Re: [Boost-users] shared_array EXC_BAD_ACCESS

From: Christopher Hunt (huntc_at_[hidden])
Date: 2005-08-01 19:52:34

I have some more information and a work-around. I can now reproduce  
this problem in my Obj-C program with the following code:

     typedef checked_array_deleter<unsigned short> deleter;
     detail::sp_counted_base_impl<unsigned short, deleter>* theP = new  
detail::sp_counted_base_impl<unsigned short, deleter>(0, deleter());

However if I define either BOOST_SP_USE_QUICK_ALLOCATOR or  
BOOST_SP_USE_STD_ALLOCATOR then all is well. :-)

Here's my new stack trace for when things don't go well:

#0	0x90012d68 in pthread_mutex_init
#1	0x00088484 in boost::detail::lightweight_mutex::lightweight_mutex()  
at lwm_pthreads.hpp:47
#2	0x00088084 in boost::detail::lightweight_mutex::lightweight_mutex()  
at lwm_pthreads.hpp:49
#3	0x00087c24 in boost::detail::sp_counted_base::sp_counted_base() at  
shared_count.hpp:98
#4	0x00086674 in boost::detail::sp_counted_base::sp_counted_base() at  
shared_count.hpp:99
#5	0x00097f64 in boost::detail::sp_counted_base_impl<unsigned short,  
boost::checked_array_deleter<unsigned short>  
 >::sp_counted_base_impl(unsigned short,  
boost::checked_array_deleter<unsigned short>) at shared_count.hpp:253
#6	0x00097f0c in boost::detail::sp_counted_base_impl<unsigned short,  
boost::checked_array_deleter<unsigned short>  
 >::sp_counted_base_impl(unsigned short,  
boost::checked_array_deleter<unsigned short>) at shared_count.hpp:253

This thus looks like something to do with allocators and  
sp_counted_based_impl...

I don't see that my Obj-C environment has set up anything interesting  
by the way of allocators, and I did create a brand-new Obj-C project to  
see if I could reproduce the problem - I couldn't... however I'm  
thinking that this might well have something to do with Obj-C...

Any ideas?

Also, if I'm to define BOOST_SP_USE_QUICK_ALLOCATOR or  
BOOST_SP_USE_STD_ALLOCATOR then which is best? I've been unable to find  
documentation on the use of these defines.

Thanks for your help.

Cheers,
-C

On 30/07/2005, at 9:28 AM, Christopher Hunt wrote:

>>> When UTFStringHolder is instantiated, I get an EXC_BAD_ACCESS and my
>>> stack trace shows that pthread_mutex_init is being called. Here's the
>>> complete stack trace:
>>>
>>> #0 0x90012730 in _pthread_mutex_init
>>> #1 0x00088424 in  
>>> boost::detail::lightweight_mutex::lightweight_mutex()
>>> at lwm_pthreads.hpp:47
>>
>> These things usually happen when you have inconsistent definitions of
>> BOOST_HAS_THREADS in the source files or libraries that form your  
>> program.
>> Does the code still fail when you try it as a single self-contained  
>> source
>> file? If it does, can you post a minimal example that fails?
> Unfortunately it is not reproducible in a single self-contained  
> file... which is interesting isn't it...
>
> Also, I've managed successfully to have a shared_array member as part  
> of another class's instantiation. The only difference that I see is  
> the timing of when they're instantiated.
>
> Could it be anything to do with the initialisation of my pthread  
> environment? (what initialises pthreads?) I'll do some experiments  
> around this. If it is of interest, this is all being done in a Mac OS  
> X Cocoa Objective-C environment. Cocoa likes to know when it is going  
> multi-threaded  
> (http://developer.apple.com/documentation/Cocoa/Conceptual/ 
> Multithreading/articles/CocoaDetaching.html) and I do let it know, but  
> maybe I should let it know earlier.
>
> Thanks for your help. I'll do some more experimentation around the  
> timing of instantiation.