Questions about production config of middel manager node

Hi,
Hi,
I have some questions about the production config of middel manager node.

As it described.(http://druid.io/docs/0.8.2/configuration/production-cluster.html)

druid.indexer.runner.javaOpts=-server -Xmx3g -XX:+UseG1GC -XX:MaxGCPauseMillis=100 -XX:+PrintGCDetails -XX:+PrintGCTimeStamps

druid.indexer.fork.property.druid.processing.buffer.sizeBytes=536870912

druid.indexer.fork.property.druid.processing.numThreads=2

druid.worker.capacity=9

We chose the r3.8xlarge type of ec whose memory is 244GB and cores is 32.

The setting capacity is 9 and num threads is 2, the total of used cores is 9 * 2 = 18. What are the remaining cores(14) used for? Is them used for computing indexing for realtime ingestion?

And there are remaining memory(244GB - 9 * 2 * 512m - 9 * 3g = 208GB), Are these remaining memory used for loading segments which haven’t been persisted to historical node?

Duplicate of https://groups.google.com/forum/#!topic/druid-user/pvG4ubRTC1Q