HP jmeter Software for -UX manual Supported -agentlibhprofoptions

To see the availability of HPjmeter metrics from hprof data collection, see –Xeprof and –agentlib:hprof Profiling Options and Their Corresponding Metrics (page 65). For additional information on collecting heap dump data, see the Java™ Troubleshooting Guide for HP-UX Systems.

NOTE:

With the addition of JVMTI in JDK 5.0, the -agentlibswitch is the preferred way to activate tools such as hprof. With -agentlib, you can take advantage of improvements in JDK 5.0 and reduce the impact of data sampling on application performance. While -Xrunhprofcan still be used to specify the JVM agent with Java 5 versions, the impact on application performance is significantly greater than when using -agentlib.

You will still need to use -Xrunhprofto specify the hprof agent for earlier supported versions of Java (1.4.x).

Here are the supported -agentlib:hprofoptions that affect the collection of profile data:

Table 5-2 Supported -agentlib:hprofoptions

heap=dumpsitesall	The heap dump shows all objects remaining in memory at the time of
	the dump. The allocation sites show where the objects were created
	during the execution of the program. Heap analysis can be used to
	locate memory leaks, and the allocation sites can be used to minimize
	the memory usage.
	To solve memory retention problems, the best practice is to use a signal
	rather than the application shutdown to obtain the heap dump. When
	the application shuts down, some references go out of scope and the
	retention problem may get eliminated just before the heap is dumped.
	Send the signal at the moment that you suspect the application is
	holding references to no longer needed objects.
	To keep the heap dump size down, try to send the signal just after a
	full garbage collection (use -verbose:gcto be notified about the
	garbage collections).
	Remember that a heap dump contains all objects, not just live objects
cpu=samplestimes	cpu=samples uses sampling as the collecting technique, while
	cpu=times uses tracing with reduction.
	• Typically, the times collected by cpu=samplestimes are CPU
	virtual times. However, HP-UX 11i versions use real CPU times
	rather than CPU virtual times unless sampling is used.
	• Some implementations of cpu=times report clock time. HPjmeter
	tries to figure out what times actually have been collected, but
	sometimes does not do it right.
	• cpu=samples and cpu=times output exclusive times.
	• Collecting heap data can be very intrusive, so we recommend that
	you measure the method times and heap usage at different times.
	However, it may make sense to specify heap=sites and
	cpu=samplestimes for the same run when you want to locate
	the allocation sites in the call graph.
thread=yn	Controls whether the stack traces collected during program execution
	will be associated with an individual thread.
	• By default, no thread identification information is stored
	(thread=n).
	• We suggest that you always specify thread=y.
	• With the thread identification in the profile file, HPjmeter can
	calculate the thread profile data for the entire application.

64 Profiling Applications