[danielszm]

I wonder why nobody ever talks about drb, a distributed system that ships with ruby. It's active in Japan, and there has been an effort to make it better known in the rest of the world with a book dedicated to the topic in english (published by Pragmatic Programmers). Still, it hasn't stirred much interest. Even if it's less advanced than DCell, it's still a recommended way to start learning about distributed computing.

[bascule]

Hello, author of Celluloid here.

I think DRb pretty cool and has long been underutilized. That said, there are a few fundamental design problems with the way it works that I think DCell solves:

1. Distributed systems really need to be built on top of asynchronous protocols, and DRb is a direct mapping of a synchronous method dispatch protocol onto a distributed systems protocol. Similar attempts at this include: CORBA and SOAP. If anyone disagrees with this I can go into more detail but I think you will find ample distributed systems literature condemning synchronous protocols. DCell is fully asynchronous (but also provides synchronous calls over an underlying asynchronous protocol)

2. DRb is multithreaded but does not provide the user with any assistance in building multithreaded programs. This becomes particularly confusing when you have to deal with a proxy object (DRb::DRbObject) in a remote scenario but not in a local scenario

[robotmay]

As an aside; Celluloid is awesome and you really made concurrent programming in Ruby better by releasing it :)

[tptacek]

It's brittle, opaque, and relies on Marshal, an interchange standard nothing else uses. It's so easy to build alternatives to Drb that use better interchanges that nobody uses Drb. And once you do that, you find it's easy to back your system with Redis or a database, which you do because it makes sense, and then you start getting pulled towards message architectures --- which are themselves usually superior to direct invocation of remote methods.

[ericb]

In my previous load testing of Drb, at 86 connections (remote objets) with even moderate use, things consistently went bad. This was independent of number of machines.

[danielszm]

Happy to see informed opinions, thank you. Sounds pretty damning, too. Thomas, are you saying that messaging is always superior to RMI, and that there is no valid use case for RMI? I am thinking out loud here, but isn't a distributed system that leverages RMI quicker to implement? Might be suitable when prototyping. Or teaching a classroom. Does that make sense?

[bisceglie]

DCell might be more advanced, but it's nowhere near ready for real-life application (1).

1. https://github.com/celluloid/dcell/commit/e3115f284084a78756...

[lucian1900]

I'm not a Ruby developer, but it looks to me that using drb when there's Celluloid is like using asyncore when there's Twisted, in Python.