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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]
.PP
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
.TP
.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
.TP
.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
.TP
.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
.TP
.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]
.RE