[HUDI-3675] Adding post write termination strategy to deltastreamer continuous mode (#5073)

- Added a postWriteTerminationStrategy to deltastreamer continuous mode. One can enable by setting the appropriate termination strategy using DeltastreamerConfig.postWriteTerminationStrategyClass. If not, continuous mode is expected to run forever.
- Added one concrete impl for termination strategy as NoNewDataTerminationStrategy which shuts down deltastreamer if there is no new data to consume from source for N consecutive rounds.

hudi-utilities/src/main/java/org/apache/hudi/utilities/deltastreamer/HoodieDeltaStreamer.java

@@ -43,6 +43,7 @@ import org.apache.hudi.common.table.timeline.HoodieTimeline;
 import org.apache.hudi.common.util.ClusteringUtils;
 import org.apache.hudi.common.util.CompactionUtils;
 import org.apache.hudi.common.util.Option;
+import org.apache.hudi.common.util.StringUtils;
 import org.apache.hudi.common.util.ValidationUtils;
 import org.apache.hudi.common.util.collection.Pair;
 import org.apache.hudi.config.HoodieClusteringConfig;
@@ -403,6 +404,9 @@ public class HoodieDeltaStreamer implements Serializable {
         + "https://spark.apache.org/docs/latest/job-scheduling.html")
     public Integer clusterSchedulingMinShare = 0;
 
+    @Parameter(names = {"--post-write-termination-strategy-class"}, description = "Post writer termination strategy class to gracefully shutdown deltastreamer in continuous mode")
+    public String postWriteTerminationStrategyClass = "";
+
     public boolean isAsyncCompactionEnabled() {
       return continuousMode && !forceDisableCompaction
           && HoodieTableType.MERGE_ON_READ.equals(HoodieTableType.valueOf(tableType));
@@ -603,6 +607,8 @@ public class HoodieDeltaStreamer implements Serializable {
      */
     private transient DeltaSync deltaSync;
 
+    private final Option<PostWriteTerminationStrategy> postWriteTerminationStrategy;
+
     public DeltaSyncService(Config cfg, JavaSparkContext jssc, FileSystem fs, Configuration conf,
                             Option<TypedProperties> properties) throws IOException {
       this.cfg = cfg;
@@ -610,6 +616,8 @@ public class HoodieDeltaStreamer implements Serializable {
       this.sparkSession = SparkSession.builder().config(jssc.getConf()).getOrCreate();
       this.asyncCompactService = Option.empty();
       this.asyncClusteringService = Option.empty();
+      this.postWriteTerminationStrategy = StringUtils.isNullOrEmpty(cfg.postWriteTerminationStrategyClass) ? Option.empty() :
+          TerminationStrategyUtils.createPostWriteTerminationStrategy(properties.get(), cfg.postWriteTerminationStrategyClass);
 
       if (fs.exists(new Path(cfg.targetBasePath))) {
         HoodieTableMetaClient meta =
@@ -695,6 +703,14 @@ public class HoodieDeltaStreamer implements Serializable {
                   }
                 }
               }
+              // check if deltastreamer need to be shutdown
+              if (postWriteTerminationStrategy.isPresent()) {
+                if (postWriteTerminationStrategy.get().shouldShutdown(scheduledCompactionInstantAndRDD.isPresent() ? Option.of(scheduledCompactionInstantAndRDD.get().getRight()) :
+                    Option.empty())) {
+                  error = true;
+                  shutdown(false);
+                }
+              }
               long toSleepMs = cfg.minSyncIntervalSeconds * 1000 - (System.currentTimeMillis() - start);
               if (toSleepMs > 0) {
                 LOG.info("Last sync ran less than min sync interval: " + cfg.minSyncIntervalSeconds + " s, sleep: "

hudi-utilities/src/main/java/org/apache/hudi/utilities/deltastreamer/NoNewDataTerminationStrategy.java

@@ -0,0 +1,56 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.hudi.utilities.deltastreamer;
+
+import org.apache.hudi.client.WriteStatus;
+import org.apache.hudi.common.config.TypedProperties;
+import org.apache.hudi.common.util.Option;
+
+import org.apache.log4j.LogManager;
+import org.apache.log4j.Logger;
+import org.apache.spark.api.java.JavaRDD;
+
+/**
+ * Post writer termination strategy for deltastreamer in continuous mode. This strategy is based on no new data for consecutive number of times.
+ */
+public class NoNewDataTerminationStrategy implements PostWriteTerminationStrategy {
+
+  private static final Logger LOG = LogManager.getLogger(NoNewDataTerminationStrategy.class);
+
+  public static final String MAX_ROUNDS_WITHOUT_NEW_DATA_TO_SHUTDOWN = "max.rounds.without.new.data.to.shutdown";
+  public static final int DEFAULT_MAX_ROUNDS_WITHOUT_NEW_DATA_TO_SHUTDOWN = 3;
+
+  private final int numTimesNoNewDataToShutdown;
+  private int numTimesNoNewData = 0;
+
+  public NoNewDataTerminationStrategy(TypedProperties properties) {
+    numTimesNoNewDataToShutdown = properties.getInteger(MAX_ROUNDS_WITHOUT_NEW_DATA_TO_SHUTDOWN, DEFAULT_MAX_ROUNDS_WITHOUT_NEW_DATA_TO_SHUTDOWN);
+  }
+
+  @Override
+  public boolean shouldShutdown(Option<JavaRDD<WriteStatus>> writeStatuses) {
+    numTimesNoNewData = writeStatuses.isPresent() ? 0 : numTimesNoNewData + 1;
+    if (numTimesNoNewData >= numTimesNoNewDataToShutdown) {
+      LOG.info("Shutting down on continuous mode as there is no new data for " + numTimesNoNewData);
+      return true;
+    }
+    return false;
+  }
+}

hudi-utilities/src/main/java/org/apache/hudi/utilities/deltastreamer/PostWriteTerminationStrategy.java

@@ -0,0 +1,39 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.hudi.utilities.deltastreamer;
+
+import org.apache.hudi.client.WriteStatus;
+import org.apache.hudi.common.util.Option;
+
+import org.apache.spark.api.java.JavaRDD;
+
+/**
+ * Post write termination strategy for deltastreamer in continuous mode.
+ */
+public interface PostWriteTerminationStrategy {
+
+  /**
+   * Returns whether deltastreamer needs to be shutdown.
+   * @param writeStatuses optional pair of scheduled compaction instant and write statuses.
+   * @return true if deltastreamer has to be shutdown. false otherwise.
+   */
+  boolean shouldShutdown(Option<JavaRDD<WriteStatus>> writeStatuses);
+
+}

hudi-utilities/src/main/java/org/apache/hudi/utilities/deltastreamer/TerminationStrategyUtils.java

@@ -0,0 +1,45 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.hudi.utilities.deltastreamer;
+
+import org.apache.hudi.common.config.TypedProperties;
+import org.apache.hudi.common.util.Option;
+import org.apache.hudi.common.util.ReflectionUtils;
+import org.apache.hudi.common.util.StringUtils;
+import org.apache.hudi.exception.HoodieException;
+
+public class TerminationStrategyUtils {
+
+  /**
+   * Create a PostWriteTerminationStrategy class via reflection,
+   * <br>
+   * if the class name of PostWriteTerminationStrategy is configured through the {@link HoodieDeltaStreamer.Config#postWriteTerminationStrategyClass}.
+   */
+  public static Option<PostWriteTerminationStrategy> createPostWriteTerminationStrategy(TypedProperties properties, String postWriteTerminationStrategyClass)
+      throws HoodieException {
+    try {
+      return StringUtils.isNullOrEmpty(postWriteTerminationStrategyClass)
+          ? Option.empty() :
+          Option.of((PostWriteTerminationStrategy) ReflectionUtils.loadClass(postWriteTerminationStrategyClass, properties));
+    } catch (Throwable e) {
+      throw new HoodieException("Could not create PostWritTerminationStrategy class " + postWriteTerminationStrategyClass, e);
+    }
+  }
+}

hudi-utilities/src/test/java/org/apache/hudi/utilities/functional/TestHoodieDeltaStreamer.java

@@ -60,6 +60,7 @@ import org.apache.hudi.utilities.HoodieClusteringJob;
 import org.apache.hudi.utilities.HoodieIndexer;
 import org.apache.hudi.utilities.deltastreamer.DeltaSync;
 import org.apache.hudi.utilities.deltastreamer.HoodieDeltaStreamer;
+import org.apache.hudi.utilities.deltastreamer.NoNewDataTerminationStrategy;
 import org.apache.hudi.utilities.schema.FilebasedSchemaProvider;
 import org.apache.hudi.utilities.schema.SchemaProvider;
 import org.apache.hudi.utilities.schema.SparkAvroPostProcessor;
@@ -738,18 +739,30 @@ public class TestHoodieDeltaStreamer extends HoodieDeltaStreamerTestBase {
     testUpsertsContinuousMode(HoodieTableType.COPY_ON_WRITE, "continuous_cow");
   }
 
+  @Test
+  public void testUpsertsCOWContinuousModeShutdownGracefully() throws Exception {
+    testUpsertsContinuousMode(HoodieTableType.COPY_ON_WRITE, "continuous_cow", true);
+  }
+
   @Test
   public void testUpsertsMORContinuousMode() throws Exception {
     testUpsertsContinuousMode(HoodieTableType.MERGE_ON_READ, "continuous_mor");
   }
 
   private void testUpsertsContinuousMode(HoodieTableType tableType, String tempDir) throws Exception {
+    testUpsertsContinuousMode(tableType, tempDir, false);
+  }
+
+  private void testUpsertsContinuousMode(HoodieTableType tableType, String tempDir, boolean testShutdownGracefully) throws Exception {
     String tableBasePath = dfsBasePath + "/" + tempDir;
     // Keep it higher than batch-size to test continuous mode
     int totalRecords = 3000;
     // Initial bulk insert
     HoodieDeltaStreamer.Config cfg = TestHelpers.makeConfig(tableBasePath, WriteOperationType.UPSERT);
     cfg.continuousMode = true;
+    if (testShutdownGracefully) {
+      cfg.postWriteTerminationStrategyClass = NoNewDataTerminationStrategy.class.getName();
+    }
     cfg.tableType = tableType.name();
     cfg.configs.add(String.format("%s=%d", SourceConfigs.MAX_UNIQUE_RECORDS_PROP, totalRecords));
     cfg.configs.add(String.format("%s=false", HoodieCompactionConfig.AUTO_CLEAN.key()));
@@ -763,6 +776,9 @@ public class TestHoodieDeltaStreamer extends HoodieDeltaStreamerTestBase {
       }
       TestHelpers.assertRecordCount(totalRecords, tableBasePath, sqlContext);
       TestHelpers.assertDistanceCount(totalRecords, tableBasePath, sqlContext);
+      if (testShutdownGracefully) {
+        TestDataSource.returnEmptyBatch = true;
+      }
       return true;
     });
   }
@@ -781,9 +797,36 @@ public class TestHoodieDeltaStreamer extends HoodieDeltaStreamerTestBase {
       }
     });
     TestHelpers.waitTillCondition(condition, dsFuture, 360);
+    if (cfg != null && !cfg.postWriteTerminationStrategyClass.isEmpty()) {
+      awaitDeltaStreamerShutdown(ds);
+    } else {
       ds.shutdownGracefully();
       dsFuture.get();
     }
+  }
+
+  static void awaitDeltaStreamerShutdown(HoodieDeltaStreamer ds) throws InterruptedException {
+    // await until deltastreamer shuts down on its own
+    boolean shutDownRequested = false;
+    int timeSoFar = 0;
+    while (!shutDownRequested) {
+      shutDownRequested = ds.getDeltaSyncService().isShutdownRequested();
+      Thread.sleep(500);
+      timeSoFar += 500;
+      if (timeSoFar > (2 * 60 * 1000)) {
+        Assertions.fail("Deltastreamer should have shutdown by now");
+      }
+    }
+    boolean shutdownComplete = false;
+    while (!shutdownComplete) {
+      shutdownComplete = ds.getDeltaSyncService().isShutdown();
+      Thread.sleep(500);
+      timeSoFar += 500;
+      if (timeSoFar > (2 * 60 * 1000)) {
+        Assertions.fail("Deltastreamer should have shutdown by now");
+      }
+    }
+  }
 
   static void deltaStreamerTestRunner(HoodieDeltaStreamer ds, Function<Boolean, Boolean> condition) throws Exception {
     deltaStreamerTestRunner(ds, null, condition);

hudi-utilities/src/test/java/org/apache/hudi/utilities/sources/TestDataSource.java

@@ -39,11 +39,14 @@ import java.util.stream.Collectors;
 public class TestDataSource extends AbstractBaseTestSource {
 
   private static final Logger LOG = LogManager.getLogger(TestDataSource.class);
+  public static boolean returnEmptyBatch = false;
+  private static int counter = 0;
 
   public TestDataSource(TypedProperties props, JavaSparkContext sparkContext, SparkSession sparkSession,
       SchemaProvider schemaProvider) {
     super(props, sparkContext, sparkSession, schemaProvider);
     initDataGen();
+    returnEmptyBatch = false;
   }
 
   @Override
@@ -54,9 +57,13 @@ public class TestDataSource extends AbstractBaseTestSource {
     LOG.info("Source Limit is set to " + sourceLimit);
 
     // No new data.
-    if (sourceLimit <= 0) {
+    if (sourceLimit <= 0 || returnEmptyBatch) {
+      LOG.warn("Return no new data from Test Data source " + counter + ", source limit " + sourceLimit);
       return new InputBatch<>(Option.empty(), lastCheckpointStr.orElse(null));
+    } else {
+      LOG.warn("Returning valid data from Test Data source " + counter + ", source limit " + sourceLimit);
     }
+    counter++;
 
     List<GenericRecord> records =
         fetchNextBatch(props, (int) sourceLimit, instantTime, DEFAULT_PARTITION_NUM).collect(Collectors.toList());