I use this GC thread to show a little GC-related benchmark.
A little Reddit thread about using memory more compactly in Java:
http://www.reddit.com/r/programming/comments/120xvf/compact_offheap_structurestuples_in_java/
The relative blog post:
http://mechanical-sympathy.blogspot.it/2012/10/compact-off-heap-structurestuples-in.html
So I have written a D version, in my test I have reduced the
amount of memory allocated (NUM_RECORDS = 10_000_000):
http://codepad.org/IhHjqUua
With this lower memory usage the D version it's more than twice
faster than the compact Java version that uses the same
NUM_RECORDS (0.5 seconds against 1.2 seconds each loop after the
first two ones).
In D I have improved the loops, I have used an align() and a
minimallyInitializedArray, this is not too much bad.
But in the main() I have also had to use a deprecated "delete",
because otherwise the GC doesn't deallocate the arrays and the
program burns all the memory (setting the array to null and using
GC.collect() isn't enough). This is not good.
Bye,
bearophile
