I don't know if marketing was involved with using the term 'isolate' or not but if they are isolates as described by companies such as Cloudflare and Google, it

I don't know if marketing was involved with using the term 'isolate' or not but if they are isolates as described by companies such as Cloudflare and Google, it might help to speak a bit more about the actual implementation at the infrastructure level. Isolates are a really interesting approach to deal with the inherent nature of scripting languages to deal with the lack of threads as most scripting languages are inherently single-thread/single-process. If you have a 2000 line ruby class named 'Dog' you can easily overwrite it with the number 42. This is awesome on one hand, however it makes scaling the vm through the use of threads too difficult as threads will share the heap and then you have to put mutexes on everything removing any performance gain you would have normally gotten. Instead the end-user has to pre-fork a ton of app vms with their own large memory consumption, their own network connections, etc and stick it behind a load balancer which is not ideal to their compiled, statically typed cousins and frankly I just don't see the future allowing these languages as we continuously march towards larger and large core count systems. I'd personally like to see more of the scripting languages adopt this construct as it addresses a really hard problem these types of languages have to deal with and makes scaling them a lot easier. To this note - if you are working on this in any of the scripting languages please let me know because it's something I'd like to help push forward. Having said that, they should never be considered as a multi-tenant (N customers) isolation 'security' barrier. They are there for scaling not security.