Re: emacs hangs in garbage collection related code

[Richard Stallman]

      So I sent a kill signal to Emacs
    and switched to GDB.

Instead of sending a signal, if you can attach to the running process
with GDB and then stop it, you should be able to get a better picture
of the innermost frame where the program is actually running.  Also,
you should be able to continue and stop again, using a conditional
breakpoint or the `finish' command to see if Emacs is really in a loop
that makes no progress.

    The second time around, I started gdb and attached it to the running
    Emacs and did a bt.  It sure seems to be the same problem.

Good, that gives you a chance to try.

The first technique is the one with the `finish' command described in
etc/DEBUG.  You may as well try that first.  You could go up by 50
frames at a time at first, if finishing frames one by one gets too
boring.

If it really is making no progress, that is bizarre, given that
marking an object should set a mark bit so it won't get processed
again.  Once you find the level that makes no progress, you should
come quickly to the bug.