java - jcmd : where can I find complementary information

Question

jcmd 是一个很有前途的工具，可以重新组合 jmap、jsp 等实用程序...
你可以找到introduction和 man page但它仍然很轻。

在网络上，我发现显然存在的命令，如 GC.heap_info，我从未能够将其用于我的测试。

其中一些命令需要特殊标志。例如，-XX:NativeMemoryTracking=detail 将为您提供 VM.native_memory 命令。

但对于其他一些人来说，不清楚如何激活它们或者它是否取决于 jdk 版本等。
我什至找不到现有命令的详尽列表。

有什么信息吗？

---

编辑谢谢@apangin response ，我已经开始按 jvm 版本计算可用命令的简短摘要。

免责声明:它仅来自代码拆解，而非真实测试

jdk8

• 帮助
• VM.uptime [选项]
• VM.flags [选项]
• VM.system_properties
• VM.command_line
• 虚拟机版本
• VM.native_memory [选项]
• VM.check_commercial_features
• VM.unlock_commercial_features
• Thread.print [选项]
• GC.run
• GC.run_finalization
• GC.rotate_log
• GC.class_stats [选项]
• GC.class_histogram [选项]
• GC.heap_dump [选项]
• ManagementAgent.start_local
• ManagementAgent.start [选项]
• ManagementAgent.stopJFR.start [选项]
• JFR.stop [选项]
• JFR.dump [选项]
• JFR.check [选项]

jdk9

只有额外的

• VM.set_flag [选项]
• VM.info
• VM.class_hierarchy [选项]
• 虚拟机.dynlibs
• VM.print_touched_methods
• JVMTI.data_dump
• JVMTI.agent_load [选项]
• GC.finalizer_info
• GC.heap_info
• ManagementAgent.status
• ManagementAgent.stop
• 编译器队列
• 编译器.codelist
• 编译器.codecache
• Compiler.directives_print
• Compiler.directives_remove
• Compiler.directives_add [选项]
• Compiler.directives_clear

Answer 1

基于@EricWang's answer , HotSpot diagnostic command sources和个人经验，我创建了完整列表 jcmd JDK 8u121 中可用的命令以及有关要求等的其他详细信息。

---

帮助[选项] [<命令名称>]

有关特定命令的更多信息，请使用 help <command> .如果没有参数，这将显示可用命令的列表。 help -all将显示所有命令的帮助。

• 影响:低

Arguments:
    command name : [optional] The name of the command for which we want help (STRING, no default value)

Options: (options must be specified using the <key> or <key>=<value> syntax)
    -all : [optional] Show help for all commands (BOOLEAN, false)

VM.uptime [选项]

打印 VM 正常运行时间。

• 影响:低

Options: (options must be specified using the <key> or <key>=<value> syntax)
    -date : [optional] Add a prefix with current date (BOOLEAN, false)

VM.flags [选项]

打印 VM 标志选项及其当前值。

• 影响:低

Options: (options must be specified using the <key> or <key>=<value> syntax)
    -all : [optional] Print all flags supported by the VM (BOOLEAN, false)

VM.system_properties

打印系统属性。

• 影响:低

VM.command_line

打印用于启动此 VM 实例的命令行。

• 影响:低

虚拟机版本

打印 JVM 版本信息。

• 影响:低

VM.native_memory [选项]

打印 native 内存使用情况。

• 影响:中
• 要求:-XX:NativeMemoryTracking=[summary|detail]

Options: (options must be specified using the <key> or <key>=<value> syntax)
    summary : [optional] request runtime to report current memory summary, which includes total reserved and committed memory, along with memory usage summary by each subsytem. (BOOLEAN, false)
    detail : [optional] request runtime to report memory allocation >= 1K by each callsite. (BOOLEAN, false)
    baseline : [optional] request runtime to baseline current memory usage, so it can be compared against in later time. (BOOLEAN, false)
    summary.diff : [optional] request runtime to report memory summary comparison against previous baseline. (BOOLEAN, false)
    detail.diff : [optional] request runtime to report memory detail comparison against previous baseline, which shows the memory allocation activities at different callsites. (BOOLEAN, false)
    shutdown : [optional] request runtime to shutdown itself and free the memory used by runtime. (BOOLEAN, false)
    statistics : [optional] print tracker statistics for tuning purpose. (BOOLEAN, false)
    scale : [optional] Memory usage in which scale, KB, MB or GB (STRING, KB)

VM.check_commercial_features

显示商业功能的状态。

• 影响:低:无影响

VM.unlock_commercial_features

解锁商业功能。

• 影响:低:无影响

Thread.print [选项]

使用堆栈跟踪打印所有线程。

• 影响:中等:取决于线程数。

Options: (options must be specified using the <key> or <key>=<value> syntax)
    -l : [optional] print java.util.concurrent locks (BOOLEAN, false)

GC.run

调用 java.lang.System.gc()。

• 影响:中等:取决于 Java 堆大小和内容。

GC.run_finalization

调用 java.lang.System.runFinalization()。

• 影响:中等:取决于 Java 内容。

GC.rotate_log

强制轮换 GC 日志文件。

• 影响:低
• 要求:-Xloggc:<filename> -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=<num>

GC.class_stats [选项] [<列>]

提供有关 Java 类元数据的统计信息。

• 影响:高:取决于 Java 堆大小和内容。
• 要求:-XX:+UnlockDiagnosticVMOptions

Arguments:
    columns : [optional] Comma-separated list of all the columns to show. If not specified, the following columns are shown: InstBytes,KlassBytes,CpAll,annotations,MethodCount,Bytecodes,MethodAll,ROAll,RWAll,Total (STRING, no default value)

Options: (options must be specified using the <key> or <key>=<value> syntax)
    -all : [optional] Show all columns (BOOLEAN, false)
    -csv : [optional] Print in CSV (comma-separated values) format for spreadsheets (BOOLEAN, false)
    -help : [optional] Show meaning of all the columns (BOOLEAN, false)

GC.class_histogram [选项]

提供有关 Java 堆使用情况的统计信息。

• 影响:高:取决于 Java 堆大小和内容。

Options: (options must be specified using the <key> or <key>=<value> syntax)
    -all : [optional] Inspect all objects, including unreachable objects (BOOLEAN, false)

GC.heap_dump [选项] <文件名>

生成 Java 堆的 HPROF 格式转储。

• 影响:高:取决于 Java 堆大小和内容。请求完整的 GC，除非 -all选项已指定。

Arguments:
    filename : Name of the dump file (STRING, no default value)

Options: (options must be specified using the <key> or <key>=<value> syntax)
    -all : [optional] Dump all objects, including unreachable objects (BOOLEAN, false)

ManagementAgent.start_local

启动本地管理代理。

• 影响:低:无影响

ManagementAgent.start [选项]

启动远程管理代理。

• 影响:低:无影响

Options: (options must be specified using the <key> or <key>=<value> syntax)
    config.file : [optional] set com.sun.management.config.file (STRING, no default value)
    jmxremote.host : [optional] set com.sun.management.jmxremote.host (STRING, no default value)
    jmxremote.port : [optional] set com.sun.management.jmxremote.port (STRING, no default value)
    jmxremote.rmi.port : [optional] set com.sun.management.jmxremote.rmi.port (STRING, no default value)
    jmxremote.ssl : [optional] set com.sun.management.jmxremote.ssl (STRING, no default value)
    jmxremote.registry.ssl : [optional] set com.sun.management.jmxremote.registry.ssl (STRING, no default value)
    jmxremote.authenticate : [optional] set com.sun.management.jmxremote.authenticate (STRING, no default value)
    jmxremote.password.file : [optional] set com.sun.management.jmxremote.password.file (STRING, no default value)
    jmxremote.access.file : [optional] set com.sun.management.jmxremote.access.file (STRING, no default value)
    jmxremote.login.config : [optional] set com.sun.management.jmxremote.login.config (STRING, no default value)
    jmxremote.ssl.enabled.cipher.suites : [optional] set com.sun.management.jmxremote.ssl.enabled.cipher.suite (STRING, no default value)
    jmxremote.ssl.enabled.protocols : [optional] set com.sun.management.jmxremote.ssl.enabled.protocols (STRING, no default value)
    jmxremote.ssl.need.client.auth : [optional] set com.sun.management.jmxremote.need.client.auth (STRING, no default value)
    jmxremote.ssl.config.file : [optional] set com.sun.management.jmxremote.ssl_config_file (STRING, no default value)
    jmxremote.autodiscovery : [optional] set com.sun.management.jmxremote.autodiscovery (STRING, no default value)
    jdp.port : [optional] set com.sun.management.jdp.port (INT, no default value)
    jdp.address : [optional] set com.sun.management.jdp.address (STRING, no default value)
    jdp.source_addr : [optional] set com.sun.management.jdp.source_addr (STRING, no default value)
    jdp.ttl : [optional] set com.sun.management.jdp.ttl (INT, no default value)
    jdp.pause : [optional] set com.sun.management.jdp.pause (INT, no default value)
    jdp.name : [optional] set com.sun.management.jdp.name (STRING, no default value)

ManagementAgent.stop

停止远程管理代理。

• 影响:低:无影响

JFR.start [选项]

开始新的 JFR 记录

• 影响:中:根据录音设置，影响范围从低到高。
• 要求:-XX:+UnlockCommercialFeatures

Options: (options must be specified using the <key> or <key>=<value> syntax)
    name : [optional] Name that can be used to identify recording, e.g. "My Recording" (STRING, no default value)
    defaultrecording : [optional] Starts the default recording, can only be combined with settings. (BOOLEAN, false)
    dumponexit : [optional] Dump running recording when JVM shuts down (BOOLEAN, no default value)
    settings : [optional] Settings file(s), e.g. profile or default. See JRE_HOME/lib/jfr (STRING SET, no default value)
    delay : [optional] Delay recording start with (s)econds, (m)inutes), (h)ours), or (d)ays, e.g. 5h. (NANOTIME, 0)
    duration : [optional] Duration of recording in (s)econds, (m)inutes, (h)ours, or (d)ays, e.g. 300s. (NANOTIME, 0)
    filename : [optional] Resulting recording filename, e.g. "C:\Users\user\My Recording.jfr" (STRING, no default value)
    compress : [optional] GZip-compress the resulting recording file (BOOLEAN, false)
    maxage : [optional] Maximum time to keep recorded data (on disk) in (s)econds, (m)inutes, (h)ours, or (d)ays, e.g. 60m, or 0 for no limit (NANOTIME, 0)
    maxsize : [optional] Maximum amount of bytes to keep (on disk) in (k)B, (M)B or (G)B, e.g. 500M, or 0 for no limit (MEMORY SIZE, 0)

JFR.stop [选项]

停止 JFR 记录

• 影响:低
• 要求:-XX:+UnlockCommercialFeatures

Options: (options must be specified using the <key> or <key>=<value> syntax)
    name : [optional] Recording name,.e.g "My Recording" (STRING, no default value)
    recording : [optional] Recording number, see JFR.check for a list of available recordings (JLONG, -1)
    discard : [optional] Skip writing data to previously specified file (if any) (BOOLEAN, false)
    filename : [optional] Copy recording data to file, e.g. "C:\Users\user\My Recording.jfr" (STRING, no default value)
    compress : [optional] GZip-compress "filename" destination (BOOLEAN, false)

JFR.dump [选项]

将 JFR 记录的内容复制到文件。必须指定名称或录制 ID。

• 影响:低
• 要求:-XX:+UnlockCommercialFeatures

Options: (options must be specified using the <key> or <key>=<value> syntax)
    name : [optional] Recording name, e.g. "My Recording" (STRING, no default value)
    recording : [optional] Recording number, use JFR.check to list available recordings (JLONG, -1)
    filename :  Copy recording data to file, i.e "C:\Users\user\My Recording.jfr" (STRING, no default value)
    compress : [optional] GZip-compress "filename" destination (BOOLEAN, false)

JFR.check [选项]

检查正在运行的 JFR 记录

• 影响:低
• 要求:-XX:+UnlockCommercialFeatures

Options: (options must be specified using the <key> or <key>=<value> syntax)
    name : [optional] Recording name, e.g. "My Recording" or omit to see all recordings (STRING, no default value)
    recording : [optional] Recording number, or omit to see all recordings (JLONG, -1)
    verbose : [optional] Print event settings for the recording(s) (BOOLEAN, false)