[trotterdylan]

> I would love to know how big the codebase is.

Sorry, can't be very specific, but rewriting all the frontend code would take a lot more effort than writing a new Python runtime :)

> It seems like writing a translator to deal with all the use cases is so much more work and risky than iteratively rewriting portions (in whatever faster more concurrent language) and using some form microservice/process message passing to communicate with legacy pieces.

We do iteratively rewrite components as well. We are pursuing multiple strategies.

> Love to know how they compose async operations currently? Is it some sort of object (e.g. Futures, promises, observables, etc)?

Most async operations are performed out-of-process by other servers.

> Is Grumpy going to have some sort of language difference (to Python) to compose async stuff (e.g. async and await)?

I'd love to support async and await at some point.

> Of course being biased towards the JVM (since I know it so well) they could get really fast concurrency if they want with Jython today. Most of the Python tools already work with Jython (assuming 2.7).

We did also do an evaluation of Jython but there were a number of technical issues that made it unsuitable for our codebase and workload. One such example is this longstanding issue: http://bugs.jython.org/issue527524. I just noticed the very recent update on that thread that implemented the workaround outlined in 2010 by Jim Baker. We tried that workaround and found we got a huge performance hit on affected code. There were a few other general performance problems as well but I can't recall all the details.

Please note I'm not at all bashing Jython, I think it's a great project with a sound design, it just wasn't right for us.

> With Jython you could always drop down into Java (or any other JVM lang) if you need more speed as well C for cpython (or even C from Java). It is unclear what you do with Grumpy with performance critical code. Can you interface with Go code or is the plan C?

You can interface with Go code directly, e.g. from the blog post:

  from __go__.net.http import ListenAndServe, RedirectHandler
  handler = RedirectHandler('http://github.com/google/grumpy', 303)
  ListenAndServe('127.0.0.1:8080', handler)