java 性能監控 工具

除了 javac java javap 之外, jdk 安裝包還提供了很多其他工具
列出 bin 目錄下的文件

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TomChens-MacBook-Pro:Commands tomchen$ ls
appletviewer    javadoc     jmap        keytool     serialver
apt     javah       jmc     native2ascii    servertool
extcheck    javap       jps     orbd        tnameserv
idlj        javaws      jrunscript  pack200     unpack200
jar     jcmd        jsadebugd   policytool  wsgen
jarsigner   jconsole    jstack      rmic        wsimport
java        jdb     jstat       rmid        xjc
java_home   jhat        jstatd      rmiregistry
javac       jinfo       jvisualvm   schemagen

jvisualvm

可以在線安裝很多插件, 這是最新的非常強大的多合一故障處理工具

生成 Heap Dump, 可以在OQL Console 執行類似 sql 語句的 OQL

jvisualvm 的 BTrace 插件

生產環境服務無法停止的時候, 而日志里的信息無法滿足我們需要時候, 可以通過這個打印調用堆棧 參數 返回值等

jconsole

也是一個圖形化的監控工具

jps 虛擬機進程狀況工具

類似于 ps 命令

jps -l
582 HttpFind
431 RefreshBlog.jar
585 sun.tools.jps.Jps

jstat 虛擬機統計信息監控工具

 jstat -gcutil 431
  S0     S1     E      O      P     YGC     YGCT    FGC    FGCT     GCT   
  0.00  57.17  12.43  24.74  42.31     13    0.044     0    0.000    0.044

從中可以看出 survivor(S0 S1) eden (E) young GC(YGC) 等參數

---

jstat -class 434
Loaded  Bytes  Unloaded  Bytes     Time   
 17095 36897.7     1899  2970.9      14.87

類加載時間為14.87

jstack java堆棧管理工具

可以查看線程死鎖

jstack 582
......
......

Found one Java-level deadlock:
"Thread-199":
  waiting to lock monitor 0x00007facb3027608 (object 0x00000007e786b528, a java.lang.Integer),
  which is held by "Thread-3"
"Thread-3":
  waiting to lock monitor 0x00007facb3026108 (object 0x00000007e786b518, a java.lang.Integer),
  which is held by "Thread-8"
"Thread-8":
  waiting to lock monitor 0x00007facb3027608 (object 0x00000007e786b528, a java.lang.Integer),
  which is held by "Thread-3"
Java stack information for the threads listed above:
"Thread-199":
    at HttpFind$SyncAdd.run(HttpFind.java:52)

- waiting to lock <0x00000007e786b528> (a java.lang.Integer)
at java.lang.Thread.run(Thread.java:722)

"Thread-3":
    at HttpFind$SyncAdd.run(HttpFind.java:53)

- waiting to lock <0x00000007e786b518> (a java.lang.Integer)
- locked <0x00000007e786b528> (a java.lang.Integer)
at java.lang.Thread.run(Thread.java:722)

"Thread-8":
    at HttpFind$SyncAdd.run(HttpFind.java:53)

- waiting to lock <0x00000007e786b528> (a java.lang.Integer)
- locked <0x00000007e786b518> (a java.lang.Integer)
at java.lang.Thread.run(Thread.java:722)


Found 1 deadlock.</pre> 
 
jhat 虛擬機堆轉儲快照分析工具

jinfo java 配置信息工具
jmap java 內存印象工具
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