Re: [Caml-list] Core breaks backtraces

[Jeremie Dimino <jdimino@janestreet.com>]

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On Wed, Dec 18, 2013 at 6:17 AM, Ivan Gotovchits <ivg@ieee.org> wrote:

>
> Hi,
>
> I've tried a fabulous core library and it broke my exceptions :)
> All backtraces are now look like this
>
>   backtrace:
>   Raised at file "map.ml", line 117, characters 16-25
>   Called from file "lib/conv.ml", line 256, characters 19-50
>

This is from sexplib. The Exn module in Core_kernel registers an exception
printer which looks like this:

  let () =
    Printexc.register_printer (fun exc ->
      match sexp_of_exn_opt exc with
      | None -> None
      | Some sexp ->
        Some (Sexp.to_string_hum ~indent:2 sexp))

Now, if we look at what sexp_of_exn_opt is doing, in sexplib/lib/conv.ml,
line 256:

  match try Some (Addrs.find addr !exn_addr_map) with Not_found -> None with

Where Addrs is a Map.Make(_).

So for any exception that is not registered with sexplib, Addrs.find will
raise Not_found. And since there is one global backtrace buffer, the
backtrace gets replaced by this one. I guess we never had this problem
because we don't use exception much and the few we have are defined "with
sexp". We will work on a fix.

I don't have a precise idea for the second part of the problem (core eating
all memory).

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