jmap

Synopsis

jmap [options ]pid

jmap [options ]executablecore

jmap [options ] [pid ]server-id@ ]remote-hostname-or-IP

options

The command-line options. SeeOptions.

pid

The process ID for which the memory map is to be printed. The process must be a Java process. To get a list of Java processes running on a machine, use thejps(1) command.

executable

The Java executable from which the core dump was produced.

core

The core file for which the memory map is to be printed.

remote-hostname-or-IP

The remote debug serverhostname orIP address. Seejsadebugd(1).

server-id

An optional unique ID to use when multiple debug servers are running on the same remote host.

Description

Thejmap command prints shared object memory maps or heap memory details of a specified process, core file, or remote debug server. If the specified process is running on a 64-bit Java Virtual Machine (JVM), then you might need to specify the-J-d64 option, for example:jmap-J-d64 -heap pid.

Note: This utility is unsupported and might not be available in future releases of the JDK. On Windows Systems where thedbgeng.dll file is not present, Debugging Tools For Windows must be installed to make these tools work. ThePATH environment variable should contain the location of thejvm.dll file that is used by the target process or the location from which the crash dump file was produced, for example:set PATH=%JDK_HOME%\jre\bin\client;%PATH%.

Options

<no option>

When no option is used, thejmap command prints shared object mappings. For each shared object loaded in the target JVM, the start address, size of the mapping, and the full path of the shared object file are printed. This behavior is similar to the Oracle Solarispmap utility.

-dump:[live,] format=b, file=filename

Dumps the Java heap inhprof binary format tofilename. Thelive suboption is optional, but when specified, only the active objects in the heap are dumped. To browse the heap dump, you can use thejhat(1) command to read the generated file.

-finalizerinfo

Prints information about objects that are awaiting finalization.

-heap

Prints a heap summary of the garbage collection used, the head configuration, and generation-wise heap usage. In addition, the number and size of interned Strings are printed.

-histo[:live]

Prints a histogram of the heap. For each Java class, the number of objects, memory size in bytes, and the fully qualified class names are printed. The JVM internal class names are printed with an asterisk (*) prefix. If thelive suboption is specified, then only active objects are counted.

-clstats

Prints class loader wise statistics of Java heap. For each class loader, its name, how active it is, address, parent class loader, and the number and size of classes it has loaded are printed.

-F

Force. Use this option with thejmap -dump orjmap -histo option when the pid does not respond. Thelive suboption is not supported in this mode.

-h

Prints a help message.

-help

Prints a help message.

-Jflag

Passesflag to the Java Virtual Machine where thejmap command is running.

See Also

• jhat(1)

• jps(1)

• jsadebugd(1)