kqueue and NFS

[Daniel Braniss]

hi,


> On 11 Nov 2020, at 12:45, Ronald Klop <ronald-lists at klop.ws> wrote:
> 
> Hi,
> 
> I don't think NFS has the possibility to push notifications about changes in the filesystem to the clients. NFSv3 is stateless so the server does not even know about the clients. NFSv4 I don't know much about, but I have never heard of notifications.
> 
I now remember having a similar chat with Rick some years ago.

> So for NFS kqueue would only trigger if the change is on the same client as where the kqueue is lurking.
> 
> Otherwise you could run some daemon on the server which pushes the notifications out of band of the NFS protocol to the clients. Which probably gives interesting results together with the caching of the NFS client. But that is another story we see at work. (postfix -> you have mail! -> NFS -> imap -> no you don't -> O yes, you have. :-) )
> 

in my case it was a python app (flask restful) that when run in debug mode would restart if some file changed,
but some days ago that stopped working, Since I had updated the kernel and the ports it took me some time
to find out what had happened, it had nothing to do with the upgrades but instead I had installed ‘watchdog.py’ which
flaks->werkseig->reload decided to use :-(  
rabbit hole indeed.

thanks,
	danny

> Regards,
> Ronald.
> 
> Van: Daniel Braniss <danny at cs.huji.ac.il>
> Datum: woensdag, 11 november 2020 09:40
> Aan: stable at freebsd.org
> Onderwerp: kqueue and NFS
>> Hi,
>> I have a vague recollection that kqueue does not work for NFS files,
>> any chance that this will be made possible?
>> cheers,
>>    danny
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