jcmd：我在哪里可以找到补充信息

时间：2017-01-27 09:53:40

标签： 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introduction和man page，但它仍然很轻。

在网络上，我发现了显然存在的命令，例如 GC.heap_info ，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将为您提供VM.native_memory命令。

但是对于其他人来说，它不清楚如何激活它们或者它是否取决于jdk版本等。
我甚至找不到现有命令的详尽清单。

任何信息？

修改的 感谢@apangin response，我开始计算jvm版本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

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

jdk9

仅限附加

  • VM.set_flag [options]
  • 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

2 个答案:

答案 0 :(得分：5)

基于@EricWang's answer，HotSpot diagnostic command sources和个人经验，我已经创建了JDK 8u121中可用的jcmd命令的完整列表，以及有关要求的其他详细信息等。

help [options] [＆lt; command name＆gt;]

有关特定命令的更多信息，请使用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)

VM.uptime [options]

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 [options]

打印VM标记选项及其当前值。

  • 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

VM.version

打印JVM版本信息。

  • 影响：低

VM.native_memory [options]

打印本机内存使用情况。

  • 影响：中等
  • 需要：-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：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)

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
  • 需要：-Xloggc:<filename> -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=<num>

GC.class_stats [options] [＆lt; columns＆gt;]

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。
  • 需要：-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 [options]

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 [options]＆lt; filename＆gt;

生成Java堆的HPROF格式转储。

  • 影响：高：取决于Java堆大小和内容。除非指定了-all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)

ManagementAgent.start_local

启动本地管理代理。

  • 影响：低：没有影响

ManagementAgent.start [options]

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)

ManagementAgent.stop

停止远程管理代理。

  • 影响：低：没有影响

JFR.start [options]

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。
  • 需要：-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 [options]

停止JFR录制

  • 影响：低
  • 需要：-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 [options]

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
  • 需要：-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 [options]

检查运行JFR记录

  • 影响：低
  • 需要：-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)

答案 1 :(得分：1)

<element [mydata]="Value"></element> 本身在应用于特定Java进程时提供此类信息，并且可选地提供特定的子命令。

如何获得帮助

  • 首先通过import { Component, OnInit, Input } from '@angular/core'; @Component({ selector: 'element', templateUrl: './element.component.html', styleUrls: ['./element.component.scss'], }) export class ElementComponent implements OnInit { @Input() public mydata:string; ngOnInit() { console.log(this.mydata); } } 或jcmd获取java进程列表，如果你还不知道目标java进程的pid，（例如我将使用pid进行java进程<强> 8976 以后续步骤为例。
  • 然后对特定的java进程应用jps子命令，例如jcmd -l，它将列出该进程的可用子命令。
  • 然后，获取有关该过程的特定命令的帮助，例如help，它将打印jcmd 8976 help子命令的帮助。
  • 然后，对流程执行特定的子命令，例如jcmd 8976 help Thread.print或Thread.print

顺便提一下，正如您所提到的，以下链接简要描述了jcmd命令：https://docs.oracle.com/javase/8/docs/technotes/guides/troubleshoot/tooldescr006.html

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