Hello Jarrett,
On Tue, Jun 2, 2009 at 8:40 PM, Diwaker Gupta
<diwa...@floatingsun.net> wrote:
I've just started to play around with D, and I'm hoping someone can
clarify this. I wrote a very simple program that just allocates lots
of objects, in order to benchmark the garbage collector in D. For
comparison, I wrote the programs in C++, Java and D:
C++: http://gist.github.com/122708
Java: http://gist.github.com/122709
D: http://gist.github.com/121790
With an iteration count of 99999999, I get the following numbers:
JAVA:
0:01.60 elapsed, 1.25 user, 0.28 system
C++:
0:04.99 elapsed, 4.97 user, 0.00 system
D:
0:25.28 elapsed, 25.22 user, 0.00 system
As you can see, D is abysmally slow compared to C++ and Java. This is
using the GNU gdc compiler. I'm hoping the community can give me some
insight on what is going on.
D's GC is not nearly as well-developed as that of Java's, and its
performance is not that stellar. Sorry, but you are not the first to
discover this by any stretch of the imagination. (On a side note, I
have a feeling you and bearophile will get on famously.)
Also, benchmarking a GC against manual memory management doesn't do
much for you. It's apples and oranges. Though it is funny to see how
badly Java beats C++ there.
Java may be able to tell that the allocation never needs to be kept and is
just reusing the same space on the stack. Heck it might even not be doing
that as you can tell that the class only ever holds the same value as i so
it might just be skipping the new all together.
