HADOOP-6056. Use java.net.preferIPv4Stack to force IPv4. Contributed by Michele Catasta.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1062543 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -263,6 +263,9 @@ Release 0.22.0 - Unreleased
     HADOOP-7104. Remove unnecessary DNS reverse lookups from RPC layer
     (Kan Zhang via todd)
 
+    HADOOP-6056. Use java.net.preferIPv4Stack to force IPv4.
+    (Michele Catasta via shv)
+
   OPTIMIZATIONS
 
     HADOOP-6884. Add LOG.isDebugEnabled() guard for each LOG.debug(..).

bin/hadoop-config.sh

@@ -69,6 +69,15 @@ if [ -f "${HADOOP_CONF_DIR}/hadoop-env.sh" ]; then
   . "${HADOOP_CONF_DIR}/hadoop-env.sh"
 fi
 
+# check if net.ipv6.bindv6only is set to 1
+bindv6only=$(/sbin/sysctl -n net.ipv6.bindv6only 2> /dev/null)
+if [ -n "$bindv6only" ] && [ "$bindv6only" -eq "1" ] && [ "$HADOOP_ALLOW_IPV6" != "yes" ]
+then
+  echo "Error: \"net.ipv6.bindv6only\" is set to 1 - Java networking could be broken"
+  echo "For more info: http://wiki.apache.org/hadoop/HadoopIPv6"
+  exit 1
+fi
+
 # some Java parameters
 if [ "$JAVA_HOME" != "" ]; then
   #echo "run java in $JAVA_HOME"
@@ -211,6 +220,9 @@ if [ "x$JAVA_LIBRARY_PATH" != "x" ]; then
 fi  
 HADOOP_OPTS="$HADOOP_OPTS -Dhadoop.policy.file=$HADOOP_POLICYFILE"
 
+# Disable ipv6 as it can cause issues
+HADOOP_OPTS="$HADOOP_OPTS -Djava.net.preferIPv4Stack=true"
+
 # put hdfs in classpath if present
 if [ "$HADOOP_HDFS_HOME" = "" ]; then
   if [ -d "${HADOOP_HOME}/hdfs" ]; then

conf/hadoop-env.sh.template

@@ -52,3 +52,6 @@ export HADOOP_JOBTRACKER_OPTS="-Dcom.sun.management.jmxremote $HADOOP_JOBTRACKER
 
 # The scheduling priority for daemon processes.  See 'man nice'.
 # export HADOOP_NICENESS=10
+
+# Allow Hadoop to run with sysctl net.ipv6.bindv6only = 1
+# export HADOOP_ALLOW_IPV6=yes