For those following, I have a PR up at
https://github.com/apache/spark/pull/22993
The implication is that ignoring MaxDirectMemorySize doesn't work out
of the box in Java 9+ now. However, you can make it work by setting
JVM flags to allow access to the new Cleaner class. Or set
MaxDirectMemorySize
I think this is a key thread, perhaps one of the only big problems,
for Java 9+ support:
https://issues.apache.org/jira/browse/SPARK-24421?focusedCommentId=16680169&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-16680169
We basically can't access a certain method
