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

[Kakadu <kakadu.hafanana@gmail.com>]

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

Best wishes,
Kakadu


On Sat, Nov 17, 2012 at 10:29 PM, Samuel Hornus <Samuel.Hornus@inria.fr>wrote:

>
> Dear all,
>
> I have two questions.
>
> 1/ I'm writing a stub to the C++ ANN library [1] to find geometric
> neighboring points in space.
> The constructor of the main class in this library uses a lot of allocation
> with the "new" C++ keyword.
> For small input point sets (e.g. 2500 points), it all seems to work fine.
> For larger ones (50 K points), the C++ constructor crashes.
> My question is : is it possible that the C++ "new" allocator differs
> sufficiently from the C-style malloc, that bad interactions with OCaml heap
> happen ?
>
> (I'm passing the input points coordinates in a plain bigarray.)
>
> 2/ Regarding bigarray: before using them, I let the C++ constructor
> access, and keep pointers inside regular OCaml [float array] or [float
> array array]. It was working well (again, for small input point set), but
> is that safe ? Or can the garbage collector eventually relocate the content
> of a  [float array]  or of a [float array array] ? so that the pointer kept
> in the C++ class would become dangling ?
>
> Thank you in advance,
> Sam
>
> [1] Approximate Nearest Neighbors http://www.cs.umd.edu/~mount/ANN/
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