merge -c 1504970 from trunk to branch-2 to fix YARN-919. Document setting default heap sizes in yarn env.sh Contributed by Mayank Bansal.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1504971 13f79535-47bb-0310-9956-ffa450edef68

hadoop-yarn-project/CHANGES.txt

@@ -681,6 +681,9 @@ Release 2.1.0-beta - 2013-07-02
     YARN-654. AMRMClient: Perform sanity checks for parameters of public
     methods (Xuan Gong via bikas)"
 
+    YARN-919. Document setting default heap sizes in yarn-env.sh (Mayank
+    Bansal via hitesh)
+
   BREAKDOWN OF HADOOP-8562 SUBTASKS AND RELATED JIRAS
 
     YARN-158. Yarn creating package-info.java must not depend on sh.

hadoop-yarn-project/hadoop-yarn/conf/yarn-env.sh

@@ -34,13 +34,47 @@ fi
 JAVA=$JAVA_HOME/bin/java
 JAVA_HEAP_MAX=-Xmx1000m 
 
+# For setting YARN specific HEAP sizes please use this
+# Parameter and set appropriately
+# YARN_HEAPSIZE=1000
+
 # check envvars which might override default args
 if [ "$YARN_HEAPSIZE" != "" ]; then
-  #echo "run with heapsize $YARN_HEAPSIZE"
   JAVA_HEAP_MAX="-Xmx""$YARN_HEAPSIZE""m"
-  #echo $JAVA_HEAP_MAX
 fi
 
+# Resource Manager specific parameters
+
+# Specify the max Heapsize for the ResourceManager using a numerical value
+# in the scale of MB. For example, to specify an jvm option of -Xmx1000m, set
+# the value to 1000.
+# This value will be overridden by an Xmx setting specified in either YARN_OPTS
+# and/or YARN_RESOURCEMANAGER_OPTS.
+# If not specified, the default value will be picked from either YARN_HEAPMAX
+# or JAVA_HEAP_MAX with YARN_HEAPMAX as the preferred option of the two.
+#export YARN_RESOURCEMANAGER_HEAPSIZE=1000
+
+# Specify the JVM options to be used when starting the ResourceManager.
+# These options will be appended to the options specified as YARN_OPTS
+# and therefore may override any similar flags set in YARN_OPTS
+#export YARN_RESOURCEMANAGER_OPTS=
+
+# Node Manager specific parameters
+
+# Specify the max Heapsize for the NodeManager using a numerical value
+# in the scale of MB. For example, to specify an jvm option of -Xmx1000m, set
+# the value to 1000.
+# This value will be overridden by an Xmx setting specified in either YARN_OPTS
+# and/or YARN_NODEMANAGER_OPTS.
+# If not specified, the default value will be picked from either YARN_HEAPMAX
+# or JAVA_HEAP_MAX with YARN_HEAPMAX as the preferred option of the two.
+#export YARN_NODEMANAGER_HEAPSIZE=1000
+
+# Specify the JVM options to be used when starting the NodeManager.
+# These options will be appended to the options specified as YARN_OPTS
+# and therefore may override any similar flags set in YARN_OPTS
+#export YARN_NODEMANAGER_OPTS=
+
 # so that filenames w/ spaces are handled correctly in loops below
 IFS=