Maybe this could be done in https://issues.apache.org/jira/browse/CASSANDRA-3347 also, but not sure what's the scope in that jira. It'd be great if the BF memory size can be captured in the JMX monitoring.
Though not sure how you would capture the "heap size" (easily that is) of the object. There is a BF.serializedSize() , can this be exposed to the BloomFilterTracker and DataTracker... and use this instead? Anyway, will let the implementor to decide/design