[HOTFIX] Bind web UI to ephemeral port in DriverSuite.

Author: JoshRosen

core/src/test/scala/org/apache/spark/DriverSuite.scala

@@ -50,7 +50,10 @@ class DriverSuite extends FunSuite with Timeouts {
 object DriverWithoutCleanup {
   def main(args: Array[String]) {
     Utils.configTestLog4j("INFO")
-    val sc = new SparkContext(args(0), "DriverWithoutCleanup")
+    // Bind the web UI to an ephemeral port in order to avoid conflicts with other tests running on
+    // the same machine (we shouldn't just disable the UI here, since that might mask bugs):
+    val conf = new SparkConf().set("spark.ui.port", "0")
+    val sc = new SparkContext(args(0), "DriverWithoutCleanup", conf)
     sc.parallelize(1 to 100, 4).count()
   }
 }