title: How to get Kafka log size efficiently?
body: <p>I am building a UI where I want to display the log size of a kafka topic and how much each consumer has read. I can read the consumer offsets from zookeeper. What would be the efficient way to get the log size of a topic. I might need to update the details say every 10 seconds. 
  I can get the log size from jmx or using a simple consumer and latest offset time. Is this the best available options or Is there any other efficient option?</p>