Does anybody know how to debug a live Emacs process?

Does anybody know how to debug a live Emacs process?

[Live System User]

Hi,

I have a live Emacs process that is stuck in a state which only
displays:

         Invalid argument #<terminal 2> in ‘get-device-terminal’

in the echo area, including when trying to execute M-x.

I was hoping to solicit assistance to help obtain information to
help Emacs and opened Bug#23378 on Monday.

If nothing can be done with gaining debug information with this
process, I guess I will just have to kill the process externally.

I am running GNU Emacs 25.0.92.1 on Gnu/Linux

Thanks.

Re: Does anybody know how to debug a live Emacs process?

[Eli Zaretskii]

> From: Live System User <nyc4bos@aol.com>
> Date: Thu, 28 Apr 2016 02:37:17 -0400
> 
> I have a live Emacs process that is stuck in a state which only
> displays:
> 
>          Invalid argument #<terminal 2> in ‘get-device-terminal’
> 
> in the echo area, including when trying to execute M-x.
> 
> I was hoping to solicit assistance to help obtain information to
> help Emacs and opened Bug#23378 on Monday.

Attach the debugger to the running process, like this:

  gdb -p PID

where PID is the process number of the Emacs process, you should be
able to see it in the display produced by the 'top' or 'ps' command.

If GDB succeeds in attaching to the process, it will stop it and
display a "(gdb)" prompt.  Then type at that prompt:

  thread apply all bt full

Then file a bug report with everything that was displayed by GDB.

Some additional information about debugging Emacs is available in the
file etc/DEBUG that is part of the distribution.

Thanks.

Re: Does anybody know how to debug a live Emacs process?

[Live System User]

Eli Zaretskii <eliz@gnu.org> writes:
Hi,
>> From: Live System User <nyc4bos@aol.com>
>> Date: Thu, 28 Apr 2016 02:37:17 -0400
>> 
>> I have a live Emacs process that is stuck in a state which only
>> displays:
>> 
>>          Invalid argument #<terminal 2> in ‘get-device-terminal’
>> 
>> in the echo area, including when trying to execute M-x.
>> 
>> I was hoping to solicit assistance to help obtain information to
>> help Emacs and opened Bug#23378 on Monday.
>
> Attach the debugger to the running process, like this:
>
>   gdb -p PID
>
> where PID is the process number of the Emacs process, you should be
> able to see it in the display produced by the 'top' or 'ps' command.
>
> If GDB succeeds in attaching to the process, it will stop it and
> display a "(gdb)" prompt.  Then type at that prompt:
>
>   thread apply all bt full
>
> Then file a bug report with everything that was displayed by GDB.
>
> Some additional information about debugging Emacs is available in the
> file etc/DEBUG that is part of the distribution.

I've added the GDB backtrace info to Bug#23378, as requested.

Thanks.

Re: Does anybody know how to debug a live Emacs process?

[Live System User]

Hi,

Eli Zaretskii <eliz@gnu.org> writes:

[...]

> Then file a bug report with everything that was displayed by GDB.
>

I sent the infomation to Bug#23378

Is it OK to kill and restart Emacs?

if more useful information can be gleaned. I can keep it around
as I don't have a reproducible receipe and this appears to be
deep into Emacs internal code.

thanks.

Re: Does anybody know how to debug a live Emacs process?

[Eli Zaretskii]

> From: Live System User <nyc4bos@aol.com>
> Cc: Eli Zaretskii <eliz@gnu.org>
> Date: Fri, 29 Apr 2016 14:18:53 -0400
> 
> > Then file a bug report with everything that was displayed by GDB.
> >
> 
> I sent the infomation to Bug#23378
> 
> Is it OK to kill and restart Emacs?
> 
> if more useful information can be gleaned. I can keep it around
> as I don't have a reproducible receipe and this appears to be
> deep into Emacs internal code.

If you can afford it, please keep the session for a couple of days,
perhaps someone will have ideas on how to investigate this.

Thanks.