4 ms·

How's the managed runtime implemented (GC, memory model, etc.)? How did you get rid of JVM and JRE class library dependencies of Scala? What's the debugging sto

How's the managed runtime implemented (GC, memory model, etc.)? How did you get rid of JVM and JRE class library dependencies of Scala? What's the debugging story? I'd be great if this kind of info found its way onto th website. Is this in any way related to vmkit? Excited about this, keep up the great work!

more_original 10y ago
Looks like it's currently using the Boehm–Demers–Weiser conservative garbage collector. In scala-native/rtlib/src/main/resources/rt.cpp it includes gc.h and allocates memory using GC_malloc, i.e. not in precise mode.
- airless_bar 10y ago
  Ouch.
  - amelius 10y ago
    The garbage collector is typically the most difficult part of a language implementation, so I'm not surprised. On the other hand, a simple GC can be sufficient for many projects.
  - broodbucket 10y ago
    They can still replace it later once they're further along with the rest of the implementation. I doubt they'll keep it.
densh 10y ago
> How's the managed runtime implemented (GC, memory model, etc.)? In a first release we're going to use Boehm GC. That's just a stepping stone, not a long-term strategy. Stay tuned for news on this front. > How did you get rid of JVM and JRE class library dependencies of Scala? We're reimplementing / porting from Apache Harmony all the things we need. > What's the debugging story? We're going to integrate with lldb. > Is this in any way related to vmkit? Not related in any way, apart from being based on LLVM.
- petecox 10y ago
  > We're reimplementing / porting from Apache Harmony all the things we need. Would GCJ be any use? They had native compilation over a decade ago. (Although developers moved on to IcedTea, iirc)
- airless_bar 10y ago
  > We're reimplementing / porting from Apache Harmony all the things we need. Doesn't that create licensing issues? You already seem to have code from Harmony in the project, but the project's license is neither Apache nor does it mention it. Additionally, won't that cause trouble with Oracle, considering the lawsuit against Google?
  - densh 10y ago
    We're are going to have an official guide on licensing in next few days.
- emeryberger 10y ago
  Hans Boehm's GC is actually really, really good. Before you embark on a massive engineering effort that will likely lead to little gain and a lot of pain, I would measure the overheads very carefully. I am not at all convinced precise GCs buy you that much over the Boehm GC for most apps, and they fundamentally kill interop with C code. (I can't recall for sure but I believe I had this conversation with Martin in a taxi ride not too long ago :)
  - needusername 10y ago
    Mono was a long time on Hans Boehm's GC and despite feeding it a lot of metadata never got satisfying results with it. Eventually they replaced it with a custom GC (SGen).

more_original 10y ago

Looks like it's currently using the Boehm–Demers–Weiser conservative garbage collector. In scala-native/rtlib/src/main/resources/rt.cpp it includes gc.h and allocates memory using GC_malloc, i.e. not in precise mode.

airless_bar 10y ago
Ouch.
- amelius 10y ago
  The garbage collector is typically the most difficult part of a language implementation, so I'm not surprised. On the other hand, a simple GC can be sufficient for many projects.
- broodbucket 10y ago
  They can still replace it later once they're further along with the rest of the implementation. I doubt they'll keep it.

densh 10y ago

> How's the managed runtime implemented (GC, memory model, etc.)? In a first release we're going to use Boehm GC. That's just a stepping stone, not a long-term strategy. Stay tuned for news on this front. > How did you get rid of JVM and JRE class library dependencies of Scala? We're reimplementing / porting from Apache Harmony all the things we need. > What's the debugging story? We're going to integrate with lldb. > Is this in any way related to vmkit? Not related in any way, apart from being based on LLVM.

petecox 10y ago
> We're reimplementing / porting from Apache Harmony all the things we need. Would GCJ be any use? They had native compilation over a decade ago. (Although developers moved on to IcedTea, iirc)
airless_bar 10y ago
> We're reimplementing / porting from Apache Harmony all the things we need. Doesn't that create licensing issues? You already seem to have code from Harmony in the project, but the project's license is neither Apache nor does it mention it. Additionally, won't that cause trouble with Oracle, considering the lawsuit against Google?
- densh 10y ago
  We're are going to have an official guide on licensing in next few days.
emeryberger 10y ago
Hans Boehm's GC is actually really, really good. Before you embark on a massive engineering effort that will likely lead to little gain and a lot of pain, I would measure the overheads very carefully. I am not at all convinced precise GCs buy you that much over the Boehm GC for most apps, and they fundamentally kill interop with C code. (I can't recall for sure but I believe I had this conversation with Martin in a taxi ride not too long ago :)
- needusername 10y ago
  Mono was a long time on Hans Boehm's GC and despite feeding it a lot of metadata never got satisfying results with it. Eventually they replaced it with a custom GC (SGen).