JVM内存分析系列（九）JDK监控和故障处理工具

jps JVM Process Status Tool，显示指定系统内所有的HotSpot虚拟机进程
jps -l 输出主类全名，如果是JAR包，则输出JAR路径
jps -v 输出虚拟机进程启动时JVM参数

jstat JVM Statistics Monitoring Tool，用于收集HotSpot虚拟机各方面的运行数据
jstat -gcutil 进程号 [刷新毫秒数]
  S0     S1     E      O      P     YGC     YGCT    FGC    FGCT     GCT  
  0.00   0.00   3.23   8.14  49.97      6    1.089     3    2.630    3.719
S0和S1：新生代2个survivor区 使用百分比
E：是新生代的伊甸区 使用百分比
O：老年代 使用百分比
P：永久代 使用百分比
YGC：minor GC，发生在新生代的GC次数
YGCT：新生代GC总耗时
FGC：major GC，发生在老年代的GC次数
FGCT：老年代GC总耗时
GCT：总GC耗时

jinfo Configuration Info for Java，显示虚拟机配置信息
jinfo 进程号

jmap Memory Map for Java，生成虚拟机的内存转储快照（heapdump文件）
jmap -dump:format=b,file=/tmp/mydump.bin 进程号
输出
Dumping heap to /tmp/mydump.bin ...
Heap dump file created

jhat JVM Heap Dump Browser，用于分析headdump文件，他会建立一个HTTP/HTML服务器，让用户可以在浏览器上查看分析结果
jhat mydump.bin
输出的信息如下
Reading from mydump.bin...
Dump file created Fri Jan 10 15:51:28 CST 2014
Snapshot read, resolving...
Resolving 2810470 objects...
Chasing references, expect 562 dots..................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
Eliminating duplicate references..................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
Snapshot resolved.
Started HTTP server on port 7000
Server is ready.
重点要分析
Show heap histogram





jstack Stack Trace for Java，显示虚拟机的线程快照
jstack -l 进程号 除堆栈外，显示关于锁的附加信息
输出信息
2014-01-10 16:00:23
Full thread dump Java HotSpot(TM) 64-Bit Server VM (20.45-b01 mixed mode):

"Worker-16" prio=10 tid=0x00007f643815e800 nid=0x1cdb in Object.wait() [0x00007f63f2765000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x0000000785fb3280> (a org.eclipse.core.internal.jobs.WorkerPool)
        at org.eclipse.core.internal.jobs.WorkerPool.sleep(WorkerPool.java:188)
        - locked <0x0000000785fb3280> (a org.eclipse.core.internal.jobs.WorkerPool)
        at org.eclipse.core.internal.jobs.WorkerPool.startJob(WorkerPool.java:220)
        at org.eclipse.core.internal.jobs.Worker.run(Worker.java:50)

   Locked ownable synchronizers:
        - None

"Worker-15" prio=10 tid=0x00007f643883f800 nid=0x1c70 in Object.wait() [0x00007f63f2967000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x0000000785fb3280> (a org.eclipse.core.internal.jobs.WorkerPool)
        at org.eclipse.core.internal.jobs.WorkerPool.sleep(WorkerPool.java:188)
        - locked <0x0000000785fb3280> (a org.eclipse.core.internal.jobs.WorkerPool)
        at org.eclipse.core.internal.jobs.WorkerPool.startJob(WorkerPool.java:220)
        at org.eclipse.core.internal.jobs.Worker.run(Worker.java:50)

   Locked ownable synchronizers:
        - None

"Attach Listener" daemon prio=10 tid=0x00007f6414003000 nid=0x1c36 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE