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List:       kde-pim
Subject:    Re: [Kde-pim] Review Request 117975: Change libmaildir listNew and listCurrent functions to explicet
From:       "Kevin Krammer" <krammer () kde ! org>
Date:       2014-05-05 11:54:31
Message-ID: 20140505115431.19582.56715 () probe ! kde ! org
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> On May 4, 2014, 12:54 p.m., Kevin Krammer wrote:
> > What if you pass NoSort to entryList() itself?
> 
> Sergio Luis Martins wrote:
> QStringList entryList( Filters filters = NoFilter, SortFlags sort = NoSort ) const;
> 
> NoSort is already the default, so no point on passing it.
> 
> What happens is that entryList() does:
> if (sort == NoSort)
> sort = d->sort;
> 
> and QDirPrivate::sort is initialized with QDir::Name | QDir::IgnoreCase
> 
> Buggy Qt IMHO
> 
> Kevin Krammer wrote:
> Wow, buggy indeed.
> Even still wrong in Qt5.
> 
> How about initializing the default to NoSort, e.g.
> QDir d( ...., QString(), NoSort );
> 
> Sergio Luis Martins wrote:
> What would be the gain ? It's also less readable, as it introduces one more \
> parameter "QString()" that people must lookup on the documentation to know what it \
> means. 
> Saves us one "d->sort = sort" assignment in the whole maildir import run though :)
> 
> Martin Steigerwald wrote:
> Kevin, okay with you to ship? Any objections left? I like that the change makes it \
> explicit that no sorting is required direct at the place where it matters. Its an \
> additional call for each folder synchronrization, but I don īt think that matters. \
> I could add a comment, but then I documentated it all in the git changelog.

Yes, the difference is jsut a matter of taste anyway


- Kevin


-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://git.reviewboard.kde.org/r/117975/#review57245
-----------------------------------------------------------


On May 4, 2014, 8:58 a.m., Martin Steigerwald wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/117975/
> -----------------------------------------------------------
> 
> (Updated May 4, 2014, 8:58 a.m.)
> 
> 
> Review request for KDEPIM, KDEPIM-Libraries, Andras Mantia, David Faure, and Sergio \
> Luis Martins. 
> 
> Bugs: 334218
> http://bugs.kde.org/show_bug.cgi?id=334218
> 
> 
> Repository: kdepim-runtime
> 
> 
> Description
> -------
> 
> On trying to find the cause for Akonadi maildir resource hogging up a Sandybridge \
> core for minutes without any notable MySQL or disk activity, Sergio recommended \
> doing a callgrind run. This revealed a bottleneck with QDir.entryList and there \
> specifically in QAlgorihmsPrivate::qSortHelper[1]. 
> Calling setSorting(QDir::NoSort) on the QDir object gets rid of the sorting. This I \
> did twice in maildir.ccp and twice in keycache.cpp for listCurrent and listNew \
> functions there. 
> It is not yet clear whether this change is safe, but on my tests it appears to do. \
> Moving and filtering mails still work okay. I will CC Andras on this as Sergio \
> tried to ping him about this change. 
> I think it is fair to say that this change has a *huge* impact on Akonadi maildir \
> performance with large maildir and I recommend to backport this for stable branch \
> as well once changing to no sorting is considered to be safe. 
> Thanks to Sergio and David for pointing out the sorting issue, telling how to \
> change to no sorting and general help. 
> See also:
> 
> Bug 334218 - synchronizations of large folders with filesystem contents hogs a \
> Sandybridge core for minutes https://bugs.kde.org/334218
> 
> [1] https://bugs.kde.org/show_bug.cgi?id=334218#c4
> 
> [2] Bug 334206 - While maildir resources synchronizes a folder KMail blocks on \
> switching to a different folder: https://bugs.kde.org/334206
> 
> 
> Diffs
> -----
> 
> resources/maildir/libmaildir/keycache.cpp f0af9c47cef63dac45ae68dd94fa17a040dc1593 
> resources/maildir/libmaildir/maildir.cpp 9bd380201a1a250ecfe354dd99946e8dae0ab668 
> 
> Diff: https://git.reviewboard.kde.org/r/117975/diff/
> 
> 
> Testing
> -------
> 
> In my tests with KMail SC 4.12.4 Debian unstable packages and Akonadi and \
> kdepimlibs from Git it works well. Well basically Akonadi maildir resource changed \
> from being a CPU hog for minutes to hardly every appearing in a 10 second \
> measurement average snapshot of atop anymore. KMail hardly blocks on folder changes \
> anymore, which I still believe to be a different issue tough[2]. 
> Mail filtering and moving mails to a different folder still works ago. And KMail is \
> subjectively much faster. It completely changes my KMail experience from being \
> unbearable at times to quite pleasant. 
> 
> Thanks,
> 
> Martin Steigerwald
> 
> 

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