I'm no expert but when you have a server, would each request be handled concurrently by a separate thread (/fibre?)? So in that sense would the server's I/O be non-blocking? (I know each thread would be blocked as it waits for the response).

Do you have a rough time frame for parallel concurrency?

What's your view on the maturity of the language?

Unfortunately, I don't have a timeframe for parallelism, it's not my area of crystal and it's a fairly tricky issue.

My (biased, i'm a core developer) view on Crystal's maturity, after using it in a few of my own side-projects, is that once crystal code compiles, it runs pretty much rock solid in production. Compiler bugs are fairly rare too, although the compiler clearly isn't as mature as gcc. The main issue you face is lack of available libraries, and being forced to make a few changes every couple months when a new release comes out with breaking changes. Depending on the size of your codebase, that could be a big issue or it could be a 5 minute easy commit.

I'm somewhat new to this so bear with me. With regards to the I/O, is it like node.js? i.e. all requests are handled inside a single thread (until Crystal gets parallelism) and when the thread waits for an I/O response (i.e. a database call), it will process some of the other requests?