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POFast memory manipulation in Java?
 

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  1. POFast memory manipulation in Java?
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    <p>I am a bit of a newbie to Java (prior experience with C on embedded platforms), so please forgive me if this question is very trivial.</p> <p>I need to implement some signal processing algorithms in Java. I know Java is probably not the best language to do this [1], but the Java requirement has come in primarily because the rest of my team is not comfortable with C at all.</p> <p>What we need to do at a high level is to read some files containing video frames, process them (gather some statistics about them) and then write them back to disk. The processing will involve reading in a few kB of data and parsing them somehow, possibly with some kind of transforms. i.e. I expect we will need to do a <em>lot</em> of byte-addressed random memory accesses. And I'll need to do about 30 frames per second and a few tens of thousands of such operations every frame (so possibly 100s of 1000s of ops per second)</p> <p>I do not know the 'internals' of Java very well, but from what I read I believe the memory that Java sees is far abstracted from the actual virtual memory that the OS itself provides [2].</p> <p>What buffer management libraries should I use so that I can get the best possible performance? I've seen a few (NIO [3], Java 2d [4], etc) but I am not able to find which is faster, or if there are any other options that I am missing. Do you guys have any suggestions or pointers [5] for me?</p> <p>I will also be doing lots of arithmetic, so are there any libraries that do 'faster' arithmetic? I come from a world where I could accelerate almost everything on the hardware but now I need to run this on a PC so I am not sure if there are any such options available.</p> <p>Any other suggestions or help you guys could provide will be much appreciated!</p> <ul> <li>[1] <a href="https://stackoverflow.com/questions/636686/signal-processing-library-in-java">Signal processing library in Java?</a></li> <li>[2] Is this understanding correct at all? Is there anywhere I can find out how "Java memory" maps to lower level memory?</li> <li>[3] <a href="http://download.oracle.com/javase/6/docs/api/java/nio/package-summary.html" rel="nofollow noreferrer">http://download.oracle.com/javase/6/docs/api/java/nio/package-summary.html</a></li> <li>[4] <a href="http://java.sun.com/products/java-media/2D/index.jsp" rel="nofollow noreferrer">http://java.sun.com/products/java-media/2D/index.jsp</a></li> <li>[5] No pun intended.</li> </ul>
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    1. COThe thing is, most signal processing in Java will look almost identical to C, because it will almost inevitably be implemented in a procedural style. I don't know why your coworkers would be so scared of this. Take away objects and Java starts to look a lot like C.
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      1. USMark Peters
    2. CO[2] This is correct. The JVM maintains its own memory and has some quite high performance garbage collection algorithms. It also does a lot of dynamic optimisation, so I would recommend writing up your algorithm and profiling it to evaluate your performance bottlenecks.
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    3. CO@MarkPeters yes, that is true - I guess it's more inertia than anything else.
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