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From Paolo Castagna <>
Subject Re: Should it be possible to extend BasicVertex<I,V,E,M>?
Date Tue, 22 May 2012 08:51:22 GMT
Benjamin Heitmann wrote:
> Users are supposed to extend HashMapVertex or EdgeListVertex (both in org.apache.giraph.graph).

HashMapVertex's Javadoc says: "User applications which need to implement their
own in-memory data structures should subclass {@link MutableVertex}.".

However, it is not possible to subclass MutableVertex for the same reason we
were discussing earlier when I wrongly tried to extend BasicVertex: putMessages
and releaseResources methods are package private.

At the moment, I do not need to subclass MutableVertex directly and I can
subclass EdgeListVertex.

However, I was thinking that, as Javadoc says, giving users the ability to
choose their own in-memory data structures could be quite useful (in particular
if some advanced users want to try to use data structures which can spill on
disk or indexes and memory mapped files (as we do with TDB in Apache Jena [1])).
Others might want to try different graph databases to overcome the 'everything
must fit into RAM' limitation.

In summary, my question is: should advanced Giraph developers be allowed to
subclass MutableVertex?



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