The distributed storage engine used by Ray is a distributed sparse hash table that
uses these features:

- incremental resizing
- double hashing
- buckets are in groups
- distributed


The run-time options:


  Distributed storage engine

       -hash-table-buckets buckets
              Sets the initial number of buckets. Must be a power of 2 !
              Default value: 262144

       -hash-table-buckets-per-group buckets
              Sets the number of buckets per group for sparse storage
              Default value: 64, Must be between >=1 and <= 64

       -hash-table-load-factor-threshold threshold
              Sets the load factor threshold for real-time resizing
              Default value: 0.6, must be >= 0.5 and < 1

       -hash-table-verbosity
              Activates verbosity for the distributed storage engine