this comment in JIRA mentions it https://issues.apache.org/jira/browse/CASSANDRA-1969?focusedCommentId=12985038&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-12985038
but in the end, it's not immediately clear. could someone give a summary of its advantages? (if it's just re-implement your own GC, why would your own GC be better?) Thanks Yang
