jmap

jmap

Display memory usage

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Synopsis

 jmap [   options   ]   pid   // local process jmap [   options   ]   executable     core   // core file jmap [   options   ] [   process-name   @]   hostname   // remote process 

Description

jmap prints memory usage information for a local or remote Java process or a Java core file. Depending on the option it is invoked with, jmap displays one of four memory usage reports . See the Options section for details. jmap can be started in three ways:

• Specify the process id of a Java process running locally to obtain configuration information about it. See jps to list local processes.

• To obtain post-mortem configuration information from a core file, specify the java executable that produced the core file and the core file itself on the command line.

• To obtain configuration information about a Java process running remotely, specify the name of the remote host, optionally prefixed by a remote process name and @ sign. jsadebugd must be running on the remote host.

In Java 5.0, jmap is experimental, unsupported, and not available on all platforms.

Options

When invoked with no options, jmap prints a memory map of the shared objects or libraries loaded by the VM. Other reports can be produced by using the options below. These options are mutually exclusive; only one may be specified.

-heap

Displays a summary of heap memory usage.

-help, -h

Prints a help message.

-histo

Displays a histogram of heap usage by class.

-permstat

Displays memory used by loaded classes, grouped by class loader.

See also

jps , jsadebugd