Caching is vital if Wikimedia servers are to avoid being overloaded. The data shows, however, that the deployment of 1.19 caused a sharp, hopefully temporary drop in the percentage of requests handled by the parser cache (the green line).
Over a period of several hours spread across 29 February and 1 March, MediaWiki 1.19 went live to all remaining Wikimedia wikis including the English Wikipedia. Although a number of problems were reported, the deployment as a whole only had to be reverted on the handful of wikis, such as Serbian and Chinese, which rely on the MediaWiki software to provide the same content in two scripts automatically (wikitech-l mailing list). As of time of writing, zhwikis and srwiki are still awaiting the fix that would allow the deployment to proceed.[update 1]
Perhaps more worryingly, the jump in the amount of traffic handled by 1.19 from approximately 10% of total traffic to a figure approaching 100% does appear to have put a significant strain on the Wikimedia servers. Specifically, system administrators have noted a sharp decline (pictured right) in the parser cache hit rate – the percentage of requests for web pages that could be handled without a need for further processing – around the time of the 1.19 deployments. System administrators will be hoping that the effect is only temporary; although its appearance is not yet fully understood, the latest data does indicate that the rate is slowly retreating back to its previous average.
In addition to working on the bug reports that flood in after virtually all large deployments (of which some 23 are currently marked as requiring a fix before 1.19 is released to external sites), developers have also been looking afresh at the issue of changing the default diff colouring (first covered in the Signpostback in December). MediaWiki 1.19 had headlined with accessibility improvements in this area, the benefits of which seemed to have ensured that the change survived a series of long discussions when it was first proposed. On the change's final deployment, however, observers noted that decreases in the contrast ratio offset the improvement for colour-blind users, forcing the change to be reverted (wikitech-l mailing list). A third design is now being trialled; nevertheless, the bold blue-and-yellow-bordered design is almost certain to provoke a fresh round of discussions which it will have to survive if it is to make it onto Wikimedia wikis.
^Shortly after publication, the deployment of a temporary fix allowed the Chinese and Serbian Wikipedias to be updated to 1.19.
§Git switchover delayed; schedule for rest of month established
Lack of server capacity was among the reasons given by WMF director Rob Lanphier this week as he explained why the Git switchover had to be postponed.
The Git switchover, which had been been scheduled for March 3, has been postponed until March 21 (wikitech-l mailing list). Announcing the decision on behalf of the Foundation, WMF director of platform engineering Rob Lanphier cited a number of factors, including the unexpected scale of the difficulties resulting from the 1.19 deployment, along with software and hardware issues that would take time to resolve. Perhaps more worryingly, there also seem to be signs that a new code review backlog (the bane of the WMF deployment team's life over the past two years) is starting to build, and that too will need to be resolved before the Git switchover if all the revisions made are to be brought across.
The delay establishes a preliminary schedule for the rest of the month, to include heavy doses of code review, resolution of the hardware and software issues holding back the switchover, a MediaWiki 1.19 release candidate, the full MediaWiki 1.19.0 release, and possibly (if resources permit) a further "mini" deployment to Wikimedia wikis of the sort which will become increasingly common after the Git switchover. Lanphier, however, was clear that the successful Git switchover remained the key objective. "Anything that distracts from that (like, for instance, a [further Wikimedia] deploy) may get postponed while we finish this off once and for all". As of time of writing, Git repositories covering core code and WMF-deployed extensions are currently in a preparatory "read-only" mode, with write-actions for the existing Subversion repository being automatically fed into them (wikitech-l mailing list).
An example of an OpenStreetMap map of the kind now in use on social networking site Foursquare
Not all fixes may have gone live to WMF sites at the time of writing; some may not be scheduled to go live for many weeks.
Data wiki one step closer: developer and former Google Summer of Code competitor Jeroen De Dauw blogged this week to confirm that he had begun work on Wikimedia Deutschland's Wikidata project. The project, which aims to ease the creation of a central interwiki and factual data repository, was described by De Dauw as "the most fundamental change Wikipedia will have seen since its inception"; certainly, it was the focus of a proposal as early as 2004. Wikimedia Deutschland outlined their intention to take on the project, which De Dauw reports he "can’t wait to get started on", in October last year (Signpost coverage). A concrete timetable for the first phase of the project (an interwiki link hub) has not yet been published.
New WMF Mobile UI/UX contractor starts: Lindsey Smith started this week as the Foundation's new Mobile User Interface (UI) and User Experience (UX) contractor, helping developers to "flush out the look, feel, and experience across all of our mobile projects". Announcing Smith's arrival on various mailing lists, Director of Mobile and Special Projects Tomasz Finc suggested that Smith's early contribution would include design advice for a "new navigational system" for the mobile platform, as well as supporting the long-awaited image upload facility.
Swift thumbnail changes reversed (again): The latest switchover of Wikimedia's file thumbnail handling backend to Swift was reverted on February 29. The rollback is the latest action to be taken following the continuance of thumbnail generation problems. It is not known when Swift will finally replace the existing structure once and for all; proponents argue that it will need to be soon if Wikimedia wikis are to continue to provide images in a resource-efficient and scalable manner.
Bugzilla debate: Developer John Du Hart sparked a long discussion on the wikitech-l mailing list again by announcing that he would be trying various bug management suites to gauge whether any were superior to Bugzilla, which Wikimedia and MediaWiki have used since August 2004. This is not the first time that the question has been raised – few would argue that Bugzilla is in any respect ideal – but historically switching costs, concerns about using proprietary software and a "better the devil you know" consideration have resulted in the status quo being retained. No decision has yet been reached about which, if any, alternatives were worth trying out.
OpenStreetMap takes Foursquare: Although not directly related to Wikimedia, quite a number of Wikimedians and developers have recently been following progress with open source mapping project OpenStreetMap (OSM), which this week became the mapping service of choice for location-based social networking website Foursquare. The site is the latest in a line of large websites to move away from the proprietary Google Maps service after it started charging larger websites to include its mapping content; transferees have also been keen to cite OSM's ideological appeal as an open source provider. The gratis and libre vector maps project, with which many Wikimedians feel a natural affinity, will celebrate its eighth birthday in June.