[GitHub] [incubator-uniffle] smallzhongfeng commented on a diff in pull request #785: [#291][part-1] feat(client): make read handler thread safe

["smallzhongfeng (via GitHub)" <gi...@apache.org>]

smallzhongfeng commented on code in PR #785:
URL: https://github.com/apache/incubator-uniffle/pull/785#discussion_r1161661615


##########
storage/src/main/java/org/apache/uniffle/storage/handler/impl/DataSkippableReadHandler.java:
##########
@@ -28,61 +29,86 @@
 import org.apache.uniffle.common.ShuffleDataResult;
 import org.apache.uniffle.common.ShuffleDataSegment;
 import org.apache.uniffle.common.ShuffleIndexResult;
+import org.apache.uniffle.common.segment.SegmentSplitter;
 import org.apache.uniffle.common.segment.SegmentSplitterFactory;
 
 public abstract class DataSkippableReadHandler extends AbstractClientReadHandler {
   private static final Logger LOG = LoggerFactory.getLogger(DataSkippableReadHandler.class);
 
-  protected List<ShuffleDataSegment> shuffleDataSegments = Lists.newArrayList();
-  protected int segmentIndex = 0;
+  private volatile int segmentSize = 0;
+  private volatile ConcurrentLinkedQueue<ShuffleDataSegment> shuffleDataSegmentsQueue;
 
   protected Roaring64NavigableMap expectBlockIds;
   protected Roaring64NavigableMap processBlockIds;
 
-  protected ShuffleDataDistributionType distributionType;
-  protected Roaring64NavigableMap expectTaskIds;
+  private SegmentSplitter segmentSplitter;
 
-  public DataSkippableReadHandler(
+  @VisibleForTesting
+  DataSkippableReadHandler(
       String appId,
       int shuffleId,
       int partitionId,
       int readBufferSize,
       Roaring64NavigableMap expectBlockIds,
       Roaring64NavigableMap processBlockIds,
-      ShuffleDataDistributionType distributionType,
-      Roaring64NavigableMap expectTaskIds) {
+      SegmentSplitter segmentSplitter) {
     this.appId = appId;
     this.shuffleId = shuffleId;
     this.partitionId = partitionId;
     this.readBufferSize = readBufferSize;
     this.expectBlockIds = expectBlockIds;
     this.processBlockIds = processBlockIds;
-    this.distributionType = distributionType;
-    this.expectTaskIds = expectTaskIds;
+    this.segmentSplitter = segmentSplitter;
+  }
+
+  public DataSkippableReadHandler(
+      String appId,
+      int shuffleId,
+      int partitionId,
+      int readBufferSize,
+      Roaring64NavigableMap expectBlockIds,
+      Roaring64NavigableMap processBlockIds,
+      ShuffleDataDistributionType distributionType,
+      Roaring64NavigableMap expectTaskIds) {
+    this(
+        appId,
+        shuffleId,
+        partitionId,
+        readBufferSize,
+        expectBlockIds,
+        processBlockIds,
+        SegmentSplitterFactory
+            .getInstance()
+            .get(distributionType, expectTaskIds, readBufferSize)
+    );
   }
 
   protected abstract ShuffleIndexResult readShuffleIndex();
 
   protected abstract ShuffleDataResult readShuffleData(ShuffleDataSegment segment);
 
+  // Thread safe
   public ShuffleDataResult readShuffleData() {
-    if (shuffleDataSegments.isEmpty()) {
-      ShuffleIndexResult shuffleIndexResult = readShuffleIndex();
-      if (shuffleIndexResult == null || shuffleIndexResult.isEmpty()) {
-        return null;
+    if (shuffleDataSegmentsQueue == null) {
+      synchronized (this) {
+        if (shuffleDataSegmentsQueue == null) {
+          ShuffleIndexResult shuffleIndexResult = readShuffleIndex();
+          if (shuffleIndexResult == null || shuffleIndexResult.isEmpty()) {
+            return null;
+          }
+          List<ShuffleDataSegment> shuffleDataSegments = segmentSplitter.split(shuffleIndexResult);
+          segmentSize = shuffleDataSegments.size();
+          final ConcurrentLinkedQueue queue = new ConcurrentLinkedQueue();

Review Comment:
   Can `queue` become a global variable?



##########
storage/src/test/java/org/apache/uniffle/storage/handler/impl/ComposedClientReadHandlerTest.java:
##########
@@ -0,0 +1,75 @@
+/*
+ * 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.uniffle.storage.handler.impl;
+
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.stream.IntStream;
+
+import org.junit.jupiter.api.Test;
+
+import org.apache.uniffle.common.ShuffleDataResult;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+public class ComposedClientReadHandlerTest extends ClientHandlerTestBase {
+
+  @Test
+  public void testSyncRead() {
+    FakeHandler hotHandler = createFakeHandler();
+    FakeHandler warmHandler = createFakeHandler();
+    FakeHandler coldHandler = createFakeHandler();
+    ComposedClientReadHandler composedClientReadHandler =
+        new ComposedClientReadHandler(null, hotHandler, warmHandler, coldHandler);
+
+    for (int i = 0; i < 300; i++) {
+      ShuffleDataResult dataResult = composedClientReadHandler.readShuffleData();
+      assertNotNull(dataResult);
+    }
+    assertNull(composedClientReadHandler.readShuffleData());
+    assertEquals(100, hotHandler.blockIds.size());
+    assertEquals(100, warmHandler.blockIds.size());
+    assertEquals(100, coldHandler.blockIds.size());
+  }
+
+  @Test
+  public void testAsyncRead() throws Exception {
+    FakeHandler hotHandler = createFakeHandler();
+    FakeHandler warmHandler = createFakeHandler();
+    FakeHandler coldHandler = createFakeHandler();
+
+    ComposedClientReadHandler composedClientReadHandler =
+        new ComposedClientReadHandler(null, hotHandler, warmHandler, coldHandler);
+
+    ExecutorService executorService = Executors.newFixedThreadPool(10);
+    CountDownLatch latch = new CountDownLatch(10);

Review Comment:
   Maybe`Awaitility.await().timeout()` is better than CountDownLatch in test. WDYT



##########
storage/src/main/java/org/apache/uniffle/storage/handler/impl/MemoryClientReadHandler.java:
##########
@@ -54,8 +54,9 @@ public MemoryClientReadHandler(
     this.expectTaskIds = expectTaskIds;
   }
 
+  // todo: make thread safe
   @Override
-  public ShuffleDataResult readShuffleData() {
+  public synchronized ShuffleDataResult readShuffleData() {

Review Comment:
   Will read write locks perform better than `synchronized`.



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