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Asked: 2026-05-15T15:48:38+00:00

I have been developing a small Java utility that uses two frameworks: Encog and

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I have been developing a small Java utility that uses two frameworks: Encog and Jetty to provide neural network functionality for a website.

The code is ‘finished’ in that it does everything it needs to do, but I have some problems with memory usage. When running on my development machine the memory usage seems to fluctuate between about 4MB and 13MB when the application is doing things (training neural networks) and at most it uses about 18MB. This is very good usage and I think it is due to the fact that I call System.GC() fairly regularly. I do this because the processing time doesn’t matter for me, but the memory usage does.

So it all works fine on my machine, but as soon as I put it online on our server (shared unix hosting with memory limits) it uses about 19MB to start with and rises to hundreds of MB of memory usage when doing things. These are the same things that I have been doing in testing. The only way, I believe, to reduce the memory usage, is to quit the application and restart it.

The only difference that I can tell is the Java Virtual Machine that it is being run on. I do not know about this and I have tried to find the reason why it is acting this way, but a lot of the documentation assumes a great knowledge of Java and Virtual Machines. Could someone please help m with some reasons why this may be happening and perhaps some things to try to stop it.

I have looked at using GCJ to compile the application, but I don’t know if this is something I should be putting a lot of time in to and whether it will actually help.

Thanks for the help!

  • UPDATE: Developing on Mac OS 10.6.3 and server is on a unix OS but I don’t know what. (Server is from WebFaction)
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  1. Editorial Team

    I think it is due to the fact that I
    call System.GC() fairly regularly

    You should not do that, it’s almost never useful.

    A garbage collector works most efficiently when it has lots of memory to play with, so it will tend to use a large part of what it can get. I think all you need to do is to set the max heap size to something like 32MB with an -Xmx32m command line parameter – the default depends on whether the JVM believes it’s running on a “server class” system, in which case it assumes that you want the application to use as much memory as it can in order to give better throughput.

    BTW, if you’re running on a 64 bit JVM on the server, it will legitimately need more memory (usually about 30%) than on a 32bit JVM due to larger references.

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