tomcat's setenv.sh for dynamic set max-memory.

setenv.sh

memory_estimate_script=$(mktemp /tmp/tmp.XXXXXXXXXX)
cat << EOF > $memory_estimate_script
import re
import os.path

if not os.path.exists("/proc/meminfo"): print 1024

with open("/proc/meminfo") as fh:
  line = fh.readline()
  if "MemTotal" in line and "kB" in line:
    m = re.search("\d+", line)
    if m:
      memory_kb = float(m.group()) * 0.7
      memory_mb = int(memory_kb / 1024)
      print memory_mb
    else:
      print 1024
EOF

memory_max_mb=$(python $memory_estimate_script)

export JAVA_HOME=/opt/java
export JAVA_OPTS="-Xms512m -Xmx"$memory_max_mb"m -XX:+UseParallelGC -Duser.timezone=Asia/Taipei -Djava.net.preferIPv4Stack=true -Djava.net.preferIPv4Addresses=true "
echo "JAVA_OPTS "$JAVA_OPTS