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. /cc @aarondav with whom I discussed parts of the design.

Author: Patrick Wendell <pwendell@gmail.com>

Closes #627 from pwendell/jdk6 and squashes the following commits:

a38a958 [Patrick Wendell] Code review feedback
94e9f84 [Patrick Wendell] SPARK-1703 Warn users if Spark is run on JRE6 but compiled with JDK7.

1 files changed, 14 insertions, 0 deletions

diff --git a/bin/compute-classpath.sh b/bin/compute-classpath.sh
index 70ac71e45d..8dc547b379 100755
--- a/bin/compute-classpath.sh
+++ b/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"
@@ -55,6 +61,14 @@ 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