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arthas/_sources/jvm.md.txt

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jvm
===
[`sysenv`在线教程](https://alibaba.github.io/arthas/arthas-tutorials?language=cn&id=command-sysenv)
> 查看当前JVM信息
### 使用参考
```
$ 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-COUNTJVM进程最大可以打开的文件描述符数
* OPEN-FILE-DESCRIPTOR-COUNTJVM当前打开的文件描述符数