bug#22214: 25.0.50; lock up with gui dialogs and clipmon-mode

[Joseph Mingrone <jrm@ftfl.ca>]

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Eli Zaretskii <eliz@gnu.org> writes:

>> From: Joseph Mingrone <jrm@ftfl.ca>
>> Cc: 22214@debbugs.gnu.org,  bburns.km@gmail.com
>> Date: Mon, 21 Dec 2015 12:41:47 -0400

>> Thread 3 (Thread 1902400 (LWP 100743)):
>> #0  0x0000000807444cfa in _sigprocmask () from /lib/libc.so.7
>> #1  0x0000000804656526 in pthread_sigmask () from /lib/libthr.so.3
>> #2  0x00000000007ab8e9 in block_atimers (oldset=0x7fffffff7970) at atimer.c:70
>> #3  0x00000000007abffc in do_pending_atimers () at atimer.c:434
>> #4  0x00000000005f803e in process_pending_signals () at keyboard.c:7043
>> #5  0x00000000006c1559 in Fmake_list (length=0, init=0) at alloc.c:2718
>> #6  0x0000000000713c2a in concat (nargs=1, args=0x7fffffff7b28, target_type=Lisp_Cons, last_special=false) at fns.c:633
>> #7  0x00000000007135d2 in Fcopy_sequence (arg=18186131) at fns.c:501
>> #8  0x00000000005f25b3 in timer_check () at keyboard.c:4452

> Thanks.

> Can you find out which thread uses up the CPU?  If that's this thread
> (the Emacs application main thread), can you use the technique
> described in etc/DEBUG under "If the symptom of the bug is that Emacs
> fails to respond" to find out whether Emacs is looping and where?

It looks like it's looping in process.c  starting at line 4565

  while (1)
    {
      bool process_skipped = false;
      ...

The gdb output below shows the steps through the looping.

Joseph

jrm@phe ~/scm/nm/emacs.git/src % /usr/local/bin/gdb ./emacs
GNU gdb (GDB) 7.10 [GDB v7.10 for FreeBSD]
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License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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This GDB was configured as "x86_64-portbld-freebsd10.1".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
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Find the GDB manual and other documentation resources online at:
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For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from ./emacs...done.
SIGINT is used by the debugger.
Are you sure you want to change it? (y or n) [answered Y; input not from terminal]
DISPLAY = :0.0
TERM = screen-256color
Breakpoint 1 at 0x5dfb54: file emacs.c, line 371.
Temporary breakpoint 2 at 0x61e9d9: file sysdep.c, line 905.
(gdb) run -Q
Starting program: /usr/home/jrm/scm/nm/emacs.git/src/emacs -Q
[New Thread 1902400 (LWP 101016)]
^Z[New Thread 16b5c00 (LWP 100130)]

Program received signal SIGTSTP, Stopped (user).
[Switching to Thread 1902400 (LWP 101016)]
0x000000080736efaa in ktimer_settime () from /lib/libc.so.7
(gdb) finish
Run till exit from #0  0x000000080736efaa in ktimer_settime () from /lib/libc.so.7
0x00000000007abd8b in set_alarm () at atimer.c:312
312                   && timer_settime (alarm_timer, TIMER_ABSTIME, &ispec, 0) == 0)
(gdb) finish
Run till exit from #0  0x00000000007abd8b in set_alarm () at atimer.c:312
run_timers () at atimer.c:382
382     }
(gdb) finish
Run till exit from #0  run_timers () at atimer.c:382
do_pending_atimers () at atimer.c:436
436           unblock_atimers (&oldset);
(gdb) finish
Run till exit from #0  do_pending_atimers () at atimer.c:436
process_pending_signals () at keyboard.c:7044
7044    }
(gdb) finish
Run till exit from #0  process_pending_signals () at keyboard.c:7044
Fmake_list (length=0, init=0) at alloc.c:2689
2689      while (size > 0)
(gdb) finish
Run till exit from #0  Fmake_list (length=0, init=0) at alloc.c:2689
0x0000000000713c2a in concat (nargs=1, args=0x7fffffff7ad8, target_type=Lisp_Cons, last_special=false) at fns.c:633
633         val = Fmake_list (make_number (result_len), Qnil);
Value returned is $1 = 105189203
(gdb) finish
Run till exit from #0  0x0000000000713c2a in concat (nargs=1, args=0x7fffffff7ad8, target_type=Lisp_Cons, last_special=false)
    at fns.c:633
Fcopy_sequence (arg=21640739) at fns.c:502
502     }
Value returned is $2 = 105189203
(gdb) finish
Run till exit from #0  Fcopy_sequence (arg=21640739) at fns.c:502
0x00000000005f25b3 in timer_check () at keyboard.c:4452
4452      timers = Fcopy_sequence (Vtimer_list);
Value returned is $3 = 105189203
(gdb) finish
Run till exit from #0  0x00000000005f25b3 in timer_check () at keyboard.c:4452
readable_events (flags=1) at keyboard.c:3313
3313      if (kbd_fetch_ptr != kbd_store_ptr)
Value returned is $4 = {tv_sec = 0, tv_nsec = -1}
(gdb) finish
Run till exit from #0  readable_events (flags=1) at keyboard.c:3313
0x00000000005f7963 in get_input_pending (flags=1) at keyboard.c:6691
6691      input_pending = (!NILP (Vquit_flag) || readable_events (flags));
Value returned is $5 = true
(gdb) finish
Run till exit from #0  0x00000000005f7963 in get_input_pending (flags=1) at keyboard.c:6691
swallow_events (do_display=false) at keyboard.c:4205
4205      if (!input_pending && timers_run != old_timers_run && do_display)
Value returned is $6 = true
(gdb) finish
Run till exit from #0  swallow_events (do_display=false) at keyboard.c:4205
wait_reading_process_output (time_limit=5, nsecs=0, read_kbd=0, do_display=false, wait_for_cell=17528851, wait_proc=0x0,
    just_wait_proc=0) at process.c:5004
5004          if (! NILP (wait_for_cell) && ! NILP (XCAR (wait_for_cell)))
(gdb) finish
Run till exit from #0  wait_reading_process_output (time_limit=5, nsecs=0, read_kbd=0, do_display=false, wait_for_cell=17528851,
    wait_proc=0x0, just_wait_proc=0) at process.c:5004
^Z
Program received signal SIGTSTP, Stopped (user).
0x000000080736efaa in ktimer_settime () from /lib/libc.so.7
(gdb) finish
Run till exit from #0  0x000000080736efaa in ktimer_settime () from /lib/libc.so.7
0x00000000007abd8b in set_alarm () at atimer.c:312
312                   && timer_settime (alarm_timer, TIMER_ABSTIME, &ispec, 0) == 0)
(gdb) finish
Run till exit from #0  0x00000000007abd8b in set_alarm () at atimer.c:312
run_timers () at atimer.c:382
382     }
(gdb) finish
Run till exit from #0  run_timers () at atimer.c:382
do_pending_atimers () at atimer.c:436
436           unblock_atimers (&oldset);
(gdb) finish
Run till exit from #0  do_pending_atimers () at atimer.c:436
process_pending_signals () at keyboard.c:7044
7044    }
(gdb) finish
Run till exit from #0  process_pending_signals () at keyboard.c:7044
0x0000000000788a69 in wait_reading_process_output (time_limit=5, nsecs=0, read_kbd=0, do_display=false, wait_for_cell=17528851,
    wait_proc=0x0, just_wait_proc=0) at process.c:4573
4573            QUIT;
(gdb) finish
Run till exit from #0  0x0000000000788a69 in wait_reading_process_output (time_limit=5, nsecs=0, read_kbd=0, do_display=false,
    wait_for_cell=17528851, wait_proc=0x0, just_wait_proc=0) at process.c:4573
^Z
Program received signal SIGTSTP, Stopped (user).
0x0000000807444cfa in _sigprocmask () from /lib/libc.so.7
(gdb) finish
Run till exit from #0  0x0000000807444cfa in _sigprocmask () from /lib/libc.so.7
0x0000000804656526 in pthread_sigmask () from /lib/libthr.so.3
(gdb) finish
Run till exit from #0  0x0000000804656526 in pthread_sigmask () from /lib/libthr.so.3
unblock_atimers (oldset=0x7fffffff7920) at atimer.c:76
76      }
(gdb) finish
Run till exit from #0  unblock_atimers (oldset=0x7fffffff7920) at atimer.c:76
do_pending_atimers () at atimer.c:438
438     }
(gdb) finish
Run till exit from #0  do_pending_atimers () at atimer.c:438
process_pending_signals () at keyboard.c:7044
7044    }
(gdb) finish
Run till exit from #0  process_pending_signals () at keyboard.c:7044
Fmake_list (length=0, init=0) at alloc.c:2689
2689      while (size > 0)
(gdb) finish
Run till exit from #0  Fmake_list (length=0, init=0) at alloc.c:2689
0x0000000000713c2a in concat (nargs=1, args=0x7fffffff7ad8, target_type=Lisp_Cons, last_special=false) at fns.c:633
633         val = Fmake_list (make_number (result_len), Qnil);
Value returned is $7 = 757173027
(gdb) finish
Run till exit from #0  0x0000000000713c2a in concat (nargs=1, args=0x7fffffff7ad8, target_type=Lisp_Cons, last_special=false)
    at fns.c:633
Fcopy_sequence (arg=21640739) at fns.c:502
502     }
Value returned is $8 = 757173027
(gdb) finish
Run till exit from #0  Fcopy_sequence (arg=21640739) at fns.c:502
0x00000000005f25b3 in timer_check () at keyboard.c:4452
4452      timers = Fcopy_sequence (Vtimer_list);
Value returned is $9 = 757173027
(gdb) finish
Run till exit from #0  0x00000000005f25b3 in timer_check () at keyboard.c:4452
readable_events (flags=1) at keyboard.c:3313
3313      if (kbd_fetch_ptr != kbd_store_ptr)
Value returned is $10 = {tv_sec = 0, tv_nsec = -1}
(gdb) finish
Run till exit from #0  readable_events (flags=1) at keyboard.c:3313
0x00000000005f7963 in get_input_pending (flags=1) at keyboard.c:6691
6691      input_pending = (!NILP (Vquit_flag) || readable_events (flags));
Value returned is $11 = true
(gdb) finish
Run till exit from #0  0x00000000005f7963 in get_input_pending (flags=1) at keyboard.c:6691
swallow_events (do_display=false) at keyboard.c:4205
4205      if (!input_pending && timers_run != old_timers_run && do_display)
Value returned is $12 = true
(gdb) finish
Run till exit from #0  swallow_events (do_display=false) at keyboard.c:4205
wait_reading_process_output (time_limit=5, nsecs=0, read_kbd=0, do_display=false, wait_for_cell=17528851, wait_proc=0x0,
    just_wait_proc=0) at process.c:5004
5004          if (! NILP (wait_for_cell) && ! NILP (XCAR (wait_for_cell)))
(gdb) next
5013          if (read_kbd && interrupt_input
(gdb) next
5020          if (read_kbd || ! NILP (wait_for_cell))
(gdb) next
5021            do_pending_window_change (0);
(gdb) next
5024          if (no_avail || nfds == 0)
(gdb) next
5025            continue;
(gdb) next
5215        }                           /* End while exit conditions not met.  */
(gdb) next
4567          bool process_skipped = false;
(gdb) next
4572          if (read_kbd >= 0)
(gdb) next
4573            QUIT;
(gdb) next
4578          if (! NILP (wait_for_cell) && ! NILP (XCAR (wait_for_cell)))
(gdb) next
4583          if (wait == TIMEOUT)
(gdb) next
4585              if (!timespec_valid_p (now))
(gdb) next
4587              if (timespec_cmp (end_time, now) <= 0)
(gdb) next
4589              timeout = timespec_sub (end_time, now);
(gdb) next
4598          if (NILP (wait_for_cell)
(gdb) next
4642          if (read_kbd < 0)
(gdb) next
4649          if (update_tick != process_tick)
(gdb) next
4681          if (wait_proc && wait_proc->raw_status_new)
(gdb) next
4683          if (wait_proc
(gdb) next
4727          if (wait_proc && just_wait_proc)
(gdb) next
4735          else if (!NILP (wait_for_cell))
(gdb) next
4737              Available = non_process_wait_mask;
(gdb) next
4738              check_delay = 0;
(gdb) next
4739              check_write = 0;
(gdb) next
4757          if (frame_garbaged && do_display)
(gdb) next
4769          no_avail = 0;
(gdb) next
4770          if ((read_kbd || !NILP (wait_for_cell))
(gdb) next
4771              && detect_input_pending ())
(gdb) next
4773              nfds = read_kbd ? 0 : 1;
(gdb) next
4774              no_avail = 1;
(gdb) next
4775              FD_ZERO (&Available);
(gdb) next
4910          xerrno = errno;
(gdb) next
4913          clear_waiting_for_input ();
(gdb) next
4916          do_pending_window_change (0);
(gdb) next
4918          if (nfds == 0)
(gdb) next
4942          if (nfds < 0)
(gdb) next
4956          if (read_kbd != 0)
(gdb) next
4983          if (read_kbd != 0
(gdb) next
4994          if (read_kbd == 0 && detect_input_pending ())
(gdb) next
4996              swallow_events (do_display);
(gdb) next
5004          if (! NILP (wait_for_cell) && ! NILP (XCAR (wait_for_cell)))
(gdb) next
5013          if (read_kbd && interrupt_input
(gdb) next
5020          if (read_kbd || ! NILP (wait_for_cell))
(gdb) next
5021            do_pending_window_change (0);
(gdb) next
5024          if (no_avail || nfds == 0)
(gdb) next
5025            continue;
(gdb) next
5215        }                           /* End while exit conditions not met.  */
(gdb)

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