If you are comfortable looking at the code then the files you need to look at
areHashMasterPartitioner
(giraph/giraph-core/src/main/java/org/apache/giraph/partition/HashMasterPartitioner.java)HashWorkerPartitioner
(giraph/giraph-core/src/main/java/org/apache/giraph/partition/HashWorkerPartitioner.java)
Master computes the number of partitions by usingcreateInitialPartitionOwners
which calls into PartitionUtils#computePartitionCount methodin most cases the
partition count is just numAvailableWorkers*numAvailableWorkers (you can see
for yourself in the code in PartitionUtils.java)
The hash function is nothing fancy it is just vertexId.hashCode() -> u can see
in code at HashWorkerPartitioner#getPartitionOwner
Hope that helps.
> Date: Fri, 28 Nov 2014 11:24:40 +0530> Subject: Graph partitioning algorithm
> From: [email protected]
> To: [email protected]
>
> Can someone help me out with the algorithm to assign node to the worker, in
> Giraph.
>
> I read somewhere that, master selects the number of partition i.e N and
> than do a
> hash(Vertex_ID)/N on each vertex to know its partition.
>
> will be thankful if someone can explain what this N means and what this
> hash function actually is.
>
> Also kindly correct my thought process if my understanding is wrong
> regarding the same or provide me some link where I can get the details.
>
>
>
> --
> *Thanks & Regards*
> *Phalguni Mukherjee*
