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.TH "JMAP" "1" "2018" "JDK 13" "JDK Commands"

.hy

.SH NAME

.PP

jmap \- print details of a specified process

.SH SYNOPSIS

.PP

\f[B]Note:\f[R] This command is experimental\ and unsupported.

.PP

\f[CB]jmap\f[R] [\f[I]options\f[R]] \f[I]pid\f[R]

.TP

.B \f[I]options\f[R]

This represents the \f[CB]jmap\f[R] command\-line options.

See \f[B]Options for the jmap Command\f[R].

.RS

.RE

.TP

.B \f[I]pid\f[R]

The process ID for which the information specified by the

\f[I]options\f[R] is to be printed.

The process must be a Java process.

To get a list of Java processes running on a machine, use either the

\f[CB]ps\f[R] command or, if the JVM processes are not running in a

separate docker instance, the \f[B]jps\f[R] command.

.RS

.PP

\f[B]Note:\f[R] JDK 10 has added support for using the Attach API when

attaching to Java processes running in a separate docker process.

However, the \f[CB]jps\f[R] command will not list the JVM processes that

are running in a separate docker instance.

If you are trying to connect a Linux host with a Virtual Machine that is

in a docker container, you must use tools such as \f[CB]ps\f[R] to look up

the PID of the JVM.

.RE

.SH DESCRIPTION

.PP

The \f[CB]jmap\f[R] command prints details of a specified running process.

.PP

\f[B]Note:\f[R]

This command is unsupported and might not be available in future

releases of the JDK.

On Windows Systems where the \f[CB]dbgeng.dll\f[R] file isn\[aq]t present,

the Debugging Tools for Windows must be installed to make these tools

work.

The \f[CB]PATH\f[R] environment variable should contain the location of

the \f[CB]jvm.dll\f[R] file that\[aq]s used by the target process or the

location from which the core dump file was produced.

.SH OPTIONS FOR THE JMAP COMMAND

.B \f[CB]\-clstats\f[R] \f[I]pid\f[R]

Connects to a running process and prints class loader statistics of Java

heap.

.RS

.RE

.B \f[CB]\-finalizerinfo\f[R] \f[I]pid\f[R]

Connects to a running process and prints information on objects awaiting

finalization.

.RS

.RE

.B \f[CB]\-histo\f[R][\f[CB]:live\f[R]] \f[I]pid\f[R]

Connects to a running process and prints a histogram of the Java object

heap.

If the \f[CB]live\f[R] suboption is specified, it then counts only live

objects.

.RS

.RE

.B \f[CB]\-dump:\f[R]\f[I]dump_options\f[R] \f[I]pid\f[R]

Connects to a running process and dumps the Java heap.

The \f[I]dump_options\f[R] include:

.RS

.IP \[bu] 2

\f[CB]live\f[R] \-\-\- When specified, dumps only the live objects; if not

specified, then dumps all objects in the heap.

.IP \[bu] 2

\f[CB]format=b\f[R] \-\-\- Dumps the Java heap in \f[CB]hprof\f[R] binary

format

.IP \[bu] 2

\f[CB]file=\f[R]\f[I]filename\f[R] \-\-\- Dumps the heap to

\f[I]filename\f[R]

.PP

Example: \f[CB]jmap\ \-dump:live,format=b,file=heap.bin\f[R] \f[I]pid\f[R]