Emacs locks up

Emacs locks up

[Joe Riel]

I've written a debugger controlled by Emacs.  It uses make-network-process
to communicate with a client over TCP.  Works fine on linux and Windows.
However, when running the client in Windows 10 in virtualbox, with Emacs
running on the host system (linux), occasionally Emacs locks up.

When that occurs I have to kill Emacs---it is otherwise unresponsive.  
Have no good idea how to fix or debug this.  Just being able to restore Emacs 
without killing it would be useful.  Any suggestions are appreciated.

-- 
Joe Riel

Re: Emacs locks up

[Eli Zaretskii]

> Date: Sat, 19 Jun 2021 14:15:22 -0700
> From: Joe Riel <joer@san.rr.com>
> 
> I've written a debugger controlled by Emacs.  It uses make-network-process
> to communicate with a client over TCP.  Works fine on linux and Windows.
> However, when running the client in Windows 10 in virtualbox, with Emacs
> running on the host system (linux), occasionally Emacs locks up.
> 
> When that occurs I have to kill Emacs---it is otherwise unresponsive.  
> Have no good idea how to fix or debug this.  Just being able to restore Emacs 
> without killing it would be useful.  Any suggestions are appreciated.

First, this is hardly the proper place for discussing bugs in Emacs.
I suggest to file a bug report with all the details, and discuss this
in the thread about the bug report.

And the first thing I'd do when Emacs hangs is attach a debugger to it
and see where it hangs and possibly also why.

Re: Emacs locks up

[Stefan Monnier via Users list for the GNU Emacs text editor]

Joe Riel [2021-06-19 14:15:22] wrote:
> I've written a debugger controlled by Emacs.  It uses make-network-process
> to communicate with a client over TCP.  Works fine on linux and Windows.
> However, when running the client in Windows 10 in virtualbox, with Emacs
> running on the host system (linux), occasionally Emacs locks up.
>
> When that occurs I have to kill Emacs---it is otherwise unresponsive.  
> Have no good idea how to fix or debug this.  Just being able to restore Emacs 
> without killing it would be useful.  Any suggestions are appreciated.

You might like to try `kill -USR2` which may(!) bring Emacs back to life
and give you a Lisp backtrace of where it's stuck.
If that doesn't work, you'll need to attach to the process with
a debugger to get the C level backtrace.


        Stefan

Re: Emacs locks up

[Joe Riel]

On Sun, 20 Jun 2021 09:40:27 -0400
Stefan Monnier via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org> wrote:

> Joe Riel [2021-06-19 14:15:22] wrote:
> > I've written a debugger controlled by Emacs.  It uses make-network-process
> > to communicate with a client over TCP.  Works fine on linux and Windows.
> > However, when running the client in Windows 10 in virtualbox, with Emacs
> > running on the host system (linux), occasionally Emacs locks up.
> >
> > When that occurs I have to kill Emacs---it is otherwise unresponsive.  
> > Have no good idea how to fix or debug this.  Just being able to restore Emacs 
> > without killing it would be useful.  Any suggestions are appreciated.  
> 
> You might like to try `kill -USR2` which may(!) bring Emacs back to life
> and give you a Lisp backtrace of where it's stuck.
> If that doesn't work, you'll need to attach to the process with
> a debugger to get the C level backtrace.

Thanks,

`kill -SIGUSR2` did restore emacs, which will be a big help.



-- 
Joe Riel

Re: Emacs locks up

[Emanuel Berg via Users list for the GNU Emacs text editor]

Joe Riel wrote:

> `kill -SIGUSR2` did restore emacs [...]

It should be enough/the same with just -USR2 or even -12
(12 is the signal number of USR2).

You can get the number with 'kill -l USR2' or verify with
'kill -l 12'.

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