[SPARK-9534] [BUILD] Enable javac lint for scalac parity; fix a lot of build warnings, 1.5.0 edition

Enable most javac lint warnings; fix a lot of build warnings. In a few cases, touch up surrounding code in the process.

I'll explain several of the changes inline in comments.

Author: Sean Owen <sowen@cloudera.com>

Closes #7862 from srowen/SPARK-9534 and squashes the following commits:

ea51618 [Sean Owen] Enable most javac lint warnings; fix a lot of build warnings. In a few cases, touch up surrounding code in the process.

1 files changed, 3 insertions, 1 deletions

diff --git a/streaming/src/main/scala/org/apache/spark/streaming/scheduler/JobScheduler.scala b/streaming/src/main/scala/org/apache/spark/streaming/scheduler/JobScheduler.scala
index 58bdda7794..7e735562dc 100644
--- a/streaming/src/main/scala/org/apache/spark/streaming/scheduler/JobScheduler.scala
+++ b/streaming/src/main/scala/org/apache/spark/streaming/scheduler/JobScheduler.scala
@@ -40,7 +40,9 @@ private[scheduler] case class ErrorReported(msg: String, e: Throwable) extends J
 private[streaming]
 class JobScheduler(val ssc: StreamingContext) extends Logging {
 
-  private val jobSets = new ConcurrentHashMap[Time, JobSet]
+  // Use of ConcurrentHashMap.keySet later causes an odd runtime problem due to Java 7/8 diff
+  // https://gist.github.com/AlainODea/1375759b8720a3f9f094
+  private val jobSets: java.util.Map[Time, JobSet] = new ConcurrentHashMap[Time, JobSet]
   private val numConcurrentJobs = ssc.conf.getInt("spark.streaming.concurrentJobs", 1)
   private val jobExecutor = Executors.newFixedThreadPool(numConcurrentJobs)
   private val jobGenerator = new JobGenerator(this)