I didnt get the point. I have slowly increasing memory load on node, no flushable memtables. How it could not be memory leak? Also running nodetool upgradesstables fails with OOM.Possible, but unlikely. See https://issues.apache.org/jira/browse/CASSANDRA-3537 for an example of a "memory leak" that wasn't.
https://rapidshare.com/files/2558346759/system.log.4.bz2
