> But an escape hatch is still an escape hatch. These mechanisms bypass the process isolation model entirely. They are shared state outside the process model, accessible concurrently by any process, with no mailbox serialization, no message copying, no ownership semantics. And when you introduce shared state into a system built on the premise of having none, you reintroduce the bugs that premise was supposed to eliminate.

No, they do bypass it. I don't know what "Technical Program Managers at Google" do but they don't seem to be using a lot of Erlang it seems ;-). ETS tables can be modeled as a process which stores data and then replies to message queries. Every update and read is equivalent to sending a message. The terms are still copied (see note * below). You're not going to read half a tuple and then it will mutate underneath as another process updates it. Traversing an ETS table is logically equivalent to asking a process for individual key-values using regular message passing.

What is different is what these are optimized for. ETS tables are great for querying and looking up data. They even have a mini query language for it (https://www.erlang.org/doc/apps/stdlib/qlc.html). Persistent terms are great for configuration values. None of them break the isolated heap and immutable data paradigm, they just optimize for certain access patterns.

Even dictionary fields they mention, when a process reads another process' dictionary it's still a signal being sent to a process and a reply needing to be received.

* Immutable binary blocks >64B can be referenced, but they are referenced when sending data using explicit messages between processes anyway.