Oracle (HotSpot) GraalVM (also Oracle) Zing OpenJ9 ExcelsiorJET
Performance was radically different between them, but the answers where the same (ok equivalent as this a whole lot of parallel code).
My co-workers can't even get their C++ compiler to be accepted by two different compilers and it is not just them. Compiler upgrades are feared events where significant effort needs to be put in.
While even the hard upgrade to Java9 from 8 was 3 extra commandline switches on startup. For a project with 168 dependencies and more than 1 million lines of code. Done in one afternoon, with the upgrade to Java 11 taking 3 minutes. (needed to add java mail to the WAR/classpath instead of expecting it to be in the JDK)
Upgrades from 5->6->7->8 where equivalent or simpler. Eleven years in two bugs due to an upgrade. One a compiler bug in 1.7.45 an other not overriding all the methods from abstract list in a list of string implementation that uppercased on retrieval. Trivial compared to C++ upgrades.
This seems backward to me. C++ has a great deal of undefined behaviour, which you don’t get in Java. And Java has had a memory model for years - until recently nobody could argue their parallel code was correct on C++.
If you want guarantees Java seems like the better option.