[Boost-users] [1.33.1] Problem with fast_pool_allocator across DLL boundaries?

From: Andrew Bancroft (ABancroft_at_[hidden])
Date: 2007-05-17 10:46:25

Platform: Win32, VC 7 & VC 8.1.

I have run into a problem using fast_pool_allocator across DLLs: it
'leaks' memory. 

In this example, DLL A:
1. declares a container type that uses fast_pool_allocator
2. provides a function to populate the container type
DLL B creates instance(s) of the container type & calls DLL A to
populate those instances.

DLL A
-----
        
struct S
{
        /* A bunch of data */
};
typedef std::list<S, boost::fast_pool_allocator<S> > container_of_s;

/* Fills s with a number of S instances */
void dll_populate_container_of_s(container_of_s &s);

DLL B
-----

void fun_a()
{
        for (int nLoop=0; nLoop<100; ++nLoop)
        {
                container_of_s sc;
                dll_populate_container_of_s(sc);

                /* manipulate sc in some way */

                /* sc is destroyed, but memory is not returned to the
pool it was allocated from */
        }
}

The problem is that the memory allocated by fast_pool_allocator inside
DLL A (by dll_populate_container_of_s) is not returned to the same pool
it was allocated from. I've tracked this down to fast_pool_allocator
being backed by a singleton. It turns out that each DLL get's it's own
copy of that singleton. So the memory allocated by
fast_pool_allocator<S> inside DLL A is returned to a different
fast_pool_allocator<S> inside DLL B.

Technically not a leak, but the end result is that repeated calls to
dll_populate_container_of_s cause more & more memory to be consumed.

Does anyone have a solution or workaround for this? Or an alternate pool
allocator?

Thanks

Andrew

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