[kde-freebsd] [patch] Digikam 2.6 - too many open files

[Oleg Sidorkin]

On Fri, Jun 15, 2012 at 3:57 PM, Alberto Villa <avilla at freebsd.org> wrote:

> On Friday 15 June 2012 12:48:48 Oleg Sidorkin wrote:
> > Original fix is a workaround of QT behavior on MacOS - as far as I
> > understand Linux is able to monitor files without opening them using
> > inotify. FreeBSD has no similar functions so QT has to open each file to
> > monitor it.
>
> Yes. inotify monitors file names, kqueue monitors file descriptors.
>
> Can you spot differences in file monitoring after you've applied your
> patch,
> anyway (maybe move some pictures away to let it start with the original
> code)?
> Due to differences in KDirWatch implementations, there is a chance that the
> final behaviour doesn't change (kqueue is able to detect modifications to
> files when monitoring a directory). In fact, it looks like code previous to
> the commit that triggered the bug was monitoring only directories, so the
> patch should have no effects apart from reduced efficiency.
>
> Anyway there is something I don't understand. I spent some time reading
> KDirWatch code, and FAM is used by default on FreeBSD. Now, FAM uses
> Gamin, and Gamin says:
>
> Gamin will only provide realtime notification of changes for at most n
> files,
> where n is the minimum value between (kern.maxfiles * 0.7) and
> (kern.maxfilesperproc - 200). Beyond that limit, files will be polled.
>
> Why is digiKam failing and not just polling transparently? Is it (or most
> likely KDE-Libs) using QFileSystemWatcher instead (which uses plain kqueue
> without falling back to polling, if I remember correctly)?
> --
> Alberto Villa, FreeBSD committer <avilla at FreeBSD.org>
> http://people.FreeBSD.org/~avilla
>
> It is hard to predict, in particular about the future.
>                -- Robert Storm Petersen
>

I'll test the monitor behavior this weekend.
Thanks
-- 
Oleg Sidorkin
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