[SPARK-49447][K8S] Fix spark.kubernetes.allocation.batch.delay to p…

…revent small values less than 100

resource-managers/kubernetes/core/src/main/scala/org/apache/spark/deploy/k8s/Config.scala

@@ -457,7 +457,7 @@ private[spark] object Config extends Logging {
       .doc("Time to wait between each round of executor allocation.")
       .version("2.3.0")
       .timeConf(TimeUnit.MILLISECONDS)
-      .checkValue(value => value > 0, "Allocation batch delay must be a positive time value.")
+      .checkValue(value => value > 100, "Allocation batch delay must be greater than 0.1s.")
       .createWithDefaultString("1s")
 
   val KUBERNETES_ALLOCATION_DRIVER_READINESS_TIMEOUT =

resource-managers/kubernetes/core/src/test/scala/org/apache/spark/scheduler/cluster/k8s/ExecutorPodsAllocatorSuite.scala

@@ -150,6 +150,14 @@ class ExecutorPodsAllocatorSuite extends SparkFunSuite with BeforeAndAfter {
     when(persistentVolumeClaimList.getItems).thenReturn(Seq.empty[PersistentVolumeClaim].asJava)
   }
 
+  test("SPARK-49447: Prevent small values less than 100 for batch delay") {
+    val m = intercept[IllegalArgumentException] {
+      val conf = new SparkConf().set(KUBERNETES_ALLOCATION_BATCH_DELAY.key, "1")
+      conf.get(KUBERNETES_ALLOCATION_BATCH_DELAY)
+    }.getMessage
+    assert(m.contains("Allocation batch delay must be greater than 0.1s."))
+  }
+
   test("SPARK-41210: Window based executor failure tracking mechanism") {
     var _exitCode = -1
     val _conf = conf.clone