linux-kernel - Re: inotify, new idea?

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Message-ID: <538091C2.6040802@nod.at>
Date:	Sat, 24 May 2014 14:34:10 +0200
From:	Richard Weinberger <richard@....at>
To:	"Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>
CC:	Lennart Sorensen <lsorense@...lub.uwaterloo.ca>,
	Jos Huisken <jos.huisken@...il.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: inotify, new idea?

Am 24.05.2014 09:52, schrieb Michael Kerrisk (man-pages):
> On 04/21/2014 10:42 AM, Richard Weinberger wrote:
>> Am 21.04.2014 09:24, schrieb Michael Kerrisk:
>>>> Does recursive monitoring even work with inotify?
>>>> Last time I've tried it did failed as soon I did a mkdir -p a/b/c/d because
>>>> mkdir() raced against the thread which installes the new watches.
>>>
>>> As I understand it, you have to program to deal with the races (rescan
>>> directories after adding watches). I recently did a lot of work
>>> updating the inotify(7) man page to discuss all the issues that I know
>>> of, and their remedies. If I missed anything, I'd appreciate a note on
>>> it, so that it can be added. See
>>> http://man7.org/linux/man-pages/man7/inotify.7.html#NOTES
>>
>> I'm aware of the rescan hack, but in my case it does not help
>> because my program must not miss any event.
>> Currently I'm using a fuse overlay filesystem to log everything.
>> Not perfect but works... :-)
> 
> Richard,
> 
> A late follow up question. How does your application deal with the
> event overflow problem (i.e., when you get a large number of events 
> much faster than your application can deal with them?

The downside of the FUSE approach is that you have to intercept
every filesystem function.
This can be a performance issue.
But due to this design the overflow problem cannot happen as the
FUSE filesystem blocks until the event has been proceed.

Thanks,
//richard
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