It appears we've discovered the issue. The server has a large number of cores, 160. We have edited /etc/ambari-server/conf/ambari.properties with: agent.threadpool.size.max=128
client.threadpool.size.max=128 (Just increasing to largest ^2 closer to 160); restarting the ambari-server, it appears the clients now register successfully. We should now be able to proceed with the installation.
... View more