Why not using async calls of `koffi`

[Jojo211209]

Koffi has async call bindings: https://koffi.dev/functions#asynchronous-calls, which runs on worker threads, so that we don't need piscina to create Javascript threads and block the threads on each request.

[Sahil1337]

I initially used Koffi’s async functions, but I ran into issues related to max call limits. So I switched to my own worker based implementation instead. I don’t remember the exact error since it was a while ago, I’ll revisit it when I have time.