GIRAPH-1085: Add InMemoryDataAccessor
Summary: When we deal with graphs which have a lot of vertices with very little total data associated with them (values + edges) we start experiencing memory problems because of too many objects created, since every vertex has multiple objects associated with it. To solve this problem, we should have a serialized partition representation (current ByteArrayPartition just keeps byte[] per vertex, not per partition). We can leverage the out-of-core infrastructure and just add data accessor which won't be backed by disk but in memory buffers.
Test Plan: Successfully ran a job which was failing without this.
Differential Revision: https://reviews.facebook.net/D60435
4 files changed
