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Java has a built-in feature for dumping heap snapshots to files in HPROF binary format. You can analyze these snapshots using all of the powerful features that YourKit Java Profiler provides for its own memory snapshots.

HPROF snapshots can be created in the following ways:

• Automatically when OutOfMemory occurs
• Explicitly from within the profler UI (Sun Java 6)

  

• Explicitly via jmap utility (Sun Java 6)

  Sun Java 6 has the jmap utility that allows to connect to running Java process and dump Java heap:
  jmap -dump:format=b,file=file_name.hprof <pid>

  The benefit is that memory can be analyzed on demand with no additional configuration of JVM or Java application. You can dump memory of any running instance of JVM that supports this feature (see the list above).

• Explicitly via jconsole utility (Sun Java 6)

  Sun Java has the jconsole utility that lets you to connect to a running Java 6 process for monitoring and management:

  Using jconsole, you can dump Java heap via HotSpotDiagnostic MBean

  

• Produced with Java's built-in basic level profiling capability HPROF

  This approach has a lot of drawbacks and is not useful nowadays, but is mentioned here to show the complete picture.

How it works

HPROF snapshots (*.hprof) can be opened the same way as YourKit Java Profiler format snapshots (*.snapshot)

Known issues

Some HPROF snapshots do not contain values of primitive types. When such snapshots are opened in the profiler, values of java.lang.String's will not be available.