MediaWiki extensions manual
Release status: stable
Implementation Ajax
Description Logs perceived latency measurements from client-side
Author(s) Patrick Reilly, Ori Livneh, Asher Feldman, Timo Tijhof, Ian Marlier
Compatibility policy Snapshots releases along with MediaWiki. Master is not backward compatible.
MediaWiki >= 1.42
Database changes No
License GNU General Public License 2.0 or later
  • $wgNavigationTimingSamplingFactor
  • $wgNavigationTimingCpuBenchmarkSamplingFactor
Quarterly downloads 4 (Ranked 141st)
Public wikis using 846 (Ranked 308th)
Translate the NavigationTiming extension if it is available at translatewiki.net
Issues Open tasks · Report a bug

The NavigationTiming extension measures perceived latency in browsers. The extension is named after the W3C Navigation Timing API in web browsers, but today collects metrics from several different browser APIs.

FAQ edit

Scope edit

The extension collects anonimised information from a sample of page views. The collection uses JavaScript and thus is limited to pageviews that:

  1. are from a modern browser, as defined by the Grade A capability check (90%+ of traffic).
  2. have the Navigation Timing API, (98% of browser traffic in 2022, 95% in Nov 2017[1])
  3. reach the "page loaded" event (99%+ of page loads).
  4. are in the random sample (configurable).

How is the information used? edit

Infrastructure for navtiming at WMF.

Engineers at Wikimedia Foundation intend to use this data to assess the impact (positive and negative) of changes to application code and server configuration. Thus guiding on-going work on site performance.

Dependencies edit

Installation edit

  • Download and move the extracted NavigationTiming folder to your extensions/ directory.
    Developers and code contributors should install the extension from Git instead, using:cd extensions/
    git clone https://gerrit.wikimedia.org/r/mediawiki/extensions/NavigationTiming
  • Add the following code at the bottom of your LocalSettings.php file:
    wfLoadExtension( 'NavigationTiming' );
    $wgNavigationTimingSamplingFactor = 1;  // 100% (1 of every 1)
  •   Done – Navigate to Special:Version on your wiki to verify that the extension is successfully installed.

Oversampling edit

Oversampling allows us to selectively sample a larger portion of the traffic coming from a particular geography, or with a specific User Agent string in the browser.

Use cases for this include:

  • obtain detailed observations of a change in performance, based data center location
  • evaluate a change in performance due to browser upgrades (e.g. upstream Firefox 57 released an internal change intended to improve performance).

Oversampling is configured using the $wgNavigationTimingOversampleFactor variable. This variable is an associative array, and the keys that are checked are "geo" and "userAgent".

If the user's country code is included in the "geo" array, then a sample is taken with frequency 1/samplerate. If the user's browser has a User Agent string that matches a key in the userAgent array, then a sample is taken with frequency 1/samplerate. No more than one oversample is taken for a given pageload.

If the page load is oversampled, the emitted event will include these properties:

  • isOversample: true
  • oversampleReason: string, whose contents are a JSON array of reasons that the oversample happened. These will be of the form "geo:XX" (where XX is the matching country code), or "ua:ABCDEF" (where ABCDEF is the matching browser's User Agent string)

Further reading edit

About the data we collect:

About the Navigation Timing API in web browsers:

Code stewardship edit

Footnotes edit