[Caml-list] Possible bug in DynArray module from ExtLib

[Caml-list] Possible bug in DynArray module from ExtLib

[Dário Abdulrehman]

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The first of the following functions causes a "Fatal error: exception
Out_of_memory", while the second works fine.
This error seems to occur when creating large arrays with more than 2
million and something entries.
Anyone noticed this error?

Thanks.

  let test_dynarray1 () =
    let a = DynArray.create () in
    for i = 1 to 2817131 do
      DynArray.add a i
    done

  let test_dynarray2 () =
    let a = DynArray.make 2817131 in
    for i = 1 to 2817131 do
      DynArray.add a i
    done


-- 
Dário Abdulrehman

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Re: [Caml-list] Possible bug in DynArray module from ExtLib

[Florian Weimer]

* Dário Abdulrehman:

> The first of the following functions causes a "Fatal error: exception
> Out_of_memory", while the second works fine.
> This error seems to occur when creating large arrays with more than 2
> million and something entries.

The exponential resizer probably exceeds Ocaml's array length limit,
while direct creation does not.

Re: [Caml-list] Possible bug in DynArray module from ExtLib

[Dário Abdulrehman]

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I took a look at the DynArray implementation and it seems to be that.

On 3/31/07, Florian Weimer <fw@deneb.enyo.de> wrote:
>
> * Dário Abdulrehman:
>
> > The first of the following functions causes a "Fatal error: exception
> > Out_of_memory", while the second works fine.
> > This error seems to occur when creating large arrays with more than 2
> > million and something entries.
>
> The exponential resizer probably exceeds Ocaml's array length limit,
> while direct creation does not.
>



-- 
Dário Abdulrehman

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Re: [Caml-list] Possible bug in DynArray module from ExtLib

[ls-ocaml-developer-2006]

Florian Weimer <fw@deneb.enyo.de> writes:

> * Dário Abdulrehman:
>
>> The first of the following functions causes a "Fatal error: exception
>> Out_of_memory", while the second works fine.
>> This error seems to occur when creating large arrays with more than 2
>> million and something entries.
>
> The exponential resizer probably exceeds Ocaml's array length limit,
> while direct creation does not.

So a smarter resizer would be required: One which compares with the
array length limit and satisfies the request with that if necessary
and possible.

Regards -- Markus

Re: [Caml-list] Possible bug in DynArray module from ExtLib

[skaller]

On Wed, 2007-04-04 at 00:40 +0200,
ls-ocaml-developer-2006@m-e-leypold.de wrote:

> > The exponential resizer probably exceeds Ocaml's array length limit,
> > while direct creation does not.
> 
> So a smarter resizer would be required: One which compares with the
> array length limit and satisfies the request with that if necessary
> and possible.

AFAIK DynArray has a resizer following my suggestion: you can
supply an arbitrary resizer function on construction, presumably with a
defaulted labelled argument (its the standard
library Buffer that doesn't have one).
I'm not sure, it's a while since I looked at ExtLib .. CC'd to
Nicolas who owns the library.

-- 
John Skaller <skaller at users dot sf dot net>
Felix, successor to C++: http://felix.sf.net