61 lines
4.1 KiB
HTML
61 lines
4.1 KiB
HTML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="Java static compilation performance considerations" />
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<meta name="abstract" content="You can determine the speed of transformation by the optimization level that you set." />
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<meta name="description" content="You can determine the speed of transformation by the optimization level that you set." />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2006" />
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<title>Java static compilation performance considerations</title>
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</head>
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<body id="tranperf"><a name="tranperf"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Java static compilation performance considerations</h1>
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<div><p>You can determine the speed of transformation by the optimization
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level that you set.</p>
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<p>Optimization level 10 transforms the fastest, but the resulting program
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is generally slower than one set at a higher optimization level. Optimization
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level 40 takes longer to transform, but is likely to run faster.</p>
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<p>A small number of Java™ programs may not optimize to level
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40. Thus, a few programs that do not run at level 40, may run at level 30
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instead. You can run programs that do not run at optimization level 40 by
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using licensed internal code optimization <a href="../rbam6/rbam6licopt.htm" target="_blank">LICOPT parameter strings</a>. However, performance at
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level 30 may be sufficient for your program.</p>
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<p>If you are having problems running Java code that seemed to work on another Java virtual
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machine, try using optimization level 30 instead of level 40. If this works,
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and your performance is acceptable, you do not need to do anything else. If
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you need better performance, see <a href="../rbam6/rbam6licopt.htm" target="_blank">LICOPT parameter strings</a> for information on how to
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enable and disable various forms of optimization. For example, you could first
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try creating the program using OPTIMIZE(40) LICOPT(NoPreresolveExtRef). If
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your application contains dead calls to classes that are not available, this
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LICOPT value allows your program to run without problems.</p>
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<p>To determine what level of optimization your Java programs were created at, you can use
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the <a href="../cl/dspjvapgm.htm" target="_blank">Display Java Program
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(DSPJVAPGM)</a> command. To change the optimization level of your Java program,
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use the <a href="../cl/crtjvapgm.htm" target="_blank">Create Java Program
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(CRTJVAPGM)</a> command.</p>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="transfor.htm" title="The Java transformer is an IBM i5/OS component that preprocesses class files to prepare them to run using the iSeries Java virtual machine. The Java transformer creates an optimized program object that is persistent and is associated with the class file.">Static compilation</a></div>
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</div>
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</body>
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</html> |