Manual:Profiling

To get more detail, you need to enable profiling. Profiling tracks code execution during a page action and reports back the percentage of total code execution that was spent in any specific function. The generated profile only includes functions that have specifically been marked to be profiled. Note that you have to set $wgDebugLogFile in LocalSettings; this is the file, to which your profiling data will be appended.

MediaWiki version:

≥ 1.18

If you are not using profiling, but have a StartProfiler.php file in the MediaWiki root folder, you may receive errors referring to /includes/Profiler.php. Deleting, or renaming, the StartProfiler.php file will resolve this error. The StartProfiler.sample file, also in the MediaWiki root folder, can serve as a template should you enable profiling in the future.

MediaWiki version:

≥ 1.8

To enable profiling, you need to modify the StartProfiler.php (see StartProfiler.sample in the MediaWiki root folder for an example). By default the file includes a ProfilerStub which just dumps profiling information. To instead direct this information to a file, edit StartProfiler.php so that it looks like this:

$wgProfiler['class'] = 'Profiler';

Then you can customize profiling options in LocalSettings.php (not StartProfiler.php; be sure to edit beneath the requirement of DefaultSettings.php).

Common configuration (both <1.7 and >1.8):

// Only record profiling info for pages that took longer than this
$wgProfileLimit = 0.0;
// Don't put non-profiling info into log file
$wgProfileOnly = false;
// Log sums from profiling into "profiling" table in db
$wgProfileToDatabase = false;
// If true, print a raw call tree instead of per-function report
$wgProfileCallTree = false;
// Should application server host be put into profiling table
$wgProfilePerHost = false;
 
// Settings for UDP profiler
$wgUDPProfilerHost = '127.0.0.1';
$wgUDPProfilerPort = '3811';
 
// Detects non-matching wfProfileIn/wfProfileOut calls
$wgDebugProfiling = false;
// Output debug message on every wfProfileIn/wfProfileOut
$wgDebugFunctionEntry = 0;
// Lots of debugging output from SquidUpdate.php
$wgDebugSquid = false;

MediaWiki version:

≤ 1.7

In MediaWiki 1.7 and earlier, instead of editing StartProfiler.php, you have to set $wgProfiling to true. This will generate basic page timing information in the file defined by $wgDebugLogFile.

In addition to the settings list above, these additional settings are available:

// Enable for more detailed by-function times in debug log
$wgProfiling  = true;
// Only profile every n requests when profiling is turned on
$wgProfileSampleRate = 1;
// If not empty, specifies profiler type to load
$wgProfilerType = '';

Advanced profiling

Once you have enabled profiling, you can trace code execution through any function that you want to investigate as a bottleneck by wrapping the function with the following code:

function doSomething() {
    wfProfileIn( __METHOD__ ); # You can replace __METHOD__ with any string. This will appear in the profile.
    
    # The actual function

    wfProfileOut( __METHOD__ );
}

After you've added this information, browse to a page in the wiki. This will generate profiling info in the log file you defined above. Change $wgProfileCallTree in LocalSettings.php to true or false for different display formats.

Logging to Database

To log profiling information to a database, set $wgProfileToDatabase = true; in LocalSettings.php. Then either run update.php (since 1.21) and the profiling table will be added or manually apply the file maintenance/archives/patch-profiling.sql (the recommended way to do this is php maintenance/patchSql.php profiling).

$wgProfileCallTree must be set to false.

Viewing Profile Info

If you log your profiling information to the database, you can view the information in a webpage by browsing to profileinfo.php. You must also set $wgEnableProfileInfo = true; in LocalSettings.php (AdminSettings.php for MediaWiki < 1.16). Then, after gathering data by browsing wiki pages, visit profileinfo.php to see how much time your profiled code is using and how many times it's being called.

To view profiling information as HTML comments appended to the bottom of a page, just add ?forceprofile=true to the URL. This feature is not in the standard product, you can enable it by adding this to StartProfiler.php:

if ( array_key_exists( 'forceprofile', $_REQUEST ) ) {
    $wgProfiler['class'] = 'ProfilerSimpleText';
} elseif ( array_key_exists( 'forcetrace', $_REQUEST ) ) {
    $wgProfiler['class'] = 'ProfilerSimpleTrace';
}

See also

• Manual:Performance tuning
• Manual:How to debug

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