jcmd
You use the jcmd
utility to 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 validjcmd
command for the selected JVM. The list of available commands forjcmd
is obtained by running thehelp
command (jcmd pid help
) wherepid
is the process ID for the running Java process. If thepid
is0
, 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 with the main class and command-line arguments that were used to launch the process (the same as using-l
). -
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 usingjcmd -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 arguments. To display the description, syntax, and a list of available 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
).
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 by using eitherkey
orkey=value
syntax.options
:-
-all
: (Optional) Show help for all commands (BOOLEAN, false) .
-
-
Compiler.codecache
-
Prints code cache layout and bounds.
Impact: Low
Permission:
java.lang.management.ManagementPermission(monitor)
-
Compiler.codelist
-
Prints all compiled methods in code cache that are alive.
Impact: Medium
Permission:
java.lang.management.ManagementPermission(monitor)
-
Compiler.queue
-
Prints methods queued for compilation.
Impact: Low
Permission:
java.lang.management.ManagementPermission(monitor)
-
Compiler.directives_add filename arguments
-
Adds compiler directives from a file.
Impact: Low
Permission:
java.lang.management.ManagementPermission(monitor)
arguments
:filename
: The name of the directives file (STRING, no default value) -
Compiler.directives_clear
-
Remove all compiler directives.
Impact: Low
Permission:
java.lang.management.ManagementPermission(monitor)
-
Compiler.directives_print
-
Prints all active compiler directives.
Impact: Low
Permission:
java.lang.management.ManagementPermission(monitor)
-
Compiler.directives_remove
-
Remove latest added compiler directive.
Impact: Low
Permission:
java.lang.management.ManagementPermission(monitor)
-
GC.class_histogram [options]
-
Provides statistics about the Java heap usage.
Impact: High — depends on Java heap size and content.
Permission:
java.lang.management.ManagementPermission(monitor)
Note:
The
options
must be specified by using eitherkey
orkey=value
syntax.options
:-
-all
: (Optional) Inspects all objects, including unreachable objects (BOOLEAN, false)
-
-
GC.class_stats [options] [arguments]
-
Provide statistics about Java class meta data.
Impact: High — depends on Java heap size and content.
Note:
The
options
must be specified by using eitherkey
orkey=value
syntax.options
:-
-all
: (Optional) Shows all columns (BOOLEAN, false) -
-csv
: (Optional) Prints in CSV (comma-separated values) format for spreadsheets (BOOLEAN, false) -
-help
: (Optional) Shows the meaning of all the columns (BOOLEAN, false)
arguments
-
columns: (Optional) Comma-separated list of all the columns to be shown. If not specified, the following columns are shown:
-
InstBytes
-
KlassBytes
-
CpAll
-
annotations
-
MethodCount
-
Bytecodes
-
MethodAll
-
ROAll
-
RWAll
-
Total
-
-
-
GC.finalizer_info
-
Provides information about the Java finalization queue.
Impact: Medium
Permission:
java.lang.management.ManagementPermission(monitor)
-
GC.heap_dump [options] [arguments]
-
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.Permission:
java.lang.management.ManagementPermission(monitor)
Note:
The following
options
must be specified by using eitherkey
orkey=value
syntax.options
:-
-all
: (Optional) Dump all objects, including unreachable objects (BOOLE AN, false)
arguments
:-
filename: The name of the dump file (STRING, no default value)
-
-
GC.heap_info
-
Provides generic Java heap information.
Impact: Medium
Permission:
java.lang.management.ManagementPermission(monitor)
-
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]
-
See JFR.check in the Java Flight Recorder Command Reference.
-
JFR.configure [options]
-
See JFR.configure in the Java Flight Recorder Command Reference.
-
JFR.dump [options]
-
See JFR.dump in the Java Flight Recorder Command Reference.
-
JFR.start [options]
-
See JFR.start in the Java Flight Recorder Command Reference.
-
JFR.stop [options]
-
See JFR.stop in the Java Flight Recorder Command Reference.
-
JVMTI.agent_load [arguments]
-
Loads JVMTI native agent.
Impact: Low
Permission:
java.lang.management.ManagementPermission(control)
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
-
Signals the JVM to do a data-dump request for JVMTI.
Impact: High
Permission:
java.lang.management.ManagementPermission(monitor)
-
ManagementAgent.start [options]
-
Starts remote management agent.
Impact: Low — no impact
Note:
The following
options
must be specified by using eitherkey
orkey=value
syntax.options
:-
config.file
: (Optional) Setscom.sun.management.config.file
(STRING, no default value) -
jmxremote.host
: (Optional) Setscom.sun.management.jmxremote.host
(STRING, no default value) -
jmxremote.port
: (Optional) Setscom.sun.management.jmxremote.port
(STRING, no default value) -
jmxremote.rmi.port
: (Optional) Setscom.sun.management.jmxremote.rmi.port
(STRING, no default value) -
jmxremote.ssl
: (Optional) Setscom.sun.management.jmxremote.ssl
(STRING, no default value) -
jmxremote.registry.ssl
: (Optional) Setscom.sun.management.jmxremote.registry.ssl
(STRING, no default value) -
jmxremote.authenticate
: (Optional) Setscom.sun.management.jmxremote.authenticate
(STRING, no default value) -
jmxremote.password.file
: (Optional) Setscom.sun.management.jmxremote.password.file
(STRING, no default value) -
jmxremote.access.file
: (Optional) Setscom.sun.management.jmxremote.access.file
(STRING, no default value) -
jmxremote.login.config
: (Optional) Setscom.sun.management.jmxremote.login.config
(STRING, no default value) -
jmxremote.ssl.enabled.cipher.suites
: (Optional) Setscom.sun.management
. -
jmxremote.ssl.enabled.cipher.suite
: (STRING, no default value) -
jmxremote.ssl.enabled.protocols
: (Optional) Setscom.sun.management.jmxremote.ssl.enabled.protocols
(STRING, no default value) -
jmxremote.ssl.need.client.auth
: (Optional) Setscom.sun.management.jmxremote.need.client.auth
(STRING, no default value) -
jmxremote.ssl.config.file
: (Optional) Setscom.sun.management.jmxremote.ssl_config_file
(STRING, no default value) -
jmxremote.autodiscovery
: (Optional) Setscom.sun.management.jmxremote.autodiscovery
(STRING, no default value) -
jdp.port
: (Optional) Setscom.sun.management.jdp.port
(INT, no default value) -
jdp.address
: (Optional) Setscom.sun.management.jdp.address
(STRING, no default value) -
jdp.source_addr
: (Optional) Setscom.sun.management.jdp.source_addr
(STR ING, no default value) -
jdp.ttl
: (Optional) Setscom.sun.management.jdp.ttl
(INT, no default value) -
jdp.pause
: (Optional) Setscom.sun.management.jdp.pause
(INT, no default value) -
jdp.name
: (Optional) Setscom.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
Permission:
java.lang.management.ManagementPermission(monitor)
-
ManagementAgent.stop
-
Stops the remote management agent.
Impact: Low — no impact
-
Thread.print [options]
-
Prints all threads with stacktraces.
Impact: Medium — depends on the number of threads.
Permission:
java.lang.management.ManagementPermission(monitor)
Note:
The following
options
must be specified by using eitherkey
orkey=value
syntax.options
:-
-l
: (Optional) Printsjava.util.concurrent
locks (BOOLEAN, false)
-
-
VM.check_commercial_features
-
Display status of commercial features
Impact: Low — no impact
-
VM.unlock_commercial_features
-
Unlock commercial features
Impact: Low — no impact
Permission:
java.lang.management.ManagementPermission(control)
-
VM.classloader_stats
-
Prints statistics about all ClassLoaders.
Impact: Low
Permission:
java.lang.management.ManagementPermission(monitor)
-
VM.class_hierarchy [options] [arguments]
-
Prints 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.
Permission:
java.lang.management.ManagementPermission(monitor)
Note:
The following
options
must be specified by using eitherkey
orkey=value
syntax.options
:-
-i
: (Optional) Inherited interfaces should be printed. (BOOLEAN, false) -
-s
: (Optional) If a class name is specified, it prints the subclasses. If the class name is not specified, only the superclasses are 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.command_line
-
Prints the command line used to start this VM instance.
Impact: Low
Permission:
java.lang.management.ManagementPermission(monitor)
-
VM.dynlibs
-
Prints the loaded dynamic libraries.
Impact: Low
Permission:
java.lang.management.ManagementPermission(monitor)
-
VM.info
-
Prints information about the JVM environment and status.
Impact: Low
Permission:
java.lang.management.ManagementPermission(monitor)
-
VM.log [options]
-
Lists current log configuration, enables/disables/configures a log output, or rotates all logs.
Impact: Low
Permission:
java.lang.management.ManagementPermission(control)
options
:Note:
The following
options
must be specified by using eitherkey
orkey=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' o r 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.flags [options]
-
Prints the VM flag options and their current values.
Impact: Low
Permission:
java.lang.management.ManagementPermission(monitor)
Note:
The following
options
must be specified by using eitherkey
orkey=value
syntax.options
:-
-all
: (Optional) Prints all flags supported by the VM (BOOLEAN, false).
-
-
VM.native_memory [options]
-
Prints native memory usage
Impact: Medium
Permission:
java.lang.management.ManagementPermission(monitor)
Note:
The following
options
must be specified by using eitherkey
orkey=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 >= 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) -
shutdown
: (Optional) Requests runtime to shutdown itself and free the memory used by runtime. (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.print_touched_methods
-
Prints all methods that have ever been touched during the lifetime of this JVM.
Impact: Medium — depends on Java content.
-
VM.set_flag [arguments]
-
Sets the VM flag option by using the provided value.
Impact: Low
Permission:
java.lang.management.ManagementPermission(control)
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]
-
Dumps the string table.
Impact: Medium — depends on the Java content.
Permission:
java.lang.management.ManagementPermission(monitor)
Note:
The following
options
must be specified by using eitherkey
orkey=value
syntax.options
:-
-verbose
: (Optional) Dumps the content of each string in the table (BOOLEAN, false)
-
-
VM.symboltable [options]
-
Dumps the symbol table.
Impact: Medium — depends on the Java content.
Permission:
java.lang.management.ManagementPermission(monitor)
Note:
The following
options
must be specified by using eitherkey
orkey=value
syntax).options
:-
-verbose
: (Optional) Dumps the content of each symbol in the table (BOOLEAN, false)
-
-
VM.systemdictionary
-
Prints the statistics for dictionary hashtable sizes and bucket length.
Impact: Medium
Permission:
java.lang.management.ManagementPermission(monitor)
Note:
The following
options
must be specified by using eitherkey
orkey=value
syntax.options
:-
verbose
: (Optional) Dump the content of each dictionary entry for all class loaders (BOOLEAN, false).
-
-
VM.system_properties
-
Prints the system properties.
Impact: Low
Permission:
java.util.PropertyPermission(*, read)
-
VM.uptime [options]
-
Prints the VM uptime.
Impact: Low
Note:
The following
options
must be specified by using eitherkey
orkey=value
syntax.options
:-
-date
: (Optional) Adds a prefix with the current date (BOOLEAN, false)
-
-
VM.version
-
Prints JVM version information.
Impact: Low
Permission:
java.util.PropertyPermission(java.vm.version, read)