Troubleshooting Tools on Solaris OS and Linux for Java SE 5.0

Monitoring Tools
Debugging Tools

Monitoring Tools

JConsole

Launch a GUI to monitor and manage Java applications and Java VMs on a local or remote machine.

• Connection to Java process or host.
• Summary of key data, for example, uptime, compilation time, objects pending finalization, and more.
• Memory statistics, including garbage collection.
• Request garbage collection.
• Thread statistics.
• Class statistics.
• Tree structure of all platform and application MBeans.
• Set the value of an MBean attribute.
• Subscribe to notification for an MBean.
• Information about the virtual machine, the compiler, the operating system.

jps

List instrumented Java virtual machines.

jstat

Display performance statistics for an instrumented Java VM:

• Behavior of the class loader
• Behavior of the HotSpot Just-in-Time compiler, totals and by method
• Behavior of the GC heap
• Behavior and sizes of the generation areas

jstatd

• Monitor for creation and termination of instrumented HotSpot Java VMs.
• Provide an interface for remote monitoring tools to attach to Java VMs.

Debugging Tools

Heap Analysis Tool (HAT)

Parse a binary heap dump, launch a web browser, and present standard queries.

• Execute standard queries, for example, classes, objects, class instances, reference chains from object rootset, reachable objects, and more.
• Specify objects to exclude from "reachable objects" query.
• Pass flags to the Java VM on which jhat is running.
• Compare objects in two dumps.

For detailed information, see J2SE 5.0 Troubleshooting and Diagnostic Guide (pdf)

HPROF profiler

Writes class profiling information to a file or a socket, in ASCII or binary.

• Heap allocation profiling.
• Heap dump.
• CPU usage - for threads, methods.
• Monitor contention profiling.

To invoke the HPROF tool: java -agentlib:hprof ToBeProfiledClass

To print the complete list of options: java -agentlib:hprof=help

jdb

Launch a simple interactive command-line debugger.

• Display Java objects and primitive values.
• List currently running threads.
• Dump the current thread stack.
• Set breakpoints.
• Step through execution.
• Examine exceptions.

jinfo

Print Java configuration information (command line flags and system properties) for a running process, from a core file, or for a remote debug server.

jmap

Print memory information for a process, a core file, or a remote debug server.

• Print shared object mappings for a process, a core file, or a remote debug server.
• Print a heap summary for a process, a core file, or a remote debug server.
• Print a histogram of all objects of a process, a core file, or a remote debug server.
• Print class loader statistics of the permanent generation.
• Pass flags to the VM.

jsadebugd

Serviceability Agent Debug Daemon, which acts as debug server.

• Attach to a Java process or a core file.
• Remote clients can attach to the server using RMI.

jstack

Print stack traces of threads for a process, core file, or remote debug server