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java自带命令行工具(jmap,jhat,jinfo)
（1）JMAP
1.作用
打印进程，core文件,和远程进程的共享对象存储map或堆存储器的详细信息。
2.使用
jmap [ options ] pid jmap [ options ] executable core jmap [ options ] [ pid ] server-id@ ] remote-hostname-or-IP
如果指定的进程是在64位Java虚拟机（JVM）上运行，那么你可能需要指定-J-d64选项，例如：jmap -J-d64 -heap pid。
3.参数选项
3.1 <no option>
当不使用选项，该jmap命令打印共享对象映射
如
C:\Users\Administrator>jmap 9208 Attaching to process ID 9208, please wait... Debugger attached successfully. Server compiler detected. JVM version is 24.75-b04 0x00000000623c0000 8016K D:\Java\jdk1.7.0_75\jre\bin\server\jvm.dll 0x0000000062ba0000 840K D:\Java\jdk1.7.0_75\jre\bin\msvcr100.dll 0x0000000062cc0000 144K D:\Java\jdk1.7.0_75\jre\bin\sunec.dll 0x0000000062cf0000 68K D:\Java\jdk1.7.0_75\jre\bin\nio.dll 0x0000000062d10000 100K D:\Java\jdk1.7.0_75\jre\bin\net.dll 0x0000000062d30000 160K D:\Java\jdk1.7.0_75\jre\bin\java.dll 0x00000000634d0000 84K D:\Java\jdk1.7.0_75\jre\bin\zip.dll 0x0000000065950000 44K D:\Java\jdk1.7.0_75\jre\bin\sunmscapi.dll 0x0000000065960000 60K D:\Java\jdk1.7.0_75\jre\bin\verify.dll 0x0000000065970000 44K D:\Java\jdk1.7.0_75\jre\bin\management.dll ...
3.2
-dump:[live,] format=b, file=filename
转储Java堆hprof二进制格式。指定live,标识转储active状态的对象。生成的文件可以由jhat命令查看。
C:\Users\Administrator>jmap -dump:format=b,file=9208_0413.hprof 9208 Dumping heap to C:\Users\Administrator\9208_0413.hprof ... Heap dump file created
3.3 -finalizerinfo
打印将要结束的对象的信息
C:\Users\Administrator>jmap -finalizerinfo 9208 Attaching to process ID 9208, please wait... Debugger attached successfully. Server compiler detected. JVM version is 24.75-b04 Number of objects pending for finalization: 0
3.4 -heap
打印垃圾收集和heap摘要信息，以及生成-wise 堆使用的堆摘要
C:\Users\Administrator>jmap -heap 9208 Attaching to process ID 9208, please wait... Debugger attached successfully. Server compiler detected. JVM version is 24.75-b04 using thread-local object allocation. Parallel GC with 4 thread(s) Heap Configuration: MinHeapFreeRatio = 0 MaxHeapFreeRatio = 100 MaxHeapSize = 2124414976 (2026.0MB) NewSize = 1310720 (1.25MB) MaxNewSize = 17592186044415 MB OldSize = 5439488 (5.1875MB) NewRatio = 2 SurvivorRatio = 8 PermSize = 21757952 (20.75MB) MaxPermSize = 85983232 (82.0MB) G1HeapRegionSize = 0 (0.0MB) Heap Usage: PS Young Generation Eden Space: capacity = 68157440 (65.0MB) used = 16646688 (15.875518798828125MB) free = 51510752 (49.124481201171875MB) 24.423875075120193% used From Space: capacity = 5242880 (5.0MB) used = 5228248 (4.986045837402344MB) free = 14632 (0.01395416259765625MB) 99.72091674804688% used To Space: capacity = 15728640 (15.0MB) used = 0 (0.0MB) free = 15728640 (15.0MB) 0.0% used PS Old Generation capacity = 88080384 (84.0MB) used = 27239848 (25.977943420410156MB) free = 60840536 (58.022056579589844MB) 30.9261231195359% used PS Perm Generation capacity = 22020096 (21.0MB) used = 15369592 (14.657585144042969MB) free = 6650504 (6.342414855957031MB) 69.7980244954427% used 10057 interned Strings occupying 867832 bytes.
3.5 -histo[:live]
打印堆的直方图
num #instances #bytes class name ---------------------------------------------- ... 877: 1 32 [Lcom.sun.jndi.ldap.pool.Pool; 878: 2 32 com.sun.org.apache.xerces.internal.impl.dv.dtd.ENTITYDatatypeValidator 879: 2 32 java.lang.Shutdown$Lock 880: 1 32 org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler 881: 2 32 com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$DTDDriver 882: 1 32 java.lang.reflect.WeakCache$CacheKey 883: 1 32 java.text.FieldPosition 884: 1 32 java.util.concurrent.atomic.AtomicReferenceFieldUpdater$AtomicReferenceFieldUpdaterImpl 885: 2 32 sun.security.x509.CertificateVersion 886: 2 32 [Lorg.apache.catalina.deploy.ContextEnvironment; 887: 1 32 [Lorg.apache.tomcat.util.net.AbstractEndpoint$Acceptor$AcceptorState; 888: 1 32 sun.nio.cs.StandardCharsets ...
3.6 -clstats
java 堆的wise统计。1.7.0_75不支持该项
（2）jhat
2.1作用
分析Java堆。该jhat命令解析Java堆转储文件并启动Web服务器。jhat命令可以让你浏览堆转储。支持OQL语法。
2.2使用
jhat [ options ] heap-dump-file
2.3参数说明
1.-stack false|true
关闭跟踪对象分配调用堆栈。默认值是true。
-refs false|true
关闭对象的引用的跟踪。默认为true。
-port port-number
设置端口的jhatHTTP服务器。默认值是7000。
-exclude exclude-file
指定列出了应当从可及的对象查询排除数据成员的文件
-baseline exclude-file
指定基准堆转储。在具有相同的对象ID两个堆转储对象被标记为不是新对象。这是用于比较两个不同的堆转储有用。
-debug int
0级表示没有调试输出
C:\Users\Administrator>jhat -port 8000 9208_0413.hprof Reading from 9208_0413.hprof... Dump file created Thu Apr 13 21:18:58 CST 2017 Snapshot read, resolving... Resolving 389761 objects... Chasing references, expect 77 dots.......................................................................... Eliminating duplicate references............................................................................ Snapshot resolved. Started HTTP server on port 8000 Server is ready.
接下来，就可以通过浏览器访问查看。http://localhost:8000/。
(3)jinfo
3.1作用
生成的配置信息。如果指定的进程是在64位JVM上运行，那么你可能需要指定-J-d64选项
3.2使用
jinfo [ option ] pid jinfo [ option ] executable core jinfo [ option ] [ servier-id ] remote-hostname-or-IP
3.3选项参数
no-option：既打印命令行标志和系统属性键值对。
-flag name
打印名和指定的命令行标志的值。
-flag [+|-]name
开启或禁止指定的布尔命令行标志。
-flag name=value
设置指定的命令行标志为指定值。
-flags
打印命令行标志传递给JVM。
-sysprops
打印Java系统属性键值对。
打印进程的命令行参数
C:\Users\Administrator>jinfo -flags 9208 Attaching to process ID 9208, please wait... Debugger attached successfully. Server compiler detected. JVM version is 24.75-b04 -Djava.util.logging.config.file=D:\apache-tomcat-7.0.67\conf\logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djava.endorsed.dirs=D:\apache-tomcat-7.0.67\endorsed -Dcatalina.base=D:\apache-tomcat-7.0.67 -Dcatalina.home=D:\apache-tomcat-7.0.67 -Djava.io. tmpdir=D:\apache-tomcat-7.0.67\temp #在catalina.sh中可以找到设置的地方
打印参数值
#值类型参数 C:\Users\Administrator>jinfo -flag NewSize 9208 -XX:NewSize=1310720 #开关类型参数 C:\Users\Administrator>jinfo -flag PrintGC 9208 -XX:-PrintGC C:\Users\Administrator>jinfo -flag Xmn 9208 no such flag ‘Xmn‘
可以总结出：-xms,-xmn系列参数不能通过jinfo指定或打印；jinfo命令作用于-XX:***格式的参数。
设置参数值
C:\Users\Administrator>jinfo -flag PrintGC 9208 -XX:-PrintGC C:\Users\Administrator>jinfo -flag +PrintGC 9208 C:\Users\Administrator>jinfo -flag PrintGC 9208 -XX:+PrintGC //2 windows环境总是失败 C:\Users\Administrator>jinfo -flag PermSize=21750000 9208 Exception in thread "main" java.io.IOException: Command failed in target VM at sun.tools.attach.WindowsVirtualMachine.execute(WindowsVirtualMachine.java:112) at sun.tools.attach.HotSpotVirtualMachine.executeCommand(HotSpotVirtualMachine.java:217) at sun.tools.attach.HotSpotVirtualMachine.setFlag(HotSpotVirtualMachine.java:190) at sun.tools.jinfo.JInfo.flag(JInfo.java:123) at sun.tools.jinfo.JInfo.main(JInfo.java:76)
http://docs.oracle.com/javase/8/docs/technotes/tools/unix/jhat.html
http://docs.oracle.com/javase/8/docs/technotes/tools/unix/jinfo.html
http://docs.oracle.com/javase/8/docs/technotes/tools/unix/jmap.html
本文出自 “简单” 博客，请务必保留此出处http://dba10g.blog.51cto.com/764602/1915801
java自带命令行工具(jmap,jhat,jinfo)