See also For information on how to compare data files, see Comparing Profiling Data Files (page 71) and Scaling Comparison Data (page 72).

Collecting Profile Data

To take full advantage of HPjmeter functionality, you can gather profiling data using -Xeproffor performance tuning and -agentlib:hproffor memory tuning when you run your application.

NOTE: If you are running the HP JDK/JRE 5.0.04 or later, you can send a signal to the running JVM to start and stop a profiling data collection period with zero preparation and no interruption of your application. See Profiling with Zero Preparation (page 62).

Profiling with -Xeprof

To profile an application, use the following command:

$ java -Xeprof:options ApplicationClassName

To profile an applet, use the following command:

$ appletviewer -J-Xeprof:options URL

where options is a list of key[=value] arguments separated by commas.

You can also stop the JVM (kill pid) or control the profiling time using the time_on or time_slice options. See the descriptions in the list of options.

The following options are especially useful in most cases:

•For CPU time, clock time, and lock contention metrics with minimal intrusion, use -Xeprof

•For exact call count information and non-array object creation profiling, use-Xeprof:inlining=disableTo see the complete list of available options, use java -Xeprof:help

-Xeprofalways collects call graph data with inclusive method times (clock and CPU), method call count, and lock contention metrics. This option uses tracing with reduction and collects the data separately for each thread.

To see the availability of HPjmeter metrics from -Xeprofdata collection, see –Xeprof and –agentlib:hprof Profiling Options and Their Corresponding Metrics (page 65).

Table 5-1 Supported -Xeprofoptions

time_on=integer

Specifies the time in seconds between the application start and the time when

 

the profile data collection will start. If no time_on option is present, the data

 

collection begins at the VM initialization.

 

 

time_on=sigusr1sigusr2

Specifies which signal will cause profiling to begin (profile data collection).

 

• Be aware that the application or the VM may already be using the sigusr

 

signals for their own purposes.

 

• Specifying a signal and a timeout at the same time is possible by repeating

 

the time_on option.

 

• Only one of the two signals can be declared to use as the signal to start

 

profiling.

 

• During the application's run, the specified signal can be delivered to the

 

Java process multiple times.

 

 

time_slice=integer

Specifies the time in seconds between the profiling start and the time when

 

profiling will be terminated.

 

• When the profiling is terminated, the profile data is written to a file. The

 

application will continue running.

 

• If time_slice is not specified, or if the application terminates before the

 

specified time elapses, but the profiling has started, the profile data will

 

be written out after the termination of the application.

 

 

Collecting Profile Data

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