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> So we got Java as the main platform for GC research Perhaps we did, but it's not because it was the only option. Python has the same need, has always been o

> So we got Java as the main platform for GC research Perhaps we did, but it's not because it was the only option. Python has the same need, has always been open source, and has been very popular for as long as Java. Ruby was even more popular than Python for a while, JavaScript might be now. Why didn't much GC research happen in those environments? Is it because people who do GC research looked down their nose at mere scripting languages, even though out in the field all of these have been used for more serious kinds of development? Or is it something else?

geodel 10y ago
It is more likely Oracle/IBM etc put more dollars where their GC is.
pjmlp 10y ago
Probably because those communities aren't welcoming much that type of research and rather use C than an improved VM stack. There are better options to run Python and Ruby than CPython and MRI in terms of performance, yet they lack mainstream adoption.
mike_hearn 10y ago
Java has a think called Jikes, which is a JVM implemented in Java, garbage collectors included. Being implemented in a higher level language makes it much easier to hack on, and in a time-pressured academic environment that makes it a more attractive platform for research than VMs written in C++ (or worse, C). Hundreds of papers have been published on Jikes-based research over the years.
- pjmlp 10y ago
  Even Cliff Click, one of the HotSpot Server Compiler authors, is nowadays pushing for doing exactly that, instead of C++ or C. Also something that many aren't aware regarding Oracle's JVM development, is the decrease of C++ code, being replaced by intrinsics and better optimizations across releases.
  - geodel 10y ago
    I compared loc of C++ JDK9 vs JDK8. JDK9 651408(C++) lines JDK8 497588(C++) lines I do not know the reason but newer JDK seems to have quite a bit more C++ code.
    - pjmlp 10y ago
      That was my understanding from following up the mailing lists discussions.
CJefferson 10y ago
Most python users aren't interested if you break C extensions, and the C extension interface strongly constrains how many parts of a Python VM can look -- have to maintain reference counts, can't change memory layout significantly, can't change how objects are represented.
weberc2 10y ago
My guess? The Python and Ruby developers have never shown any great interest in performance. Javascript performance only become recently popular. EDIT: I should clarify that "Python and Ruby developers" is meant to mean the language implementers, not ordinary users. And this isn't intended to be a dig at those languages--only that they clearly have different goals for their languages than implementors of Java, Go, C++, etc.
- deleted 10y ago
  [deleted]
ScottBurson 10y ago
I think the short answer is that it's just a massive amount of difficult work to get one of these high-performance GC algorithms implemented, and it has to be highly customized to the language implementation. Also, the original implementations of Python and Ruby are so slow in general that it's not clear that improving the GC is the best use of one's time. In the open-source Common Lisp world, CMUCL and SBCL have for years used Douglas Crosher's multigenerational collector. Guido and Matz would have done well to use it too -- it's much better, probably, than either of theirs. It's still far behind the JVM, but the point is, Python and Ruby didn't necessarily need the very latest research; they just needed 1995 technology instead of 1975 technology.
user5994461 10y ago
Python is using reference counting.

geodel 10y ago

It is more likely Oracle/IBM etc put more dollars where their GC is.

pjmlp 10y ago

Probably because those communities aren't welcoming much that type of research and rather use C than an improved VM stack. There are better options to run Python and Ruby than CPython and MRI in terms of performance, yet they lack mainstream adoption.

mike_hearn 10y ago

Java has a think called Jikes, which is a JVM implemented in Java, garbage collectors included. Being implemented in a higher level language makes it much easier to hack on, and in a time-pressured academic environment that makes it a more attractive platform for research than VMs written in C++ (or worse, C). Hundreds of papers have been published on Jikes-based research over the years.

pjmlp 10y ago
Even Cliff Click, one of the HotSpot Server Compiler authors, is nowadays pushing for doing exactly that, instead of C++ or C. Also something that many aren't aware regarding Oracle's JVM development, is the decrease of C++ code, being replaced by intrinsics and better optimizations across releases.
- geodel 10y ago
  I compared loc of C++ JDK9 vs JDK8. JDK9 651408(C++) lines JDK8 497588(C++) lines I do not know the reason but newer JDK seems to have quite a bit more C++ code.
  - pjmlp 10y ago
    That was my understanding from following up the mailing lists discussions.

CJefferson 10y ago

Most python users aren't interested if you break C extensions, and the C extension interface strongly constrains how many parts of a Python VM can look -- have to maintain reference counts, can't change memory layout significantly, can't change how objects are represented.

weberc2 10y ago

My guess? The Python and Ruby developers have never shown any great interest in performance. Javascript performance only become recently popular. EDIT: I should clarify that "Python and Ruby developers" is meant to mean the language implementers, not ordinary users. And this isn't intended to be a dig at those languages--only that they clearly have different goals for their languages than implementors of Java, Go, C++, etc.

deleted 10y ago
[deleted]

ScottBurson 10y ago

I think the short answer is that it's just a massive amount of difficult work to get one of these high-performance GC algorithms implemented, and it has to be highly customized to the language implementation. Also, the original implementations of Python and Ruby are so slow in general that it's not clear that improving the GC is the best use of one's time. In the open-source Common Lisp world, CMUCL and SBCL have for years used Douglas Crosher's multigenerational collector. Guido and Matz would have done well to use it too -- it's much better, probably, than either of theirs. It's still far behind the JVM, but the point is, Python and Ruby didn't necessarily need the very latest research; they just needed 1995 technology instead of 1975 technology.

user5994461 10y ago

Python is using reference counting.