From 37025ec47915a9857be74c5de26b4ec7d1a18547 Mon Sep 17 00:00:00 2001
From: Konstantin Shvachko <shv@apache.org>
Date: Sun, 23 Jan 2011 22:08:34 +0000
Subject: [PATCH] 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                 |  3 +++
 bin/hadoop-config.sh        | 12 ++++++++++++
 conf/hadoop-env.sh.template |  3 +++
 3 files changed, 18 insertions(+)

diff --git a/CHANGES.txt b/CHANGES.txt
index ea48f338f1..22bdb94c2b 100644
--- a/CHANGES.txt
+++ b/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(..).
diff --git a/bin/hadoop-config.sh b/bin/hadoop-config.sh
index 025dbc0a29..f9acdd87db 100644
--- a/bin/hadoop-config.sh
+++ b/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
diff --git a/conf/hadoop-env.sh.template b/conf/hadoop-env.sh.template
index ce7ccc8909..fb8bc97ca1 100644
--- a/conf/hadoop-env.sh.template
+++ b/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