anyone know if there is a limit to number of concurrent unrepl sessions over a single socket repl? For example could N users connect to the same socket repl and have idependent unrepl sessions?

yep

the sessions should be independent (if they aren't that's a bug)

or what do you mean by "single socket repl"?

a single tcp connection, or a single port with multiple connections to that port?

single port

so a jar running with a while true Thread/sleep in the main and a socket repl exposed at a port

Thanks for the info.