概述

用於檢視某個程序的 mmap 記憶體。

例項場景

例如我想知道某一個 程序（pid）分配的記憶體的情況，分配了那些記憶體地址，總的大小又有多大,就可以使用 pmap ,根絕具體的例子可以檢視 Spring Boot “記憶體洩漏”？看看美團大牛是如何排查的

使用

使用我們直接

man pmap 

NAME
       pmap - report memory map of a process

SYNOPSIS
       pmap [ -x | -d ] [ -q ] pids...
       pmap -V

DESCRIPTION
       The pmap command reports the memory map of a process or processes.

GENERAL OPTIONS
       -x   extended       Show the extended format.
       -d   device         Show the device format.
       -q   quiet          Do not display some header/footer lines.
       -V   show version   Displays version of program.

EXTENDED AND DEVICE FORMAT FIELDS
       Address:   start address of map
       Kbytes:    size of map in kilobytes
       RSS:       resident set size in kilobytes
       Dirty:     dirty pages (both shared and private) in kilobytes
       Mode:      permissions on map: read, write, execute, shared, private (copy on write)
       Mapping:   file backing the map, or ’[ anon ]’ for allocated memory, or  ’[ stack ]’ for the program stack
       Offset:    offset into the file

例如我輸入

pmap -x  22243 

00002ba744000000    1920    1844    1844 rw---    [ anon ]
00002ba7441e0000   63616       0       0 -----    [ anon ]
00002ba748000000    1800    1800    1800 rw---    [ anon ]
00002ba7481c2000   63736       0       0 -----    [ anon ]
00007ffdc7eee000      84      36      36 rw---    [ stack ]
00007ffdc7f06000       4       4       0 r-x--    [ anon ]
ffffffffff600000       4       0       0 r-x--    [ anon ]
----------------  ------  ------  ------
total kB         7981256 1246612 1232744

其中第二項就是實際佔用記憶體大小，該例子中是佔用了1.2G 的記憶體。

參考

• https://mp.weixin.qq.com/s/K-6CPo1haIe65KZPdTHSrA