[GitHub] [druid] a2l007 commented on a diff in pull request #13269: Add a OverlordHelper that cleans up durable storage objects in MSQ

[GitBox <gi...@apache.org>]

a2l007 commented on code in PR #13269:
URL: https://github.com/apache/druid/pull/13269#discussion_r1008503684


##########
extensions-core/multi-stage-query/src/main/java/org/apache/druid/msq/indexing/DurableStorageCleaner.java:
##########
@@ -0,0 +1,106 @@
+/*
+ * 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.druid.msq.indexing;
+
+import com.google.common.collect.Sets;
+import com.google.inject.Inject;
+import org.apache.druid.indexing.overlord.TaskRunner;
+import org.apache.druid.indexing.overlord.TaskRunnerWorkItem;
+import org.apache.druid.indexing.overlord.helpers.OverlordHelper;
+import org.apache.druid.java.util.common.concurrent.ScheduledExecutors;
+import org.apache.druid.java.util.common.logger.Logger;
+import org.apache.druid.msq.shuffle.DurableStorageOutputChannelFactory;
+import org.apache.druid.storage.StorageConnector;
+import org.joda.time.Duration;
+
+import java.io.IOException;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.stream.Collectors;
+
+/**
+ * This method polls the durable storage for any stray directories, i.e. the ones that donot have a controller task
+ * associated with it and cleans them periodically.
+ * This ensures that the tasks which that have exited abruptly or have failed to clean up the durable storage themselves
+ * donot pollute it with worker outputs and temporary files. See {@link DurableStorageCleanerConfig} for the configs.
+ */
+public class DurableStorageCleaner implements OverlordHelper
+{
+
+  private static final Logger LOG = new Logger(DurableStorageCleaner.class);
+
+  private final DurableStorageCleanerConfig config;
+  private final StorageConnector storageConnector;
+  private final TaskRunner taskRunner;
+
+  @Inject
+  public DurableStorageCleaner(
+      final DurableStorageCleanerConfig config,
+      final StorageConnector storageConnector,
+      final TaskRunner taskRunner
+  )
+  {
+    this.config = config;
+    this.storageConnector = storageConnector;
+    this.taskRunner = taskRunner;
+  }
+
+  @Override
+  public boolean isEnabled()
+  {
+    return config.isEnabled();
+  }
+
+  @Override
+  public void schedule(ScheduledExecutorService exec)
+  {
+    LOG.info("Starting the DurableStorageCleaner with the config [%s]", config);
+
+    ScheduledExecutors.scheduleWithFixedDelay(
+        exec,
+        Duration.standardSeconds(config.getInitialDelaySeconds()),
+        Duration.standardSeconds(config.getDelaySeconds()),
+        () -> {
+          try {
+            Set<String> allDirectories = new HashSet<>(storageConnector.ls(""));
+            Set<String> runningTaskIds = taskRunner.getRunningTasks()
+                                                   .stream()
+                                                   .map(TaskRunnerWorkItem::getTaskId)
+                                                   .map(DurableStorageOutputChannelFactory::getControllerDirectory)
+                                                   .collect(Collectors.toSet());
+            Set<String> unknownDirectories = Sets.difference(allDirectories, runningTaskIds);
+            LOG.info(
+                "Following directories donot have a corresponding MSQ task associated with it:\n%s\nThese will get cleaned up.",
+                unknownDirectories
+            );
+            for (String unknownDirectory : unknownDirectories) {
+              LOG.info("");

Review Comment:
   Can we log the directory name here?



##########
core/src/main/java/org/apache/druid/storage/StorageConnector.java:
##########
@@ -104,4 +105,6 @@
    * @throws IOException
    */
   void deleteRecursively(String path) throws IOException;
+
+  List<String> ls(String dirName) throws IOException;

Review Comment:
   Can we make the method name more readable, `listFiles` maybe? Javadocs and unit tests would be useful for this method as well.



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