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

[Loris Bennett]

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.
>
> The only way to win is not to play.  Which is what Pascal suggests
> with using emacs tramp to avoid nfs client and instead use ssh or
> other to access those files.  Because tramp operates entirely in
> userspace it can't lock up the same way.

I mount remote directories via sshfs in my laptop so that I can access
them both via a terminal and within emacs.  I experience hang-ups if
I switch my connection from ethernet to wireless, which changes the IP
address.  I haven't noticed other programs having problems when the
network changes, but then again, I don't use that many other programs.

As I understand it, sshfs is also implemented in userspace, so is there
some other reason why tramp might be more robust with respect to changes
in the network configuration?

Cheers,

Loris

> Bob
>
> P.S. Emacs has been rock solid for me for the last decade.  I can't
> remember the last time I experienced an emacs crash.  Bugs in
> behavior?  Sure.  But no crashes.


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