick PHP Profiler acting more like a plugin (running on each page load) and Xdebug working more behind the scenes and providing cachegrind files. These files can be viewed in cachegrind tools to drill in to the badly performing aspects of your applications and find the issues.

If you need a free tool it can be difficult to find a PHP profiling tool that has all of the features you may want and the interface that you like all rolled into one. Identifying what kind of data you are looking for and what information you need from a profiling tool will allow you to choose the best solution for your needs.

Ruslan Yakushev has posted some quick instructions on how to get Xdebug, the popular PHP debugger, enabled in the recently released WebMatrix tool from Microsoft.

When WebMatrix is used to build or modify a PHP-based web application the debugging tasks can be greatly simplified if Xdebug extension is used. This post explains how to install and use Xdebug extension with WebMatrix.

It's a simple six-step process (complete with screenshots) that shows you how to enable it in your php.ini, test that it's working with a simple buggy script and configure both the location to the correct DLL file and an output directory to create cachegrind files.

In a new post to the jfoobar blog today Wilco Jansen looks at two methods of profiling available to Joomla CMS users to help get the most performance out of your PHP applications - one onside Joomla and the other using XDebug.

In this article I want to explain the basics of profiling and profiling tools available in Joomla and PHP. In follow up articles I will explain the usage of the tools presented in this blog. I will also try to set up a performance analyses so we can see what the state of Joomla 1.6 is, but that is also for later concern. This article is based on tools that are freely available for almost all platforms.

The post is pretty quick and is more of an exposure to the two technologies than a detailed guide. Enabling the Joomla profiling is just a matter of turning on the "Debug System" command in the "Global Configuration" panel to add additional data to the logs. On the PHP side (at a lower level) you can get even more detail with XDebug including the output of a cachegrind file that can be tool through a tool for better visualization (like KCacheGrind or Webgrind).

Douglas Clifton has the next part of his "PHP Specificity" series posted today - a brief look at debugging in PHP applications.

In this fourth installment of the PHP Specificity series I'm going to break from the theme of content management packages momentarily and get into a topic that is not so dear to the programmer's heart. Debugging is a necessary evil and can be painful at times. But the reward, when it happens, is that eureka moment when you find the bug and squash it.

He mentions two helpful tools - DBG (though dead?) and the very popular XDebug that includes a profiler with Cachegrind output.

Douglas Clifton has a quick new post to his blog looking at an invaluable tool in application development (and not just in PHP) - cachegrind output.

Valgrind is a entire suite of open-source tools, including basic debugging, profiling, and more advanced techniques such as threading, memory management, and leak detection. For the purposes of this article, I will focus on Cachegrind, and in particular within the domain of Web applications. Although there are a number of developers contributing to Valgrind, Julian Seward is the original designer and author.

He talks about the cachegrind software and the PHP-based profiler that can create these files - XDebug. He also includes a list of a few of the cachegrind viewers including KCachegrind and Webgrind.

In this new post on the Zend Developer Zone Richard Thomas points out a way he's creates to mimic the cachgrind software that parses XDebug profile output.

Cachegrind provides a nice graphical display of your profiling information but I run Mac OSX [...] What I needed was a way to replicate the old Xdebug 1.x functionality. From this the idea of "PHPGrind" was born. Right now its just a proof of concept but I am hoping with some more understanding of the cachegrind format I can make it into something as useful as the graphical versions.

His application grabs the cachegrind file and processes through it to pull out the events, version information and the target profiled and outputs them in a simple loop at end.

Commentors on the post also suggest Webgrind and MacallGrind.

Andreas Gohr has a new blog post today that talks about a way to really get to know your code better - use XDebug to see it from the inside out.

Xdebug is a PHP extension which helps you to understand, debug and profile PHP. It can help you to find bottlenecks or give you an quick overview what happens in code you aren't familiar with, yet.

The post gives a brief overview of the installation of the extension (building a shared module) and shows how to get started with profiling an application. He talks about the cachegrind tool you can use to parse the results and the kcachegrind app that will make the results a bit more visual.

As a bonus, he also throws in a bit about function tracing - picking out each small bit of functionality in the code (the function/methods) and gathering stats for each.

The xml.it blog passes on a quick tip for something that was exactly what they were looking for:

We were looking for a simple open-source PHP profiler, without any fancy IDEs like Zend bundled together. After a little search, we found one: Xdebug, debugger and profiler tool for PHP.

XDebug is "extension helps you debugging your script by providing a lot of valuable debug information. The debug information that Xdebug can provide includes the following: stack traces, memory allocation and protection for infinite recursions".

The xml.it blog passes on a quick tip for something that was exactly what they were looking for:

We were looking for a simple open-source PHP profiler, without any fancy IDEs like Zend bundled together. After a little search, we found one: Xdebug, debugger and profiler tool for PHP.

XDebug is "extension helps you debugging your script by providing a lot of valuable debug information. The debug information that Xdebug can provide includes the following: stack traces, memory allocation and protection for infinite recursions".