Dumps JVM application stack in case CPU load exceeds allowed threshold

auto-dump.sh

#!/bin/bash

#
# Dumps JVM application stack in case CPU load exceeds allowed threshold.
#
# This script is supposed to be called regularly, e.g. cron entry:
#
#     */5 * * * * /opt/apps/stack-dumps/auto-dump.sh
#

# Where to put stack dumps.
export TARGET_DIR="/opt/apps/stack-dumps"

export JSTACK_BIN="/usr/java/jdk1.7.0_79/bin/jstack"

# Target JVM PID-file.
export PID_FILE="/opt/apps/site/site.pid"

# Stack will be dumped only if the following maximal allowed CPU load is exceeded.
export CPU_THRESHOLD="90"


function die() {
  echo "ERROR: $@" 1>&2
  exit 1
}

function getCpuLoad() {
  local load=$(top -bn1 | grep "Cpu(s)" | sed "s/.*, *\([0-9.]*\)%*id.*/\1/" | awk '{print 100 - $1}')

  local __rc=$1
  if [[ "$__rc" ]]; then
      eval ${__rc}="'$load'"
  else
      echo "$load"
  fi
}

function dumpStack() {
  local PID=$(cat ${PID_FILE})
  local TIME=$(date +%Y%m%d-%H%M%S-%N)
  local FILE_NAME="${TARGET_DIR}/stack-${PID}-${TIME}.dump"

  echo "Dumping PID=${PID} -> ${FILE_NAME}"

  ${JSTACK_BIN} ${PID} >${FILE_NAME} 2>&1
}

function main() {
  local LOAD="$(getCpuLoad)"

  echo "CPU load: ${LOAD}"

  if [ ${LOAD} -ge ${CPU_THRESHOLD} ]; then
    dumpStack
  fi
}

[ -f ${PID_FILE} ] || die "${PID_FILE} missing"
[ -d ${TARGET_DIR} ] || die "${TARGET_DIR} missing"

main