jmap命令(Java Memory Map)



可以输出所有内存中对象的工具,甚至可以将VM 中的heap,以二进制输出成文本。使用方法 jmap -histo pid。如果连用SHELL jmap -histo pid>a.log可以将其保存到文本中去,在一段时间后,使用文本对比工具,可以对比出GC回收了哪些对象。jmap -dump:format=b,file=outfile 3024可以将3024进程的内存heap输出出来到outfile文件里,再配合MAT(内存分析工具(Memory Analysis Tool),使用参见:或与jhat (Java Heap Analysis Tool)一起使用,能够以图像的形式直观的展示当前内存是否有问题。


jmap -J-d64 -heap pid



       jmap [ option ] pid

       jmap [ option ] executable core

       jmap [ option ] [server-id@]remote-hostname-or-IP



executable Java executable from which the core dump was produced.

(可能是产生core dump的java可执行程序)

core 将被打印信息的core dump文件

remote-hostname-or-IP 远程debug服务的主机名或ip

server-id 唯一id,假如一台主机上多个远程debug服务


-dump:[live,]format=b,file=<filename> 使用hprof二进制形式,输出jvm的heap内容到文件=. live子选项是可选的,假如指定live选项,那么只输出活的对象到文件.

-finalizerinfo 打印正等候回收的对象的信息.

-heap 打印heap的概要信息,GC使用的算法,heap的配置及wise heap的使用情况.

-histo[:live] 打印每个class的实例数目,内存占用,类全名信息. VM的内部类名字开头会加上前缀”*”. 如果live子参数加上后,只统计活的对象数量.

-permstat 打印classload和jvm heap长久层的信息. 包含每个classloader的名字,活泼性,地址,父classloader和加载的class数量. 另外,内部String的数量和占用内存数也会打印出来.

-F 强迫.在pid没有相应的时候使用-dump或者-histo参数. 在这个模式下,live子参数无效.

-h | -help 打印辅助信息

-J 传递参数给jmap启动的jvm.

pid 需要被打印配相信息的java进程id,创业与打工的区别 – 博文预览,可以用jps查问.


1)、[fenglb@ccbu-156-5 ~]$ jmap -histo 4939


2)、[fenglb@ccbu-156-5 ~]$ jmap -dump:format=b,file=test.bin 4939

Dumping heap to /home/fenglb/test.bin …

Heap dump file created

3 thoughts on “jmap命令(Java Memory Map)

  1. Hey I know this is off topic but I was wondering if you knew of any widgets I
    could add to my blog that automatically tweet my newest twitter updates.
    I’ve been looking for a plug-in like this for quite some time and was hoping maybe you would have some experience with something like this.
    Please let me know if you run into anything. I truly enjoy reading
    your blog and I look forward to your new updates.

  2. I have been exploring for a bit for any high-quality articles or blog posts on this kind of house . Exploring in Yahoo I at last stumbled upon this website. Reading this information So i’m glad to express that I have a very just right uncanny feeling I discovered just what I needed. I such a lot definitely will make certain to do not overlook this site and give it a glance on a continuing basis.

Leave a Reply

Your email address will not be published. Required fields are marked *