[racket] FW: q about code for partitions

What you describe seems more like a bug in partitions than a documentation bug.
Do you have a small example that provoke a segfault?

/Jens Axel


2014-07-17 12:41 GMT+02:00 Jos Koot <jos.koot at gmail.com>:
> The documentation of partitions has not yet been updated, as far as I can
> see in version 6.0.1.13--2014-07-08(7735dd0/a) [3m]. I don't want to hurry
> up things (there may be other priorities) but when the docs will be updated,
> I think they should include a warning against calling function partitions
> from two concurrently running futures or threads. Reason is the non atomic
> memoization. (let alone calling set-partitions-cache in one process while
> another one is consulting/updating the cache)
>
> Calling partitions from two concurrent futures gives me a segfault. Not a
> surprise.
> Up to now calling from two concurrent threads gives me correct results, but
> slows down vvveeerrryyy much.
> I assume concurrent threads can lead to the same problems as concurrent
> futures, though.
> If I understand places correctly, calling from concurrent places should go
> well. Do I understand correctly?
>
> Jos
>
>> -----Original Message-----
>> From: Vincent St-Amour [mailto:stamourv at ccs.neu.edu]
>> Sent: domingo, 29 de junio de 2014 22:52
>> To: Eric Dobson
>> Cc: Jos Koot; Matthew Flatt; Jens Axel Søgaard; Racket Users List
>> Subject: Re: [racket] FW: q about code for partitions
>>
>> Ah, that explains it. Thanks!
>>
>> Vincent
>>
>>
>> At Sun, 29 Jun 2014 12:32:48 -0700,
>> Eric Dobson wrote:
>> >
>> > Vincent: exact-zero? is defined through 'make-predicate' which uses
>> > contract machinery to generate the function. I filed a
>> couple of bugs
>> > tracking some of the slowness issues. There is no `contract` form
>> > though so I doubt that the coach will find it.
>> >
>> >
>> http://bugs.racket-lang.org/query/?cmd=view%20audit-trail&data
> base=default&pr=14610
>> >
>> http://bugs.racket-lang.org/query/?cmd=view%20audit-trail&data
> base=default&pr=14611
>> >
>> > On Sun, Jun 29, 2014 at 11:53 AM, Jos Koot
>> <jos.koot at gmail.com> wrote:
>> > > Great work, Jens. I am glad my approach as been adopted
>> (and much improved
>> > > without deviating from the original idea of simpler
>> recurrence). When can we
>> > > expect it in the next nightly build?
>> > >
>> > > Thanks, Jos
>> > >
>> > >> -----Original Message-----
>> > >> From: jensaxelsoegaard at gmail.com
>> > >> [mailto:jensaxelsoegaard at gmail.com] On Behalf Of Jens
>> Axel Søgaard
>> > >> Sent: domingo, 29 de junio de 2014 12:48
>> > >> To: Matthew Flatt
>> > >> Cc: Jos Koot; Racket Users List
>> > >> Subject: Re: [racket] FW: q about code for partitions
>> > >>
>> > >> I have made a new vector version using zero? instead of
>> exact-zero?.
>> > >>
>> > >> To give users a chance to remove the cache after doing
>> > >> partitions calculations,
>> > >> I have added set-partitions-cache.
>> > >>
>> > >>    Code:
>> > >>
>> > >> https://github.com/soegaard/racket/blob/patch-14/pkgs/math-pkg
>> > > s/math-lib/math/private/number-theory/partitions.rkt
>> > >>
>> > >>    Discussion:
>> > >>     https://github.com/plt/racket/pull/697
>> > >>
>> > >> /Jens Axel
>> > >>
>> > >>
>> > >> 2014-06-29 12:44 GMT+02:00 Jens Axel Søgaard
>> <jensaxel at soegaard.net>:
>> > >> > 2014-06-29 8:47 GMT+02:00 Matthew Flatt <mflatt at cs.utah.edu>:
>> > >> >> It looks like "partitions2.rkt" ends up calling a
>> contract-wrapped
>> > >> >> variant of `exact-zero?`.
>> > >> >
>> > >> > That explains why Eric saw an improvement, when the used #f
>> > >> instead of
>> > >> > 0 as the not-cached-yet value.
>> > >> >
>> > >> > /Jens Axel
>> > >>
>> > >>
>> > >>
>> > >> --
>> > >> --
>> > >> Jens Axel Søgaard
>> > >
>> > >
>> > > ____________________
>> > >   Racket Users list:
>> > >   http://lists.racket-lang.org/users
>> >
>> > ____________________
>> >   Racket Users list:
>> >   http://lists.racket-lang.org/users
>
>
> ____________________
>   Racket Users list:
>   http://lists.racket-lang.org/users



-- 
--
Jens Axel Søgaard