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What is the impact to put -d64 into the Liferay 5.2, weblogic 10 over Solaris environment? What is the impact of choosing Xms=Xmx=8GB and PermGen=1g, in that setup.

[Hands on experience: I see some Null exceptions occasionally, but the application is on and I don't see problems data, or visually. It's a test environment, not any production. ]

Thank you for any comment

Aleš
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hephestos
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These options impact performance so there will not be any functional impact to your application.

-d64 explained : What impact, if any, does the -d64 switch have on Sun JVM resident memory usage?

Xms=Xmx=8GB, PermGen=1g : These are Heap Size settings, these will influence the GC algorithm running time.

Community
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Aleš
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  • So basically the 100% performance gain I got now, is because of just using values such as Xms and Xmx and Permgen ? If I read right, then only on Solaris is -d64 not usefull, while on other OSes it should have a meaningful purpose. Did I get it correctly ? – hephestos Dec 20 '12 at 11:28
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    Yes, that 100% performance gain is due improved GC settings (provided that you have not changed anything else). Increasing Heap size means less work for JVM and thus better throughput. The `-d64` has impact also on Solaris, this allows you to run in 64-bit JVM mode which then allows you to have bigger heap sizes. – Aleš Dec 20 '12 at 23:12
  • ok then one last to close it at all, is if you have the will to answer how do you measure the best values to reach this point??(...Basically I used the instict...which is not really good choice selector...) – hephestos Dec 20 '12 at 23:35
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    Its definitely not easy to tune properly the GC settings. You need to enable full GC logging, observe the GC behavior and its frequency and then modify the settings accordingly. After several iterations you usually empirically determine what fits best to your specific application needs. – Aleš Dec 20 '12 at 23:48