Re: [Caml-list] Segfault in C++ stub with many 'new' allocations

[Samuel Hornus <Samuel.Hornus@inria.fr>]

On 17 nov. 2012, at 19:35, Kakadu wrote:

> 2) AFAIR there are functions like register_global_root which prevents GC from moving values.

Thank you Kakadu. It is interesting to know that one can use this function directly. I knew its existence only through the CAML[x]param* macros…

Regarding my first question, if it can help, here is the relevant part of my C++ code:
---8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<---
ANNbd_tree * create_bd_tree_flat(ANNcoord * arr, int n, int dim)
{
	// ANNcoord = double
	// ANNpoint = double*
	// ANNpointArray = double**

    ANNbd_tree * ptr;
    std::cerr << "\nCreating flat Bd_tree with " << n << " points of dim " << dim;

    ANNpointArray ptarr = new ANNpoint[n];
    for( int i = 0; i < n; ++i )
    {
        ptarr[i] = arr + dim * i;
    }
    std::cerr << " CHK ";
    ptr = new ANNbd_tree(ptarr,n,dim); // Crashes here when 'n' is big
    std::cerr << "done";
    return ptr;
}

extern "C" value ann_create_bd_tree_flat_ba (value ba, value n, value dim)
{
    CAMLparam3(ba,n,dim);
    ANNbd_tree * ptr = create_bd_tree_flat((ANNcoord*)Caml_ba_data_val(ba), Int_val(n), Int_val(dim));
    CAMLreturn ((value)ptr);
}
---8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<---

The second function is called from OCaml, and the crash happens in the first function, in the constructor ANNbd_tree() ("CHK" is printed on the terminal, "done" is not)
-- 
Sam