Fix for flaky test SimpleBlocksIT.testAddBlockWhileDeletingIndices (#…

…11492) (#11496)

(cherry picked from commit a3c7952)

Signed-off-by: Ankit Kala <ankikala@amazon.com>
Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

server/src/internalClusterTest/java/org/opensearch/blocks/SimpleBlocksIT.java

@@ -47,6 +47,7 @@
 import org.opensearch.cluster.block.ClusterBlockLevel;
 import org.opensearch.cluster.metadata.IndexMetadata;
 import org.opensearch.cluster.metadata.IndexMetadata.APIBlock;
+import org.opensearch.cluster.metadata.ProcessClusterEventTimeoutException;
 import org.opensearch.cluster.routing.ShardRouting;
 import org.opensearch.common.settings.Settings;
 import org.opensearch.index.IndexNotFoundException;
@@ -491,10 +492,20 @@ public void testAddBlockWhileDeletingIndices() throws Exception {
                     } catch (InterruptedException e) {
                         throw new AssertionError(e);
                     }
-                    try {
-                        assertAcked(client().admin().indices().prepareDelete(indexToDelete));
-                    } catch (final Exception e) {
-                        exceptionConsumer.accept(e);
+                    int pendingRetries = 3;
+                    boolean success = false;
+                    while (success == false && pendingRetries-- > 0) {
+                        try {
+                            assertAcked(client().admin().indices().prepareDelete(indexToDelete));
+                            success = true;
+                        } catch (final Exception e) {
+                            Throwable cause = ExceptionsHelper.unwrapCause(e);
+                            if (cause instanceof ProcessClusterEventTimeoutException && pendingRetries > 0) {
+                                // ignore error & retry
+                                continue;
+                            }
+                            exceptionConsumer.accept(e);
+                        }
                     }
                 }));
             }