Regarding the caching, we would need to agree between apps and web about the url and smaxage parameter as Adam noted so that the urls are *exactly* the same to not bloat varnish and reuse the same cached objects across platforms.
It is an extremely adhoc and brittle solution but seems like it would be the greatest win.
20% of the traffic from searches by being only in android and web beta seems a lot to me, and we should work on reducing it, otherwise when it hits web stable we're going to crush the servers, so caching seems the highest priority.
Let's chime in https://phabricator.wikimedia.org/T124216 and continue the cache discussion there.
Regarding the validity of results with opening text only, how should we proceed? Adam?
On Wed, Jan 20, 2016 at 9:34 PM, David Causse dcausse@wikimedia.org wrote:
Hi,
Yes we can combine many factors, from templates (quality but also disambiguation/stubs), size and others. Today cirrus uses mostly the number of incoming links which (imho) is not very good for morelike. On enwiki results will also be scored according the weights defined in https://en.wikipedia.org/wiki/MediaWiki:Cirrussearch-boost-templates.
I wrote a small bash to compare results : https://gist.github.com/nomoa/93c5097e3c3cb3b6ebad Here is some random results from the list (Semetimes better, sometimes worse) :
$ sh morelike.sh Revolution_Muslim Defaults "title": "Chess", "title": "Suicide attack", "title": "Zachary Adam Chesser", ======= Opening text no boost links "title": "Hungarian Revolution of 1956", "title": "Muslims for America", "title": "Salafist Front",
$ sh morelike.sh Chesser Defaults "title": "Chess", "title": "Edinburgh", "title": "Edinburgh Corn Exchange", ======= Opening text no boost links "title": "Dreghorn Barracks", "title": "Edinburgh Chess Club", "title": "Threipmuir Reservoir",
$ sh morelike.sh Time_%28disambiguation%29 Defaults "title": "Atlantis: The Lost Empire", "title": "Stargate", "title": "Stargate SG-1", ======= Opening text no boost links "title": "Father Time (disambiguation)", "title": "The Last Time", "title": "Time After Time",
Le 20/01/2016 19:34, Jon Robson a écrit :
I'm actually interested to see whether this yields better results in certain examples where the algorithm is lacking [1]. If it's done as an A/B test we could even measure things such as click throughs in the related article feature (whether they go up or not)
Out of interest is it also possible to take article size and type into account and not returning any morelike results for things like disambiguation pages and stubs?
[1] https://www.mediawiki.org/wiki/Topic:Swsjajvdll3pf8ya
On Wed, Jan 20, 2016 at 9:47 AM, Adam Baso abaso@wikimedia.org wrote:
One thing we could do regarding the quality of the output is check results against a random sample of popular articles (example approach to find some articles) on mdot Wikipedia. Presuming that improves the quality of the recommendations or at least does not degrade them, we should consider adding the enhancement task to a future sprint, with further instrumentation and A/B testing / timeboxed beta test, etc.
Joaquin, smaxage (e.g., 24 hour cached responses) does seem a good fix for now for further reduction of client perceived wait, at least for non-cold cache requests, even if we stop beating up the backend. Does anyone know of a compelling reason to not do that for the time being? The main thing that comes to mind as always is growing the Varnish cache object pool - probably not a huge deal while the thing is only in beta, but on the stable channel maybe noteworthy because it would run on probably most pages (but that's what edge caches are for, after all).
Erik, from your perspective does use of smaxage relieve the backend sufficiently?
If we do smaxage, then Web, Android, iOS should standardize their URLs so we get more cache hits at the edge across all clients. Here's the URL I see being used on the web today from mobile web beta:
https://en.m.wikipedia.org/w/api.php?action=query&format=json&format...
-Adam
On Wed, Jan 20, 2016 at 7:45 AM, Joaquin Oltra Hernandez jhernandez@wikimedia.org wrote:
I'd be up to it if we manage to cram it up in a following sprint and it is worth it.
We could run a controlled test against production with a long batch of articles and check median/percentiles response time with repeated runs and highlight the different results for human inspection regarding quality.
It's been noted previously that the results are far from ideal (which they are because it is just morelike), and I think it would be a great idea to change the endpoint to a specific one that is smarter and has some cache (we could do much more to get relevant results besides text similarity, take into account links, or see also links if there are, etc...).
As a note, in mobile web the related articles extension allows editors to specify articles to show in the section, which would avoid queries to cirrussearch if it was more used (once rolled into stable I guess).
I remember that the performance related task was closed as resolved (https://phabricator.wikimedia.org/T121254#1907192), should we reopen it or create a new one?
I'm not sure if we ended up adding the smaxage parameter (I think we didn't), should we? To me it seems a no-brainer that we should be caching this results in varnish since they don't need to be completely up to date for this use case.
On Tue, Jan 19, 2016 at 11:54 PM, Erik Bernhardson ebernhardson@wikimedia.org wrote:
Both mobile apps and web are using CirrusSearch's morelike: feature which is showing some performance issues on our end. We would like to make a performance optimization to it, but before we would prefer to run an A/B test to see if the results are still "about as good" as they are currently.
The optimization is basically: Currently more like this takes the entire article into account, we would like to change this to take only the opening text of an article into account. This should reduce the amount of work we have to do on the backend saving both server load and latency the user sees running the query.
This can be triggered by adding these two query parameters to the search api request that is being performed:
cirrusMltUseFields=yes&cirrusMltFields=opening_text
The API will give a warning that these parameters do not exist, but they are safe to ignore. Would any of you be willing to run this test? We would basically want to look at user perceived latency along with click through rates for the current default setup along with the restricted setup using only opening_text.
Erik B.
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