[ 
https://issues.apache.org/jira/browse/HUDI-1138?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17390890#comment-17390890
 ] 

ASF GitHub Bot commented on HUDI-1138:
--------------------------------------

yihua commented on a change in pull request #3233:
URL: https://github.com/apache/hudi/pull/3233#discussion_r680311587



##########
File path: 
hudi-timeline-service/src/main/java/org/apache/hudi/timeline/service/handlers/MarkerHandler.java
##########
@@ -0,0 +1,484 @@
+/*
+ * 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.timeline.service.handlers;
+
+import org.apache.hudi.common.config.SerializableConfiguration;
+import org.apache.hudi.common.engine.HoodieEngineContext;
+import org.apache.hudi.common.metrics.Registry;
+import org.apache.hudi.common.model.IOType;
+import org.apache.hudi.common.table.view.FileSystemViewManager;
+import org.apache.hudi.common.util.collection.ImmutablePair;
+import org.apache.hudi.exception.HoodieException;
+import org.apache.hudi.exception.HoodieIOException;
+import org.apache.hudi.timeline.service.TimelineService;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import io.javalin.Context;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FSDataInputStream;
+import org.apache.hadoop.fs.FSDataOutputStream;
+import org.apache.hadoop.fs.FileStatus;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.util.StringUtils;
+import org.apache.log4j.LogManager;
+import org.apache.log4j.Logger;
+
+import java.io.BufferedReader;
+import java.io.BufferedWriter;
+import java.io.Closeable;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.Collectors;
+
+import static org.apache.hudi.timeline.service.RequestHandler.jsonifyResult;
+
+/**
+ * REST Handler servicing marker requests.
+ *
+ * The marker creation requests are handled asynchronous, while other types of 
requests
+ * are handled synchronous.
+ *
+ * Marker creation requests are batch processed periodically by a thread.  
Each batch
+ * processing thread adds new markers to a marker file.  Given that marker 
file operation
+ * can take time, multiple concurrent threads can run at the same, while they 
operate
+ * on different marker files storing mutually exclusive marker entries.  At 
any given
+ * time, a marker file is touched by at most one thread to guarantee 
consistency.
+ * Below is an example of running batch processing threads.
+ *
+ *           |-----| batch interval
+ * Thread 1  |-------------------------->| writing to MARKERS1
+ * Thread 2        |-------------------------->| writing to MARKERS2
+ * Thread 3               |-------------------------->| writing to MARKERS3
+ */
+public class MarkerHandler extends Handler {
+  public static final String MARKERS_FILENAME_PREFIX = "MARKERS";
+  private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();
+  private static final Logger LOG = LogManager.getLogger(MarkerHandler.class);
+  // Margin time for scheduling the processing of the next batch of marker 
creation requests
+  private static final long SCHEDULING_MARGIN_TIME_MS = 5L;
+
+  private final Registry metricsRegistry;
+  private final ScheduledExecutorService executorService;
+  // A cached copy of all markers in memory
+  // Mapping: {markerDirPath -> all markers}
+  private final Map<String, Set<String>> allMarkersMap = new HashMap<>();
+  // A cached copy of marker entries in each marker file, stored in 
StringBuilder for efficient appending
+  // Mapping: {markerDirPath -> {markerFileIndex -> markers}}
+  private final Map<String, Map<Integer, StringBuilder>> fileMarkersMap = new 
HashMap<>();
+  // A list of pending futures from async marker creation requests
+  private final List<CreateMarkerCompletableFuture> createMarkerFutures = new 
ArrayList<>();
+  // A list of use status of marker files. {@code true} means the file is in 
use by a {@code BatchCreateMarkerRunnable}
+  private final List<Boolean> markerFilesUseStatus;

Review comment:
       Makes sense.  Fixed.

##########
File path: 
hudi-timeline-service/src/main/java/org/apache/hudi/timeline/service/handlers/MarkerHandler.java
##########
@@ -0,0 +1,484 @@
+/*
+ * 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.timeline.service.handlers;
+
+import org.apache.hudi.common.config.SerializableConfiguration;
+import org.apache.hudi.common.engine.HoodieEngineContext;
+import org.apache.hudi.common.metrics.Registry;
+import org.apache.hudi.common.model.IOType;
+import org.apache.hudi.common.table.view.FileSystemViewManager;
+import org.apache.hudi.common.util.collection.ImmutablePair;
+import org.apache.hudi.exception.HoodieException;
+import org.apache.hudi.exception.HoodieIOException;
+import org.apache.hudi.timeline.service.TimelineService;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import io.javalin.Context;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FSDataInputStream;
+import org.apache.hadoop.fs.FSDataOutputStream;
+import org.apache.hadoop.fs.FileStatus;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.util.StringUtils;
+import org.apache.log4j.LogManager;
+import org.apache.log4j.Logger;
+
+import java.io.BufferedReader;
+import java.io.BufferedWriter;
+import java.io.Closeable;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.Collectors;
+
+import static org.apache.hudi.timeline.service.RequestHandler.jsonifyResult;
+
+/**
+ * REST Handler servicing marker requests.
+ *
+ * The marker creation requests are handled asynchronous, while other types of 
requests
+ * are handled synchronous.
+ *
+ * Marker creation requests are batch processed periodically by a thread.  
Each batch
+ * processing thread adds new markers to a marker file.  Given that marker 
file operation
+ * can take time, multiple concurrent threads can run at the same, while they 
operate
+ * on different marker files storing mutually exclusive marker entries.  At 
any given
+ * time, a marker file is touched by at most one thread to guarantee 
consistency.
+ * Below is an example of running batch processing threads.
+ *
+ *           |-----| batch interval
+ * Thread 1  |-------------------------->| writing to MARKERS1
+ * Thread 2        |-------------------------->| writing to MARKERS2
+ * Thread 3               |-------------------------->| writing to MARKERS3
+ */
+public class MarkerHandler extends Handler {
+  public static final String MARKERS_FILENAME_PREFIX = "MARKERS";
+  private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();
+  private static final Logger LOG = LogManager.getLogger(MarkerHandler.class);
+  // Margin time for scheduling the processing of the next batch of marker 
creation requests
+  private static final long SCHEDULING_MARGIN_TIME_MS = 5L;
+
+  private final Registry metricsRegistry;
+  private final ScheduledExecutorService executorService;
+  // A cached copy of all markers in memory
+  // Mapping: {markerDirPath -> all markers}
+  private final Map<String, Set<String>> allMarkersMap = new HashMap<>();
+  // A cached copy of marker entries in each marker file, stored in 
StringBuilder for efficient appending
+  // Mapping: {markerDirPath -> {markerFileIndex -> markers}}
+  private final Map<String, Map<Integer, StringBuilder>> fileMarkersMap = new 
HashMap<>();
+  // A list of pending futures from async marker creation requests
+  private final List<CreateMarkerCompletableFuture> createMarkerFutures = new 
ArrayList<>();
+  // A list of use status of marker files. {@code true} means the file is in 
use by a {@code BatchCreateMarkerRunnable}
+  private final List<Boolean> markerFilesUseStatus;
+  // Batch process interval in milliseconds
+  private final long batchIntervalMs;
+  // Parallelism for reading and deleting marker files
+  private final int parallelism;
+  private transient HoodieEngineContext hoodieEngineContext;
+  // Lock for synchronous processing of marker creating requests
+  private volatile Object createMarkerRequestLockObject = new Object();
+  // Next batch process timestamp in milliseconds
+  private long nextBatchProcessTimeMs = 0L;
+  // Last marker file index used, for finding the next marker file index in a 
round-robin fashion
+  private int lastMarkerFileIndex = 0;
+
+  public MarkerHandler(Configuration conf, TimelineService.Config 
timelineServiceConfig,
+                       HoodieEngineContext hoodieEngineContext, FileSystem 
fileSystem,
+                       FileSystemViewManager viewManager, Registry 
metricsRegistry) throws IOException {
+    super(conf, timelineServiceConfig, fileSystem, viewManager);
+    LOG.debug("MarkerHandler FileSystem: " + this.fileSystem.getScheme());
+    LOG.debug("MarkerHandler Params: batchNumThreads=" + 
timelineServiceConfig.markerBatchNumThreads
+        + " batchIntervalMs=" + timelineServiceConfig.markerBatchIntervalMs + 
"ms");
+    this.hoodieEngineContext = hoodieEngineContext;
+    this.metricsRegistry = metricsRegistry;
+    this.batchIntervalMs = timelineServiceConfig.markerBatchIntervalMs;
+    this.parallelism = timelineServiceConfig.markerParallelism;
+    this.executorService = 
Executors.newScheduledThreadPool(timelineServiceConfig.markerBatchNumThreads);
+
+    List<Boolean> isMarkerFileInUseList = new 
ArrayList<>(timelineServiceConfig.markerBatchNumThreads);

Review comment:
       Yes.  Fixed.




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> Re-implement marker files via timeline server
> ---------------------------------------------
>
>                 Key: HUDI-1138
>                 URL: https://issues.apache.org/jira/browse/HUDI-1138
>             Project: Apache Hudi
>          Issue Type: Improvement
>          Components: Writer Core
>    Affects Versions: 0.9.0
>            Reporter: Vinoth Chandar
>            Assignee: Ethan Guo
>            Priority: Blocker
>              Labels: pull-request-available
>             Fix For: 0.9.0
>
>
> Even as you can argue that RFC-15/consolidated metadata, removes the need for 
> deleting partial files written due to spark task failures/stage retries. It 
> will still leave extra files inside the table (and users will pay for it 
> every month) and we need the marker mechanism to be able to delete these 
> partial files. 
> Here we explore if we can improve the current marker file mechanism, that 
> creates one marker file per data file written, by 
> Delegating the createMarker() call to the driver/timeline server, and have it 
> create marker metadata into a single file handle, that is flushed for 
> durability guarantees
>  
> P.S: I was tempted to think Spark listener mechanism can help us deal with 
> failed tasks, but it has no guarantees. the writer job could die without 
> deleting a partial file. i.e it can improve things, but cant provide 
> guarantees 



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