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https://issues.apache.org/jira/browse/GIRAPH-243?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Alessandro Presta resolved GIRAPH-243.
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Resolution: Fixed
Fix included in GIRAPH-244
> EdgeListVertex performance is sub-optimal
> -----------------------------------------
>
> Key: GIRAPH-243
> URL: https://issues.apache.org/jira/browse/GIRAPH-243
> Project: Giraph
> Issue Type: Improvement
> Components: graph
> Reporter: Alessandro Presta
> Assignee: Alessandro Presta
>
> Iterating over outgoing edges (both vertex id and value) in an EdgeListVertex
> is O(n log n): you have to iterate over getOutEdgesIterator and call
> getEdgeValue (which is logarithmic) at each iteration.
> If we store the edge list as a list of Edge<I, E> (instead of the current two
> lists), iteration becomes linear time (which I think is what most people
> expect from an adjacency-list representation).
> Furthermore, I think we can avoid sorting the list by ID: addEdge and
> removeEdge are currently linear-time because we are using an ArrayList, so
> the binary search doesn't help much. If we don't sort, at least addEdge
> becomes amortized constant-time.
> This improvement would require an API change: getOutEdgesIterator should
> iterate over Edge<I, E> as opposed to just I.
> What I propose is to have both iterators (the current one could be called
> getNeighborsIterator), with a default implementation of the neighbors
> iterator in terms of the edges iterator, and optimizations left to
> implementors (e.g. IntIntNullIntVertex).
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