试图找到泄漏！对于pmap来说，anon意味着什么？ [英] Trying to locate a leak! What does anon mean for pmap?

问题描述

我正在尝试找到我的内存在linux中运行的java进程的位置。有人建议我使用pmap -x来确切了解内存的作用。

I'm trying to locate where my memory has gone for a java process running in linux. Someone suggested I use pmap -x to see exactly what the memory is doing.

输出真的很长但基本上很重要的部分是重复这个：

The output is really long but basically a good portion of it is a repeat of this:

00007fbf75f6a000    1016       -       -       - rwx--    [ anon ]
00007fbf76068000      12       -       -       - -----    [ anon ]

这究竟是什么意思？为什么我有这么多的条目（4000 +）？

What exactly does this mean? Why do I have so many entries of this (4000+)?

推荐答案

Anon块是通过malloc分配的大块或者mmap - 查看联机帮助页。因此，它们与Java堆无关（除了整个堆应该存储在这样一个块中的事实）。

Anon blocks are "large" blocks allocated via malloc or mmap -- see the manpages. As such, they have nothing to do with the Java heap (other than the fact that the entire heap should be stored in just such a block).

根据我的经验，线程堆栈也使用anon块。如果你看到很多anon块都具有相同的大小，并且该大小为512k到4Mb（对于我运行的Tomcat进程，下面的示例重复了十几次），这可能是原因。根据程序的不同，您可能需要多达几十个;如果你看到数千，这意味着你有线程问题。

In my experience, thread stacks also use anon blocks. If you see a lot of anon blocks that all have the same size, and that size is 512k to 4Mb (the example below is repeated over a dozen times for a Tomcat process that I have running), that's the likely cause. Depending on the program, you may have up to a few dozen of these; if you're seeing thousands, it means you have a problem with threading.

b089f000    504K rwx--    [ anon ]
b091d000     12K -----    [ anon ]
b0920000    504K rwx--    [ anon ]
b099e000     12K -----    [ anon ]
b09a1000    504K rwx--    [ anon ]
b0a1f000     12K -----    [ anon ]

但这留下了一个问题：为什么您使用 pmap 来诊断Java内存问题吗？

But that leaves a question: why are you using pmap to diagnose a Java memory issue?

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