SPARK-1703 Warn users if Spark is run on JRE6 but compiled with JDK7.

This add some guards and good warning messages if users hit this issue.

Author: pwendell

bin/compute-classpath.sh

@@ -32,6 +32,12 @@ CLASSPATH="$SPARK_CLASSPATH:$SPARK_SUBMIT_CLASSPATH:$FWDIR/conf"
 
 ASSEMBLY_DIR="$FWDIR/assembly/target/scala-$SCALA_VERSION"
 
+if [ -n "${JAVA_HOME}" ]; then
+  JAR_CMD="${JAVA_HOME}/bin/jar"
+else
+  JAR_CMD="jar"
+fi
+
 # First check if we have a dependencies jar. If so, include binary classes with the deps jar
 if [ -f "$ASSEMBLY_DIR"/spark-assembly*hadoop*-deps.jar ]; then
   CLASSPATH="$CLASSPATH:$FWDIR/core/target/scala-$SCALA_VERSION/classes"
@@ -54,6 +60,14 @@ else
   else
     ASSEMBLY_JAR=`ls "$ASSEMBLY_DIR"/spark-assembly*hadoop*.jar`
   fi
+  jar_error_check=$($JAR_CMD -tf $ASSEMBLY_JAR org/apache/spark/SparkContext 2>&1)
+  if [[ "$jar_error_check" =~ "invalid CEN header" ]]; then
+    echo "Loading Spark jar with '$JAR_CMD' failed. "
+    echo "This is likely because Spark was compiled with Java 7 and run "
+    echo "with Java 6. (see SPARK-1703). Please use Java 7 to run Spark "
+    echo "or build Spark with Java 6."
+    exit 1
+  fi
   CLASSPATH="$CLASSPATH:$ASSEMBLY_JAR"
 fi
 

bin/spark-class

@@ -138,7 +138,14 @@ if [ -e "$TOOLS_DIR"/target/spark-tools*[0-9Tg].jar ]; then
 fi
 
 # Compute classpath using external script
-CLASSPATH=`$FWDIR/bin/compute-classpath.sh`
+CLASSPATH_OUTPUT=$($FWDIR/bin/compute-classpath.sh)
+if [[ "$?" != "0" ]]; then
+  echo "$CLASSPATH_OUTPUT"
+  exit 1
+else
+  CLASSPATH=$CLASSPATH_OUTPUT
+fi
+
 if [[ "$1" =~ org.apache.spark.tools.* ]]; then
   CLASSPATH="$CLASSPATH:$SPARK_TOOLS_JAR"
 fi

make-distribution.sh

@@ -50,6 +50,20 @@ if [ $? == -1 ] ;then
     exit -1;
 fi
 
+if [ -z "${JAVA_HOME}" ]; then
+  echo "Error: JAVA_HOME is not set, cannot proceed."
+  exit -1
+fi
+
+JAVA_CMD=$JAVA_HOME/bin/java
+JAVA_VERSION=$($JAVA_CMD -version 2>&1)
+if ! [[ "$JAVA_VERSION" =~ "1.6" ]]; then
+  echo "Error: Java version was not 1.6. Spark must be compiled with JDK 1.6 "
+  echo "(see SPARK-1703). Output from 'java -version' was:"
+  echo "$JAVA_VERSION"
+  exit -1
+fi
+
 # Initialize defaults
 SPARK_HADOOP_VERSION=1.0.4
 SPARK_YARN=false