[FLINK-1183] Generate gentle notification message when Flink is start…

…ed with Java 6

This closes apache#296.

flink-runtime/src/main/scala/org/apache/flink/runtime/jobmanager/JobManager.scala

@@ -60,6 +60,8 @@ Actor with ActorLogMessages with ActorLogging {
 
  log.info(s"Starting job manager at ${self.path}.")
 
+ checkJavaVersion
+
  val (archiveCount,
  profiling,
  cleanupInterval,
@@ -443,6 +445,16 @@ Actor with ActorLogMessages with ActorLogging {
  log.error(t, s"Could not properly unregister job ${jobID} form the library cache.")
  }
  }
+
+ private def checkJavaVersion {
+ var javaVersion = System.getProperty("java.version")
+ if (javaVersion.substring(0, 3).toDouble < 1.7) {
+ JobManager.LOG.warn("Warning: Flink is running with Java 6. " +
+ "Java 6 is not maintained any more by Oracle or the OpenJDK community. " +
+ "Flink currently supports Java 6, but may not in future releases," +
+ " due to the unavailability of bug fixes security patched.")
+ }
+ }
 }
 
 object JobManager {