#!/bin/bash

set -eu

pid=$1

rss=$(ps -orss -p $pid | tail -n 1)
run=0
echo "ts,current,diff,running_total"
echo "$( date -u +'%Y-%m-%d %T'),$rss,0,0"
while true; do
  sleep 20
  rss2=$(ps -orss -p $pid | tail -n 1)
  [[ -z "$rss2" ]] && exit 0
  diff=$((rss2 - rss))
  run=$((run + diff))
  echo "$( date -u +'%Y-%m-%d %T'),$rss2,$diff,$run"
  rss=$rss2
done