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Date: Sun, 03 Jun 2012 17:26:21 -0400
From: Ken Brown <kbrown AT cornell DOT edu>
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To: cygwin AT cygwin DOT com
Subject: Re: "emacs -nw" hangs in a terminal
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On 6/3/2012 12:52 PM, Christopher Faylor wrote:
> On Sun, Jun 03, 2012 at 08:54:20AM -0400, Ken Brown wrote:
>> On 6/2/2012 11:08 PM, Christopher Faylor wrote:
>>> On Fri, May 25, 2012 at 04:07:32PM -0400, Ken Brown wrote:
>>>> On 5/25/2012 2:49 PM, Ken Brown wrote:
>>>>> On 5/25/2012 10:35 AM, Corinna Vinschen wrote:
>>>>>> I applied a patch which calls the signal handler after cleanup. The
>>>>>> downside is that the signal handler is only called if select is called
>>>>>> from the main thread. A better patch would perhaps be to stop all
>>>>>> threads, call the signal handler, and restart the threads afterwards,
>>>>>> but this is more tricky.
>>>>>
>>>>> Thanks! That fixes it. I appreciate all your work on this.
>>>>>
>>>>> I'm in the process now of testing to see if this also fixes an emacs
>>>>> crash I've been getting when I build emacs with GSettings support
>>>>> (http://cygwin.com/ml/cygwin-xfree/2012-04/msg00048.html).
>>>>
>>>> Here's what I'm now seeing with that build.  If I start emacs and do
>>>> 'M-x shell', emacs hangs (but doesn't crash).  Attaching gdb and doing a
>>>> backtrace of all threads, I see that cygwin_select has been called in
>>>> two threads other than the main one:
>>>>
>>>> Thread 8 (Thread 2784.0x19c):
>>>> #0  0x7702013d in ntdll!RtlEnableEarlyCriticalSectionEventCreation ()
>>>>      from /c/windows/SysWOW64/ntdll.dll
>>>> #1  0x7702013d in ntdll!RtlEnableEarlyCriticalSectionEventCreation ()
>>>>      from /c/windows/SysWOW64/ntdll.dll
>>>> #2  0x74fe0bdd in WaitForMultipleObjectsEx ()
>>>>      from /c/windows/syswow64/KERNELBASE.dll
>>>> #3  0x00000004 in ?? ()
>>>> #4  0x74ed1a2c in KERNEL32!GetVolumePathNamesForVolumeNameA ()
>>>>      from /c/windows/syswow64/kernel32.dll
>>>> #5  0xff11c868 in ?? ()
>>>> #6  0x74ed4208 in KERNEL32!CheckForReadOnlyResource ()
>>>>      from /c/windows/syswow64/kernel32.dll
>>>> #7  0x00000004 in ?? ()
>>>> #8  0x610d0b24 in select_stuff::wait (this=0xff11cba4, readfds=0xff11cb00,
>>>>       writefds=0xff11cae0, exceptfds=0xff11cac0, ms=4294967295)
>>>>       at
>>>> /ext/build/netrel/src/cygwin-snapshot-20120525-1/winsup/cygwin/select.cc:320
>>>> #9  0x610d154b in cygwin_select (maxfds=13, readfds=0xff11cc70,
>>>>       writefds=0xff11cc50, exceptfds=0xff11cc30, to=0x0)
>>>>       at
>>>> /ext/build/netrel/src/cygwin-snapshot-20120525-1/winsup/cygwin/select.cc:158
>>>> #10 0x610b2b5a in poll (fds=0x8012db00, nfds=3, timeout=-1)
>>>>       at
>>>> /ext/build/netrel/src/cygwin-snapshot-20120525-1/winsup/cygwin/poll.cc:87
>>>> #11 0x610d5575 in _sigfe () from /usr/bin/cygwin1.dll
>>>> #12 0xffffffff in ?? ()
>>>> #13 0x8012db00 in ?? ()
>>>> #14 0x6ac1e759 in g_main_loop_run () from /usr/bin/cygglib-2.0-0.dll
>>>> #15 0x6ad96d40 in g_dbus_proxy_call_with_unix_fd_list_sync ()
>>>>      from /usr/bin/cyggio-2.0-0.dll
>>>> #16 0x6ac401ef in g_thread_proxy () from /usr/bin/cygglib-2.0-0.dll
>>>> #17 0x610fca42 in pthread::thread_init_wrapper (arg=0x80130e00)
>>>>       at
>>>> /ext/build/netrel/src/cygwin-snapshot-20120525-1/winsup/cygwin/thread.cc:2104
>>>> #18 0x61086f62 in thread_wrapper (arg=0x0)
>>>>       at
>>>> /ext/build/netrel/src/cygwin-snapshot-20120525-1/winsup/cygwin/miscfuncs.cc:547
>>>> #19 0x00000000 in ?? ()
>>>>
>>>> Thread 7 (Thread 2784.0xb4c):
>>>> #0  0x7702013d in ntdll!RtlEnableEarlyCriticalSectionEventCreation ()
>>>>      from /c/windows/SysWOW64/ntdll.dll
>>>> #1  0x7702013d in ntdll!RtlEnableEarlyCriticalSectionEventCreation ()
>>>>      from /c/windows/SysWOW64/ntdll.dll
>>>> #2  0x74fe0bdd in WaitForMultipleObjectsEx ()
>>>>      from /c/windows/syswow64/KERNELBASE.dll
>>>> #3  0x00000003 in ?? ()
>>>> #4  0x74ed1a2c in KERNEL32!GetVolumePathNamesForVolumeNameA ()
>>>>      from /c/windows/syswow64/kernel32.dll
>>>> #5  0xff21c858 in ?? ()
>>>> #6  0x74ed4208 in KERNEL32!CheckForReadOnlyResource ()
>>>>      from /c/windows/syswow64/kernel32.dll
>>>> #7  0x00000003 in ?? ()
>>>> #8  0x610d0b24 in select_stuff::wait (this=0xff21cb94, readfds=0xff21caf0,
>>>>       writefds=0xff21cad0, exceptfds=0xff21cab0, ms=4294967295)
>>>>       at
>>>> /ext/build/netrel/src/cygwin-snapshot-20120525-1/winsup/cygwin/select.cc:320
>>>> #9  0x610d154b in cygwin_select (maxfds=8, readfds=0xff21cc60,
>>>>       writefds=0xff21cc40, exceptfds=0xff21cc20, to=0x0)
>>>>       at
>>>> /ext/build/netrel/src/cygwin-snapshot-20120525-1/winsup/cygwin/select.cc:158
>>>> #10 0x610b2b5a in poll (fds=0x8009b3c0, nfds=1, timeout=-1)
>>>>       at
>>>> /ext/build/netrel/src/cygwin-snapshot-20120525-1/winsup/cygwin/poll.cc:87
>>>> #11 0x610d5575 in _sigfe () from /usr/bin/cygwin1.dll
>>>> #12 0xffffffff in ?? ()
>>>> #13 0x8009b3c0 in ?? ()
>>>> #14 0x6ac1e759 in g_main_loop_run () from /usr/bin/cygglib-2.0-0.dll
>>>> #15 0x63e32eca in gvdb_table_walk ()
>>>>      from /usr/lib/gio/modules/cygdconfsettings.dll
>>>> #16 0x6ac401ef in g_thread_proxy () from /usr/bin/cygglib-2.0-0.dll
>>>> #17 0x610fca42 in pthread::thread_init_wrapper (arg=0x8009c700)
>>>>       at
>>>> /ext/build/netrel/src/cygwin-snapshot-20120525-1/winsup/cygwin/thread.cc:2104
>>>> #18 0x61086f62 in thread_wrapper (arg=0x0)
>>>>       at
>>>> /ext/build/netrel/src/cygwin-snapshot-20120525-1/winsup/cygwin/miscfuncs.cc:547
>>>> #19 0x00000000 in ?? ()
>>>>
>>>> It looks like these threads are being used by GLib, which is running a
>>>> loop that calls poll, which calls cygwin_select.  So maybe the "better
>>>> patch" that you referred to would fix this hang.
>>>
>>> Ken, can you confirm/deny that the changes that I just made to select()
>>> at least still work as well as Corinna's temporary (that's what the
>>> ChangeLog says at least) change above?  They are in the latest snapshot.
>>
>> No, they don't.  There's no crash, but I'm seeing two problems in emacs
>> and a problem with the X server.  My emacs tests were done with emacs-24
>> in mintty on 64-bit Windows 7.  I wanted to test it under X also, but I
>> couldn't because of the X server problem.
>>
>> 1. When I type into emacs, it's very slow to echo the keystrokes and
>> respond.
>>
>> 2. When I start a shell under emacs (<Alt-X>shell<return>), the shell
>> doesn't finish initializing.  It doesn't display a prompt, and it
>> doesn't execute commands I type.
>>
>> 3. If I start the X server using the Start Menu shortcut, startxwin
>> never finishes, and the xterm window doesn't display.  I have to kill
>> startxwin from a terminal.
>
> All of the above should be fixed in the upcoming snapshot.

Confirmed.  Everything seems to work as it did after Corinna's change.

Ken


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