> Any sufficiently advanced distributed systems contains a buggy implementation of Erlang?
Why won't you say that about machine code? The JVM simply operates at a lower level than Erlang, hence it can be used to implement Erlang, and, it turns out that doing so might gives better results than current Erlang VMs implemented in C, because there are man-decades (or centuries) of shared functionality that's already in the JVM.
> By rewriting (or heavily reconfiguring) the GC, adding a scheduler, etc
You don't need to rewrite or heavily configure the GC (besides, which one? There are plenty of JVM GCs) -- just to use it as Erlang does, or one that is pauseless no matter how you use it (two implementations, one commercial and one open-source under development at Red Hat). Also, you don't need to add a scheduler. One of the world's best implementations of a work-stealing scheduler, also with about a decade of effort behind it by Doug Lea, is packaged with the JDK. See here[1] to get a feel for the effort behind it.
> It sounds like it's not quite the case, especially around distributed systems.
Erlang doesn't add anything not already found in high-quality, battle-tested libraries like JGroups[2] when it comes to clustering (actually, JGroups is more powerful than Erlang's clustering). The JVM ecosystem is so huge that it's very hard to come up with something (other than syntax) that doesn't already have a solid implementation out there.
I'd really like to retrofit Erjang to use Quasar rather than Kilim (Quasar is just better maintained, more battle-tested and probably faster).
I really believe that running Erlang on the JVM is a win for everyone. The Erlang community simply doesn't have a tenth of the resources that are put into OpenJDK[3]. Why not enjoy the benefits?
Greenspun's tenth rule is tongue-in-cheek and usually followed by something like "...including Erlang itself".
I get it. I see the huge benefits in a ground-up design for Erlang in the JVM. (Said design should definitely use existing GC, scheduler, etc.).
However, while what you are describing is technically the JVM, it's sort of a Ship of Theseus (with the GC replaced, with static binary manipulation by Quasar, etc.). This isn't a bad thing, but it's not what I'd normally associate with the JVM and its ecosystem.
I've got a bit of a "chip on my shoulder" regarding what I see as a pretty terrible experience with Akka. I feel strongly that preemption makes a huge difference in usability. With Akka, there are too many caveats relating to things you can and cannot do. Rather than simplifying my life, Akka gives me a whole bunch of additional ways I can break my application. While it could be said that "being a professional engineer" means solidly understanding my tools, I don't feel that is a scalable way to build development teams.
I'd love an out-of-the-box "erlang mode" switch (or some sort of launcher) that would give me these safe behaviors. Something along the lines of Percona for MySQL.
Reach out to me directly with email (in profile). This has been a fascinating discussion and I'm very interested in learning more.
But you don't need to replace the GC. HotSpot alone comes with a choice of 3 (or 4) GCs, and a fifth will join them. As of Java 9, HotSpot will support pluggable JITs (written in Java!). Quasar's bytecode manipulation is common practice among a large number of JVM tools, including one of the most popular Maven plugins, many of the most popular JVM profilers, and Spring. It isn't some exotic technique.
And don't forget -- the JVM is a spec with many implementations (including some for hard-realtime systems), although I'm talking of OpenJDK's HotSpot here.
I totally agree about preemption (and Akka, obviously). Blocking a thread (userspace or kernel) is the essential abstraction of imperative programming (or, more accurately, suspending a continuation) of that is the essence of imperative programming (even functional imperative programming, like Erlang and Clojure).
Why won't you say that about machine code? The JVM simply operates at a lower level than Erlang, hence it can be used to implement Erlang, and, it turns out that doing so might gives better results than current Erlang VMs implemented in C, because there are man-decades (or centuries) of shared functionality that's already in the JVM.
> By rewriting (or heavily reconfiguring) the GC, adding a scheduler, etc
You don't need to rewrite or heavily configure the GC (besides, which one? There are plenty of JVM GCs) -- just to use it as Erlang does, or one that is pauseless no matter how you use it (two implementations, one commercial and one open-source under development at Red Hat). Also, you don't need to add a scheduler. One of the world's best implementations of a work-stealing scheduler, also with about a decade of effort behind it by Doug Lea, is packaged with the JDK. See here[1] to get a feel for the effort behind it.
> It sounds like it's not quite the case, especially around distributed systems.
Erlang doesn't add anything not already found in high-quality, battle-tested libraries like JGroups[2] when it comes to clustering (actually, JGroups is more powerful than Erlang's clustering). The JVM ecosystem is so huge that it's very hard to come up with something (other than syntax) that doesn't already have a solid implementation out there.
I'd really like to retrofit Erjang to use Quasar rather than Kilim (Quasar is just better maintained, more battle-tested and probably faster).
I really believe that running Erlang on the JVM is a win for everyone. The Erlang community simply doesn't have a tenth of the resources that are put into OpenJDK[3]. Why not enjoy the benefits?
[1]: https://www.youtube.com/watch?v=sq0MX3fHkro
[2]: http://www.jgroups.org/
[3]: like a groundbreaking optimizing compiler that will start being used in Java 9, and can be especially appropriate for compiling Erlang: https://wiki.openjdk.java.net/display/Graal/Publications%20a...