RE: [Swarm-Support] memory problems

[Marshall, James A R]

Paul,
  just to remind you, I had a look at memory leaks to do with probes over
the last year or so and wrote some test code... could be related to
Marcello's problem:
http://www.santafe.edu/projects/swarm/archive/list-archive.0209/0072.html
  Not sure if that was the last word I had to say on the subject, as the
mailing list archives seem to be in a bit of a sorry state ... searching
doesn't work, archives after May 2002 aren't indexed, and I can't find any
of the archives for 2003.
  Hope this is of some help,
        James

---
Dr James A R Marshall
Complex Systems Modelling Group (COSMIC)
Department of Earth Science and Engineering
Imperial College London
Tel: +44 (0)20 7594 7493
Fax: +44 (0)20 7594 7444
Container World Project - http://www.ese.ic.ac.uk/research/containerworld/



-----Original Message-----
From: Paul E. Johnson [mailto:address@hidden
Sent: 04 June 2003 16:27
To: address@hidden
Subject: Re: [Swarm-Support] memory problems


THanks very much for pointing me at this problem. As I expected, it is a 
memory leak related to probe creation, and I'm going to keep trying to 
understand why it happens.

pj


Marcello wrote:

>Thanks a lot for the reply. Following Paul's suggestion, I wrote a
>method to make the computations I needed on the agents, so I do not need
>EZDistribution anymore. 
>
>In case someone might be interested in debugging the memory leak, I have
>done some experiments with EZDistribution (and EZBin as well), and the
>problem does not seem to be related with dropping the object: I found
>that there is a huge memory usage increase even when only *one*
>EZDistribution is created, and each agent only updates it. 
>
>Specifically, I create a single instance of EZDistribution in
>SwarmModel, which can be accessed by each agent via a method call. 
>Now each agent calls the collection upon which EZDistribution operates,
>the agent cleans up the collection and add new agents, updates the
>distribution and forget about it. Even in this case, I can get my
>program using up to 300mg in a little while.
>
>CODE
>in Swarm model (- buildObjects )
>
>  somePeople=[List create: [self getZone]];
>
>  somePeopleTab=[EZBin createBegin: [self getZone]];
>  [somePeopleTab setTitle: "stats"];
>  [somePeopleTab setGraphics:0];
>  [somePeopleTab setBinCount: 5];
>  [somePeopleTab setLowerBound: 0];
>  [somePeopleTab setUpperBound: 5];
>  [somePeopleTab setCollection: somePeople ];
>  [somePeopleTab setProbedSelector: M(getTypology) ];
>  [somePeopleTab createEnd];
>
>//// other code
>
>- getSomePeople {
>
>return somePeople;
>} 
>
>
>- getSomePeopleTab {
>
>return somePeopleTab;
>} 
>
>
>(In Agent.m)
>
>  id observed;
>  id group;
>
>    group=[model getSomePeople];
>    [group removeAll];
> 
>   //this fill up "group"
>  for (i=0; i<10;i++) {
>    while ([group contains: (observed = [self look])] ) ; 
>     [group addLast:observed];
> }
>  [[model getSomePeopleTab] update]; //if I remove this, no memory
>problem occurs. With this line, the program grows (very roughly) about
>1mg for each thousand calls .
>
>
>// other unrelated stuff
>
>
>
>
>
>Thanks again
>marcello
>
>
>
>
>On Tue, 2003-06-03 at 20:35, Paul E Johnson wrote:
>  
>
>>I agree that the drop on the EZDistribution object should give all the 
>>memory back, but I don't think most people have tried to use that class 
>>in this way and so, if there is a memory leak, we have not been alerted 
>>to it yet.  I found a memory leak, which I still have not solved, in a 
>>method that used probes to retrieve double-valued variables, and if you 
>>are doing that, I expect you could see the same issue.
>>
>>I think that you should redesign your class so that each agent only 
>>creates one EZDistribution as an instance variable and then use it over 
>>and over.  There is no need to create and drop at every time.
>>
>>The other (better!) possibility is you should find a better way to 
>>collect the information you want.  For example, are you just trying to 
>>get a tabulation of how many agents there are in each group?  If so, 
>>consider using a method like (off the top of my head, excuse typos)
>>
>>
>>suppose there is an instance variable
>>
>>int tabulator[6]; //need 6 because your example shows values from 0 to 5
>>                   //not 5 binCount as you have;
>>
>>and somewhere you initialize that to 0's
>>
>>Then call a method that does the tabulation. This will be much faster 
>>than creating a big old EZDistribution.
>>
>>- tabulateDistribution
>>{
>>    id index = [group begin];
>>    id anObject;
>>
>>    for (anObject=[index next]; [index getLoc == Member]; 
>>anObject=[index next])
>>        {
>>       int agentValue = [anObject getTypology];
>>       tabulator[agentValue]++;
>>         }
>>}
>>
>>
>>Or, if you just want to calculate an average or standard deviation, you 
>>can do that more easily with EZGraph, I can show you how if you need.
>>
>>Sorry, gotta run to a meeting.
>>    
>>


-- 
Paul E. Johnson                       email: address@hidden
Dept. of Political Science            http://lark.cc.ukans.edu/~pauljohn
University of Kansas                  Office: (785) 864-9086
Lawrence, Kansas 66045                FAX: (785) 864-5700


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