Yes. I moved a few repository from java 8 up to Java 21.
Java 8 -> 9 is the largest source of annoyances, past that it's essentially painless.
You just change a line (the version of the JRE) and you get a faster JVM with better GC.
And with ZGC nowadays garbage collection is essentially a solved problem.
I worked on a piece of software serving almost 5 million requests per second on a single (albeit fairly large) box off a single JVM and I was still seeing GC pauses below the single millisecond (~800 usec p99 stop the world pauses) despite the very high allocation rate (~60gb/sec).
Java 8 -> 9 is the largest source of annoyances, past that it's essentially painless.
You just change a line (the version of the JRE) and you get a faster JVM with better GC.
And with ZGC nowadays garbage collection is essentially a solved problem.
I worked on a piece of software serving almost 5 million requests per second on a single (albeit fairly large) box off a single JVM and I was still seeing GC pauses below the single millisecond (~800 usec p99 stop the world pauses) despite the very high allocation rate (~60gb/sec).
The JVM is a marvel of software engineering.