Understanding Node.js 'V8 Isolates' and Multitenancy Security

V8 Isolates provide independent instances of the V8 engine, each with its own heap and garbage collector, used to run untrusted code securely without the overhead of full processes.

Traditional Node.js runs in a single Isolate. If you are building a 'Function-as-a-Service' (FaaS) or allowing users to upload custom scripts, you shouldn't run them in the main Isolate. Using libraries like isolated-vm, you can create a sandbox with restricted memory and CPU time. This is much lighter than worker_threads and significantly safer than eval() or vm.runInContext().