[7.5][ML] Always refresh dest index before starting analytics process (#48090) (#48197)

If a job stops right after reindexing is finished but before
we refresh the destination index, we don't refresh at all.
If the job is started again right after, it jumps into the analyzing state.
However, the data is still not searchable.
This is why we were seeing test failures that we start the process
expecting X rows (where X is lower than the expected number of docs)
and we end up getting X+.

We fix this by moving the refresh of the dest index right before
we start the process so it always ensures the data is searchable.

Closes #47612

Backport of #48090

Author: dimitris-athanasiou

x-pack/plugin/ml/qa/native-multi-node-tests/src/test/java/org/elasticsearch/xpack/ml/integration/RegressionIT.java

@@ -236,7 +236,6 @@ public void testWithOnlyTrainingRowsAndTrainingPercentIsFifty() throws Exception
             "Finished analysis");
     }
 
-    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/47612")
     public void testStopAndRestart() throws Exception {
         initialize("regression_stop_and_restart");
 

x-pack/plugin/ml/qa/native-multi-node-tests/src/test/java/org/elasticsearch/xpack/ml/integration/RunDataFrameAnalyticsIT.java

@@ -548,7 +548,6 @@ public void testLazyAssignmentWithModelMemoryLimitTooHighForAssignment() throws
             "Stopped analytics");
     }
 
-    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/47612")
     public void testOutlierDetectionStopAndRestart() throws Exception {
         String sourceIndex = "test-outlier-detection-stop-and-restart";
 

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/DataFrameAnalyticsManager.java

@@ -15,9 +15,6 @@
 import org.elasticsearch.action.admin.indices.get.GetIndexAction;
 import org.elasticsearch.action.admin.indices.get.GetIndexRequest;
 import org.elasticsearch.action.admin.indices.get.GetIndexResponse;
-import org.elasticsearch.action.admin.indices.refresh.RefreshAction;
-import org.elasticsearch.action.admin.indices.refresh.RefreshRequest;
-import org.elasticsearch.action.admin.indices.refresh.RefreshResponse;
 import org.elasticsearch.action.support.ContextPreservingActionListener;
 import org.elasticsearch.client.node.NodeClient;
 import org.elasticsearch.cluster.ClusterState;
@@ -160,34 +157,18 @@ private void reindexDataframeAndStartAnalysis(DataFrameAnalyticsTask task, DataF
         }
 
         // Reindexing is complete; start analytics
-        ActionListener<RefreshResponse> refreshListener = ActionListener.wrap(
+        ActionListener<BulkByScrollResponse> reindexCompletedListener = ActionListener.wrap(
             refreshResponse -> {
                 if (task.isStopping()) {
                     LOGGER.debug("[{}] Stopping before starting analytics process", config.getId());
                     return;
                 }
                 task.setReindexingTaskId(null);
-                startAnalytics(task, config, false);
-            },
-            error -> task.updateState(DataFrameAnalyticsState.FAILED, error.getMessage())
-        );
-
-        // Refresh to ensure copied index is fully searchable
-        ActionListener<BulkByScrollResponse> reindexCompletedListener = ActionListener.wrap(
-            bulkResponse -> {
-                if (task.isStopping()) {
-                    LOGGER.debug("[{}] Stopping before refreshing destination index", config.getId());
-                    return;
-                }
                 task.setReindexingFinished();
                 auditor.info(
                     config.getId(),
                     Messages.getMessage(Messages.DATA_FRAME_ANALYTICS_AUDIT_FINISHED_REINDEXING, config.getDest().getIndex()));
-                ClientHelper.executeAsyncWithOrigin(client,
-                    ClientHelper.ML_ORIGIN,
-                    RefreshAction.INSTANCE,
-                    new RefreshRequest(config.getDest().getIndex()),
-                    refreshListener);
+                startAnalytics(task, config, false);
             },
             error -> task.updateState(DataFrameAnalyticsState.FAILED, error.getMessage())
         );

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/DataFrameAnalyticsTask.java

@@ -79,6 +79,7 @@ public StartDataFrameAnalyticsAction.TaskParams getParams() {
     }
 
     public void setReindexingTaskId(Long reindexingTaskId) {
+        LOGGER.debug("[{}] Setting reindexing task id to [{}] from [{}]", taskParams.getId(), reindexingTaskId, this.reindexingTaskId);
         this.reindexingTaskId = reindexingTaskId;
     }
 

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/extractor/DataFrameDataExtractor.java

@@ -237,7 +237,9 @@ public List<String> getFieldNames() {
     public DataSummary collectDataSummary() {
         SearchRequestBuilder searchRequestBuilder = buildDataSummarySearchRequestBuilder();
         SearchResponse searchResponse = executeSearchRequest(searchRequestBuilder);
-        return new DataSummary(searchResponse.getHits().getTotalHits().value, context.extractedFields.getAllFields().size());
+        long rows = searchResponse.getHits().getTotalHits().value;
+        LOGGER.debug("[{}] Data summary rows [{}]", context.jobId, rows);
+        return new DataSummary(rows, context.extractedFields.getAllFields().size());
     }
 
     public void collectDataSummaryAsync(ActionListener<DataSummary> dataSummaryActionListener) {

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/process/AnalyticsProcessManager.java

@@ -77,6 +77,9 @@ public void runJob(DataFrameAnalyticsTask task, DataFrameAnalyticsConfig config,
                 return;
             }
 
+            // First we refresh the dest index to ensure data is searchable
+            refreshDest(config);
+
             ProcessContext processContext = new ProcessContext(config.getId());
             if (processContextByAllocation.putIfAbsent(task.getAllocationId(), processContext) != null) {
                 finishHandler.accept(ExceptionsHelper.serverError("[" + processContext.id
@@ -143,10 +146,12 @@ private void processData(DataFrameAnalyticsTask task, DataFrameAnalyticsConfig c
             refreshDest(config);
             LOGGER.info("[{}] Result processor has completed", config.getId());
         } catch (Exception e) {
-            String errorMsg = new ParameterizedMessage("[{}] Error while processing data [{}]", config.getId(), e.getMessage())
-                .getFormattedMessage();
-            LOGGER.error(errorMsg, e);
-            processContextByAllocation.get(task.getAllocationId()).setFailureReason(errorMsg);
+            if (task.isStopping() == false) {
+                String errorMsg = new ParameterizedMessage("[{}] Error while processing data [{}]", config.getId(), e.getMessage())
+                    .getFormattedMessage();
+                LOGGER.error(errorMsg, e);
+                processContextByAllocation.get(task.getAllocationId()).setFailureReason(errorMsg);
+            }
         } finally {
             closeProcess(task);