As an example of the consistency jhsdb provides, all of its mode support the 'common options' -pid (to specify target JVM's process ID), -exe (to specify target executable), -core (to specify target core dump file), and -help (to display options specific to each mode). The jhsdb tool can also be used to analyze core information associated with a crashed JVM if the core file and executable are provided. The jhsdb tool can be attached and applied to a running JVM (including one that is hanging) via its process identifier (PID) similar to how several other tools (including jcmd) work. For example, the jhsdb command-line syntax for getting help for each of the 'modes' is identical.

The jhsdb tool not only provides a single tool that encompasses functionality of multiple other tools, but it also provides a single, consistent approach to applying these different functions. The jhsdb tool is described on its Oracle JDK 9 Documentation Early Access page, 'You use the jhsdb tool to attach to a Java process or to launch a postmortem debugger to analyze the content of a core-dump from a crashed Java Virtual Machine (JVM).' The tool comes with several 'modes' and several of these modes correspond in name and function with individual command-line tools available in previous JDK distributions. In this post, I focus on a new command-line tool delivered with JDK 9 for dealing with performance and serviceability issues: jhsdb. JDK 9 is bringing new command-line tools with multiple tools specifically related to new JDK 9 features such as modularity ( jlink and jmod) and enhanced deprecation ( jdeprscan). I like to use the command-line tools provided with the JDK in the early steps of analyzing performance and other issues with Java-based applications and have blogged on tools such as jcmd, jps, jstat, jinfo, jhat and jmap, jrunscript, jstack, and jdeps.

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