| This. Writing the sort of applications that I get involved with, it's frequently the case whilst it's true that 1 OS thread/java thread was a theoretical scalability limitation - in practice we were never likely to hit it (and there was always the 'get a bigger computer'). But: the complexity mavens inside our company and projects we rely upon get bitten by an obsessive need to chase 'scalability' /at all costs/. Which is fine, but the downside to that is the negative consequences of coloured functions comes into play. We end up suffering having to deal with vert.x or kotlin or whatever flavour-of-the-month solution is that is /inherently/ harder to reason about than a linear piece of code. If you're in a c# project, the you get a library that's async, and boom, game over. If loom gets even within performance shouting distance of those other models, it's ought to kill (for all but the edgiest of edge-cases) reactive programming in the java space dead. You might be able to make a case - obviously depending on your use cases which are not mine - that extracting, say, 50% more scalability is worth the downsides. If that number is, say, 5%, then for the vast majority of projects the answer is going to be 'no'. I say 'ought to', as I fear the adage that "developers love complexity the way moths love flames - and often with the same results". I see both engineers and projects (Hibernate and keycloak, IIRC) have a great deal of themselves invested in their Rx position, and I already sense that they're not going to give it up without a fight. So: the headline number is less important than "for virtually everyone you will no longer have to trade simplicity for scalability". I can't wait! |
1. Demanding scalability for inappropriate projects and at any cost is something I've seen too, and on investigation it was usually related to former battle scars. A software system that stops scaling at the wrong time can be horrific for the business. Some of them never recover, the canonical example being MySpace, but I've heard of other examples that were less public. In finance entire multi-year IT projects by huge teams have failed and had to be scrapped because they didn't scale to even current business needs, let alone future needs. Emergency projects to make something "scale" because new customers have been on-boarded, or business requirements changed, are the sort of thing nobody wants to get caught up in. Over time these people graduate into senior management where they become architects who react to those bad experiences by insisting on making scalability a checkbox to tick.
Of course there's also trying to make easy projects more challenging, resume-driven development etc too. It's not just that. But that's one way it can happen.
2. Rx type models aren't just about the cost of threads. An abstraction over a stream of events is useful in many contexts, for example, single-threaded GUIs.