Using the HPROF Profiler

HPROF is a simple profiler agent shipped with the Java 2 SDK. It is a dynamically linked library that interacts with the Java^TM Virtual Machine Profiler Interface (JVMPI) and writes out profiling information either to a file or to a socket in ASCII or binary format. This information can be further processed by a profiler front-end tool such as HAT.

HPROF can present CPU usage, heap allocation statistics, and monitor contention profiles. In addition, it can also report complete heap dumps and states of all of the monitors and threads in the Java virtual machine. For more details on the HPROF profiler, see the JDK documentation at:

http://java.sun.com/j2se/1.4.2/docs/guide/jvmpi/jvmpi.html

Once HPROF is installed, its libraries are loaded into the server process.

You can configure Web Server

To Install the HPROF Profiler

1. Access the Admin Console.

2. Click the Edit Java Settings tab in the home page.

   The JVM General Settings screen appears.

3. Click Profilers.

4. Click New.

   The Create JVM Profiler popup appears.

5. Type the Name and select the JVM Profiler option to enable the profiler. Leave the Class Path and Native Library Path fields blank.

6. Click New to configure the JVM options.

7. Click OK.

   Edit the server.xml file as appropriate

   <! --hprof options -->
   <profiler name="hprof" enabled="true"
   <jvm-options>
   -Xrunhprof:file=log.txt,options
   </jvm-options>
   </profiler>

   ---

   Note –

   Do not use the -Xrs flag.

   ---

   Here is an example of options you can use:

   -Xrunhprof:file=log.txt,thread=y,depth=3

   The file option is important because it determines where the stack dump is written in step 6.

   The syntax of HPROF options is as follows:

   -Xrunhprof[:help]|[:option=value,option2=value2, ...]

   Using help lists options that can be passed to HPROF. The output is as follows:

   Hprof usage: -Xrunhprof[:help]|[:<option>=<value>, ...]
   Option Name and Value Description Default
   heap=dump|sites|all heap profiling allcpu=samples|old CPU 
   usage offformat=a|b ascii or binary output 
   afile=<file> write data to file java.hprof(.txt for ascii)
   net=<host>:<port> send data over a socket write to filedepth=<size> 
   stack trace depth 4cutoff=<value> 
   output cutoff point 0.0001lineno=y|n line number in traces? 
   ythread=y|n thread in traces? ndoe=y|n dump on exit? y

8. Change the PRODUCT_BIN assignment in the /install_dir/instance_dir/bin/startserv file from:

   PRODUCT_BIN=webservd-wdog to PRODUCT_BIN=webservd

9. Start the server by running the startserv script.

   As the server runs in the foreground, the command prompt returns only after the server has been stopped.

10. Find the process ID of the server process in another window or terminal.

    % ps -ef | grep webservd

    This command lists two webservd processes. Look at the PPID (parent process ID) column and identify which of the two processes is the parent process and which is the child process. Note the PID (process ID) of the child process ID.

11. Send a SIGQUIT signal (signal 3) to the child process:

    % kill -QUIT child_PID

12. Run the stopserv script from another window to stop the Web Server.

    % ./stopserv

    Stopping the server writes an HPROF stack dump to the file you specified using the file HPROF option. For general information about using a stack dump, see Generating a Stack Trace for Debugging.