How to find process using high memory in Linux

http://kerneltalks.com/howto/find-process-using-high-memory-in-linux

Learn how to find process using high memory on linux server. This helps in tracking down issues and troubleshooting utilization problems.

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Many times you came to know system memory is highly utilized using utility like sar. You want to find processes hogging on memory. To find that, we will be using sort function of process status ps command in this article. We will be sorting ps output with RSS values. RSS is Resident Set Size. This values shows how much memory from physical RAM allocated to particular process. It does not include swapped out memory numbers. Since, we troubleshooting processes using high physical memory RSS fits for our criteria.

Lets see below example :

Shell

# ps aux --sort -rss |head -10 USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND oracle_admin 14400 0.0 11.8 36937384 31420276 ? Ss 2016 86:41 ora_mman_DB1 oracle_admin 14405 0.2 11.3 36993676 30023868 ? Ss 2016 1676:11 ora_DB3 oracle_admin 14416 0.2 11.3 36993676 30023656 ? Ss 2016 1722:47 ora_DB3 oracle_admin 14410 0.2 11.3 36993676 30020400 ? Ss 2016 1702:09 ora_DB3 oracle_admin 14421 0.2 11.3 36993676 30018272 ? Ss 2016 1754:25 ora_DB3 oracle_admin 14440 0.0 10.5 36946868 27887152 ? Ss 2016 130:30 ora_mon_DB3 oracle_admin 15855 0.0 6.9 19232424 18298484 ? Ss 2016 41:01 ora_mman_DB4 oracle_admin 15857 0.1 6.7 19288720 17966276 ? Ss 2016 161:45 ora_DB4 oracle_admin 15864 0.1 6.7 19288720 17964584 ? Ss 2016 173:36 ora_DB4

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# ps aux --sort -rss |head -10 USER           PID %CPU %MEM    VSZ   RSS     TTY STAT START   TIME COMMAND oracle_admin  14400  0.0 11.8 36937384 31420276 ?   Ss    2016  86:41 ora_mman_DB1 oracle_admin  14405  0.2 11.3 36993676 30023868 ?   Ss    2016 1676:11 ora_DB3 oracle_admin  14416  0.2 11.3 36993676 30023656 ?   Ss    2016 1722:47 ora_DB3 oracle_admin  14410  0.2 11.3 36993676 30020400 ?   Ss    2016 1702:09 ora_DB3 oracle_admin  14421  0.2 11.3 36993676 30018272 ?   Ss    2016 1754:25 ora_DB3 oracle_admin  14440  0.0 10.5 36946868 27887152 ?   Ss    2016 130:30 ora_mon_DB3 oracle_admin 15855  0.0  6.9 19232424 18298484 ?   Ss    2016  41:01 ora_mman_DB4 oracle_admin 15857  0.1  6.7 19288720 17966276 ?   Ss    2016 161:45 ora_DB4 oracle_admin 15864  0.1  6.7 19288720 17964584 ?   Ss    2016 173:36 ora_DB4

In above output we sorted processes with RSS and shown only top 10 one. RSS value in output is in Kb. Lets verify this output for top most process with pid 14400.

Shell

# free total used free shared buffers cached Mem: 264611456 96146728 168464728 0 1042972 75377436 -/+ buffers/cache: 19726320 244885136 Swap: 67108860 539600 66569260

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# free              total       used       free     shared    buffers     cached Mem:     264611456   96146728  168464728          0    1042972   75377436 -/+ buffers/cache:   19726320  244885136 Swap:     67108860     539600   66569260

On our system we have 264611456Kb physical RAM (highlighted entry in above output). Out of which 11.8% is used by process 14400 (from ps output above) which comes to 31224151Kb. This value matches RSS value of 31420276Kb (in ps output above)!
So above method works good when you try to find processes using highest physical memory on system!
You can even use another methods to get high memory using processes like top, htop etc. but this article aimed at using ps.