Improve the scale & performance of the MD-SAL in-memory data store.

The system performance for Service chaining objects is as follows:

Performance was around 400 req/sec the entire time and CPU only 4%.

After all GC was done it took heap memory for 1M simple objects was around 1.5GB.

The controller was run with the following JVM parameters:

-Xmx4G -XX:+UseG1GC -XX:MaxPermSize=512m -Xms4G

We need to optimize the memory utilization. Also, the low memory utilization may indicate contention. Needs to be profiled and potential bottlenecks identified and removed.