https://gist.github.com/patmandenver/cadb5f3eb567a439ec01

#
  # Cutom Environment Variables for Tomcat
  #
  ############################################
  export JAVA_HOME=/usr/lib/jvm/java-7-oracle/jre
  export PATH=${JAVA_HOME}/bin:${PATH}
   
  ############################################
  #
  # JAVA_OPTS
  # You could do all this in one export command
  # But I am going to be long winded and explain
  # Why and add links
  #
  # Oracle Notes
  # - https://docs.oracle.com/javase/8/docs/technotes/tools/windows/java.html
  # - A good visual
  # https://redstack.wordpress.com/2011/01/06/visualising-garbage-collection-in-the-jvm/
  #############################################
   
   
  # -server
  # Select the java HotSpot Server JVM
  # The 64-bit version of the JDK support only the Server VM,
  # so in that case the option is implicit
  # ... so it's redundant to today's world but it make me feel good.
  export JAVA_OPTS="-server"
   
  # -Xms/Xmx
  # Xms Sets the initial size of the Heap
  # Xmx sets the Maximum size of the Heap.
  # http://stackoverflow.com/questions/16087153/what-happens-when-we-set-xmx-and-xms-equal-size
  # http://crunchify.com/jvm-tuning-heapsize-stacksize-garbage-collection-fundamental/
  export JAVA_OPTS="$JAVA_OPTS -Xms1024M -Xmx1024M"
   
  # -NewSize/MaxNewSize
  # Set the size of the young generation
  # Most newly created objects are made here
  # Objects taht did not become unreachbale and survice the young
  # Generation heap are copied to the Old Generation
  # See http://www.cubrid.org/blog/dev-platform/understanding-java-garbage-collection
  # https://redstack.wordpress.com/2011/01/06/visualising-garbage-collection-in-the-jvm/
  export JAVA_OPTS="$JAVA_OPTS -XX:NewSize=512m -XX:MaxNewSize=512m"
   
  # -PermSize/MaxPermSize
  # Store classes and interned character strings
  # http://stackoverflow.com/questions/12114174/what-does-xxmaxpermsize-do
  # Warning!
  # Decprecated in Java 8!! replace -XX:MetaspaceSize !!!
  export JAVA_OPTS="$JAVA_OPTS -XX:PermSize=256m -XX:MaxPermSize=256m"
   
  # -UseConcMarkSweepGC
  # Also called the low latency GC since pausing time is very short
  # When this is enabled it also enabled
  # -XX:+UseParNewGC Potentially speed up your generation GC
  # by a factor equal to the number of CPUS
  # (see http://stackoverflow.com/questions/2101518/difference-between-xxuseparallelgc-and-xxuseparnewgc)
  # http://www.cubrid.org/blog/dev-platform/understanding-java-garbage-collection/
  export JAVA_OPTS="$JAVA_OPTS -XX:+UseConcMarkSweepGC"
   
  # -XX:+CMSIncrementalMode
  #
  # I am not going to set this one but it's worthe mentioning
  # It has been deprecated in Java 8. It is useful when you have 1 or 2
  # CPU machine. It helps reduce latency by doing smaller garbage collections
  # see thies sites for details
  # http://www.fixdeveloper.com/2014/03/jvm-tuning-cmsincrementalmode-overrides.html
  # http://www.oracle.com/technetwork/java/javase/gc-tuning-6-140523.html#icms
   
   
  # -CMSClassUnloadingEnabled
  # In an old school java program classes are forever. But with
  # Modern languages like Groovy... Classes are created at runtime, every
  # scirpt may create a few new classes. With this set the PermGen space will
  # Be garbage collecte3d. Without this you have a memory Leak.
  #
  # Must also have UseConcMarkSweepGC set for this to work.
  #
  # http://stackoverflow.com/questions/3334911/what-does-jvm-flag-cmsclassunloadingenabled-actually-do
  export JAVA_OPTS="$JAVA_OPTS -XX:+CMSClassUnloadingEnabled"
   
   
  # -DisableExlicitGC
  # Explicit calls to System.gc() are completely ignored
  #
  # http://stackoverflow.com/questions/12847151/setting-xxdisableexplicitgc-in-production-what-could-go-wrong
  export JAVA_OPTS="$JAVA_OPTS -XX:+DisableExplicitGC"
   
  # -HeapDumpPath
  # Set the file where the heap dump will write out its error
  export JAVA_OPTS="$JAVA_OPTS -XX:HeapDumpPath=/10x13/logs/tomcat8/java_heapdump_pid_%p.log"
   
  # -java.awt.headless
  # Basically tell the JVM not to load awt libraries
  # Your server is not a desktop app, there is more to this rule than that.
  # If you want to go into it check out.
  # https://blog.idrsolutions.com/2013/08/what-is-headless-mode-in-java/
  # http://www.oracle.com/technetwork/articles/javase/headless-136834.html
  export JAVA_OPTS="$JAVA_OPTS -Djava.awt.headless=true"
   
   
  # -java.security.egd
  # This one is abit of a debate
  # If you don't set this it will use /dev/random on startup
  # which can block and make tomcat startup slower.
  # But it's technically more secure... but no one has shown
  # a way to break the results of urandom which is faster.
  # For more details see.
  # http://www.2uo.de/myths-about-urandom/
  export JAVA_OPTS="$JAVA_OPTS -Djava.security.egd=file:/dev/./urandom"
   
  #################################################
  # CATALINA_OPTS
  # This are basically JAVA_OPTS but only used by tomcat
  # and only run on Tomcat start see
  # http://stackoverflow.com/questions/11222365/catalina-opts-vs-java-opts-what-is-the-difference
  # for more details
  #
  ################################################
   
   
  # -jmcremot..
  # Turn onthe jmxremote so you can use JConsole or VisualVM
  # to monito the jvm remotely
  # See
  # https://tomcat.apache.org/tomcat-7.0-doc/monitoring.html
  # http://www.mkyong.com/tomcat/jconsole-jmx-remote-access-on-tomcat/
  # http://www.javaworld.com/article/2072322/from-jconsole-to-visualvm.html
  export CATALINA_OPTS="$CATALINA_OPTS -Dcom.sun.management.jmxremote"
  export CATALINA_OPTS="$CATALINA_OPTS -Dcom.sun.management.jmxremote.port=9090"
  export CATALINA_OPTS="$CATALINA_OPTS -Dcom.sun.management.jmxremote.authenticate=false"
  export CATALINA_OPTS="$CATALINA_OPTS -Dcom.sun.management.jmxremote.ssl=false"
  #This gets the local IP address
  IP_ADDR=`ip route get 8.8.8.8 | awk '{print $NF; exit}'`
  export CATALINA_OPTS="$CATALINA_OPTS -Djava.rmi.server.hostname=$IP_ADDR"
   
   
   
  export CATALINA_HOME=/10x13/apps/tomcat8
  export CATALINA_OUT=/10x13/logs/tomcat8/catalina.out
  export CATALINA_PID=/var/run/tomcat8/tomcat.pid