heapdump size vs hprof size [英] heapdump size vs hprof size

问题描述

当我的jboss服务器运行xms为4096m，xmx为4096m，permsize为512m时，我最近以hprof格式创建了一个heapdump。

I recently made a heapdump in a hprof format when my jboss server was running with a xms of 4096m and xmx of 4096m and a permsize of 512m.

hprof生成的文件超过5GB。当我在visualvm，mat analyzer或yourkit中加载heapdump时，我只看到大约1gb的总字节数。我已经尝试更改yourkit中的可访问性范围，但它没有显示超过1 GB。

The hprof file generated is over 5gb. When I load the heapdump in visualvm, mat analyzer or yourkit, I only see a total bytes of approximately 1gb. I've tried changed the reachability scope in yourkit but it does not show more than 1 gb.

知道文件大小与显示的heapdump大小的这个巨大差异会导致什么？

Any idea what this big difference in filesize vs displayed heapdump size can cause?

ps：我正在使用jdk1.6.0_23

ps: I'm using jdk1.6.0_23

不幸的是我不允许在这里提交截图。

Unfortunately I'm not allowed to submit screenshots here.

在文件系统上，hprof大小为5.227.659 kb，在yourkit中它指出：

On the filesystem the hprof size is of 5.227.659 kb and in yourkit it states:

对象：9.738.282 /浅尺寸740 mb /保留尺寸：740 mb其中可达到的字符串：6.652.515（68％）/浅尺寸：381 mb（51％）/保留大小：381 MB（51％）

Objects: 9.738.282 / shallow size 740 mb / retained size: 740 mb String reachable among them: 6.652.515 (68%) / shallow size: 381 mb (51%) / retained size: 381 MB (51%)

最大保留大小是一个字节[] 206.810.176

The largest retained size is a byte[] of 206.810.176

推荐答案

您是否尝试过无法访问的对象直方图（您可以在概述页面的顶部找到该链接）？在我的一个大小为1509MB的堆叠中，垫子只显示454MB，但其余部分基本上是垃圾，果然，无法到达的对象直方图中浅堆的总和是966MB。

Did you try "Unreachable Objects Histogram" (you can find the link from the top of "Overview" page)? In one of my heapdumps sized 1509MB, mat shows only 454MB, but the rest is essentially garbage, and sure enough, the sum of "Shallow Heap" in unreachable objects histogram is 966MB.

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