Cygwin 1.7: Concurrency Issue with Shared State Initialization
Christopher Faylor
cgf-use-the-mailinglist-please@cygwin.com
Fri Mar 12 21:29:00 GMT 2010
On Fri, Mar 12, 2010 at 04:48:14PM +0100, Schmidt, Oliver wrote:
>Hi,
>
>> Does the patch help?
>
>As the issue is sporadic it's not that easy to come up with a conclusive
>answer...
>
>I downloaded http://cygwin.com/snapshots/cygwin1-20100309.dll.bz2,
>unpacked and renamed the DLL and used it as drop-in replacement to the
>1.7.1 DLL.
>
>I experienced three times by now the effect that echo.exe "hangs" without
>using significant CPU time.
Is echo being run under a bash shell? From the command prompt? In a
.bat file? Repeatedly in a loop?
>Attaching a MSVC debugger I could only find
>out that in all three cases the executable stays in this endless loop:
>
>7D6373D2 cmp dword ptr ds:[7D6A0220h],edi
>7D6373D8 jne 7D628061
>7D6373DE lea eax,[ebp-28h]
>7D6373E1 push eax
>7D6373E2 push ebx
>7D6373E3 call 7D61CCB1
>7D6373E8 cmp eax,ebx
>7D6373EA jge 7D6373D2
>
>I'm sort of reluctant to present this information this way as I'm afraid
>I'm to give someone a bum steer. However I haven't had this effect so far
>with with the 1.7.1 DLL so it would be at least one possible explanation
>that the patch has a bug showing up in the very sporadic case it is
>supposed to fix.
If you also grab cygwin1-*.dbg.bz2 and uncompress it next to cygwin1.dll
as "cygwin1.dbg" you should be able to attach to a hung process with gdb
and get a backtrace with symbols:
c:\>c:\cygwin\bin\gdb /bin/echo.exe <pid>
(gdb) bt
That may provide more details about where the process is hanging.
Also if you can capture the first few screens after typing:
(gdb) x/80x $esp
(gdb) <just hit enter here>
that would be useful.
cgf
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