ibm-information-center/dist/eclipse/plugins/i5OS.ic.rzaha_5.4.0.1/callperf.htm

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<h1 class="topictitle1">Java call trace performance tools</h1>
<div><p>Java™ method call traces provide significant performance
information about the time that is spent in each Java method. </p>
<p>On other Java virtual machines, you may have used the -prof (profiling)
option on the <samp class="codeph">java</samp> command. To enable method call tracing
on an iSeries™ server,
you must specify the Enable Performance Collection (ENBPFRCOL) command on
the Create Java Program (CRTJVAPGM) command line. After creating
your Java program
with this keyword, you can start the collection of method call traces by using
a Performance Explorer (PEX) definition that includes the call/return trace
type.</p>
<p>Call/return trace output produced with the Print Performance Explorer Report
(PRTPEXRPT) command shows the central processing unit (CPU) time for each
call for every Java method that is traced. In some cases, you may not
be able to enable all of the class files for call return tracing. Or, you
may be calling native methods and system functions that are not enabled for
tracing. In this situation, all of the CPU time that is spent in these methods
or system functions accumulates. Then, it is reported to the last Java method
that is called and has been enabled.</p>
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<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="tuning.htm" title="You should take several aspects of Java application performance into consideration when building a Java application for your iSeries server.">Tune Java program performance with IBM Developer Kit for Java</a></div>
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<div class="relconcepts"><strong>Related concepts</strong><br />
<div><a href="evenperf.htm" title="The iSeries Java virtual machine enables the trace of certain Java events.">Java event trace performance tools</a></div>
<div><a href="runtperf.htm" title="Understanding the following considerations can help you improve the performance of your Java applications.">Java performance considerations</a></div>
<div><a href="gc.htm" title="Garbage collection is the process of freeing storage that is used by objects that are no longer referred to by a program. With garbage collection, programmers no longer have to write error prone code to explicitly &#34;free&#34; or &#34;delete&#34; their objects. This code frequently results in &#34;memory leak&#34; program errors. The garbage collector automatically detects an object or group of objects that the user program can no longer reach. It does this because there are no references to that object in any program structure. Once the object has been collected, you can allocate the space for other uses.">Java garbage collection</a></div>
<div><a href="jnmiperf.htm" title="Native method invocation on an iSeries server may not perform as well as native method invocation on other platforms.">Java Native Method Invocation performance considerations</a></div>
<div><a href="jmiperf.htm" title="Method inlining can significantly improve method call performance. Any method that is final is a potential candidate for inlining.">Java method inlining performance considerations</a></div>
<div><a href="excperf.htm" title="The iSeries exception architecture allows versatile interrupt and retry capabilities. It also allows mixed language interaction. Throwing Java exceptions on an iSeries server may be more expensive than on other platforms. This should not affect overall application performance unless Java exceptions are routinely used in the normal application path.">Java exception performance considerations</a></div>
<div><a href="profperf.htm" title="System wide central processing unit (CPU) profiling calculates the relative amount of CPU time that is spent in each Java method and all system functions in use by your Java program.">Java profiling performance tools</a></div>
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<div class="reltasks"><strong>Related tasks</strong><br />
<div><a href="colpdc.htm" title="To collect Java performance data on an iSeries server, follow these steps.">Collect Java performance data</a></div>
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