Comment by byroot

1 year ago

So first it's a bit annoying to read this when I busted my ass for several weeks to refactor Active Record to make it more compatible with the Fiber use case in 7.2.

But also there is very little benefit to it for the vast majority of Rails applications out there.

Unless you are doing micro-services or something like that, your typical Rails application isn't IO heavy enough to run more than 2 perhaps 3 threads before contending.

So the overwhelming majority of Rails applications wouldn't see any benefit from being served via falcon, quite the opposite.

Async is great to enable some use cases where people would have to reach to Node before, but Rails will never be a good solution for that, if you want to do some sort of light proxy or websocket notification thing, Rails isn't a good solution, you want something much lighter.

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byroot

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skunkworker  1 year ago

I will be curious to see what JRuby's fiber implementation is like in their upcoming version, currently I work on JRuby rails deployments with dozens of threads across hundreds of nodes. There's definitely some learning curves and tuning necessary when you have 40 threads in contention over a particular shared resource vs 3-5 on regular CRuby.

tinco  1 year ago

Wouldn't fibers work well for ActionCable applications? Lots of connections being kept alive, with sparse activity on them?

  • byroot  1 year ago

    Yes. But just for the Action Cable parts, as in you'd deploy Action Cable standalone with falcon, and then keep Puma or whatever for the purely transactional requests.

    If you don't, you'll notice that your Action Cable latency will be all over the place when a transaction request comes in.

    It's acceptable for "hobby" use, but if you try to provide a good user experience with reasonable latency, you can't just collocate Action Cable and the rest of Rails in a single process.

    • mosselman  1 year ago

      Wow this sounds very smart.

      Do you have any tutorial somewhere on how to use Falcon for this? I am getting some strange errors that would probably be covered in a basic tutorial already.