The jvmstat technology adds light weight performance and configuration instrumentation to the HotSpot JVM and provides a set of monitoring APIs and tools for monitoring the performance of the HotSpot JVM in production environments. The instrumentation is designed such that it is 'always on', yet has negligible performance impact. The monitoring interfaces added to the HotSpot JVM are proprietary and may or may not be supported in future versions of the HotSpot JVM.
The instrumented HotSpot JVM ships with J2SE 1.4.2, providing always-on instrumentation. The jvmstat 2.0 tools included with this distribution can only monitor Java applications running on the HotSpot 1.4.2 JVM as distributed with Sun's J2SE 1.4.2 product. The jvmstat tools prior to version 2.0 cannot be used to monitor Java applications running on the HotSpot 1.4.2 JVM. The jvmstat 2.0 tools can be used to remote monitor HotSpot 1.4.1 JVMs when connecting through a jvmstat 1.0 perfagent; however, some features, such as many of the jvmstat formatted output options, will not work properly.
The jvmstat monitoring tools work in conjunction with a specific version of the instrumented HotSpot JVM. Before configuring and using the jvmstat tools, first download and install J2SE 1.4.2 for your operating environment. You can choose either the J2SE 1.4.2 SDK or JRE. Once you have a working J2SE 1.4.2 installation, you are ready to install the jvmstat tools. Follow the platform specific instructions for UNIX platforms and Windows platforms.
The jvmstat feature includes a number of tools:
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jvmstat |
A tool to sample and log instrumentation |
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jvmps |
A tool providing a simple Java process listing |
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visualgc |
A tool to graphically display instrumentation |
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perfagent |
A server providing remote access to instrumentation |
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jvmsnap |
A tool to snapshot instrumentation and output as name/value pairs |
Please see the Tool Documentation page for more details on these tools.
The instrumented HotSpot JVM exports a set of instrumentation objects, or counters as they are frequently called. The set of counters exported by a JVM is not static, as a JVM may create certain counters only when appropriate arguments are specified on the command line. Furthermore, different versions of a JVM may export very different sets of instrumentation than previous versions. The names and data structures of instrumentation objects are uncommitted and may change without notice.
Please see the Instrumentation Documentation page for more details on the instrumentation exported by the 1.4.2 version of the instrumented HotSpot JVM.
Support
The jvmstat tools are officially unsupported. If you are expericencing a problem, please check the jvmstat FAQ for solutions. If you are still experiencing problems, or have additional questions, please send an email to jvmstat-support@sun.com .