[FRIAM] FW: Distribution / Parallelization of ABM's

[Douglas Roberts]

Hi, Gunther.

I don't want to start any language wars either.  I have seen some of these
java performance studies as well... Regardless, I have yet to see a
well-written real-world java application that can outperform an equivalent
well-written C++ app, java garbage collection being one of the numerous
reasons why.

There is, after all, a reason that there are so few java apps running on any
of the TeraGrid HPC resources.

One limit of the HPJava environment is that it is primarily for use with
data parallel or SIMD (Single Instruction Multiple Data) synchronous
applications.  This type of parallel application is almost by definition
*not* an agent based simulation. In reality most if not all distributed
agent based simulations are MIMD (Multiple Instruction Multiple Data)
asynchronous applications when implemented in an HPC environment.  HPJava
will provide no help here.

--Doug

-- 
Doug Roberts, RTI International
droberts at rti.org
doug at parrot-farm.net
505-455-7333 - Office
505-670-8195 - Cell

On 10/7/06, Günther Greindl <g.greindl at aon.at> wrote:
>
> Hello Doug,
>
> I guess your friend is aware of this:
>
> http://www.hpjava.org/
>
> (a Java wrapper to interface with a native MPI package).
> What speaks against this?
>
> >   2. java runs 3-4 times slower than C, C++, Fortran, and machine time
> >   is expensive, and finally
>
> There have already been many studies (also published on this
> list ;-) that this is a prejudice. Java apps can be made to
> run just as fast as C/C++ - if you take care programming.
> (I _don't_ want to start a language war!)
>
> Best Regards,
> Günther
>
>
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