Synopsis
jstat [ options ] pid [ interval[s|ms] [ count ]]
jstat [ options ] pid@hostname[:port] [ interval[s|ms] [ count ]]
Description
jstat probes a running JVM
once or repeatedly and displays statistics about its class loading,
just-in-time compilation, memory, or garbage collection performance.
The type of information to be displayed is specified by
options. A local process to be probed is
specified by its process id, as returned, for example, by
jps. A remote Java process may be probed by
specifying the remote process id, the remote host name, and the port
number on which the remote host's
rmiregistry server is running (if other than the
default of 1099). The remote host must also be running the
jstatd server.
By default, jstat probes the specified Java VM
once. You may also specify a probe interval, in milliseconds or
seconds, to have it probe repeatedly. If you do this, you may
additionally specify a total number of probes it should conduct.
jconsole can report many of the same statistics
that jstat does but displays them in graphical
rather than tabular form. In Java 5.0, jinfo is
experimental, unsupported, and not available on all platforms.
Options
- -help
-
Displays a help message.
- -options
-
Displays a list of report types that jstat can
display. You must use one of the listed options each time you run
jstat.
- -version
-
Displays the jstat version information and exits.
- -h n
-
When jstat probes the Java process repeatedly,
this option specifies how often it should repeat the table headers in
its output. This option must follow one of the report type options
below.
- -t
-
Adds a Timestamp column to the report generated by
jstat. The column displays elapsed time (in
seconds) since the target Java process was started.
The following options specify the type of statistics to be reported
by jstat. Unless you run
jstat with -help,
-options or -version, you must
specify exactly one of these options, and it must be the first option
on the command line. Most of the options produce detailed reports of
garbage collection minutiae. Consult Sun's tool
documentation (part of the JDK documentation bundle) for the
interpretation of these reports.
- -class
-
Reports the number of classes loaded and their size in
kilobytes.
- -compiler
-
Reports the amount of just-in-time compilation that has been
performed, and how long it has taken.
- -gc
-
Reports heap garbage collection statistics.
- -gccapacity
-
Reports capacity information of the garbage
collector's various memory pools.
- -gccause
-
Like the -gcutil report but includes information
about the cause of the most recent garbage collection.
- -gcnew
-
Reports information on the "new
generation" memory pools of the garbage collector.
- -gcnewcapacity
-
Reports capacity information for the garbage
collector's "new
generation" memory pools.
- -gcold
-
Reports information on the old generation and permanent memory pools
of the garbage collector.
- -gcoldcapacity
-
Reports capacity information for the garbage
collector's old generation memory pools.
- -gcpermcapacity
-
Reports capacity information for the garbage
collector's permanent generation.
- -gcutil
-
Reports garbage collection summaries.
- -printcompilation
-
Reports additional information about just-in-time compilation,
including the method names of compiled methods.
See also
jconsole, jps,
jstatd
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