Prevent ContextClassLoader of Actor from becoming ClassLoader of Exec…

…utor.

core/src/main/scala/org/apache/spark/executor/Executor.scala

@@ -112,11 +112,10 @@ private[spark] class Executor(
     }
   }
 
-  // Create our ClassLoader and set it on this thread
+  // Create our ClassLoader
   // do this after SparkEnv creation so can access the SecurityManager
   private val urlClassLoader = createClassLoader()
   private val replClassLoader = addReplClassLoaderIfNeeded(urlClassLoader)
-  Thread.currentThread.setContextClassLoader(replClassLoader)
 
   // Akka's message frame size. If task result is bigger than this, we use the block manager
   // to send the result back.