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  1. #1
    RonaldJJames is offline Member
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    Default 32 bit JRE vs 64 bit JRE

    We have an unsupported 3rd party reporting application, (Panscopic’s Scopeserver running under Tomcat), that has started having out of memory errors when running very large reports. Long term, we’re looking for a replacement, but short term I’m wondering if I can upgrade the underlying Java run-time environment to 64 bit. We’re currently running under a 32 bit version of Java on 64 bit MS Windows with 12Gb RAM.
    Given that Java compiles to byte-code and the run time environment enables that code to run on a variety of platforms,
    • Will Java .class files compiled under a 32 bit version of the compiler run under a 64 bit version of the run time environment?
    • If the software runs, is it likely that Out-Of-Memory problems might go away, at least until we hit 64 bit limits?

  2. #2
    jim829 is offline Senior Member
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    Default Re: 32 bit JRE vs 64 bit JRE

    I cannot authoritatively say for certain but it is probably ok since it is the JVM that manages memory in conjunction with the local OS. Otherwise, applets developed on various platforms would not run on all machines.

    It really depends on what is causing the problem. A possible scenario is that there may be some internal limit on report sizes that throws a memory exception
    when the limit is reached. Or it could be hitting a point where the software just chews up memory. So with more memory you may just delay the inevitable.

    The best route IMO would be to simply stand up a test server using the 64 bit version with sufficient memory and try and re-create the problem. But I
    am pretty certain you already thought of that.

    Regards,
    Jim
    The Java™ Tutorial | SSCCE | Java Naming Conventions
    Poor planning our your part does not constitute an emergency on my part.

  3. #3
    gimbal2 is offline Just a guy
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    Default Re: 32 bit JRE vs 64 bit JRE

    Quote Originally Posted by RonaldJJames View Post
    • Will Java .class files compiled under a 32 bit version of the compiler run under a 64 bit version of the run time environment?
    Of course. Basic research into what this tool (Java) is you're using would have told you that instantly. Java is cross-platform; compile once, run everywhere.

    • If the software runs, is it likely that Out-Of-Memory problems might go away, at least until we hit 64 bit limits?
    There is only one answer: maybe. If you give more heap space you'll be able to load larger reports, but if the software contains a memory leak then it will likely eventually gobble up all memory there is, even if you throw terabytes at it. It will just take longer. Since you state that this only happens when loading larger reports, you likely can solve this with more memory.

    It helps to actually learn something about the JVM, because if you go down this road you are going to get into the wonderful territory of tuning. Just throwing a larger heap at the application will likely cause other problems, such as performance issues with the garbage collector.
    "Syntactic sugar causes cancer of the semicolon." -- Alan Perlis

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