Best way to tell what application/process is using swap?

Question

I have 16G RAM, and 8G swap partition. I'm running Unity 17.04. I have a problem where my buff/cache goes to 11M, and my swap used goes to around 3500. Previously I almost never used any swap space, and I've never monitored the buff/cache.

I believe that it's an application with a memory leak, but I could be wrong.

Simple question. Is there any easy way to determine with application/process is, or has been, using swap?

Answer 1

You can find that how much does special process uses swap partition by this command :

cat /proc/"PID"/status | grep "^VmSwap"

And you can find PID by this command:

ps -A | grep "Application_name"

But if you want to find which processes are using the swap partition, you can use this script:

#!/bin/bash
for i in /proc/*/status ; do
    vmswap=$(cat $i | grep "^VmSwap")
    echo "$vmswap" | grep -qv ' 0 kB'
    if [ $? == 0 ] && [ "$vmswap" != "" ] ; then
        echo "$i : $vmswap"
    fi
done

Then you can find the application name from its PID that's returned by the script.

Update: I changed this script to create log file every 10 second (you can change the time) and in that file you can see many processes from the moment you run this script up to now:

#!/bin/bash
counter=1
touch ~/swap_process_usage.log
while true ; do
    echo -e "************************************\nSwap's process in count $counter " >> ~/swap_process_usage.log
    for i in /proc/*/status ; do
        vmswap=$(cat $i | grep "^VmSwap")
        echo "$vmswap" | grep -qv ' 0 kB'
        if [ $? == 0 ] && [ "$vmswap" != "" ] ; then
            pid=$(echo "$i" | tr -d /proc/ | tr -d status)
            proc_name=$(ps -p $pid -o comm=)
            echo "$proc_name : $pid : $vmswap" >> ~/swap_process_usage.log
        fi
    done
    sleep 10s
    counter=$((counter+1))
done

And you can set this script to run at startup so it creates log every time.