Weekend Learning: Troubleshooting row cache enqueue locks

Check out MOS document ID 278316.1 to get up to speed with "Troubleshooting: "WAITED TOO LONG FOR A ROW CACHE ENQUEUE LOCK! "" which was created for Oracle databases 8i but appears to be completely relevant for us today on 11g and 12c databases!  There are a TON of other articles linked on here as well that you should take a look too!!