Hi Carter,
D is very interesting and I've written some code with it and gotten to
know it a bit. I'm close, but not quite ready to take the plunge of
using it as my primary high performance language. Although there are
claims about it being the same in speed as C or C++ I have found it to
be roughly 35% slower for programs coded in the same fashion. On the
other hand, it probably has the potential to be faster than C once it
matures.
D is basically C or C++ cleaned up significantly and with higher level
features such as garbage collection and iterators and it's really a joy
to use - and if you know C you will be comfortable right away with D.
D is low level which is the appeal for me. You can use it right along
with C, link in the object files with very little trouble. All the
data types are the same. For instance if you want that 30% I talked
about you can write the core engine in C but do the hard stuff in D.
The big issue with Java is memory. I cannot see building a high
performance program that makes sophisticated use of lots of memory.
I think you could build a small fairly high performance program in Java,
but modern Monte Carlo programs would be serious memory hogs with
Java. When several of us tested Mogo in the big scalability study,
memory was a big issue EVEN though it was written in C (or C++.) The
issue was that Mogo allocates a certain fixed number of nodes to the UCT
tree contained in memory and when you run Mogo at a high level, these
nodes are exhausted. Mogo compensates by pruning and re-using certain
nodes, but there is likely some performance loss.
This of course is not an issue confined to Mogo, but all the high
performance MC programs need to deal with the same issues since the
current techniques build as much of the game tree in memory as possible.
I don't want to start a flame war, but I think performance is an issue
with Java too. It's true that you can write some programs that are
very fast in Java, even comparable to C, but you definitely lose the
low level flexibility of C. It makes it harder to shoot yourself in
the foot but it still limits your performance. Of course you can
always pick and choose your benchmarks to find one that verifies the
conclusions you want to believe in, but I believe you will ALWAYS be
able to write high performance code in C (even if it's ugly) but with
Java you will only be able to write some high performance code. (This
is rather analogous to assembly vs C, no restrictions in assembly so
there are still a few corners where you cannot get all the speed out of
C - it's even more-so with high level languages such as Java. But I
believe D doesn't suffer any more than C and is probably even more
optimizable, although the compilers are not there yet.)
The only feasible choice that I can imagine currently is C, C++ or D for
super high performance programs. I personally would consider D a much
better choice than Java if you are looking for something higher level
than C and C++ and don't mind taking a small performance hit. It
seems likely to me that the performance hit of D will go away in time
but I'm not a prophet. This is claimed of Java, but I don't believe
it will every be true in general, although it will probably be true in
specific cases.
Of concern is 64 bit support in D. I don't know where that is now.
I'm still using C but I'm keeping a close eye on D.
- Don
Carter Cheng wrote:
Thanks for the responses.
1) I guess for this seki question I was wondering if it was as easy to define
as liveness without seki. The reason I am interested in this is I am curious
about absolutely correct scoring functions and whether they currently cope well
with advanced seki situations or not. I have been looking at some of the cases
listed on the Sensei's Library. A cursory look seems to indicate that they are
very difficult to classify- and any seki classifier might need some knowledge
of killing shapes.
2) You are correct Jason I transposed the symbols for some reason I actually meant 3^(n^2) but typed it in backwards.
3) Also thanks for the links. I have taken a look at some of the code. I am not sure I
will be writing in Java or D and most likely will be implementing the system in something
like C++. I am worried about Java's speed since it's interpreted (which still means a x2
slowdown even with the JIT and Hotspot compilation and selective inlining). D I am just
not too familiar with I am wondering what advantages it brings over C++. I am primarily
concerned about maturity issues. I am not trying to start a discussion on which language
is "better", but those are my initial impressions.
I am primarily interested in creating a very basic go bot at this point and use it for primarily data gathering. I have been curious about certain aspects of game searches and how they apply to go and how reinforcement learning works etc. I figure being a complete beginner at this it will take some time before I have any meaningful insights into how everything works to contribute anything.
Regards,
Carter.
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