Since JRockit is dead this post might not be interesting, but anyway …

I have never used JRockit Real Time (JRRT). At a customer site I could see that JRRT was installed and the custom said that they used it.

But there was also installed a newer regular JRockit and that was what they were actually using.

So what was going on?

In the past there were several different JRockit distributions. JRockit Mission Control (JRMC), JRRT, ..?

Now there is only one. So when you download the latest JRockit version it contains JRMC and JRRT. There is no separate JRRT executable.

The only difference between a JRockit and JRRT is that JRRT supports deterministic garbage collection

You enable deterministic garbage collection via the Xgc command line option:
-Xgc:deterministic

Or the deprecated
-Xgcprio:deterministic

The customer did not use either of them, so they did not use JRRT 🙂