patmandenver · August 16, 2015 15:30 · Aug 16, 2015
diff --git a/setenv.sh b/setenv.sh
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+#
+# 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
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