[EMAIL PROTECTED] wrote:
I disagree with the permise of what you are saying. Let me say "the
wrong thing"
1. There are no open source virtual machines that are presently
practical to run high volume production code (yes I know you all run
kaffe whatever for XYZ and love it to death, but I mean non-entusiasts
would run it too).
2. There are no Java virtual machines period that are presently
practical to run high volume production code.
I meant Java virtual machines written in Java... sorry
Language at some level is basically irrelevant but the VM will be to at
least some level native code. It has not yet been demonstrated that a
high performance optimizing runtime compiler (one that is competitive
with production grade VMs) can be built in Java.
At present there is more of a divide between people who are interested
in what is theoretically possible and "forward looking" (which I think
buys into Java marketing just a bit too much) and those who are merely
interested in the more practical aspect of a high performance open
source VM.
More or less I am not sure that both camps will be satisfiable with one
code base though a modular approach might make this possible. This may
give into Conway's law just a little too early (not modularity which is
just good practice but the division of modules ;-) ).
There are also other divisions within our group which must find
compromise, consensus or atrophy. There are those who want to pick one
of the existing open source projects and seed the projece. There are
those who want to code from the ground up (some completely including the
API). There are those who want to wait or pray for a corporate donation.
I suggest this present-minded compromise. Work can begin *now* on a
small modular native-code portable (macro/micro/)kernel. I would
suggest that it is most practical to do in C (because of cross
compilation and portability). I would suggest that it not be done in
C++ (because it would not be wise to deal with the name mangling/etc
issues at this level, although I kind of think C++ may be a better
solution for the higher levels above).
I will start:
#include<stdio.h>
main () {
printf("Harmony JVM version .001\n");
}
That is only a start. We can build a layer for plugging in a
bootstrapper for Java code for those who want to code an interpreter in
Java. We can code a layer for plugging in a primordial classloader
written in C/C++ or Java. We can code a bytecode interpreter.
Should donations or code that can be reused be discovered, we can base
said modules on such code. Open source software darwinism will take
care of most of the other decisions for us.
-Andy
Aaron Hamid wrote:
As a purely idle bystander and armchair speculator, I'm with Steve on
this one. It seems the community has roughly aggregated into "VM in
Java" and "VM in C/C++" camps. Both camps appear to have large and
robust support and actual working implementations behind them. In the
former I see "JikesRVM" and "JNode". I think the Java-in-Java horse
has been beaten to death and hopefully we can agree that it is not
only feasible, but works today and brings its own set of benefits.
Likewise in the "VM in C/C++" camp there is GCJ "and friends" (which
already have a long track record and fresh ideas, and amicability with
large established GNU projects), as well as some respectable
independent offers such as JCVM and MudgeVM.
Instead of shoehorning the two camps into one VM, how about accepting,
for the meantime, two somewhat independent lines of /investigation/.
I have doubts that a "universal framework interface" could be applied
to both implementations without lots of pain and impedence mismatch
(especially the boundary-crossing-problem), but I am sure that each
can take what is applicable from the other without having the other's
set of interfaces forced on them.
In the end, it might turn out to be useful to have two independent
implementations, possibly front-ended by a, um, front-end. I imagine
the "VM in C/C++" may have characteristics that make it more amenable
to low-latency desktop use, while the "VM in Java" may have throughput
characteristics that make it more amenable to server side use (again,
wild speculation on my part).
Since it is (at least to me) entirely non-obvious yet what the
ultimate architecture should be, why not just let two investigations
proceed in parallel with those parties interested in the respective
technologies participating under the umbrella of "harmony" instead of
being shut out because they happen not to prefer the language or
architecture that has been pre-emptively mandated.
Aaron
Nick Lothian wrote:
Last Friday, I made the following proposal:
http://mail-archives.apache.org/mod_mbox/incubator-harmony-dev
/200505.mbox/[EMAIL PROTECTED]
In the context of the current discussion I'd like to re-advocate
that proposal. It is consistent with what Stefano has suggested.
To summarize:
1. Leverage existing momentum by seeding the project with two
existing VMs 2. Leverage existing work by focusing on modularity of
major reusable components (including components from outside of the
seed VMs).
3. Concurrently design new VM cores.
Modularizing the seed VMs will provide the group with a great deal
of insight into how new VM cores should be built. I say "cores" for
three
reasons: a) the cores will (by defn) be small, so with a modular
framework, having multiple cores should be feasible, b) different
cores can target different needs, c) we can explore different
implementation strategies.
--Steve
+1
After looking through the code of Jikes I'm voting for this proposal
(and the use of Jikes as a seed VM) because a) Jikes seems a fairly
mature, and it appears somewhat modular already
b) I am (much) more likely to be able to contribute to Jikes than a
C-based VM
I do have some concerns about the build process that Jikes currently
has, but Steve has already spoken about addressing that.
There are probably licence issues that would need resolving, too.
This isn't meant as a negative vote against other VMs - Steve's proposal
explicitly mentions working on other VMs in parrel.
If people were going to work on JCVM (for instance) then I would imagine
some enhancements could be shared, particularly to the parts of JCVM
written in Java. It would also enable us to understand the interface
requirements between parts of the VM better than most of us currently
do.
Nick
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