emit shuffle pod watch exception

resource-managers/kubernetes/core/src/main/scala/org/apache/spark/scheduler/cluster/k8s/KubernetesExternalShuffleManager.scala

@@ -106,18 +106,14 @@ private[spark] class KubernetesExternalShuffleManagerImpl(
   }
 
   private def addShufflePodToCache(pod: Pod): Unit = shufflePodCache.synchronized {
-    if (shufflePodCache.contains(pod.getSpec.getNodeName)) {
-      val registeredPodName = shufflePodCache.get(pod.getSpec.getNodeName).get
-      logError(s"Ambiguous specification of shuffle service pod. " +
-        s"Found multiple matching pods: ${pod.getMetadata.getName}, " +
-        s"${registeredPodName} on ${pod.getSpec.getNodeName}")
-
-      throw new SparkException(s"Ambiguous specification of shuffle service pod. " +
-        s"Found multiple matching pods: ${pod.getMetadata.getName}, " +
-        s"${registeredPodName} on ${pod.getSpec.getNodeName}")
-    } else {
-        shufflePodCache(pod.getSpec.getNodeName) = pod.getStatus.getPodIP
+    if (shufflePodCache.exists(kv => kv._1 == pod.getSpec.getNodeName
+      && kv._2 != pod.getStatus.getPodIP)) {
+      val registeredPodIP = shufflePodCache(pod.getSpec.getNodeName)
+      logWarning(s"Ambiguous specification of shuffle service pod. " +
+        s"Found multiple matching pods: ${pod.getMetadata.getName}(${pod.getStatus.getPodIP}), " +
+        s"$registeredPodIP on ${pod.getSpec.getNodeName}, will update")
     }
+    shufflePodCache(pod.getSpec.getNodeName) = pod.getStatus.getPodIP
   }
 
   override def stop(): Unit = {