Number of GC events and GC time **per day**

gcstat.sh

#!/usr/bin/env bash

set -e

# Java process ID
PID="$(pgrep java)"

# convert `ps -o etime` output format to second
function psetime_converter() {
  echo "$(cat -)" | awk '
  BEGIN { FS = ":" }
  {
    if (NF == 2) {
      print $1*60 + $2
    } else if (NF == 3) {
      split($1, a, "-");
      if (a[2] != "" ) {
        print ((a[1]*24+a[2])*60 + $2) * 60 + $3;
      } else {
        print ($1*60 + $2) * 60 + $3;
      }
    }
  }
  '
}

# get running time
RUNNING_TIME="$(ps -o etime= -p "${PID}" | psetime_converter)"
RUNNING_TIME_DAY="$(echo "${RUNNING_TIME} / (60 * 60 * 24)" | bc -l)"

# extract jstat statistics
## YGC: Minor GC (New generation) count
## YGCT: Minor GC (New generation) time
## FGC: Full GC (Old generation) count
## FGCT: Full GC (Old generation) time
## GCT: All GC time
JSTAT_RESULT="$(sudo jstat -gcutil "${PID}")"
echo "${JSTAT_RESULT}"
IFS=" " read -r -a JSTAT_GC_VALUES <<< "$(echo "${JSTAT_RESULT}" | tail -n 1 | awk '{print $7,$8,$9,$10,$11}')"

# formatting
function average_stat() {
  echo "$1 ${RUNNING_TIME_DAY}" | awk '{print sprintf("%.2f", $1 / $2)}'
}

# print statistics
echo "Averaged GC info"
echo -e "YGC:\t $(average_stat "${JSTAT_GC_VALUES[0]}")"
echo -e "YGCT:\t $(average_stat "${JSTAT_GC_VALUES[1]}")"
echo -e "FGC:\t $(average_stat "${JSTAT_GC_VALUES[2]}")"
echo -e "FGCT:\t $(average_stat "${JSTAT_GC_VALUES[3]}")"
echo -e "GCT:\t $(average_stat "${JSTAT_GC_VALUES[4]}")"