On 6/18/2014 1:46 PM, Ken Brown wrote:
> On 6/18/2014 11:06 AM, Filipp Gunbin wrote:
>> I'm not sure whether this is Cygwin-specific, but I'm not able to test
>> it on other OS, so here are the steps to reproduce:
>>
>> emacs -Q
>> C-x C-r <some_file>
>
> You mean C-x C-f
>
>> M-x auto-revert-tail-mode
>> wait for few seconds -> emacs crashes
>
> I can confirm this, but on 32-bit Cygwin only; there's no crash on
> 64-bit Cygwin. (This is a refreshing change from the emacs crashes
> people have been reporting on 64-bit Cygwin.)
>
> Here's the backtrace:
>
> #0 0x00000000 in ?? ()
> No symbol table info available.
> #1 0x610f842f in pthread_mutex::lock (this=0x0)
> at /usr/src/debug/cygwin-1.7.30-1/winsup/cygwin/thread.cc:1745
> self = <optimized out>
> result = <optimized out>
> __PRETTY_FUNCTION__ = "int pthread_mutex::lock()"
> #2 0x00000201 in ?? ()
> No symbol table info available.
>
> Lisp Backtrace:
> "gfile-add-watch" (0x288dc8)
> "file-notify-add-watch" (0x2890c8)
> "byte-code" (0x289340)
> "auto-revert-notify-add-watch" (0x289778)
> "auto-revert-buffers" (0x289b4c)
> "apply" (0x289b48)
> "byte-code" (0x289dc0)
> "timer-event-handler" (0x28a1fc)
>
> I'll look into this. In the meantime, you can work around it by
> configuring --with-file-notification=no.
I'm afraid I ran into a brick wall trying to debug this. I wanted to see what
gfile-add-watch was doing, so I ran emacs under gdb with a breakpoint at
Fgfile_add_watch and then a breakpoint at g_file_monitor (a Glib function
called by Fgfile_add_watch). When I tried to step through this function, I hit
an assertion violation in gdb. This is repeatable. A log of the gdb session
is appended below.
The problem occurs only on 32-bit Cygwin. On 64-bit Cygwin, I can step through
Fgfile_add_watch without a problem.
Filipp, do you want to try debugging this yourself? Maybe your debugging
skills are better than mine. (You'll need to install glib2.0-debuginfo.)
Ken
$ gdb /usr/bin/emacs-w32.exe
GNU gdb (GDB) 7.6.50.20130728-cvs (cygwin-special)
[...]
Reading symbols from /usr/bin/emacs-w32.exe...Reading symbols from
/usr/lib/debug/usr/bin/emacs-w32.exe.dbg...done.
done.
(gdb) b Fgfile_add_watch
Breakpoint 1 at 0x5f7a3f: file
/usr/src/debug/emacs-24.3.91-2/src/gfilenotify.c, line 170.
(gdb) r -Q
Starting program: /usr/bin/emacs-w32.exe -Q
[...]
Breakpoint 1, Fgfile_add_watch (file=-2145740495, flags=13798510,
callback=-2146880150)
at /usr/src/debug/emacs-24.3.91-2/src/gfilenotify.c:170
170 GFileMonitorFlags gflags = G_FILE_MONITOR_NONE;
(gdb) b g_file_monitor
Breakpoint 2 at 0x6a357e50: file /usr/src/debug/glib2.0-2.38.2-2/gio/gfile.c,
line 5338.
(gdb) c
Continuing.
[...]
Breakpoint 2, g_file_monitor (file=0x80061530,
flags=(G_FILE_MONITOR_WATCH_MOUNTS | G_FILE_MONITOR_SEND_MOVED),
cancellable=0x0, error=0x0)
at /usr/src/debug/glib2.0-2.38.2-2/gio/gfile.c:5338
5338 {
(gdb) n
5339 if (g_file_query_file_type (file, 0, cancellable) ==
G_FILE_TYPE_DIRECTORY)
(gdb) n
5338 {
(gdb) n
5339 if (g_file_query_file_type (file, 0, cancellable) ==
G_FILE_TYPE_DIRECTORY)
(gdb) n
5340 return g_file_monitor_directory (file,
(gdb) n
5339 if (g_file_query_file_type (file, 0, cancellable) ==
G_FILE_TYPE_DIRECTORY)
(gdb) n
5341 flags &
~G_FILE_MONITOR_WATCH_HARD_LINKS,
(gdb) n
5340 return g_file_monitor_directory (file,
(gdb) n
5345 }
(gdb) n
5340 return g_file_monitor_directory (file,
(gdb) n
g_file_monitor_directory (file=0x80061530,
flags=(G_FILE_MONITOR_WATCH_MOUNTS | G_FILE_MONITOR_SEND_MOVED),
cancellable=0x0, error=0x0)
at /usr/src/debug/glib2.0-2.38.2-2/gio/gfile.c:5235
5235 {
(gdb) n
5238 g_return_val_if_fail (G_IS_FILE (file), NULL);
(gdb) n
/netrel/src/gdb-7.6.50-4/gdb/infrun.c:1942: internal-error: resume: Assertion
`pc_in_thread_step_range (pc, tp)' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n) y
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