Why Java (server VM) is faster than D?

[John Colvin via Digitalmars-d]

On Monday, 3 August 2015 at 16:41:42 UTC, Steven Schveighoffer 
wrote:
> On 8/3/15 12:31 PM, Dmitry Olshansky wrote:
>> On 03-Aug-2015 19:27, aki wrote:
>>> When I was trying to port some Java program to D,
>>> I noticed Java is faster than D.
>>> I made a simple bench mark test as follows.
>>> Then, I was shocked with the result.
>>>
>>> test results on Win8 64bit (smaller is better)
>>> Java(1.8.0,64bit,server): 0.677
>>> C++(MS vs2013): 2.141
>>> C#(MS vs2013): 2.220
>>> D(DMD 2.067.1): 2.448
>>> D(GDC 4.9.2/2.066): 2.481
>>> Java(1.8.0,32bit,client): 3.060
>>>
>>> Does anyone know the magic of Java?
>>>
>>> Thanks, Aki.
>>>
>>
>> Devirtualization? HotSpot is fairly aggressive in that regard.
>
> Yeah, I think that's it. virtual calls cannot be inlined by the 
> D compiler, but could be inlined by hotspot. You can fix this 
> by making the derived class final, or marking the method final, 
> and always using a reference to the derived type. If you need 
> virtualization still, you will have to deal with lower 
> performance.
>
> -Steve

Yup. I get very similar numbers to aki for his version, but 
changing two lines:

final class SubFoo : Foo {

int test(F)(F obj, int repeat) {

or less generally:

int test(SubFoo obj, int repeat) {

gets me down to 0.182s with ldc on OS X