Re: I need your help! C++ exception in coroutine Crashes.

["Aidin Abedi" <aidinabedi@...>]

Hi

I solved the issue. I was running a luajit-modified 5.1.3 dll (the
jit-compiler was still not enabled). I switch to the official dll
(upgrading to 5.1.4 at the same time) and the crashing went away. now
all exceptions are catched. I will investigate later if this is an
luajit bug or just 5.1.3.

I thank you for your time. I'm also more aware that exceptions and
longjumps don't necessarily mix well.
I'm new to the mailing list and so far it is really a great resource.

Aidin

On Fri, Oct 3, 2008 at 10:36 PM, Ronald Lamprecht
<R.Lamprecht@t-online.de> wrote:
> Hi,
>
> May be your crash is not related to lua coroutines at all. I can confirm the
> statement of Alex that mixing up C++ exceptions with C longjumps is very
> critical. If you did not change the lua defaults for Windows you end up
> throwing an C++ exception that is caught by Lua and resubmitted as a C
> longjump! Unix like OS will use _longjmp/_setjmp and will likely run without
> problems.
>
> At our Enigma project (http://www.nongnu.org/enigma), we do not use
> coroutines, but do throw exceptions in the C++ engine which may pass several
> layers of Lua/C++ stack frames until caught. When switching the project from
> Lua 4.1 to Lua 5.1 we did run into sporadic crashes just on Windows. I
> finally solved this problem by redefinition of "LUAI_TRY" for Windows by
> adding to luaconf.h:
>
>> #if defined(__cplusplus) && defined(CXXLUA)
>> #undef LUAI_TRY
>> #define LUAI_TRY(L,c,a) try { a } catch(lua_longjmp*) \
>>        { if ((c)->status == 0) (c)->status = -1; }
>> #endif
>>
>> #endif
>
> If you like to check the related macros and changes, have look at our svn
> repository, revision 187. The problem had been discussed on our mailing list
> in June 2006
> (http://lists.gnu.org/archive/html/enigma-devel/2006-06/threads.html).
>
> Greets,
>
> Ronald
>
> Bilyk, Alex wrote:
>>
>> Well, this pattern ought to work as long as you don't call anything
>> L-related in your Cleanup(). You are likely to leak memory though, but it
>> shouldn't crash. Generally though, C++ exceptions and non-local C jumps that
>> Lua uses for coroutine management don't play well together.
>>
>> -----Original Message-----
>> From: lua-bounces@bazar2.conectiva.com.br
>> [mailto:lua-bounces@bazar2.conectiva.com.br] On Behalf Of Aidin Abedi
>> Sent: Thursday, October 02, 2008 2:05 PM
>> To: Lua list
>> Subject: Re: I need your help! C++ exception in coroutine Crashes.
>>
>> Thank you for your replies.
>> I have a panic handler but its not called since I only use lua_pcall.
>> I use exception-handling outside and it seems like coroutine.resume
>> disables it.
>> The code at its grittiest:
>>
>> ----------------------------------------
>> C++:
>>
>> int main() {
>>        try {
>>                lua_pcall(L, ...);
>>
>>        } catch (...) {
>>                Cleanup();
>>                exit(0);
>>        }
>>
>>        return 0;
>> }
>>
>> int ThrowCppException(lua_State *L) {
>>        throw "I'm a exception";
>>        return 0;
>> }
>>
>> ----------------------------------------
>> Lua:
>>
>> print "main"
>> ThrowCppException() -- app catches exception and exits gracefully
>>
>> function foo()
>>        print "coroutine"
>>        ThrowCppException() -- app crashes without catching exception
>> end
>>
>> co = coroutine.create(foo)
>> coroutine.resume(co)
>> ----------------------------------------
>>
>>
>> On Thu, Oct 2, 2008 at 9:57 PM, Bilyk, Alex <ABilyk@maxis.com> wrote:
>>>
>>> Do you handle the exception in the same function or someplace outside?
>>>
>>> -----Original Message-----
>>> From: lua-bounces@bazar2.conectiva.com.br
>>> [mailto:lua-bounces@bazar2.conectiva.com.br] On Behalf Of Patrick Donnelly
>>> Sent: Thursday, October 02, 2008 11:49 AM
>>> To: Lua list
>>> Subject: Re: I need your help! C++ exception in coroutine Crashes.
>>>
>>> On Thu, Oct 2, 2008 at 6:37 AM, Aidin Abedi <aidinabedi@gmail.com> wrote:
>>>>
>>>> Hello
>>>>
>>>> I've embedded lua and when I call a c++ function (that throws a c++
>>>> exception) inside a coroutine my app crashes badly. Windows just says:
>>>>
>>>> "Runtime Error!
>>>> This application has requested the Runtime to terminate it in an unusual
>>>> way.
>>>> Please contact the application's support team for more information."
>>>>
>>>> I do have a c++ exception-catch outside the pcall. There is no crash
>>>> if I call the same function (that throws a exception) from inside
>>>> lua's main-thread.
>>>>
>>>> This issue must have been detected before. Please help me!
>>>> I appreciate any ideas. I thank you for your time.
>>>>
>>> It sounds to me like you did a generic lua_call in the main thread
>>> (instead of lua_resume). When Lua catches the error, and no error
>>> handler was set for that thread, it will exit the main application.
>>> You should implement a panic handler to check if this is the case.
>>>
>>> Cheers,
>>>
>>> --
>>> -Patrick Donnelly
>>>
>>> "One of the lessons of history is that nothing is often a good thing
>>> to do and always a clever thing to say."
>>>
>>> -Will Durant
>>>
>>
>



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Aidin Abedi - IT Support
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