The Heap and CPU Profiling Agent (HPROF) is a simple profiler agent shipped with the Java 2 SDK. It is a dynamically linked library that interacts with the Java Virtual Machine Profiler Interface (JVMPI) and writes out profiling information either to a file or to a socket in ASCII or binary format.
HPROF can monitor CPU usage, heap allocation statistics, and contention profiles. In addition, it can also report complete heap dumps and states of all the monitors and threads in the Java virtual machine. For more details on the HPROF profiler, see the technical article at http://java.sun.com/developer/technicalArticles/Programming/HPROF.html.
After HPROF is enabled using the following instructions, its libraries are loaded into the server process.
Use the Admin Console. In the developer profile, select the Enterprise Server component and the JVM Settings tab. In the cluster profile, select the JVM Settings component under the relevant configuration. Then select the Profiler tab.
Edit the following fields:
Profiler Name – hprof
Profiler Enabled – true
Classpath – (leave blank)
JVM Option – Select Add, type the HPROF JVM option in the Value field, then check its box. The syntax of the HPROF JVM option is as follows:
Here is an example of params you can use:
The file parameter determines where the stack dump is written.
Using help lists parameters 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 all cpu=samples|old CPU usage off format=a|b ascii or binary output a file=<file> write data to file java.hprof (.txt for ascii) net=<host>:<port> send data over a socket write to file depth=<size> stack trace depth 4 cutoff=<value> output cutoff point 0.0001 lineno=y|n line number in traces? y thread=y|n thread in traces? n doe=y|n dump on exit? y
Do not use help in the JVM Option field. This parameter prints text to the standard output and then exits.
The help output refers to the parameters as options, but they are not the same thing as JVM options.
Restart the Enterprise Server.
This writes an HPROF stack dump to the file you specified using the file HPROF parameter.