前言
大家都知道有很多开源的监控工具,本次只使用了jmap,了解简单使用,谢谢,下面话不多说了,来一起看看详细的介绍吧
使用方法如下:
开始了,922是我的tomcat进程
帮助命令查看,有哪些命令可以使用。
[root@bogon /]# jmap -help
Usage:
jmap [option] <pid>
(to connect to running process)
jmap [option] <executable <core>
(to connect to a core file)
jmap [option] [server_id@]<remote server IP or hostname>
(to connect to remote debug server)
where <option> is one of:
<none> to print same info as Solaris pmap
-heap to print java heap summary
-histo[:live] to print histogram of java object heap; if the "live"
suboption is specified, only count live objects
-clstats to print class loader statistics
-finalizerinfo to print information on objects awaiting finalization
-dump:<dump-options> to dump java heap in hprof binary format
dump-options:
live dump only live objects; if not specified,
all objects in the heap are dumped.
format=b binary format
file=<file> dump heap to <file>
Example: jmap -dump:live,format=b,file=heap.bin <pid>
-F force. Use with -dump:<dump-options> <pid> or -histo
to force a heap dump or histogram when <pid> does not
respond. The "live" suboption is not supported
in this mode.
-h | -help to print this help message
-J<flag> to pass <flag> directly to the runtime system
使用1:jmap pid 查看基本信息
[root@bogon /]# jmap 922
Attaching to process ID 922, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.111-b14
0x0000000000400000 7K /usr/local/software/java/bin/java
0x0000003ddde00000 153K /lib64/ld-2.12.so
0x0000003dde200000 22K /lib64/libdl-2.12.so
0x0000003dde600000 1881K /lib64/libc-2.12.so
0x0000003ddea00000 142K /lib64/libpthread-2.12.so
0x0000003ddee00000 45K /lib64/librt-2.12.so
0x0000003ddf200000 585K /lib64/libm-2.12.so
0x0000003de0e00000 111K /lib64/libresolv-2.12.so
0x0000003de9e00000 91K /lib64/libgcc_s-4.4.7-20120601.so.1
0x00007f90de586000 26K /lib64/libnss_dns-2.12.so
0x00007f913c39d000 250K /usr/local/software/java/jre/lib/amd64/libsunec.so
0x00007f913cbf2000 90K /usr/local/software/java/jre/lib/amd64/libnio.so
0x00007f913d103000 113K /usr/local/software/java/jre/lib/amd64/libnet.so
0x00007f913d31a000 49K /usr/local/software/java/jre/lib/amd64/libmanagement.so
0x00007f919a43b000 121K /usr/local/software/java/jre/lib/amd64/libzip.so
0x00007f919a656000 64K /lib64/libnss_files-2.12.so
0x00007f919a874000 220K /usr/local/software/java/jre/lib/amd64/libjava.so
0x00007f919aaa0000 64K /usr/local/software/java/jre/lib/amd64/libverify.so
0x00007f919acef000 16584K /usr/local/software/java/jre/lib/amd64/server/libjvm.so
0x00007f919bce2000 100K /usr/local/software/java/lib/amd64/jli/libjli.so
使用2 :查看堆信息,jmap -heap pid
[root@bogon /]# jmap -heap 922
Attaching to process ID 922, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.111-b14
using parallel threads in the new generation.
using thread-local object allocation.
Concurrent Mark-Sweep GC
Heap Configuration:
MinHeapFreeRatio = 40
MaxHeapFreeRatio = 70
MaxHeapSize = 4294967296 (4096.0MB) 最大堆大小
NewSize = 3221225472 (3072.0MB) 新生代大小
MaxNewSize = 3221225472 (3072.0MB) 最大分配新生代内存
OldSize = 1073741824 (1024.0MB) 老年代大小
NewRatio = 2
SurvivorRatio = 8 新生代与老年代的比例
MetaspaceSize = 21807104 (20.796875MB)
CompressedClassSpaceSize = 1073741824 (1024.0MB)
MaxMetaspaceSize = 17592186044415 MB
G1HeapRegionSize = 0 (0.0MB)
Heap Usage: 堆的使用情况
New Generation (Eden + 1 Survivor Space): 新生代
capacity = 2899116032 (2764.8125MB)
used = 384206560 (366.4079284667969MB)
free = 2514909472 (2398.404571533203MB)
13.25254166301682% used
Eden Space: 新生代 eden区空间
capacity = 2577006592 (2457.625MB)
used = 378654344 (361.11292266845703MB)
free = 2198352248 (2096.512077331543MB)
14.693572968555294% used
From Space: 2个Survivor区域 其中一个就是这个from区
capacity = 322109440 (307.1875MB)
used = 5552216 (5.295005798339844MB)
free = 316557224 (301.89249420166016MB)
1.723704837709817% used
To Space:2个Survivor区域 其中一个就是这个to区
capacity = 322109440 (307.1875MB)
used = 0 (0.0MB)
free = 322109440 (307.1875MB)
0.0% used
concurrent mark-sweep generation: 老年代 eden区空间
capacity = 1073741824 (1024.0MB)
used = 846734040 (807.5085067749023MB)
free = 227007784 (216.49149322509766MB)
78.85825261473656% used
使用3:jmap -histo pid 查看一些class的使用情况,
jmap -histo 922
由于里面比较多内容,所以放弃了,可以自己使用一下,如果电脑展示不了一屏呢,可以这样。
jmap -histo 922 >dump.txt 导出文件,可以自己看了
下面是我自己导出的文件信息
num #instances(实例数量) #bytes(字节) class name
----------------------------------------------
1: 174069 1579369600 [C
2: 4403 122732640 [I
3: 9571 16889072 [B
4: 157680 3784320 java.lang.String
5: 38279 3674784 java.util.jar.JarFile$JarFileEntry
6: 70982 2271424 java.util.HashMap$Node
7: 13235 1164680 java.lang.reflect.Method
8: 6001 1028952 [Ljava.util.HashMap$Node;
又或者可以过滤信息,命令:jmap -histo 922 |grep dubbo 过滤一下,就过滤你想要的信息
使用4:jmap -histo:live pid >dump.txt
这个和使用3差不多,都是在统计,只不过这个是在统计正在使用的对象,然后dump对象信息。
这种命令都是结合其它的命令一起使用的,以后会有文章结合一起分析,同学有什么好的工具也分享出来,一起学习,本篇只介绍jmap
总结
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