The issue isn't so much Java the language, as it is being aware of the GC, and developing with it in mind.
So if you're latency sensitive then all of your code needs to be aggressive at avoiding object creation. All of your code becomes part of "the fast path", even if it's in a different thread.
Or you isolate your fast path in a different process or a non-GC'd runtime, the later being the approach taken here by Instagram.
[1] http://15721.courses.cs.cmu.edu/spring2018/papers/02-inmemor...
Well, Java has the advantage of being platform (and to a certain degree, runtime) independent, plus a robust set of best practices and ecosystem when it comes to modules and library handling, which is pretty hard to get done right for C/C++ projects.
What is the benefit of that? Who on earth runs a DB written in Java on windows? Any useful server software will end up using platform native features, be it SQL server, MySQL, HBase, ...
