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

[Bing Li <lb...@gm...>]

Dear Joshua,

Thanks so much for your reply!

In my system, there are a lot of graphs. To speed the ranking, concurrency
solution is designed. But the memory is costed a lot.

For the edgeSet, the reason is that I need to set weights for each edge.
The weights depend on my system's application tightly. May I have other way
to set the weights and save the memory?

Best regards,
Bing

On Thu, Sep 27, 2012 at 12:48 AM, Joshua O'Madadhain <
jos...@gm...> wrote:

> 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
> organization.
>
>