While investigating JDK-8185090 I noticed that KeepAliveCache.run could be better implemented.

It looks like this code

                for (KeepAliveKey key : keysToRemove) {
                    removeVector(key);
                }

acquires the lock for every key, but we're already holding the lock, and it looks like a simple

removeAll(keysToRemove)

would suffice.

I'm sure there's more low-hanging fruit here, if we cared to fix.