[andoriyu]

Well, ruby was able to be concurrent for a while now. It has lightweight cooperative threads, it has reactor loops. The problem was/is/will be - lack of gems that support either of them.

EventMachine was a nightmare to work on and to work with, but with fibers it and some wrappers you could write some neat code. Most library were making a lot of bad assumptions - "there is a GIL and i'm running on a full thread and also wtf are threads in general, never heard of it?"

Almost no one in ruby world thought about writing a better code to make application faster, it was always about either finding a better gem or adding more application servers. Here is the closest ruby has been towards concurrency https://github.com/igrigorik/em-synchrony guess why it never took off.

Ruby 3.0 is a first step towards having libraries being aware that they are in on fiber and not thread.