Automatic recomendations unstable

I think I saw a thread about the instability of Automatic Recommendations since Collections were rolled out, but I can't find it now. (Member recommendations is also a little unstable, but less so.)

The most visible part of the instability is that the number of "new" recommendations goes up and down a lot, and never seems to agree with itself between the member home page, the count in the "Show # new recommendations" link on the right-hand side of the recs page, and the number of items that come up when that link is clicked on. I just saw 0, 2, and 1, respectively.

A second problem is that "Show recommendations by date" doesn't sort the same way twice. This is probably closely related to the previous thing, since I went from one "NEW!" recommendation to three. Clicking the link again will shuffle the display order. Presumably, the order in which books found their way into my recommendations doesn't change, so why does the order in which sort-by-date dislpays?

The last symptom is less obvious, in part because this was happening a little before Collections came out -- but it used to happen under very specific (if hard to grasp) circumstances before. When I click on the "Why?" link for a recommendation, it displays "Recommendation based on:" but doesn't give the basis. Frankly, I'd like to know why the hell 501 Web Site Secrets: Unleash the Power of Google, Amazon, eBay and More showed up in my recommendations, but until the "Why?" link works, I'm not going to find out.

My homepage states the correct number of new automatic recommendations (2) but my recommendations page however hasn't deducted the (3) ignored ones (thus giving the number of 5).

My homepage gives me different numbers and titles of automatic recommendations every time it refreshes.

AnnaClaire's description of the problem is very clear, and seems to cover all the issues. If anyone would like to see what has already been said these are the previous threads:

http://www.librarything.com/topic/67228
http://www.librarything.com/topic/66844
http://www.librarything.com/topic/66480#1331080

I've fixed the instability and, I think, the non-jibing between home and recommendations.

It was basically too much re-calculation. Every time it recalculates it does some subtle random shuffling, stressing some of your books more than others, etc. This is a good thing, but too much of it and it looks, well, random. It now does this only when you haven't been on the site in a while (ie., your data has expired out of memory), or your number of (relevant) books has changed by more than 2.

The non-jibing seems to have been an instance of the recalculation. If it recalculated every time, they never jibbed by definition. But tell me if anyone sees a problem with it.

It seems stable for me now. The numbers match, and don't keep jiggling around. Thank you.

I think this may need to be relooked at.

The past couple of weeks, the numbers again don't match between the message on my home pg telling me how many new recommendations there are - vs. the actual count shown when I click on it.
e.g if I'm told I have 8 new recommendations, there's actually only 1 or 2 when I go to look.

I ran into a related situation this morning.

Yesterday I had 283 recommendations. This morning I awoke to 400+, yet I'm told there are only 4 new recommendations.

7>

Any chance that the recommendations you've previously said "No Thanks" to have reappeared?

No, they're all different. I spent a good chunk of yesterday getting my list of recommendations down from over 700 to the 283 that I mentioned. The new ones that appeared this morning were truly new.

Sorry about the numbers. It's juggling two different definitions of "new." I need to get to the bottom of it.

It's an interesting question, if I redo it:

What does new mean? Is it about being less than X days old, or about you not having clicked through to see the page?

Good question. For me, I'd like it to mean I haven't clicked through to the page. That's how the New label for Connections works, right? But either meaning is ok really.

Oh, if you're looking at it that way, I really wish pressing No Thanks didn't insert a rec at that point in the page later on. (i.e. place 10 or later)

Huh?

Huh?

Sometimes a new recommendation is inserted in the same place where a No Thanks was issued rather than appearing at the top of the list. It doesn't happen immediately so it's not always noticed.

Here's an example:



The recommendation at #79 is new and thrust between two older recs, while the one recommendation at the top of my list marked new isn't new at all.

eta: I think lorax had the right idea that these are older 'no thanks' recommendations coming back to bother us.

It's hard to tell at the time, but I remember being interested in some of those "middle" recommendations. I don't think they were No Thanks before.

I think the system is filling in the gaps of No Thanks first, and using the date of the original No Thanks rec. Since the listed date is old, there isn't any notice of new recs. If it runs out of No Thanks spots, it starts adding places on the top and treats those as new.

using the date of the original No Thanks rec

Maybe. Some of the new recs in the middle of my list had dates from 2008.

Interesting. I doubt they're no-thanks coming back directly, but the no-thanks is work based. If the work number changes... well, I'm not totally sure.

I don't know if it's a side effect of pruning my list every day, but new LT recs no longer appear at the top of the date sorted list at all.

No, not the same work with a different work number. LT is putting a 2nd rec in its place, since there's an empty spot.

moved to new bug tracker http://www.librarything.com/topic/99418