I find WASM interesting from a technical perspective, but not from a practical one.
VMs are cheap, but not “let’s run thousands of them on ‘the edge’ in case we get a request for any of them!” cheap.
5 ms cold starts vs 500+ ms for containers
3 MB memory vs 35 MB for a similar container
No context switch between different tenants' code
No virtualization overhead
I'm sure these numbers would be different today, for instance with Firecracker, but there's probably still a memory and/or cold start advantage to V8 isolates.
https://blog.cloudflare.com/cloud-computing-without-containe...
In almost all cloud deployment, whether transparently or not, you'll have a hypervisor/VM underneath for hardware-level/strong isolation reasons. Using wasm on top of that stack only for isolation purposes might not be the best use of it. Having said that, if wasm is useful for other reasons (e.g., you need to run wasm blobs on behalf of your users/customers), then my (admittedly biased) view is that you should run these in an extremely specialized VM, that has the ability to run the blob and little else.
If you do this, it is entirely possible to have a VM that can run wasm and still only consume a few MBs and cold start/scale to 0 in milliseconds. On kraft.cloud we do this (eg, https://docs.kraft.cloud/guides/wazero/ , wazero, 20ms cold start).
