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  24 .TH "JMAP" "1" "2020" "JDK 14" "JDK Commands"
  25 .hy
  26 .SH NAME
  27 .PP
  28 jmap \- print details of a specified process
  29 .SH SYNOPSIS
  30 .PP
  31 \f[B]Note:\f[R] This command is experimental and unsupported.
  32 .PP
  33 \f[CB]jmap\f[R] [\f[I]options\f[R]] \f[I]pid\f[R]
  34 .TP
  35 .B \f[I]options\f[R]
  36 This represents the \f[CB]jmap\f[R] command\-line options.
  37 See \f[B]Options for the jmap Command\f[R].
  38 .RS
  39 .RE
  40 .TP
  41 .B \f[I]pid\f[R]
  42 The process ID for which the information specified by the
  43 \f[I]options\f[R] is to be printed.
  44 The process must be a Java process.
  45 To get a list of Java processes running on a machine, use either the
  46 \f[CB]ps\f[R] command or, if the JVM processes are not running in a
  47 separate docker instance, the \f[B]jps\f[R] command.
  48 .RS
  49 .PP
  50 \f[B]Note:\f[R] JDK 10 has added support for using the Attach API when
  51 attaching to Java processes running in a separate docker process.
  52 However, the \f[CB]jps\f[R] command will not list the JVM processes that
  53 are running in a separate docker instance.
  54 If you are trying to connect a Linux host with a Virtual Machine that is
  55 in a docker container, you must use tools such as \f[CB]ps\f[R] to look up
  56 the PID of the JVM.
  57 .RE
  58 .SH DESCRIPTION
  59 .PP
  60 The \f[CB]jmap\f[R] command prints details of a specified running process.
  61 .PP
  62 \f[B]Note:\f[R]
  63 .PP
  64 This command is unsupported and might not be available in future
  65 releases of the JDK.
  66 On Windows Systems where the \f[CB]dbgeng.dll\f[R] file isn\[aq]t present,
  67 the Debugging Tools for Windows must be installed to make these tools
  68 work.
  69 The \f[CB]PATH\f[R] environment variable should contain the location of
  70 the \f[CB]jvm.dll\f[R] file that\[aq]s used by the target process or the
  71 location from which the core dump file was produced.
  72 .SH OPTIONS FOR THE JMAP COMMAND
  73 .TP
  74 .B \f[CB]\-clstats\f[R] \f[I]pid\f[R]
  75 Connects to a running process and prints class loader statistics of Java
  76 heap.
  77 .RS
  78 .RE
  79 .TP
  80 .B \f[CB]\-finalizerinfo\f[R] \f[I]pid\f[R]
  81 Connects to a running process and prints information on objects awaiting
  82 finalization.
  83 .RS
  84 .RE
  85 .TP
  86 .B \f[CB]\-histo\f[R][\f[CB]:live\f[R]] \f[I]pid\f[R]
  87 Connects to a running process and prints a histogram of the Java object
  88 heap.
  89 If the \f[CB]live\f[R] suboption is specified, it then counts only live
  90 objects.
  91 .RS
  92 .RE
  93 .TP
  94 .B \f[CB]\-dump:\f[R]\f[I]dump_options\f[R] \f[I]pid\f[R]
  95 Connects to a running process and dumps the Java heap.
  96 The \f[I]dump_options\f[R] include:
  97 .RS
  98 .IP \[bu] 2
  99 \f[CB]live\f[R] \-\-\- When specified, dumps only the live objects; if not
 100 specified, then dumps all objects in the heap.
 101 .IP \[bu] 2
 102 \f[CB]format=b\f[R] \-\-\- Dumps the Java heap in \f[CB]hprof\f[R] binary
 103 format
 104 .IP \[bu] 2
 105 \f[CB]file=\f[R]\f[I]filename\f[R] \-\-\- Dumps the heap to
 106 \f[I]filename\f[R]
 107 .PP
 108 Example: \f[CB]jmap\ \-dump:live,format=b,file=heap.bin\f[R] \f[I]pid\f[R]
 109 .RE