Date: Tue, 24 Jan 2006 18:53:58 +0100 From: Jean-Yves Lefort <jylefort@FreeBSD.org> To: Alex Dupre <ale@FreeBSD.org> Cc: ports@FreeBSD.org, kris@obsecurity.org Subject: Re: fam vs gamin Message-ID: <20060124185358.085c7af4.jylefort@FreeBSD.org> In-Reply-To: <43D558E1.5080703@FreeBSD.org> References: <20060123040721.GA95972@xor.obsecurity.org> <43D47E36.1070906@FreeBSD.org> <20060123212614.6f570f8f.jylefort@FreeBSD.org> <43D558E1.5080703@FreeBSD.org>
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On Mon, 23 Jan 2006 23:29:53 +0100
Alex Dupre <ale@FreeBSD.org> wrote:
> Jean-Yves Lefort wrote:
> > The delays are likely caused by the fact that you have reached the
> > file descriptor limit; beyond that limit, gamin can no longer monitor
> > files with kqueue, and has to periodically lstat() them. You should
> > try to set a very large kern.maxfiles in /boot/loader.conf (you need
> > one file descriptor per monitored file); see pkg-message for details.
>=20
> Yes, I did it, but the problem about delays was different (not a matter
> of a few seconds related to kqueue or polling). Today I discovered it's
> present also with polling and probably due to this (from gam_channel.c):
>=20
> /**
> * Todo: check if write will block, or use non-blocking options
> */
>=20
> I suspect the write to one client blocks and until some events are read
> no more events are delivered even to other clients.
You're probably right. Good catch.
> > However, events should never be lost (although they can be
> > substantially delayed when monitoring a very large directory on a slow
> > machine, because event processing time increases linearly with the
> > number of files contained in the directory). Please cc your findings
> > to me.
>=20
> Of course. Today I had no time to test the kqueue backend, but I'll do
> it tomorrow. If I remember correctly, this was the scenario where I
> detected lost events:
> - a few dirs with thousans file (5 dirs with 2000 files)
> - new fam connection and 5 monitors on these dirs
> - one or two directory correctly delivered Exists events for the
> existing files, the others delivered only Exists and EndExist for the
> directories, as if they were empty
>=20
> In any case I'll be more precise tomorrow.
Are you sure that:
- you were monitoring the directories with FAMMonitorDirectory() and
not FAMMonitorFile()?
- you had the permission to open the directories?
--=20
Jean-Yves Lefort
jylefort@FreeBSD.org
http://lefort.be.eu.org/
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