Troubleshooting Tools on Solaris OS and Linux for Java SE 6

Monitoring Tools
Debugging Tools
Scripting 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, host, or JMX agent.
• Graphical overview of CPU usage, heap memory, threads, classes.
• Summary of key data, for example, uptime, compilation time, objects pending finalization, and more.
• Memory statistics, including garbage collection.
• Request garbage collection.
• Thread statistics.
• Deadlock detection.
• Class statistics.
• Tree structure of all platform and application MBeans.
• Set the value of an MBean attribute.
• Invoke operation on an MBean, for example, perform a heap dump.
• Subscribe to notification for an MBean.
• Information about the virtual machine, the compiler, the operating system.
• Pass flags to VM on which JConsole is running.

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

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.

jhat

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.
• Turn on or off object allocation tracking.
• Turn on or off object reference tracking.
• Specify objects to exclude from "reachable objects" query.
• Pass flags to the Java VM on which jhat is running.
• Develop custom queries with buit-in Object Query Language.
• Compare objects in two dumps.

jinfo

• Print command line flags and system properties for a running process, from a core file, or for a remote debug server.
• Dynamically set, unset, or change the value of certain Java VM flags for a process.

jmap

• Print shared object mappings for a process, a core file, or a remote debug server.
• Dump the Java heap (all objects or only live objects) of a process, a core file, or a remote debug server in binary format to a file.
• Force the Java heap dump of a process if the process does not respond.
• Print a heap summary for a process, a core file, or a remote debug server.
• Print a histogram (all objects or only live objects) of a process, a core file, or a remote debug server.
• Print information on objects awaiting finalization.
• 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
• Print information about concurrent locks for a process, core file, or remote debug server
• Force the stack dump for a process if the process does not respond

Scripting Tools

jrunscript

• Command-line script shell: Evaluate or execute a script in interactive or batch mode.
• Pass flag to the VM.
• Set Java system properties.