C++ vs. Java Performance

[manderson5192]

2) Interesting...On the USFIRST.org beta testing forums, team 67 posted this:

the almost-empty loops we've timed run about 50 times faster in C++ than in Java.

Is there really no noticeable performance hit?

...and a couple, related question:

4) How does the Java vision API compare to the C++ one? Is there a large speed difference?

5) After having beta tested in java, will your team use it this year?

6) When do you think everything will be released for us non-beta-testers?

Thanks again!
-Matt

[Abrakadabra]

Originally Posted by manderson5192

2) Interesting...On the USFIRST.org beta testing forums, team 67 posted this:

"the almost-empty loops we've timed run about 50 times faster in C++ than in Java. "

Is there really no noticeable performance hit?

...and a couple, related question:

4) How does the Java vision API compare to the C++ one? Is there a large speed difference?
...

I'm not a Beta tester, but I did talk with Brad Miller (father of WPILib) at RiverRage, and he spoke to two of your questions:

Re: Performance - Yes, C++, which compiles down to native machine code is always going to be faster than Java in pure speed tests, because Java has to take the extra step through the virtual machine. However, for our application, most (if not all) of the time-critical pieces are done in the FPGA libraries, where the JVM isn't a factor.

Re: Vision libraries - the vision processing code remains in C++, and is accessed in Java via wrappers that use the JNI (Java Native Interface), so again, there is no Java performance penalty involved.

HTH.

[Jared Russell]

Originally Posted by manderson5192

2) Interesting...On the USFIRST.org beta testing forums, team 67 posted this:



Is there really no noticeable performance hit?

...and a couple, related question:

4) How does the Java vision API compare to the C++ one? Is there a large speed difference?

5) After having beta tested in java, will your team use it this year?

6) When do you think everything will be released for us non-beta-testers?

Thanks again!
-Matt

I would argue that an empty loop hardly makes for a meaningful speed test. But yes - perfectly written Java will almost always lose in a performance test against perfectly written C++. But to Java's credit, it is often easier to write good Java than it is to write good C++, which can tip the scales back in Java's favor. Regardless, FIRST robots really don't tend to do anything all that computationally complicated.

4) None at all as far as I can tell. It's the same code running underneath it all.

5) Definitely - it is much more accessible to our students than C++.

6) Not sure. "Soon" seems to be the general consensus. Definitely in advance of build season.

[manderson5192]

Thanks for the help, guys! At this point, it sounds like team 948 will be going java as well =D.

[BradAMiller]

Originally Posted by manderson5192

2) Interesting...On the USFIRST.org beta testing forums, team 67 posted this:

...and a couple, related question:

4) How does the Java vision API compare to the C++ one? Is there a large speed difference?

The Java vision stuff is actually written in C++ for high performance. In Java you refer to pointers to C++ image objects to make sure that there are no slowdowns due to any complex image processing that needs to get done.

6) When do you think everything will be released for us non-beta-testers?

Yesterday

Thanks again!
-Matt

[Dragonos]

Where can I download it?

[derekwhite]

See Bill's Blog for the release announcement:

http://frcdirector.blogspot.com/2009...ot-bill-2.html