Artberri

WP XHProf Profiler plugin is an easy way to profile your plugins and themes when you are coding or debugging. To get it done it uses XHProf, a PHP profiler made by the Facebook Dev Team (you must install it before activating the plugin).
<h4>Usage</h4>
By default the profiling is disabled, activate <code>WP_DEBUG</code> on your <code>wp-config.php</code> to enable it. After doing it, all your wordpress pages will have a link at bottom with the profiling data.
<h4>¿What is XHProf?</h4>
From <a href="" title="From PHP documentation" rel="nofollow ugc">http://www.php.net/manual/en/intro.xhprof.php</a>
XHProf is a light-weight hierarchical and instrumentation based profiler. During the data collection phase, it keeps track of call counts and inclusive metrics for arcs in the dynamic callgraph of a program. It computes exclusive metrics in the reporting/post processing phase, such as wall (elapsed) time, CPU time and memory usage. A functions profile can be broken down by callers or callees. XHProf handles recursive functions by detecting cycles in the callgraph at data collection time itself and avoiding the cycles by giving unique depth qualified names for the recursive invocations.
XHProf includes a simple HTML based user interface (written in PHP). The browser based UI for viewing profiler results makes it easy to view results or to share results with peers. A callgraph image view is also supported.
XHProf reports can often be helpful in understanding the structure of the code being executed. The hierarchical nature of the reports can be used to determine, for example, what chain of calls led to a particular function getting called.
XHProf supports ability to compare two runs (a.k.a. “diff” reports) or aggregate data from multiple runs. Diff and aggregate reports, much like single run reports, offer “flat” as well as “hierarchical” views of the profile.
Additional documentation can be found via the xhprof website » [http://pecl.php.net/package/xhprof]
<h4>Support</h4>
Comments, questions, feature requests and bug reports are welcome: <a href="http://www.berriart.com/en/xhprof-profiler/" title="XHProf Profiler" rel="nofollow ugc">http://www.berriart.com/en/xhprof-profiler/</a>

WP XHProf Profiler

Adds PHP profiling support to your Wordpress using Facebook's XHProf Profiler.

Modern Tribe, Inc.

Jonathan Brinley

Peter Chester

You can use this plugin to manually log data or to capture logging on WordPress actions. You can capture load time, memory, backrace, data dumps, urls, and server IPs.
This is designed to either be managed using wp-config.php and logging OR using the admin and debugbar plugin ( https://wordpress.org/extend/plugins/debug-bar/ ). Most of the following documentation applies equally to the settings panel or the wp-config.php vars. Either one works fine. The only exception is the DEBUG_LOG configuration which is only supported as a wp-config var.
Firstly, you can manually log things using the following function:
<pre><code>do_action( 'log', $message, $group, $data );
</code></pre>
The $group allows you to selectively output logging based on groups of log messages. The $message is the string you want to see in the log. $data is an optional parameter for the data that you want to display in the log (objects, arrays, or any other sort of data really).
To render messages to the log, you must configure wp-config.php as follows:
Run debug on only these groups. Use ‘ALL’ to debug everything. The group ‘ACTIONS’ is reserved for WordPress actions.
<pre><code>define( 'DEBUG_GROUPS', 'ACTIONS,default,myspecialgroup' );
</code></pre>
Display these outputs in the log for each log message.
<pre><code>define( 'DEBUG_PARAMS', 'time,timedelta,memory,memorydelta,data,backtrace,url,server' );
</code></pre>
WordPress actions that you wish to log.
<pre><code>define( 'DEBUG_ACTIONS', 'wp_head,switch_theme,wp_footer' );
</code></pre>
Optional restriction by URL (useful on MU installs).
<pre><code>define( 'DEBUG_URLS', 'myurl.com' );
</code></pre>
Minimum time in milliseconds required to register a log entry as being slow. Default 0 for no minumum.
<pre><code>define( 'DEBUG_MIN_TIME', 500 );
</code></pre>
Minimum memory in killobytes required to register a log entry as being heavy. Default 0 for no minumum.
<pre><code>define( 'DEBUG_MIN_MEM', 1024 );
</code></pre>
Path to log file or set to TRUE to use php error log. Default FALSE for no logging.
<pre><code>define( 'DEBUG_LOG', '/path/to/writable/log/file' );
</code></pre>
or
<pre><code>define( 'DEBUG_LOG', TRUE );
</code></pre>
<h4>Todo</h4>
<ul>
<li>Add variable for sample rate so that this could run randomly on production installs</li>
<li>Admin panel per site</li>
<li>Admin panel globally</li>
<li>WordPress error logging</li>
<li>Mysql query logging</li>
<li>WP_Error integration</li>
<li>Alerts ex: if this takes more than this much memory then log it…</li>
</ul>

Debugger

You can use this plugin to manually log data or to capture logging on WordPress actions. You can capture load time, memory, backrace, data dumps, urls …

WP XHProf Profiler vs Debugger