Clojure does hot code reloading as a built in. You essentially send code to a running system and you change it. It’s enabled by a dynamic class loader. I wouldn’t say it’s common outside of Clojure though, the whole language and ecosystem is built around this concept.

To be clear: JVM enables the feature, so “technically” JVM allows hot code reload. Not sure how useful this is in practice for non-Clojure JVM users.