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

[Eli Zaretskii <eliz@gnu.org>]

> 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.