[stevan]

> if you have long running sessions and do several upgrades, are you running N versions of the code & eating up RAM because the old sessions aren’t complete?

I believe Erlang supports two versions running along each other. They capped it at two because back when this was developed there wasn't enough RAM. Joe Armstrong gave at least one talk where he says if he'd have liked to support arbitrary number of versions and garbage collect them as old sessions complete.

> Thus I stand by that there’s no “generic” solution you can bolt onto an arbitrary language.

The main point of the post is centered around Barbara Liskov saying "maybe we need languages that are a little bit more complete now". I'm not interested in the limitations of current languages, I'm interested in the future possibilities.

[vlovich123]

There’s no free lunch and I’m suggesting the trade offs to support this are not worth it vs simpler approaches of doing a graceful drain & upgrade approach w/ a timeout for long running sessions if those may exist (+ if you have a lot of large state to migrate, it could be insanely long to complete an upgrade). This is because availability will never be 100% anyway in any scenario and this kind of transition can easily fit within your failure budget.