jcmd:我在哪里可以找到补充信息

Question

jcmd:我在哪里可以找到补充信息

Rom*_*ain 8 java jvm

jcmd是重新组合jmap,jsp等实用程序的有前途的工具......
你可以找到介绍和手册页,但它仍然很轻.

在网络上,我发现显然存在像GC.heap_info这样的命令,我从来没有能够用于我的测试.

其中一些命令需要特殊标志.例如,-XX:NativeMemoryTracking=detail会给你VM.native_memory命令.

但是对于其他一些人来说,不清楚如何激活它们或者它是否依赖于jdk版本等等.
我甚至找不到现有命令的详尽列表.

任何信息？

将 Thx 编辑为@apangin响应,我已经开始通过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,而不是真正的测试

jdk8

救命
VM.uptime [选项]
VM.flags [选项]
VM.system_properties
VM.command_line
VM.version
VM.native_memory [选项]
VM.check_commercial_features
VM.unlock_commercial_features
Thread.print [options]
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 [options]
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 [options]
VM.dynlibs
VM.print_touched_methods
JVMTI.data_dump
JVMTI.agent_load [options]
GC.finalizer_info
GC.heap_info
ManagementAgent.status
ManagementAgent.stop
Compiler.queue
Compiler.codelist
Compiler.codecache
Compiler.directives_print
Compiler.directives_remove
Compiler.directives_add [options]
Compiler.directives_clear

Answer 1

apa*_*gin 6

基于@ EricWang的回答,HotSpot诊断命令源和个人经验,我已经创建了jcmdJDK 8u121中可用命令的完整列表以及有关要求等的其他详细信息.

帮助[选项] [<命令名>]

有关特定命令用法的更多信息help <command>.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)

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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)

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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)

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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

VM.version

打印JVM版本信息.

影响:低

VM.native_memory [选项]

打印本机内存使用量.

影响:中等
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)

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VM.check_commercial_features

显示商业功能的状态.

影响:低:没有影响

VM.unlock_commercial_features

解锁商业功能.

影响:低:没有影响

Thread.print [options]

使用stacktraces打印所有线程.

影响:中: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)

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GC.run

调用java.lang.System.gc().

影响:中:取决于Java堆大小和内容.

GC.run_finalization

调用java.lang.System.runFinalization().

影响:中:取决于Java内容.

GC.rotate_log

强制旋转GC日志文件.

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

GC.class_stats [options] [<columns>]

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)

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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)

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GC.heap_dump [options] <filename>

生成Java堆的HPROF格式转储.

影响:高:取决于Java堆大小和内容.除非-all指定选项,否则请求完整的GC .

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)

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ManagementAgent.start_local

启动本地管理代理.

影响:低:没有影响

ManagementAgent.start [选项]

启动远程管理代理.

影响:低:没有影响

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)

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ManagementAgent.stop

停止远程管理代理.

影响:低:没有影响

JFR.start [选项]

开始新的JFR录制

影响:中:根据录制的设置,影响范围可以从低到高.
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)

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JFR.stop [选项]

停止JFR录制

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)

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JFR.dump [选项]

将JFR记录的内容复制到文件.必须指定名称或记录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)

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JFR.check [选项]

检查运行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)

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Answer 2

Eri*_*ang 1

jcmd当应用于特定的 Java 进程时，它本身提供此类信息，并且可选地提供特定的子命令。

如何获得帮助：

如果您还不知道目标java进程的pid，首先通过jps或获取java进程列表（例如，我将在后续步骤中以pid 8976的java进程为例）。jcmd -l

help然后在特定的java进程上应用子命令，例如jcmd 8976 help，它将列出该进程可用的子命令。

然后，获取进程上特定命令的帮助，例如jcmd 8976 help Thread.print，它将打印Thread.print子命令的帮助。

然后，在进程上执行特定的子命令，例如jcmd 8976 Thread.print或jcmd 8976 Thread.print | less -N

顺便说一下，正如您提到的，以下链接简要描述了 jcmd 命令：https ://docs.oracle.com/javase/8/docs/technotes/guides/troubleshoot/tooldescr006.html

`jcmd <pid> help -all` 将列出可用命令及其概要。 (2认同)

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