[ML] Shave off DeleteExpiredDataIT runtime (#39557)

This commit parallelizes some parts of the test
and its remove an unnecessary refresh call.
On my local machine it shaves off about 15 seconds
for a test execution time of ~64s (down from ~80s).
This test is still slow but progress over perfection.

Relates #37339

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

@@ -5,6 +5,7 @@
  */
 package org.elasticsearch.xpack.ml.integration;
 
+import org.elasticsearch.action.ActionFuture;
 import org.elasticsearch.action.bulk.BulkRequestBuilder;
 import org.elasticsearch.action.bulk.BulkResponse;
 import org.elasticsearch.action.index.IndexRequest;
@@ -77,9 +78,6 @@ public class DeleteExpiredDataIT extends MlNativeAutodetectIntegTestCase {
                 .setRefreshPolicy(WriteRequest.RefreshPolicy.IMMEDIATE)
                 .get();
         assertThat(bulkResponse.hasFailures(), is(false));
-
-        // Ensure all data is searchable
-        client().admin().indices().prepareRefresh(DATA_INDEX).get();
     }
 
     @After
@@ -94,6 +92,17 @@ public class DeleteExpiredDataIT extends MlNativeAutodetectIntegTestCase {
     }
 
     public void testDeleteExpiredData() throws Exception {
+        // Index some unused state documents (more than 10K to test scrolling works)
+        BulkRequestBuilder bulkRequestBuilder = client().prepareBulk();
+        bulkRequestBuilder.setRefreshPolicy(WriteRequest.RefreshPolicy.IMMEDIATE);
+        for (int i = 0; i < 10010; i++) {
+            String docId = "non_existing_job_" + randomFrom("model_state_1234567#" + i, "quantiles", "categorizer_state#" + i);
+            IndexRequest indexRequest = new IndexRequest(AnomalyDetectorsIndex.jobStateIndexWriteAlias(), "doc", docId);
+            indexRequest.source(Collections.emptyMap());
+            bulkRequestBuilder.add(indexRequest);
+        }
+        ActionFuture<BulkResponse> indexUnusedStateDocsResponse = bulkRequestBuilder.execute();
+
         registerJob(newJobBuilder("no-retention").setResultsRetentionDays(null).setModelSnapshotRetentionDays(1000L));
         registerJob(newJobBuilder("results-retention").setResultsRetentionDays(1L).setModelSnapshotRetentionDays(1000L));
         registerJob(newJobBuilder("snapshots-retention").setResultsRetentionDays(null).setModelSnapshotRetentionDays(2L));
@@ -104,6 +113,8 @@ public class DeleteExpiredDataIT extends MlNativeAutodetectIntegTestCase {
 
         long now = System.currentTimeMillis();
         long oneDayAgo = now - TimeValue.timeValueHours(48).getMillis() - 1;
+
+        // Start all jobs
         for (Job.Builder job : getJobs()) {
             putJob(job);
 
@@ -117,7 +128,14 @@ public class DeleteExpiredDataIT extends MlNativeAutodetectIntegTestCase {
             // Run up to a day ago
             openJob(job.getId());
             startDatafeed(datafeedId, 0, now - TimeValue.timeValueHours(24).getMillis());
+        }
+
+        // Now let's wait for all jobs to be closed
+        for (Job.Builder job : getJobs()) {
             waitUntilJobIsClosed(job.getId());
+        }
+
+        for (Job.Builder job : getJobs()) {
             assertThat(getBuckets(job.getId()).size(), is(greaterThanOrEqualTo(47)));
             assertThat(getRecords(job.getId()).size(), equalTo(1));
             List<ModelSnapshot> modelSnapshots = getModelSnapshots(job.getId());
@@ -143,6 +161,7 @@ public class DeleteExpiredDataIT extends MlNativeAutodetectIntegTestCase {
             waitForecastToFinish(job.getId(), forecastDefaultExpiryId);
             waitForecastToFinish(job.getId(), forecastNoExpiryId);
         }
+
         // Refresh to ensure the snapshot timestamp updates are visible
         client().admin().indices().prepareRefresh("*").get();
 
@@ -175,16 +194,8 @@ public class DeleteExpiredDataIT extends MlNativeAutodetectIntegTestCase {
             assertThat(countForecastDocs(forecastStat.getJobId(), forecastStat.getForecastId()), equalTo(forecastStat.getRecordCount()));
         }
 
-        // Index some unused state documents (more than 10K to test scrolling works)
-        BulkRequestBuilder bulkRequestBuilder = client().prepareBulk();
-        bulkRequestBuilder.setRefreshPolicy(WriteRequest.RefreshPolicy.IMMEDIATE);
-        for (int i = 0; i < 10010; i++) {
-            String docId = "non_existing_job_" + randomFrom("model_state_1234567#" + i, "quantiles", "categorizer_state#" + i);
-            IndexRequest indexRequest = new IndexRequest(AnomalyDetectorsIndex.jobStateIndexWriteAlias(), "doc", docId);
-            indexRequest.source(Collections.emptyMap());
-            bulkRequestBuilder.add(indexRequest);
-        }
-        assertThat(bulkRequestBuilder.get().status(), equalTo(RestStatus.OK));
+        // Before we call the delete-expired-data action we need to make sure the unused state docs were indexed
+        assertThat(indexUnusedStateDocsResponse.get().status(), equalTo(RestStatus.OK));
 
         // Now call the action under test
         client().execute(DeleteExpiredDataAction.INSTANCE, new DeleteExpiredDataAction.Request()).get();