JVM相关命令
dashboard——当前系统的实时数据面板
显示当前 tomcat 的实时信息。
使用方式：dashboard
数据说明
ID: Java 级别的线程 ID，注意这个 ID 不能跟 jstack 中的 nativeID 一一对应。
NAME: 线程名
GROUP: 线程组名
PRIORITY: 线程优先级, 1~10 之间的数字，越大表示优先级越高
STATE: 线程的状态
CPU%: 线程的 cpu 使用率。比如采样间隔 1000ms，某个线程的增量 cpu 时间为 100ms，则 cpu 使用率=100/1000=10%
DELTA_TIME: 上次采样之后线程运行增量 CPU 时间，数据格式为秒
TIME: 线程运行总 CPU 时间，数据格式为分:秒
INTERRUPTED: 线程当前的中断位状态
DAEMON: 是否是 daemon 线程
thread
查看当前线程信息，查看线程的堆栈。
参数说明
| 参数名称 | 参数说明 |
|---|---|
| id | 线程 id |
| [n:] | 指定最忙的前 N 个线程并打印堆栈 |
| [b] | 找出当前阻塞其他线程的线程 |
| [i ] | 指定 cpu 使用率统计的采样间隔，单位为毫秒，默认值为 200 |
| [–all] | 显示所有匹配的线程 |
举例：thread -n 3
jvm
查看当前 JVM 信息。
示例：
$ jvm
RUNTIME
--------------------------------------------------------------------------------------------------------------
MACHINE-NAME 37@ff267334bb65
JVM-START-TIME 2020-07-23 07:50:36
MANAGEMENT-SPEC-VERSION 1.2
SPEC-NAME Java Virtual Machine Specification
SPEC-VENDOR Oracle Corporation
SPEC-VERSION 1.8
VM-NAME Java HotSpot(TM) 64-Bit Server VM
VM-VENDOR Oracle Corporation
VM-VERSION 25.201-b09
INPUT-ARGUMENTS []
CLASS-PATH demo-arthas-spring-boot.jar
BOOT-CLASS-PATH /usr/lib/jvm/java-8-oracle/jre/lib/resources.jar:/usr/lib/jvm/java-8-oracle/j
re/lib/rt.jar:/usr/lib/jvm/java-8-oracle/jre/lib/sunrsasign.jar:/usr/lib/jvm/
java-8-oracle/jre/lib/jsse.jar:/usr/lib/jvm/java-8-oracle/jre/lib/jce.jar:/us
r/lib/jvm/java-8-oracle/jre/lib/charsets.jar:/usr/lib/jvm/java-8-oracle/jre/l
ib/jfr.jar:/usr/lib/jvm/java-8-oracle/jre/classes
LIBRARY-PATH /usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib
--------------------------------------------------------------------------------------------------------------
CLASS-LOADING
--------------------------------------------------------------------------------------------------------------
LOADED-CLASS-COUNT 7529
TOTAL-LOADED-CLASS-COUNT 7529
UNLOADED-CLASS-COUNT 0
IS-VERBOSE false
--------------------------------------------------------------------------------------------------------------
COMPILATION
--------------------------------------------------------------------------------------------------------------
NAME HotSpot 64-Bit Tiered Compilers
TOTAL-COMPILE-TIME 14921(ms)
--------------------------------------------------------------------------------------------------------------
GARBAGE-COLLECTORS
--------------------------------------------------------------------------------------------------------------
PS Scavenge name : PS Scavenge
[count/time (ms)] collectionCount : 7
collectionTime : 68
PS MarkSweep name : PS MarkSweep
[count/time (ms)] collectionCount : 1
collectionTime : 47
--------------------------------------------------------------------------------------------------------------
MEMORY-MANAGERS
--------------------------------------------------------------------------------------------------------------
CodeCacheManager Code Cache
Metaspace Manager Metaspace
Compressed Class Space
Copy Eden Space
Survivor Space
MarkSweepCompact Eden Space
Survivor Space
Tenured Gen
--------------------------------------------------------------------------------------------------------------
MEMORY
--------------------------------------------------------------------------------------------------------------
HEAP-MEMORY-USAGE init : 268435456(256.0 MiB)
[memory in bytes] used : 18039504(17.2 MiB)
committed : 181403648(173.0 MiB)
max : 3817865216(3.6 GiB)
NO-HEAP-MEMORY-USAGE init : 2555904(2.4 MiB)
[memory in bytes] used : 33926216(32.4 MiB)
committed : 35176448(33.5 MiB)
max : -1(-1 B)
--------------------------------------------------------------------------------------------------------------
OPERATING-SYSTEM
--------------------------------------------------------------------------------------------------------------
OS Linux
ARCH amd64
PROCESSORS-COUNT 3
LOAD-AVERAGE 29.53
VERSION 4.15.0-52-generic
--------------------------------------------------------------------------------------------------------------
THREAD
--------------------------------------------------------------------------------------------------------------
COUNT 30
DAEMON-COUNT 24
PEAK-COUNT 31
STARTED-COUNT 36
DEADLOCK-COUNT 0
--------------------------------------------------------------------------------------------------------------
FILE-DESCRIPTOR
--------------------------------------------------------------------------------------------------------------
MAX-FILE-DESCRIPTOR-COUNT 1048576
OPEN-FILE-DESCRIPTOR-COUNT 100
Affect(row-cnt:0) cost in 88 ms.
THREAD 相关
COUNT: JVM 当前活跃的线程数
DAEMON-COUNT: JVM 当前活跃的守护线程数
PEAK-COUNT: 从 JVM 启动开始曾经活着的最大线程数
STARTED-COUNT: 从 JVM 启动开始总共启动过的线程次数
DEADLOCK-COUNT: JVM 当前死锁的线程数
文件描述符相关
MAX-FILE-DESCRIPTOR-COUNT：JVM 进程最大可以打开的文件描述符数
OPEN-FILE-DESCRIPTOR-COUNT：JVM 当前打开的文件描述符数
sysprop
查看当前 JVM 的系统属性(System Property)。
使用示例：
$ sysprop
KEY VALUE
-------------------------------------------------------------------------------------------------------------------------------------
java.runtime.name Java(TM) SE Runtime Environment
sun.boot.library.path /Library/Java/JavaVirtualMachines/jdk1.8.0_51.jdk/Contents/Home/jre/lib
java.vm.version 25.51-b03
user.country.format CN
gopherProxySet false
java.vm.vendor Oracle Corporation
java.vendor.url http://java.oracle.com/
path.separator :
java.vm.name Java HotSpot(TM) 64-Bit Server VM
file.encoding.pkg sun.io
user.country US
sun.java.launcher SUN_STANDARD
sun.os.patch.level unknown
java.vm.specification.name Java Virtual Machine Specification
user.dir /private/var/tmp
java.runtime.version 1.8.0_51-b16
java.awt.graphicsenv sun.awt.CGraphicsEnvironment
java.endorsed.dirs /Library/Java/JavaVirtualMachines/jdk1.8.0_51.jdk/Contents/Home/jre/lib/endors
ed
os.arch x86_64
java.io.tmpdir /var/folders/2c/tbxwzs4s4sbcvh7frbcc7n000000gn/T/
line.separator
java.vm.specification.vendor Oracle Corporation
os.name Mac OS X
sun.jnu.encoding UTF-8
java.library.path /Users/wangtao/Library/Java/Extensions:/Library/Java/Extensions:/Network/Libra
ry/Java/Extensions:/System/Library/Java/Extensions:/usr/lib/java:.
sun.nio.ch.bugLevel
java.specification.name Java Platform API Specification
java.class.version 52.0
sun.management.compiler HotSpot 64-Bit Tiered Compilers
os.version 10.12.6
user.home /Users/wangtao
user.timezone Asia/Shanghai
java.awt.printerjob sun.lwawt.macosx.CPrinterJob
file.encoding UTF-8
java.specification.version 1.8
user.name wangtao
java.class.path .
java.vm.specification.version 1.8
sun.arch.data.model 64
java.home /Library/Java/JavaVirtualMachines/jdk1.8.0_51.jdk/Contents/Home/jre
sun.java.command Test
java.specification.vendor Oracle Corporation
user.language en
awt.toolkit sun.lwawt.macosx.LWCToolkit
java.vm.info mixed mode
java.version 1.8.0_51
java.ext.dirs /Users/wangtao/Library/Java/Extensions:/Library/Java/JavaVirtualMachines/jdk1.
8.0_51.jdk/Contents/Home/jre/lib/ext:/Library/Java/Extensions:/Network/Library
/Java/Extensions:/System/Library/Java/Extensions:/usr/lib/java
sun.boot.class.path /Library/Java/JavaVirtualMachines/jdk1.8.0_51.jdk/Contents/Home/jre/lib/resour
ces.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_51.jdk/Contents/Home/jre/li
b/rt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_51.jdk/Contents/Home/jre/l
ib/sunrsasign.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_51.jdk/Contents/H
ome/jre/lib/jsse.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_51.jdk/Content
s/Home/jre/lib/jce.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_51.jdk/Conte
nts/Home/jre/lib/charsets.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_51.jd
k/Contents/Home/jre/lib/jfr.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_51.
jdk/Contents/Home/jre/classes
java.vendor Oracle Corporation
file.separator /
java.vendor.url.bug http://bugreport.sun.com/bugreport/
sun.cpu.endian little
sun.io.unicode.encoding UnicodeBig
sun.cpu.isalist
查询指定配置
$ sysprop java.version
java.version=1.8.0_51
修改指定配置
$ sysprop user.country
user.country=US
$ sysprop user.country CN
Successfully changed the system property.
user.country=CN
sysenv
查看当前 JVM 的环境属性(System Environment Variables)。
使用参考：
USAGE:
sysenv [-h] [env-name]
SUMMARY:
Display the system env.
EXAMPLES:
sysenv
sysenv USER
WIKI:
https://arthas.aliyun.com/doc/sysenv
OPTIONS:
-h, --help this help
<env-name> env name
使用示例
$ sysenv
KEY VALUE
----------------------------------------------------------------------------------------------------------------------------
PATH /Users/admin/.sdkman/candidates/visualvm/current/bin:/Users/admin/.sdkman/candidates/ja
va/current/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Applications/Wireshark.app/Contents/
MacOS
SDKMAN_VERSION 5.7.3+337
JAVA_HOME /Users/admin/.sdkman/candidates/java/current
JAVA_MAIN_CLASS_65244 demo.MathGame
TERM xterm-256color
LANG zh_CN.UTF-8
AUTOJUMP_SOURCED 1
COLORTERM truecolor
LOGNAME admin
XPC_SERVICE_NAME 0
PWD /Users/admin/code/ali/arthas/demo
TERM_PROGRAM_VERSION 3.2.5
_ /Users/admin/.sdkman/candidates/java/current/bin/java
SHELL /bin/bash
TERM_PROGRAM iTerm.app
SDKMAN_PLATFORM Darwin
USER admin
ITERM_PROFILE Default
TMPDIR /var/folders/0r/k561bkk917gg972stqclbz9h0000gn/T/
XPC_FLAGS 0x0
TERM_SESSION_ID w0t4p0:60BC264D-9649-42AC-A7E4-AF85B69F93F8
__CF_USER_TEXT_ENCODING 0x1F5:0x19:0x34
Apple_PubSub_Socket_Ren /private/tmp/com.apple.launchd.DwmmjSQsll/Render
der
COLORFGBG 7;0
HOME /Users/admin
SHLVL 1
AUTOJUMP_ERROR_PATH /Users/admin/Library/autojump/errors.log
vmoption
查看，更新 VM 诊断相关的参数。
查看所有option
[arthas@56963]$ vmoption
KEY VALUE ORIGIN WRITEABLE
---------------------------------------------------------------------------------------------
HeapDumpBeforeFullGC false DEFAULT true
HeapDumpAfterFullGC false DEFAULT true
HeapDumpOnOutOfMemory false DEFAULT true
Error
HeapDumpPath DEFAULT true
CMSAbortablePrecleanW 100 DEFAULT true
aitMillis
CMSWaitDuration 2000 DEFAULT true
CMSTriggerInterval -1 DEFAULT true
PrintGC false DEFAULT true
PrintGCDetails true MANAGEMENT true
PrintGCDateStamps false DEFAULT true
PrintGCTimeStamps false DEFAULT true
PrintGCID false DEFAULT true
PrintClassHistogramBe false DEFAULT true
foreFullGC
PrintClassHistogramAf false DEFAULT true
terFullGC
PrintClassHistogram false DEFAULT true
MinHeapFreeRatio 0 DEFAULT true
MaxHeapFreeRatio 100 DEFAULT true
PrintConcurrentLocks false DEFAULT true
更新指定的option
$ vmoption PrintGC true
Successfully updated the vm option.
NAME BEFORE-VALUE AFTER-VALUE
------------------------------------
PrintGC false true
getstatic
通过 getstatic 命令可以方便的查看类的静态属性。使用方法为getstatic class_name field_name
$ getstatic demo.MathGame random
field: random
@Random[
serialVersionUID=@Long[3905348978240129619],
seed=@AtomicLong[120955813885284],
multiplier=@Long[25214903917],
addend=@Long[11],
mask=@Long[281474976710655],
DOUBLE_UNIT=@Double[1.1102230246251565E-16],
BadBound=@String[bound must be positive],
BadRange=@String[bound must be greater than origin],
BadSize=@String[size must be non-negative],
seedUniquifier=@AtomicLong[-3282039941672302964],
nextNextGaussian=@Double[0.0],
haveNextNextGaussian=@Boolean[false],
serialPersistentFields=@ObjectStreamField[][isEmpty=false;size=3],
unsafe=@Unsafe[sun.misc.Unsafe@2eaa1027],
seedOffset=@Long[24],
]
ognl
执行 ognl 表达式
参数说明
| 参数名称 | 参数说明 |
|---|---|
| express | 执行的表达式 |
| [c:] | 执行表达式的 ClassLoader 的 hashcode，默认值是 SystemClassLoader |
| [classLoaderClass:] | 指定执行表达式的 ClassLoader 的 class name |
| [x] | 结果对象的展开层次，默认值 1 |
调用静态函数
$ ognl '@java.lang.System@out.println("hello")'
null
获取静态函数字段
$ ognl '@demo.MathGame@random'
@Random[
serialVersionUID=@Long[3905348978240129619],
seed=@AtomicLong[125451474443703],
multiplier=@Long[25214903917],
addend=@Long[11],
mask=@Long[281474976710655],
DOUBLE_UNIT=@Double[1.1102230246251565E-16],
BadBound=@String[bound must be positive],
BadRange=@String[bound must be greater than origin],
BadSize=@String[size must be non-negative],
seedUniquifier=@AtomicLong[-3282039941672302964],
nextNextGaussian=@Double[0.0],
haveNextNextGaussian=@Boolean[false],
serialPersistentFields=@ObjectStreamField[][isEmpty=false;size=3],
unsafe=@Unsafe[sun.misc.Unsafe@28ea5898],
seedOffset=@Long[24],
]
来源
Arthas官网
