The Signpost

Technology report

Optimism over LastModified and MoodBar, but change in clock time causes downtime

LastModified trial results are in

The "page last modified" display with the LastModified extension disabled...
...and with the extension enabled.

The results from last month's trial of the LastModified extension were published this week on the Wikimedia blog. The first analyses have indicated a significant positive impact, suggesting that the extension – which makes the time since a page's last edit much more prominent in the interface – could eventually find its way onto Wikimedia wikis.

This more prominent display (see right) was added to some 20,000 English Wikipedia articles, linking directly to the full revision history. The results of this trial were nevertheless surprising: rather than click on the new timestamp, visitors preferred to click directly on the history tab, indicating salience of its location. "The increase was particularly strong for anonymous editors and readers, who landed on the history page more than twice as often (+120.6%) [as the control sample]", explained Steven Walling, on behalf of the Foundation's editor engagement experiments (E3) team. "For registered users, there was a smaller but still significant increase in article history views (+42%). This result was seen even when we controlled for repeat clicks on either link".

Despite this apparently positive result, Foundation developers (perhaps feeling the effect of recent controversies) seem wary of pushing the extension onto communities for the moment. Anonymised data has been released, but thereafter the E3 team will simply move onto new experiments – such as "transforming this timestamp into a more direct call to edit articles that are severely outdated, though clearly the point at which an article becomes out of date is somewhat subjective" – rather than handing over the extension to a deployment focused team.

Also published this week was an extensive analysis of the impact of the already-deployed MoodBar extension. That research, also suggestive of a broadly positive impact, is expected to be followed up with a further study to eliminate the possibility of selection bias.

Leap second causes problems

American website Time.gov correctly identifies the passage of the 61st second of the 60th minute of the 24th hour of June 30.

"At midnight UTC on July 1, Wikimedia’s search cluster stopped working" (Wikimedia blog). The proximal cause was surprising: the insertion of a single leap second, so that June 30 officially had 86,401 seconds rather than the usual 86,400. This caused significant problems, not just on Wikimedia wikis but across the web, affecting sites such as Reddit, Foursquare and LinkedIn. Wikimedia's search services were restored in slightly less than two hours.

As Lead Platform Architect Tim Starling explained, "leap seconds are added to our clocks once every few years so that the sun will be directly overhead of the Royal Observatory in Greenwich at precisely 12:00. Some people believe that the desire to keep these two time standards synchronised is anachronistic, and that it would be better to let them drift apart for 600 years and then add a single “leap hour”. I’m sure many computer engineers would breathe a sigh of relief if such a change were implemented."

A knock on, more general problem was finally resolved on July 2 following technical work by the WMF's network operations team (wikitech-l mailing list). Given that those problems seem to have affected the Foundation's servers hosted only in Tampa, Florida (and not their Ashburn, Virginia counterparts), the implication is that ageing hardware that is expensive to replace could have exacerbated the problem. The Signpost hopes to publish an interview with a member of the operations team about this and other recent issues in the near future.

In brief

Signpost poll
HTML5
You can now give your opinion on next week's poll: Which of these best sums up your view about the recent performance of Wikimedia wikis? Last week's poll result has also been slightly corrected.

Not all fixes may have gone live to WMF sites at the time of writing; some may not be scheduled to go live for several weeks.


















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