Here is one report that shows performance results that are more commiserate with my own personal experience:
From: http://verify.stanford.edu/uli/java_cpp.html : a bit dated but still relevant --
Here the results for my 400 MHz Pentium II PC running RedHat 5.2 / 6.1:
| Version | Execution Environment | Execution Time |
| Java array | JVM 1.1.5 v7 / 1.2 pre-v2 / 1.2.2 rc2 | 192s / 96s / 118s |
| HotSpot Server 1.3.0 / IBM Classic VM 1.3.0 | 16.7s / 10.7s | |
| HotSpot Server 1.3.1beta-b15 | 16.3s | |
| Java Vector | JVM 1.1.5 v7 / 1.2 pre-v2 / 1.2.2 rc2 | 698s / 481s / 543s |
| HotSpot Server 1.3.0 / IBM Classic VM 1.3.0 | 46.5s / 71.5s | |
| HotSpot Server 1.3.1beta-b15 | 45.6s | |
| Java ArrayList | JVM 1.2 pre-v2 / 1.2.2 rc2 | - / 260s |
| HotSpot Server 1.3.0 / IBM Classic VM 1.3.0 | 18.8s / 62.8s | |
| HotSpot Server 1.3.1beta-b15 | 18.8s | |
| C++ pointer | gcc version egcs-2.90.29 / 2.95 | 3.6s / 3.3s |
| C++ object | gcc version egcs-2.90.29 / 2.95 | 5.7s / 3.9s |
| C++ vector | gcc version egcs-2.90.29 / 2.95 | 6.0s / 5.9s |
| C++ STL | gcc version egcs-2.90.29 / 2.95 | 3.8s / 3.9s |
Here more results for a Sun Ultra 10 running Solaris 8 (SunOS 5.8).
| Version | Execution Environment | Execution Time |
| Java array | HotSpot Server VM 1.3.0 | 17.4s |
| Java ArrayList | HotSpot Server VM 1.3.0 | 26.3s |
| C++ pointer | Sun CC 5.1 | 5.22s |
| gcc 2.95.2 | 5.84s | |
| C++ STL | gcc 2.95.2 | 6.55s |
--Doug
On 10/7/06, Douglas Roberts <[EMAIL PROTECTED]> wrote:
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
[EMAIL PROTECTED]
[EMAIL PROTECTED]
505-455-7333 - Office
505-670-8195 - CellOn 10/7/06, Günther Greindl < [EMAIL PROTECTED]> 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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--
Doug Roberts, RTI International
[EMAIL PROTECTED]
[EMAIL PROTECTED]
505-455-7333 - Office
505-670-8195 - Cell
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