Java Monitoring Tools

To gain insight into the JVM itself, Java monitoring tools are required. A number of tools
come with the JDK:

jcmd
Prints basic class, thread, and VM information for a Java process. This is suitable
for use in scripts; it is executed like this:
% jcmd process_id command optional_arguments
Supplying the command help will list all possible commands, and supplying help
<command> will give the syntax for a particular command.

jconsole
Provides a graphical view of JVM activities, including thread usage, class usage, and
GC activities.

jhat
Reads and helps analyze memory heap dumps. This is a postprocessing utility.

jmap
Provides heap dumps and other information about JVM memory usage. Suitable
for scripting, though the heap dumps must be used in a postprocessing tool.

jinfo
Provides visibility into the system properties of the JVM, and allows some system
properties to be set dynamically. Suitable for scripting.

jstack
Dumps the stacks of a Java process. Suitable for scripting.

jstat
Provides information about GC and class-loading activities. Suitable for scripting.

jvisualvm
A GUI tool to monitor a JVM, profile a running application, and analyze JVM heap
dumps (which is a postprocessing activity, though jvisualvm can also take the heap
dump from a live program).

These tools fits into these broad areas:
• Basic VM information
• Thread information
• Class information
• Live GC analysis
• Heap dump postprocessing
• Profiling a JVM