Re: how to clean user

On 10/23/2013 02:44 PM, Tad Szuba wrote:
> Hi!
>
> One question more ...

Please keep discussions on the list.

> Let's say; the process of activating agent's inference in Prolog will be
> activated 10 000 times (or more)
> with abolish/1 at the end of every activation ...
>
> There will be any stack overflow danger ??

Why would there be?  The program is not on the stack anyway.  If
you the code each time in a new module (and I guess try to destroy)
the old one) you'll have 10,000 modules with in each of them the
(now empty) predicates.  That might be a serious amount of lost
memory.  You'd better to a bit of testing and math.

	Cheers --- Jan

>
> With best regards
> Tad
> ////////////////////
>
> -----Oryginalna wiadomość----- From: Jan Wielemaker
> Sent: Wednesday, October 23, 2013 1:45 PM
> To: Tad Szuba ; Prolog mailing list
> Subject: Re: how to clean user
>
> Tad,
>
> There are enough ways to isolate and clean data.  A total reset
> is hardly ever a good idea and pretty hard to implement because
> there is a lot of state in the system.  Eventually,
> SWI-Prolog is likely to get a transactional database, which can
> simplify some of these scenarios.
>
> A bigger worry for this type of dynamically swapping code however is
> that not everything is reclaimed, so you will suffer from memory leaks.
> Notably modules, predicates and functors (name/arity pairs) are never
> reclaimed.  Modules can be wiped, but the module structure is not
> deleted and while the clauses of a predicate are truely removed, the
> predicate structure is not.
>
> So, somehow you have to ensure that you reuse modules and predicates
> if you want to run 24*7.
>
> Cheers --- Jan
>
> On 10/23/2013 01:29 PM, Tad Szuba wrote:
>> Hi!
>>
>> Thanks! - now I will experiment with abolish/1
>>
>> However; I think, that function for reseting the user is necessary.
>>
>> I case of "intelligent agents" ; even single agent is restarting again
>> and again his business planning strategy ;
>>
>> from scratch, because new facts are emerging and continuation of
>> previous thread of inference is bad solution.
>>
>> With best regards
>> Tad
>> //////////////////////////////////
>>
>>
>> -----Oryginalna wiadomość----- From: Jan Wielemaker
>> Sent: Wednesday, October 23, 2013 1:03 PM
>> To: Tad Szuba ; Paul Singleton
>> Subject: Re: how to clean user
>>
>> On 10/23/2013 11:48 AM, Tad Szuba wrote:
>>> Hi!
>>>
>>> My Java --> Prolog --> Java system
>>>      for A. Smith Invisible Hand of Market simulations is "almost
>>> working"
>>>
>>>    however I face problem ...
>>>
>>> When Prolog is used for next agent to infer for him (file
>>> wantsToBuy4878293086935712258)
>>>
>>> Prolog "user"  remembers predicates from previous inference (file
>>> wantsToBuy126437475720758049)
>>>
>>> see:
>>> ERROR: c:/users/user/workspace/mainmodule4254950593641732242.pl:1:
>>>     import/1: No permission to import
>>> wantsToBuy4878293086935712258:goodsWB/5 into user (already imported from
>>> wantsToBuy126437475720758049)
>>>
>>> Question is on how to reset/clean "user" without total restart of Prolog
>>> ...
>>
>> I guess that the simplest option is to make sure it isn't imported into
>> user in the first place.  I.e., do not export anything from your modules
>> and simply call the predicate in its module.
>>
>> But, you can also call abolish/1 on these predicates.  Abolish on an
>> imported predicate removes the import, not the predicate itself.
>>
>> Cheers --- Jan
>>
>>>
>>> I have found some old (2004) discussion regarding this problem between
>>> Paul and Michal Jakob from
>>> FEE Czech Technical University Prague; but without clear solution.
>>>
>>> With best regards
>>> Tad Szuba
>>> Cracow, Poland
>>>
>>
>

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