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List:       kde-pim
Subject:    Re: [Kde-pim] Nepomukfeeder updates almost ready
From:       Christian Mollekopf <chrigi_1 () fastmail ! fm>
Date:       2012-12-26 15:44:53
Message-ID: 2956891.9jqFOr5fc8 () myhost2
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Hey,

I made another bunch of fixes, turned the finding of skipped items into a 
recurring task, and turn the change-recorder off now if the feeder is disabled 
entirely. In my testing so far this system behaves much better than what we 
used to have.

I plan on committing this to 4.10 if noone objects within the next days. (I'll 
write a mail to release-team first).

The code is here:
http://quickgit.kde.org/?p=clones%2Fkdepim-
runtime%2Fcmollekopf%2FpimRuntimeClone.git&a=shortlog&h=c2ca91566953c57af119634f65b5bd73bac7e7fa

Cheers,
Christian


On Sunday 23 December 2012 17.54:18 Christian Mollekopf wrote:
> Heya,
> 
> To cut right to the chase; I revamped the feeders a bit, think it's much
> better than what we had before, and would like to get it into 4.10. So feel
> free to skip if you don't care.
> 
> I moved to a recurring, query based approach for the initial-indexing. That
> means, instead of doing a single initial-indexing when the feeder is
> executed the first time, and relying purely on updates from the
> change-recorder afterwards, the initial-indexing is now more a maintenance
> task (which is currently running on every start), and queries for all not
> yet indexed items.
> 
> That is necessary, as the initial assumption that we can index items faster
> than notifications come in didn't hold true, which resulted in the feeder
> regularly being overloaded with stuff to index.
> 
> The initial query approach resulted in n queries for n items, which is way
> too slow to be feasible for all items (it is taking ages, literally). The
> only alternative approach I found is; we run two queries, one in akonadi
> and one in nepomuk, each querying for *all* available items. Comparing the
> two lists, results in the list of items which have not been indexed yet. Of
> course, that misses any changes on items which have been indexed before,
> but have been modified since then, so it's not ideal either.
> These queries are fairly efficient as they result in a single sql query per
> db (as opposed to n),  although with a huge result set. I could query my db
> of ~100'000 items in ~20s (i7 processor).
> 
> Since I figured changes on emails, which are mostly just flags, are
> negligible, I switched the email initial-indexing to that new approach.
> 
> Non-email items continue to be indexed as usual, meaning there is one query
> per item, which allows us to detect modifications as well. That is slow as
> usual, but since we usually have a lot more email items than non-email
> items, it works well enough.
> 
> Another important advantage is that we can thus now also skip large batches
> of new/changed items, knowing they will be picked up by the
> initial-indexing eventually. That also allows us to turn off the
> change-recorder when the feeder is turned off (which is another problem if
> we rely on the change- recorder too much).
> 
> One remaining problem is that we get loads of notifications of changed/added
> items, which I think are mostly due to sync-on-demand updates, updating the
> cache (and not actual new emails or whatnot). I also often get flag change
> notifications on my offline imap accounts, which I don't really know why
> yet. That of course would lead to loads of items being indexed over and
> over again, but that can be mitigated somewhat since we now can skip larger
> batches of items.
> 
> Besides I made some performance improvements, such as the cache I mentioned
> previously (200% performance boost), or that new items are now indexed
> without any queries, which gives another boost of 10%-20% or so.
> 
> Overall, I think we should get this into 4.10 as fast as possible. The patch
> is somewhat large (and way to late in the process), but IMO the previous
> feeders are broken enough to justify this. So what do you think? Should I
> commit this to 4.10 in a couple of commits, or only master and then
> backport it for 4.10.1?
> 
> Cheers,
> Christian
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> KDE PIM home page at http://pim.kde.org/
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