Anyone have any performance comparisons against other Ruby implementations? I assume performance is the main reason someone would adopt this right?
Other Ruby implementations suffer from not being compatible with the MRI ecosystem, you have to port them over. In theory because they're the same language, gems would be easily portable, but the sheer amount of combinatorial work involved means they slowly accrete into separate ecosystems. It's relatively easy to port a gem over and maintain it, but if you don't keep doing it, they'll become incompatible.
MRI has the largest install base, and the biggest gem library, and the largest number of eyes on it. Sure, JRuby and Rubinius are faster, but Ruby was never a language chosen for speed, so most devs reach for MRI first and then only branch out when requirements force them out.
For me, the differences between MRI and other implementations effectively make them different languages, I'd jump to Elixir before giving JRuby a shot. I have a sense that other Rubies, except maybe Opal, will always be niche.
So, yes, on the surface of it, this particular Ruby build might appeal to people looking for performance.
But from a language research position it is interesting to decouple concepts like GC from the language so that they can be studied and optimized as a pattern and then be potentially reapplied to any language runtime.
I agree that some concepts might be pulled into MRI Ruby 3, but OMR may be a powerful testbed for language researchers to debate GC strategies and measure effects in various languages before committing to a single language integration.
Similarly, improvements in OMR can be shared among all languages using it; ie, because we build both IBM's Java JDK and Ruby on top of OMR, Ruby can benefit from investment in Java, and Java can benefit from improvements in the Ruby community.
It may be worth rembering that today's (1.9 and later) "MRI" started life as an alternative to MRI called "YARV". For a while there was a lot of talk about Rubinius as potentially being the basis of a similar replacement and becoming the "MRI" of the future. While there is less talk recently about Rubinius in that role, its absolutely not impossible that a competing core engine could be adopted as the mainline implementation of Ruby again.
1. It is mostly compatible with Gems. 2. It is faster and accepted by the Core Team. 3. Most importantly, license. Both MRI and YARV, the two CRuby implmentation are all MIT. It is highly unlikely JRuby or OMR could be used as mainline.
Ruby also suffers from the lack of a formal VM, so other implementations are merely similar rather than being guaranteed to run all programs. This is not the same with JVM vendors, where choice of IBM vs Oracle is largely based on extrinsic features rather than intrinsic compatibility. (Or at least you have to get in really deep to find differences-- in Rails you usually find incompatibilities that stop you from even starting the app).
I have considered it deeply. Many of our enterprise systems are Java-based, so JRuby's ability to call Java methods directly without implanting services would be a huge pragmatic boon. But every time I consider that I have to balance it against being able to use a constellation of gems in Rails. For example, nokogiri (libxml) is used in a ton of stuff. Sure there are Java equivalents, but that isn't the issue. Rather I would have to reimplement or find replacements for everything we use that depends on that without introducing side-effects. In my experience that's really hard unless it's a toy application without many dependencies. (Read: opposite of most enterprise Ruby apps)
Also, as a gem author I've tried to support jruby along with MRI, but it requires jumping through a lot more hoops. Of course any cross-platform code requires more work to support, but it's a pressure on small devs. If no one needs it, no one helps support it, so then it becomes another gem that is effectively MRI-only. Kind of a viscous cycle.
Nokogiri natively supports JRuby, no equivalent searching required.
CExts are basically the only place where this issue really pops up and all the major CExt gems (Like nokogiri) support JRuby.
The deal breaker for me is the very slow startup time for tests and no gains for run once scripts. I've seen people developing with MRI and doing CI on JRuby to work around that. It's worth doing that only if you have a service running with some real load. Most internal services do nothing almost all the time.
The reality of JRuby startup times make it not a good fit for scripting tasks but otherwise server and threaded tasks are a great fit. Since using JRuby more recently I feel the ecosystem support is probably the best of the non-MRIs. I rarely run into compatibility issues. Conversely JRuby's Java integration has been a very useful feature that no other Ruby implementation offers.
Wha? Sorry but this sounds pretty FUDdish. I have never had an issue with JRuby to the extent that you are describing. Do you have some examples?
I know of many large app deployments in JRuby at large household name companies.
The only thing JRuby doesnt have is the relatively niche CExt functions.
Still a ways to to go, but we've built out a reasonable foundation to start with.
[1]: http://www.slideshare.net/MatthewGaudet/experiments-in-shari...