src/jdk.jcmd/share/man/jcmd.md

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title: 'JCMD(1) JDK @@VERSION_SHORT@@ | JDK Commands'
date: @@COPYRIGHT_YEAR@@
lang: en
---

## Name

jcmd - send diagnostic command requests to a running Java Virtual Machine
(JVM)

## Synopsis

`jcmd` \[*pid* \| *main-class*\] *command*... \| `PerfCounter.print` \| `-f`
*filename*

`jcmd` \[`-l`\]

`jcmd` `-h`

*pid*
:   When used, the `jcmd` utility sends the diagnostic command request to the
    process ID for the Java process.

*main-class*
:   When used, the `jcmd` utility sends the diagnostic command request to all
    Java processes with the specified name of the main class.

*command*
:   The `command` must be a valid `jcmd` command for the selected JVM. The list
    of available commands for `jcmd` is obtained by running the `help` command
    (`jcmd` *pid* `help`) where *pid* is the process ID for the running Java
    process.

`Perfcounter.print`
:   Prints the performance counters exposed by the specified Java process.

`-f` *filename*
:   Reads and executes commands from a specified file, *filename*.

`-l`
:   Displays the list of Java Virtual Machine process identifiers that are not
    running in a separate docker process along with the main class and
    command-line arguments that were used to launch the process. If the JVM is
    in a docker process, you must use tools such as `ps` to look up the PID.

    **Note:**

    Using `jcmd` without arguments is the same as using `jcmd -l`.

`-h`
:   Displays the `jcmd` utility's command-line help.

## Description

The `jcmd` utility is used to send diagnostic command requests to the JVM. It
must be used on the same machine on which the JVM is running, and have the same
effective user and group identifiers that were used to launch the JVM. Each
diagnostic command has its own set of options and arguments. To display the description,
syntax, and a list of available options and arguments for a diagnostic command, use the
name of the command as the argument. For example:

>   `jcmd` *pid* `help` *command*

If arguments contain spaces, then you must surround them with single or double
quotation marks (`'` or `"`). In addition, you must escape single or double
quotation marks with a backslash (`\`) to prevent the operating system shell
from processing quotation marks. Alternatively, you can surround these
arguments with single quotation marks and then with double quotation marks (or
with double quotation marks and then with single quotation marks).

If you specify the process identifier (*pid*) or the main class (*main-class*)
as the first argument, then the `jcmd` utility sends the diagnostic command
request to the Java process with the specified identifier or to all Java
processes with the specified name of the main class. You can also send the
diagnostic command request to all available Java processes by specifying `0` as
the process identifier.

## Commands for jcmd

The *command* must be a valid `jcmd` diagnostic command for the selected JVM.
The list of available commands for `jcmd` is obtained by running the `help`
command (`jcmd` *pid* `help`) where *pid* is the process ID for a running Java
process. If the *pid* is `0`, commands will be sent to all Java processes. The
main class argument will be used to match, either partially or fully, the class
used to start Java. If no options are given, it lists the running Java process
identifiers that are not in separate docker processes along with the main class
and command-line arguments that were used to launch the process (the same as
using `-l`).

`jcmd` *commands* may take options and arguments.  *Options* are specified using
either *key* or *key*`=`*value* syntax.  *Arguments* are given as just a value,
never name=value.


The following commands are available:

`help` \[*options*\] \[*arguments*\]
:   For more information about a specific command.

    *arguments*:

    -   *command name*: The name of the command for which we want help (STRING,
        no default value)

    **Note:**

    The following *options* must be specified using either *key* or
    *key*`=`*value* syntax.

    *options*:

    -   `-all`: (Optional) Show help for all commands (BOOLEAN, false) .

`Compiler.CodeHeap_Analytics`  \[*function*\] \[*granularity*\]
:   Print CodeHeap analytics

    Impact: Low: Depends on code heap size and content. Holds CodeCache_lock during analysis step, usually sub-second duration.

    *arguments*:

    -   *function*: (Optional) Function to be performed (aggregate, UsedSpace, FreeSpace, MethodCount, MethodSpace, MethodAge, MethodNames, discard (STRING, all)

    -   *granularity*: (Optional) Detail level - smaller value -> more detail (INT, 4096)

`Compiler.codecache`
:   Prints code cache layout and bounds.

    Impact: Low

`Compiler.codelist`
:   Prints all compiled methods in code cache that are alive.

    Impact: Medium

`Compiler.directives_add` *arguments*
:   Adds compiler directives from a file.

    Impact: Low

    *arguments*:

    -   *filename*: The name of the directives file (STRING, no default value)

`Compiler.directives_clear`
:   Remove all compiler directives.

    Impact: Low

`Compiler.directives_print`
:   Prints all active compiler directives.

    Impact: Low

`Compiler.directives_remove`
:   Remove latest added compiler directive.

    Impact: Low

`Compiler.memory` \[*options*\]
:   Print compilation footprint

    Impact: Medium: Pause time depends on number of compiled methods

    **Note:**

    The *options* must be specified using either *key* or *key*`=`*value*
    syntax.

    *options*:

    -   `-H`: (Optional) Human readable format (BOOLEAN, false)
    -   `-s`: (Optional) Minimum memory size (MEMORY SIZE, 0)

`Compiler.perfmap` \[*arguments*\] (Linux only)
:   Write map file for Linux perf tool.

    Impact: Low

    *arguments*:

    -   *filename*: (Optional) The name of the map file.  If %p is specified in the filename, it is expanded to the JVM's PID. (FILE, "/tmp/perf-%p.map")

`Compiler.queue`
:   Prints methods queued for compilation.

    Impact: Low

`GC.class_histogram` \[*options*\]
:   Provides statistics about the Java heap usage.

    Impact: High --- depends on Java heap size and content.

    **Note:**

    The *options* must be specified using either *key* or *key*`=`*value*
    syntax.

    *options*:

    -   `-all`: (Optional) Inspects all objects, including unreachable objects
        (BOOLEAN, false)
    -  `-parallel`: (Optional) Number of parallel threads to use for heap inspection.
       0 (the default) means let the VM determine the number of threads to use.
       1 means use one thread (disable parallelism). For any other value the VM will
       try to use the specified number of threads, but might use fewer. (INT, 0)

`GC.finalizer_info`
:   Provides information about the Java finalization queue.

    Impact: Medium

`GC.heap_dump` \[*options*\] *filename*
:   Generates a HPROF format dump of the Java heap.

    Impact: High --- depends on the Java heap size and content. Request a full
    GC unless the `-all` option is specified.

    **Note:**

    The following *options* must be specified using either *key* or
    *key*`=`*value* syntax.

    *options*:

    -   `-all`: (Optional) Dump all objects, including unreachable objects
        (BOOLEAN, false)
    -   `-gz`: (Optional) If specified, the heap dump is written in gzipped format
         using the given compression level. 1 (recommended) is the fastest, 9 the
         strongest compression. (INT, 1)
    -   `-overwrite`: (Optional) If specified, the dump file will be overwritten if
         it exists (BOOLEAN, false)
    -   `-parallel`: (Optional) Number of parallel threads to use for heap dump. The VM will try to use the specified number of threads, but might use fewer. (INT, 1)

    *arguments*:

    -   *filename*: The name of the dump file.  If %p is specified in the filename, it is expanded to the JVM's PID. (FILE, no default value)

`GC.heap_info`
:   Provides generic Java heap information.

    Impact: Medium

`GC.run`
:   Calls `java.lang.System.gc()`.

    Impact: Medium --- depends on the Java heap size and content.

`GC.run_finalization`
:   Calls `java.lang.System.runFinalization()`.

    Impact: Medium --- depends on the Java content.

`JFR.check` \[*options*\]
:   Show information about a running flight recording

    Impact: Low

    **Note:**

    The *options* must be specified using either *key* or *key*`=`*value*
    syntax. If no parameters are entered, information for all active recordings is shown.

    *options*:

    -   `name`: (Optional) Name of the flight recording. (STRING, no default value)

    -   `verbose`: (Optional) Flag for printing the event settings for the recording
        (BOOLEAN, false)

`JFR.configure` \[*options*\]
:   Set the parameters for a flight recording

    Impact: Low

    **Note:**

    The *options* must be specified using either *key* or *key*`=`*value*
    syntax. If no parameters are entered, the current settings are displayed.

    *options*:

    -   `dumppath`: (Optional) Path to the location where a recording file is written
        in case the VM runs into a critical error, such as a system
        crash. (STRING, The default location is the current directory)

    -   `globalbuffercount`: (Optional) Number of global buffers. This option is
        a legacy option: change the `memorysize` parameter to alter the number of
        global buffers. This value cannot be changed once JFR has been initialized.
        (STRING, default determined by the value for `memorysize`)

    -   `globalbuffersize`: (Optional) Size of the global buffers, in bytes. This
        option is a legacy option: change the `memorysize` parameter to alter
        the size of the global buffers. This value cannot be changed once JFR
        has been initialized. (STRING, default determined by the value for `memorysize`)

    -   `maxchunksize`: (Optional) Maximum size of an individual data chunk in bytes
        if one of the following suffixes is not used: 'm' or 'M' for megabytes OR
        'g' or 'G' for gigabytes. This value cannot be changed once JFR has been
        initialized. (STRING, 12M)

    -   `memorysize`: (Optional) Overall memory size, in bytes if one of the following
        suffixes is not used: 'm' or 'M' for megabytes OR 'g' or 'G' for gigabytes.
        This value cannot be changed once JFR has been initialized. (STRING, 10M)

    -   `repositorypath`: (Optional) Path to the location where recordings are stored
        until they are written to a permanent file. (STRING, The default location is
        the temporary directory for the operating system. On Linux operating systems,
        the temporary directory is `/tmp`. On Windwows, the temporary directory is
        specified by the `TMP` environment variable.)

    -   `preserve-repository=`{`true`\|`false`} : Specifies whether files stored in
        the disk repository should be kept after the JVM has exited. If false, files
        are deleted. By default, this parameter is disabled.

    -   `stackdepth`: (Optional) Stack depth for stack traces. Setting this value
        greater than the default of 64 may cause a performance degradation.
        This value cannot be changed once JFR has been initialized.  (LONG, 64)

    -   `thread_buffer_size`: (Optional) Local buffer size for each thread in bytes if one
        of the following suffixes is not used: 'k' or 'K' for kilobytes or 'm' or 'M'
        for megabytes. Overriding this parameter could reduce performance and is
        not recommended. This value cannot be changed once JFR has been initialized.
        (STRING, 8k)

    -   `samplethreads`: (Optional) Flag for activating thread sampling. (BOOLEAN, true)

`JFR.dump` \[*options*\]
:   Write data to a file while a flight recording is running

    Impact: Low

    **Note:**

    The *options* must be specified using either *key* or *key*`=`*value* syntax.
    No options are required. The recording continues to run after the data is written.

    *options*:

    -   `begin`: (Optional) Specify the time from which recording data will be included
        in the dump file. The format is specified as local time. (STRING, no default value)

    -   `end`: (Optional) Specify the time to which recording data will be included in the
        dump file. The format is specified as local time. (STRING, no default value)

        **Note:** For both `begin` and `end`, the time must be in a format that can be read
        by java.time.LocalTime::parse(STRING), java.time.LocalDateTime::parse(STRING)
        or java.time.Instant::parse(STRING). For example, "13:20:15", "2020-03-17T09:00:00"
        or "2020-03-17T09:00:00Z".

        **Note:** `begin` and `end` times correspond to the timestamps found within the recorded
        information in the flight recording data.

        Another option is to use a time relative to the current time that is specified
        by a negative integer followed by "s", "m" or "h".  For example, "-12h", "-15m" or "-30s"

    -   `filename`: (Optional) Name of the file to which the flight recording data
        is dumped. If no filename is given, a filename is generated from the PID and
        the current date. The filename may also be a directory in which case, the filename
        is generated from the PID and the current date in the specified directory.
        If %p and/or %t is specified in the filename, it expands to the JVM's PID and
        the current timestamp, respectively.
        (FILE, no default value)

    -   `maxage`: (Optional) Length of time for dumping the flight recording data
        to a file. (INTEGER followed by 's' for seconds 'm' for minutes or 'h' for hours,
        no default value)

    -   `maxsize`: (Optional) Maximum size for the amount of data to dump from a flight
        recording in bytes if one of the following suffixes is not used: 'm' or 'M' for megabytes
        OR 'g' or 'G' for gigabytes. (STRING, no default value)

    -   `name`: (Optional) Name of the recording. If no name is given, data
        from all recordings is dumped. (STRING, no default value)

    -   `path-to-gc-roots`: (Optional) Flag for saving the path to garbage collection (GC)
        roots at the time the recording data is dumped. The path information is useful for
        finding memory leaks but collecting it can cause the application to pause for
        a short period of time. Turn on this flag only when you have an application
        that you suspect has a memory leak. (BOOLEAN, false)

`JFR.start` \[*options*\]
:   Start a flight recording

    Impact: Low

    **Note:**

    The *options* must be specified using either *key* or *key*`=`*value*
    syntax. If no parameters are entered, then a recording is started with default values.

    *options*:

    -   `delay`: (Optional) Length of time to wait before starting to record
        (INTEGER followed by 's' for seconds 'm' for minutes or 'h' for hours, 0s)

    -   `disk`: (Optional) Flag for also writing the data to disk while recording
        (BOOLEAN, true)

    -   `dumponexit`: (Optional) Flag for writing the recording to disk when the
        Java Virtual Machine (JVM) shuts down. If set to 'true' and no value is given
        for `filename`, the recording is written to a file in the directory where
        the process was started. The file name is a system-generated name that
        contains the process ID, the recording ID and the current time stamp.
        (For example: `id-1-2019_12_12_10_41.jfr`) (BOOLEAN, false)

    -   `duration`: (Optional) Length of time to record. Note that `0s` means forever
        (INTEGER followed by 's' for seconds 'm' for minutes or 'h' for hours, 0s)

    -   `filename`: (Optional) Name of the file to which the flight recording data
        is written when the recording is stopped. If no filename is given, a filename
        is generated from the PID and the current date and is placed in the directory
        where the process was started. The filename may also be a directory in which case,
        the filename is generated from the PID and the current date in the specified directory.
        If %p and/or %t is specified in the filename, it expands to the JVM's PID
        and the current timestamp, respectively.
        (FILE, no default value)

    -   `maxage`: (Optional) Maximum time to keep the recorded data on disk. This
        parameter is valid only when the `disk` parameter is set to `true`. Note
        `0s` means forever. (INTEGER followed by 's' for seconds 'm'
        for minutes or 'h' for hours, 0s)

    -   `maxsize`: (Optional) Maximum size of the data to keep on disk in bytes if one
        of the following suffixes is not used: 'm' or 'M' for megabytes OR 'g' or 'G' for gigabytes.
        This parameter is valid only when the `disk` parameter is set to 'true'. The value must
        not be less than the value for the `maxchunksize` parameter set with the `JFR.configure` command.
        (STRING, 0 (no maximum size))

    -   `name`: (Optional) Name of the recording. If no name is provided, a name is generated.
        Make note of the generated name that is shown in the response to the command so that
        you can use it with other commands. (STRING, system-generated default name)

    -   `path-to-gc-roots`: (Optional) Flag for saving the path to garbage collection (GC)
        roots at the end of a recording. The path information is useful for finding memory leaks
        but collecting it is time consuming. Turn on this flag only when you
        have an application that you suspect has a memory leak. If the `settings` parameter
        is set to 'profile', then the information collected includes the stack trace
        from where the potential leaking object was allocated. (BOOLEAN, false)

    -   `settings`: (Optional) Name of the settings file that identifies which events to record.
        To specify more than one file, separate the names with a comma (','). Include the path
        if the file is not in `JAVA-HOME`/lib/jfr. The following profiles are included with
        the JDK in the `JAVA-HOME`/lib/jfr directory: 'default.jfc': collects a predefined set
        of information with low overhead, so it has minimal impact on performance and can be
        used with recordings that run continuously; 'profile.jfc': Provides more data than the
        'default.jfc' profile, but with more overhead and impact on performance. Use this
        configuration for short periods of time when more information is needed. Use `none` to
        start a recording without a predefined configuration file.
        (STRING, `JAVA-HOME`/lib/jfr/default.jfc)

    Event settings and .jfc options can be specified using the following syntax:

    -   `option`: (Optional) Specifies the option value to modify. To list available
        options, use the `JAVA_HOME`/bin/jfr tool.

    -   `event-setting`: (Optional) Specifies the event setting value to modify. Use the form:
        `<event-name>#<setting-name>=<value>`
        To add a new event setting, prefix the event name with '+'.

    You can specify values for multiple event settings and .jfc options by
    separating them with a whitespace. In case of a conflict between a parameter
    and a .jfc option, the parameter will take precedence. The whitespace
    delimiter can be omitted for timespan values, i.e. 20ms. For more
    information about the settings syntax, see Javadoc of the jdk.jfr
    package.

`JFR.stop` \[*options*\]
:   Stop a flight recording

    Impact: Low

    **Note:**

    The *options* must be specified using either *key* or *key*`=`*value*
    syntax. If no parameters are entered, then no recording is stopped.

    *options*:

    -   `filename`: (Optional) Name of the file to which the recording is
        written when the recording is stopped. If %p and/or %t is specified
        in the filename, it expands to the JVM's PID and the current
        timestamp, respectively. If no path is provided, the data from the
        recording is discarded. (FILE, no default value)

    -   `name`: (Optional) Name of the recording (STRING, no default value)


`JFR.view` \[*options*\]
:   Display event data in predefined views.

    Impact: Medium

    **Note:**

    The *options* must be specified using either *key* or *key*`=`*value*
    syntax. If no parameters are entered, then a list of available views
    are displayed.

    *options*:

    -   `cell-height`: (Optional) Maximum number of rows in a table cell.
        (INT, default value depends on the view)

    -   `maxage`: (Optional) Length of time for the view to span.
        (INT followed by 's' for seconds 'm' for minutes or 'h' for hours,
        default value is 10m)

    -   `maxsize`: (Optional) Maximum size for the view to span in bytes if one
        of the following suffixes is not used: 'm' or 'M' for megabytes OR
        'g' or 'G' for gigabytes. (STRING, default value is 32MB)

    -   `truncate`: (Optional) Maximum number of rows in a table cell.
        (INT, default value depends on the view)

    -   `verbose`: (Optional) Displays the query that makes up the view.
        (BOOLEAN, default value is false)

    -   `width`: (Optional) The width of the view in characters. (INT,
        default value depends on the view)

    *arguments*:

    -   `view`: Name of the view or event type to display. Use `help JFR.view`
        to see a list of available views. (STRING, no default value)

    The view parameter can be an event type name. Use `JFR.view types` to see
    a list. To display all views, use `JFR.view all-views`. To display all
    events, use `JFR.view all-events`.

`JVMTI.agent_load` \[*arguments*\]
:   Loads JVMTI native agent.

    Impact: Low

    *arguments*:

    -   *library path*: Absolute path of the JVMTI agent to load. (STRING, no
        default value)

    -   *agent option*: (Optional) Option string to pass the agent. (STRING, no
        default value)

`JVMTI.data_dump`
:   Signal the JVM to do a data-dump request for JVMTI.

    Impact: High

`ManagementAgent.start` \[*options*\]
:   Starts remote management agent.

    Impact: Low --- no impact

    **Note:**

    The following *options* must be specified using either *key* or
    *key*`=`*value* syntax.

    *options*:

    -   `config.file`: (Optional) Sets `com.sun.management.config.file`
        (STRING, no default value)

    -   `jmxremote.host`: (Optional) Sets `com.sun.management.jmxremote.host`
        (STRING, no default value)

    -   `jmxremote.port`: (Optional) Sets `com.sun.management.jmxremote.port`
        (STRING, no default value)

    -   `jmxremote.rmi.port`: (Optional) Sets
        `com.sun.management.jmxremote.rmi.port` (STRING, no default value)

    -   `jmxremote.ssl`: (Optional) Sets `com.sun.management.jmxremote.ssl`
        (STRING, no default value)

    -   `jmxremote.registry.ssl`: (Optional) Sets
        `com.sun.management.jmxremote.registry.ssl` (STRING, no default value)

    -   `jmxremote.authenticate`: (Optional) Sets
        `com.sun.management.jmxremote.authenticate` (STRING, no default value)

    -   jmxremote.password.file: (Optional) Sets
        `com.sun.management.jmxremote.password.file` (STRING, no default value)

    -   `jmxremote.access.file`: (Optional) Sets
        `com.sun.management.jmxremote.acce ss.file` (STRING, no default value)

    -   `jmxremote.login.config`: (Optional) Sets
        `com.sun.management.jmxremote.log in.config` (STRING, no default value)

    -   `jmxremote.ssl.enabled.cipher.suites`: (Optional) Sets
        `com.sun.management`.

    -   `jmxremote.ssl.enabled.cipher.suite`: (STRING, no default value)

    -   `jmxremote.ssl.enabled.protocols`: (Optional) Sets
        `com.sun.management.jmxr emote.ssl.enabled.protocols` (STRING, no
        default value)

    -   `jmxremote.ssl.need.client.auth`: (Optional) Sets
        `com.sun.management.jmxre mote.need.client.auth` (STRING, no default
        value)

    -   `jmxremote.ssl.config.file`: (Optional) Sets
        `com.sun.management.jmxremote. ssl_config_file` (STRING, no default
        value)

    -   `jmxremote.autodiscovery`: (Optional) Sets
        `com.sun.management.jmxremote.au todiscovery` (STRING, no default
        value)

    -   `jdp.port`: (Optional) Sets `com.sun.management.jdp.port` (INT, no
        default value)

    -   `jdp.address`: (Optional) Sets `com.sun.management.jdp.address`
        (STRING, no default value)

    -   `jdp.source_addr`: (Optional) Sets `com.sun.management.jdp.source_addr`
        (STRING, no default value)

    -   `jdp.ttl`: (Optional) Sets `com.sun.management.jdp.ttl` (INT, no
        default value)

    -   `jdp.pause`: (Optional) Sets `com.sun.management.jdp.pause` (INT, no
        default value)

    -   `jdp.name`: (Optional) Sets `com.sun.management.jdp.name` (STRING, no
        default value)

`ManagementAgent.start_local`
:   Starts the local management agent.

    Impact: Low --- no impact

`ManagementAgent.status`
:   Print the management agent status.

    Impact: Low --- no impact

`ManagementAgent.stop`
:   Stops the remote management agent.

    Impact: Low --- no impact

`System.dump_map` \[*options*\] (Linux only)
:   Dumps an annotated process memory map to an output file.

    Impact: Low

    **Note:**

    The following *options* must be specified using either *key* or
    *key*`=`*value* syntax.

    *options*:

    -    `-H`: (Optional) Human readable format (BOOLEAN, false)
    -    `-F`: (Optional) File path.  If %p is specified in the filename, it is expanded to the JVM's PID.  (FILE, "vm_memory_map_%p.txt")

`System.map` \[*options*\] (Linux only)
:   Prints an annotated process memory map of the VM process.

    Impact: Low

    **Note:**

    The following *options* must be specified using either *key* or
    *key*`=`*value* syntax.

    *options*:

    -    `-H`: (Optional) Human readable format (BOOLEAN, false)

`System.native_heap_info` (Linux only)
:   Attempts to output information regarding native heap usage through malloc_info(3). If unsuccessful outputs "Error: " and a reason.

    Impact: Low

`System.trim_native_heap` (Linux only)
:   Attempts to free up memory by trimming the C-heap.

    Impact: Low

`Thread.dump_to_file` \[*options*\] *filepath*
:   Dump threads, with stack traces, to a file in plain text or JSON format.

    Impact: Medium: Depends on the number of threads.

    **Note:**

    The following *options* must be specified using either *key* or
    *key*`=`*value* syntax.

    *options*:

    -   `-overwrite`: (Optional) May overwrite existing file (BOOLEAN, false)
    -   `-format`: (Optional) Output format ("plain" or "json") (STRING, plain)

    *arguments*:

    -   *filepath*:  The file path to the output file.  If %p is specified in the filename, it is expanded to the JVM's PID.  (FILE, no default value)

`Thread.print` \[*options*\]
:   Prints all threads with stacktraces.

    Impact: Medium --- depends on the number of threads.

    **Note:**

    The following *options* must be specified using either *key* or
    *key*`=`*value* syntax.

    *options*:

    -   `-e`: (Optional) Print extended thread information (BOOLEAN, false)
    -   `-l`: (Optional) Prints `java.util.concurrent` locks (BOOLEAN, false)

`Thread.vthread_scheduler`
:   Print the virtual thread scheduler, and the delayed task schedulers that support
    virtual threads doing timed operations.

    Impact: Low

`Thread.vthread_pollers`
:   Print the I/O pollers that support virtual threads doing blocking network I/O operations.

    Impact: Low

`VM.cds` \[*arguments*\]
:   Dump a static or dynamic shared archive that includes all currently loaded classes.

    Impact: Medium --- pause time depends on number of loaded classes

    *arguments*:

    -   *subcmd*:  must be either `static_dump` or `dynamic_dump` (STRING, no default value)
    -   *filename*: (Optional) Name of the shared archive to be dumped.  If %p is specified in the filename, it is expanded to the JVM's PID.  (FILE, "java_pid%p_\<subcmd\>.jsa")

    If `dynamic_dump` is specified, the target JVM must be started with the JVM option
    `-XX:+RecordDynamicDumpInfo`.

`VM.class_hierarchy` \[*options*\] \[*arguments*\]
:   Print a list of all loaded classes, indented to show the class hierarchy.
    The name of each class is followed by the ClassLoaderData\* of its
    ClassLoader, or "null" if it is loaded by the bootstrap class loader.

    Impact: Medium --- depends on the number of loaded classes.

    **Note:**

    The following *options* must be specified using either *key* or
    *key*`=`*value* syntax.

    *options*:

    -   `-i`: (Optional) Inherited interfaces should be printed. (BOOLEAN,
        false)

    -   `-s`: (Optional) If a classname is specified, print its subclasses
         in addition to its superclasses. Without this option only the
         superclasses will be printed. (BOOLEAN, false)

    *arguments*:

    -   *classname*: (Optional) The name of the class whose hierarchy should be
        printed. If not specified, all class hierarchies are printed. (STRING,
        no default value)

`VM.classes` \[*options*\]
:   Print all loaded classes

    Impact: Medium: Depends on number of loaded classes.

    The following *options* must be specified using either *key* or
    *key*`=`*value* syntax.

    *options*:

    -   `-verbose`: (Optional) Dump the detailed content of a Java class.
        Some classes are annotated with flags: `F` = has, or inherits, a non-empty finalize method,
        `f` = has final method, `W` = methods rewritten, `C` = marked with `@Contended` annotation,
        `R` = has been redefined, `S` = is shared class (BOOLEAN, false)

`VM.classloader_stats`
:   Print statistics about all ClassLoaders.

    Impact: Low

`VM.classloaders` \[*options*\]
:   Prints classloader hierarchy.

    Impact: Medium --- Depends on number of class loaders and classes loaded.

    The following *options* must be specified using either *key* or
    *key*`=`*value* syntax.

    *options*:

    -   `show-classes`: (Optional) Print loaded classes. (BOOLEAN, false)
    -   `verbose`: (Optional) Print detailed information. (BOOLEAN, false)
    -   `fold`: (Optional) Show loaders of the same name and class as one. (BOOLEAN, true)

`VM.command_line`
:   Print the command line used to start this VM instance.

    Impact: Low

`VM.dynlibs`
:   Print loaded dynamic libraries.

    Impact: Low

`VM.events` \[*options*\]
:   Print VM event logs

    Impact: Low --- Depends on event log size.

    *options*:

    **Note:**

    The following *options* must be specified using either *key* or
    *key*`=`*value* syntax.

    -   `log`: (Optional) Name of log to be printed.
        If omitted, all logs are printed. (STRING, no default value)
    -   `max`: (Optional) Maximum number of events to be printed (newest first).
        If omitted or zero, all events are printed. (INT, 0)

`VM.flags` \[*options*\]
:   Print the VM flag options and their current values.

    Impact: Low

    **Note:**

    The following *options* must be specified using either *key* or
    *key*`=`*value* syntax.

    *options*:

    -   `-all`: (Optional) Prints all flags supported by the VM (BOOLEAN,
        false).

`VM.info`
:   Print information about the JVM environment and status.

    Impact: Low

`VM.log` \[*options*\]
:   Lists current log configuration, enables/disables/configures a log output,
    or rotates all logs.

    Impact: Low

    *options*:

    **Note:**

    The following *options* must be specified using either *key* or
    *key*`=`*value* syntax.

    -   `output`: (Optional) The name or index (\#) of output to configure.
        (STRING, no default value)

    -   `output_options`: (Optional) Options for the output. (STRING, no
        default value)

    -   `what`: (Optional) Configures what tags to log. (STRING, no default
        value )

    -   `decorators`: (Optional) Configures which decorators to use. Use 'none'
        or an empty value to remove all. (STRING, no default value)

    -   `disable`: (Optional) Turns off all logging and clears the log
        configuration. (BOOLEAN, no default value)

    -   `list`: (Optional) Lists current log configuration. (BOOLEAN, no
        default value)

    -   `rotate`: (Optional) Rotates all logs. (BOOLEAN, no default value)

`VM.metaspace`  \[*options*\]
:   Prints the statistics for the metaspace

    Impact: Medium --- Depends on number of classes loaded.

    **Note:**

    The following *options* must be specified using either *key* or
    *key*`=`*value* syntax.

    *options*:

    -   `basic`: (Optional) Prints a basic summary (does not need a safepoint). (BOOLEAN, false)
    -   `show-loaders`: (Optional) Shows usage by class loader. (BOOLEAN, false)
    -   `show-classes`: (Optional) If show-loaders is set, shows loaded classes for each loader. (BOOLEAN, false)
    -   `by-chunktype`: (Optional) Break down numbers by chunk type. (BOOLEAN, false)
    -   `by-spacetype`: (Optional) Break down numbers by loader type. (BOOLEAN, false)
    -   `vslist`: (Optional) Shows details about the underlying virtual space. (BOOLEAN, false)
    -   `chunkfreelist`: (Optional) Shows details about global chunk free lists (ChunkManager). (BOOLEAN, false)
    -   `scale`: (Optional) Memory usage in which to scale. Valid values are: 1, KB, MB
        or GB (fixed scale) or "dynamic" for a dynamically chosen scale. (STRING, dynamic)

`VM.native_memory` \[*options*\]
:   Print native memory usage

    Impact: Medium

    **Note:**

    The following *options* must be specified using either *key* or
    *key*`=`*value* syntax.

    *options*:

    -   `summary`: (Optional) Requests runtime to report current memory
        summary, which includes total reserved and committed memory, along with
        memory usage summary by each subsystem. (BOOLEAN, false)

    -   `detail`: (Optional) Requests runtime to report memory allocation &gt;=
        1K by each callsite. (BOOLEAN, false)

    -   `baseline`: (Optional) Requests runtime to baseline current memory
        usage, so it can be compared against in later time. (BOOLEAN, false)

    -   `summary.diff`: (Optional) Requests runtime to report memory summary
        comparison against previous baseline. (BOOLEAN, false)

    -   `detail.diff`: (Optional) Requests runtime to report memory detail
        comparison against previous baseline, which shows the memory allocation
        activities at different callsites. (BOOLEAN, false)

    -   `statistics`: (Optional) Prints tracker statistics for tuning purpose.
        (BOOLEAN, false)

    -   `scale`: (Optional) Memory usage in which scale, KB, MB or GB (STRING,
        KB)

`VM.set_flag` \[*arguments*\]
:   Sets VM flag option using the provided value.

    Impact: Low

    *arguments*:

    -   *flag name*: The name of the flag that you want to set (STRING, no
        default value)

    -   *string value*: (Optional) The value that you want to set (STRING, no
        default value)

`VM.stringtable` \[*options*\]
:   Dump string table.

    Impact: Medium --- depends on the Java content.

    **Note:**

    The following *options* must be specified using either *key* or
    *key*`=`*value* syntax.

    *options*:

    -   `-verbose`: (Optional) Dumps the content of each string in the table
        (BOOLEAN, false)

`VM.symboltable` \[*options*\]
:   Dump symbol table.

    Impact: Medium --- depends on the Java content.

    **Note:**

    The following *options* must be specified using either *key* or
    *key*`=`*value* syntax).

    *options*:

    -   `-verbose`: (Optional) Dumps the content of each symbol in the table
        (BOOLEAN, false)

`VM.system_properties`
:   Print system properties.

    Impact: Low

`VM.systemdictionary`
:   Prints the statistics for dictionary hashtable sizes and bucket length.

    Impact: Medium

    **Note:**

    The following *options* must be specified using either *key* or
    *key*`=`*value* syntax.

    *options*:

    -   `verbose`: (Optional) Dump the content of each dictionary entry for all
        class loaders (BOOLEAN, false) .

`VM.uptime` \[*options*\]
:   Print VM uptime.

    Impact: Low

    **Note:**

    The following *options* must be specified using either *key* or
    *key*`=`*value* syntax.

    *options*:

    -   `-date`: (Optional) Adds a prefix with the current date (BOOLEAN,
        false)

`VM.version`
:   Print JVM version information.

    Impact: Low