Re: It's almost 2016 and when (single-threaded) Emacs hangs, you gotta be smashing your keyboard!

[Rasmus <rasmus@gmx.us>]

Hi,

Bob Proulx <bob@proulx.com> writes:

> Pascal J. Bourguignon wrote:
>> Alexander Shukaev writes:
>> > In this particular case, I'm talking about Linux and directories
>
>> > mounted from network.
>> 
>> Yeah, right.
>> 
>> This freezes unix, not emacs.  You might prefer to access remote files
>> using tramp.
>
> I want to emphasize this.  If you are accessing files over NFS and for
> whatever reason the NFS server goes away this causes the NFS client in
> the local kernel to wait.  The "freeze" you are seeing is a freeze in
> the NFS client and not Emacs.  The problem is in the kernel not emacs.
>
> NFS client is implemented in the kernel.  When it locks up there is
> absolutely nothing an application can do to unlock the kernel.  This
> has been a plague on NFS forever.  Problems with the NFS client are
> the one thing that may require the workstation to be rebooted.
> Because if it were an application in userspace one could kill and
> restart it.  But because NFS is implemented in the kernel the only way
> to kill and restart the kernel is to reboot.

Interesting write-up.  Thanks.

As an aside: I used to have this problem when I would connect to my NFS
server at home, where I would add symlinks to ~ (e.g. ~/music/ ->
/mnt/nas/music).  When I’d put the laptop to sleep without disconnecting
first and then waking it at some other place, my computer would not even
be able to restart as I recall!

I think I usually managed to recover by issuing something like,
    umount -fl /mnt/nas/music
But it’s a few years back, so I might be looking at the wrong script...

Rasmus

-- 
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