Re: [Jung-support] Does PageRank Take Much Memory?

[Joshua O'M. <jos...@gm...>]

Bing:

You're creating a lot of objects, so the memory usage is going to go up.
 Since you're not actually running out of memory, it sounds like the Java
garbage collector is doing its job; as soon as the graph and ranker go out
of scope (i.e., when the rank() method returns) they are eligible for GC
and will be collected when the space is needed.  It's not clear that you
have an actual problem here.

I would point out that there's not necessarily a lot of point to building
an edgeSet, i.e., the Graph encodes this information itself so there's no
need for you to do it again.  That is, just build the Graph instead of the
edge set and you'll save some space (and time) right there.

Joshua

On Wed, Sep 26, 2012 at 8:50 AM, Bing Li <lb...@gm...> wrote:

> Dear all,
>
> It is found that a large amount of memory is taken when ranking with
> PageRank, from JUNG 2.0.1. When starting to rank, the memory consumption
> goes high and when the ranking is done, it memory usage gets low.
>
> According to jconsole, the memory usage jumps with a large range, such as
> 200M ~1.2G. Is it normal?
>
> I am still not sure if it is caused by PageRank. However, I notice one
> problem that I have to initialize an instance of PageRank and Graph each
> time when ranking a group.
>
> I think it must be better if the PageRank or Graph can be reused. When a
> new graph is available, PageRank or Graph can be reset or cleared. But no
> such methods are available, right? Any other ways to solve the potential
> problem?
>
> The code is listed as follows. The method is invoked many times because
> there are a lot of graphs in my systems and each of them must be ranked
> periodically. So the memory usage goes up and down in a large range
> periodically.
>
>         public Map<T, Double> Rank(HashMap<T, Vertex<T>> vertexMap,
> Set<Edge<T>> edgeSet)
>         {
>                 HashMap<T, Double> finalRankMap = new HashMap<T, Double>();
>                 PageRank<Vertex<T>, Edge<T>> ranker;
>                 Graph<Vertex<T>, Edge<T>> graph = new
> DirectedSparseMultigraph<Vertex<T>, Edge<T>>();
>                 for (Edge<T> edge : edgeSet)
>                 {
>                         graph.addEdge(edge, edge.GetSourceVertex(),
> edge.GetDestinationVertex(), EdgeType.DIRECTED);
>                 }
>                 ranker = new PageRank<Vertex<T>, Edge<T>>(graph,
> this.weightTransformer, RankingConfig.RANDOM_JUMP_PROPABILITY);
>                 ranker.evaluate();
>
>                 for (Vertex<T> vertex : vertexMap.values())
>                 {
>                         try
>                         {
>                                 finalRankMap.put(vertex.GetKey(),
> ranker.getVertexScore(vertex));
>                         }
>                         catch (IllegalArgumentException e)
>                         {
>                                 e.printStackTrace();
>                         }
>                 }
>                 return finalRankMap;
>         }
>
> I appreciates so much for your help!
>
> Best regards,
> Bing
>
>
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-- 
jos...@gm.........sites.google.com/site/joshuaomadadhain/
   Joshua O'Madadhain: Information Scientist, Musician, Philosopher-At-Tall
It's that moment of dawning comprehension that I live for.  -- Bill
Watterson
 My opinions are too rational and insightful to be those of any
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