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Posted to issues@flink.apache.org by GitBox <gi...@apache.org> on 2022/07/01 04:16:32 UTC
[GitHub] [flink] reswqa commented on a diff in pull request #19960: [FLINK-27907][runtime] implement disk read and write logic for hybrid shuffle
reswqa commented on code in PR #19960:
URL: https://github.com/apache/flink/pull/19960#discussion_r911601331
##########
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/hybrid/HsSubpartitionFileReader.java:
##########
@@ -0,0 +1,379 @@
+/*
+ * 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.flink.runtime.io.network.partition.hybrid;
+
+import org.apache.flink.annotation.VisibleForTesting;
+import org.apache.flink.api.java.tuple.Tuple2;
+import org.apache.flink.core.memory.MemorySegment;
+import org.apache.flink.runtime.io.network.buffer.Buffer;
+import org.apache.flink.runtime.io.network.buffer.BufferRecycler;
+import org.apache.flink.runtime.io.network.partition.BufferReaderWriterUtil;
+
+import javax.annotation.Nullable;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.util.Deque;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.Queue;
+import java.util.concurrent.LinkedBlockingDeque;
+
+import static org.apache.flink.runtime.io.network.partition.BufferReaderWriterUtil.positionToNextBuffer;
+import static org.apache.flink.runtime.io.network.partition.BufferReaderWriterUtil.readFromByteChannel;
+import static org.apache.flink.util.Preconditions.checkNotNull;
+import static org.apache.flink.util.Preconditions.checkState;
+
+/**
+ * This component is responsible for reading data from disk.
+ *
+ * <p>In order to access the disk as sequentially as possible {@link HsSubpartitionFileReader} need
+ * to be able to compare priorities.
+ */
+public class HsSubpartitionFileReader implements Comparable<HsSubpartitionFileReader> {
+ /**
+ * Prevent other consumers from starving. This default value needs to be tuning experimentally
+ * or introduced a configuration option.
+ */
+ public static final int MAX_BUFFERS_READ_AHEAD = 5;
+
+ private final ByteBuffer headerBuf = BufferReaderWriterUtil.allocatedHeaderBuffer();
+
+ private final int subpartitionId;
+
+ private final FileChannel dataFileChannel;
+
+ private final HsSubpartitionViewNotifier notifier;
+
+ private final CachedRegionManager cachedRegionManager;
+
+ private final BufferIndexManager bufferIndexManager;
+
+ private final Deque<BufferIndexOrError> loadedBuffers = new LinkedBlockingDeque<>();
+
+ private boolean isFailed;
+
+ public HsSubpartitionFileReader(
+ int subpartitionId,
+ FileChannel dataFileChannel,
+ HsSubpartitionViewNotifier notifier,
+ HsFileDataIndex dataIndex) {
+ this.subpartitionId = subpartitionId;
+ this.dataFileChannel = dataFileChannel;
+ this.notifier = notifier;
+ this.bufferIndexManager = new BufferIndexManager();
+ this.cachedRegionManager = new CachedRegionManager(subpartitionId, dataIndex);
+ }
+
+ /** Refresh downstream consumption progress for another round scheduling of reading. */
+ public void updateConsumptionProgress() {
+ bufferIndexManager.updateLastConsumed(notifier.getConsumingOffset());
+ }
+
+ @Override
+ public boolean equals(Object o) {
+ if (this == o) {
+ return true;
+ }
+ if (o == null || getClass() != o.getClass()) {
+ return false;
+ }
+ HsSubpartitionFileReader that = (HsSubpartitionFileReader) o;
+ return subpartitionId == that.subpartitionId;
+ }
+
+ @Override
+ public int hashCode() {
+ return Objects.hash(subpartitionId);
+ }
+
+ /**
+ * Read subpartition data into buffers.
+ *
+ * <p>This transfers the ownership of used buffers to this class. It's this class'
+ * responsibility to release the buffers using the recycler when no longer needed.
+ *
+ * <p>Calling this method does not always use up all the provided buffers. It's this class'
+ * decision when to stop reading. Currently, it stops reading when: 1) buffers are used up, or
+ * 2) reaches the end of the subpartition data within the region, or 3) enough data have been
+ * read ahead the downstream consuming offset.
+ */
+ public synchronized boolean readBuffers(Queue<MemorySegment> buffers, BufferRecycler recycler)
+ throws IOException {
+ if (isFailed) {
+ return false;
+ }
+ int firstBufferToLoad = bufferIndexManager.getNextToLoad();
+ if (firstBufferToLoad < 0) {
+ return true;
+ }
+
+ // If lookup result is empty, it means that one the following things have happened:
+ // 1) The target buffer has not been spilled into disk.
+ // 2) The target buffer has not been released from memory.
+ // So, just skip this round reading.
+ if (!cachedRegionManager.updateCachedRegionIfNeeded(firstBufferToLoad).isPresent()) {
+ return true;
+ }
+
+ moveFileOffsetToBuffer(firstBufferToLoad);
+
+ int numRemainingBuffersInRegion =
+ cachedRegionManager.getRemainingBuffersInRegion(firstBufferToLoad);
+
+ int indexToLoad;
+ int numLoaded = 0;
+ while (!buffers.isEmpty()
+ && numRemainingBuffersInRegion-- > 0
+ && (indexToLoad = bufferIndexManager.getNextToLoad()) >= 0) {
+ MemorySegment segment = buffers.poll();
+ Buffer buffer;
+ try {
+ if ((buffer = readFromByteChannel(dataFileChannel, headerBuf, segment, recycler))
+ == null) {
+ buffers.add(segment);
+ break;
+ }
+ } catch (Throwable throwable) {
+ buffers.add(segment);
+ throw throwable;
+ }
+
+ loadedBuffers.add(BufferIndexOrError.newBuffer(buffer, indexToLoad));
+ bufferIndexManager.updateLastLoaded(indexToLoad);
+ cachedRegionManager.updateBufferAndFileOffset(indexToLoad, dataFileChannel.position());
+ ++numLoaded;
+ }
+
+ if (loadedBuffers.size() <= numLoaded) {
+ notifier.notifyDataAvailableFromDisk();
+ }
+
+ return true;
+ }
+
+ public synchronized void fail(Throwable failureCause) {
+ checkState(!isFailed, "subpartition file reader has already failed.");
+ isFailed = true;
+ BufferIndexOrError bufferIndexOrError;
+ // empty from tail, in-case subpartition view consumes concurrently and gets the wrong order
+ while ((bufferIndexOrError = loadedBuffers.pollLast()) != null) {
+ if (!bufferIndexOrError.isError()) {
+ checkNotNull(bufferIndexOrError.buffer).recycleBuffer();
+ }
+ }
+
+ loadedBuffers.add(BufferIndexOrError.newError(failureCause));
+ notifier.notifyDataAvailableFromDisk();
+ }
+
+ /** Provides priority calculation logic for io scheduler. */
+ @Override
+ public int compareTo(HsSubpartitionFileReader that) {
+ return Long.compare(this.getNextOffsetToLoad(), that.getNextOffsetToLoad());
+ }
+
+ public void prepareForScheduling() {
+ updateConsumptionProgress();
+ }
+
+ // ------------------------------------------------------------------------
+ // Methods only for testing
+ // ------------------------------------------------------------------------
+
+ @VisibleForTesting
+ Deque<BufferIndexOrError> getLoadedBuffers() {
+ return loadedBuffers;
+ }
+
+ @VisibleForTesting
+ BufferIndexManager getBufferIndexManager() {
+ return bufferIndexManager;
+ }
+
+ // ------------------------------------------------------------------------
+ // Internal Methods
+ // ------------------------------------------------------------------------
+
+ private void moveFileOffsetToBuffer(int bufferIndex) throws IOException {
+ Tuple2<Integer, Long> indexAndOffset = cachedRegionManager.tryGetFileOffset(bufferIndex);
+ dataFileChannel.position(indexAndOffset.f1);
+ for (int i = 0; i < bufferIndex - indexAndOffset.f0; ++i) {
+ positionToNextBuffer(dataFileChannel, headerBuf);
+ }
+ dataFileChannel.position(indexAndOffset.f1);
+ }
+
+ /** Returns Long.MAX_VALUE if shouldn't load. */
+ private long getNextOffsetToLoad() {
+ int bufferIndex = bufferIndexManager.getNextToLoad();
+ if (bufferIndex < 0) {
+ return Long.MAX_VALUE;
+ } else {
+ return cachedRegionManager.getFileOffset(bufferIndex);
+ }
+ }
+
+ /** Indicates a buffer with index or an error. */
+ public static class BufferIndexOrError {
+ @Nullable public final Buffer buffer;
+ public final int index;
+ public final Throwable throwable;
Review Comment:
fixed.
##########
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/hybrid/HsSubpartitionFileReader.java:
##########
@@ -0,0 +1,379 @@
+/*
+ * 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.flink.runtime.io.network.partition.hybrid;
+
+import org.apache.flink.annotation.VisibleForTesting;
+import org.apache.flink.api.java.tuple.Tuple2;
+import org.apache.flink.core.memory.MemorySegment;
+import org.apache.flink.runtime.io.network.buffer.Buffer;
+import org.apache.flink.runtime.io.network.buffer.BufferRecycler;
+import org.apache.flink.runtime.io.network.partition.BufferReaderWriterUtil;
+
+import javax.annotation.Nullable;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.util.Deque;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.Queue;
+import java.util.concurrent.LinkedBlockingDeque;
+
+import static org.apache.flink.runtime.io.network.partition.BufferReaderWriterUtil.positionToNextBuffer;
+import static org.apache.flink.runtime.io.network.partition.BufferReaderWriterUtil.readFromByteChannel;
+import static org.apache.flink.util.Preconditions.checkNotNull;
+import static org.apache.flink.util.Preconditions.checkState;
+
+/**
+ * This component is responsible for reading data from disk.
+ *
+ * <p>In order to access the disk as sequentially as possible {@link HsSubpartitionFileReader} need
+ * to be able to compare priorities.
+ */
+public class HsSubpartitionFileReader implements Comparable<HsSubpartitionFileReader> {
+ /**
+ * Prevent other consumers from starving. This default value needs to be tuning experimentally
+ * or introduced a configuration option.
+ */
+ public static final int MAX_BUFFERS_READ_AHEAD = 5;
+
+ private final ByteBuffer headerBuf = BufferReaderWriterUtil.allocatedHeaderBuffer();
+
+ private final int subpartitionId;
+
+ private final FileChannel dataFileChannel;
+
+ private final HsSubpartitionViewNotifier notifier;
+
+ private final CachedRegionManager cachedRegionManager;
+
+ private final BufferIndexManager bufferIndexManager;
+
+ private final Deque<BufferIndexOrError> loadedBuffers = new LinkedBlockingDeque<>();
+
+ private boolean isFailed;
+
+ public HsSubpartitionFileReader(
+ int subpartitionId,
+ FileChannel dataFileChannel,
+ HsSubpartitionViewNotifier notifier,
+ HsFileDataIndex dataIndex) {
+ this.subpartitionId = subpartitionId;
+ this.dataFileChannel = dataFileChannel;
+ this.notifier = notifier;
+ this.bufferIndexManager = new BufferIndexManager();
+ this.cachedRegionManager = new CachedRegionManager(subpartitionId, dataIndex);
+ }
+
+ /** Refresh downstream consumption progress for another round scheduling of reading. */
+ public void updateConsumptionProgress() {
+ bufferIndexManager.updateLastConsumed(notifier.getConsumingOffset());
+ }
+
+ @Override
+ public boolean equals(Object o) {
+ if (this == o) {
+ return true;
+ }
+ if (o == null || getClass() != o.getClass()) {
+ return false;
+ }
+ HsSubpartitionFileReader that = (HsSubpartitionFileReader) o;
+ return subpartitionId == that.subpartitionId;
+ }
+
+ @Override
+ public int hashCode() {
+ return Objects.hash(subpartitionId);
+ }
+
+ /**
+ * Read subpartition data into buffers.
+ *
+ * <p>This transfers the ownership of used buffers to this class. It's this class'
+ * responsibility to release the buffers using the recycler when no longer needed.
+ *
+ * <p>Calling this method does not always use up all the provided buffers. It's this class'
+ * decision when to stop reading. Currently, it stops reading when: 1) buffers are used up, or
+ * 2) reaches the end of the subpartition data within the region, or 3) enough data have been
+ * read ahead the downstream consuming offset.
+ */
+ public synchronized boolean readBuffers(Queue<MemorySegment> buffers, BufferRecycler recycler)
+ throws IOException {
+ if (isFailed) {
+ return false;
+ }
+ int firstBufferToLoad = bufferIndexManager.getNextToLoad();
+ if (firstBufferToLoad < 0) {
+ return true;
+ }
+
+ // If lookup result is empty, it means that one the following things have happened:
+ // 1) The target buffer has not been spilled into disk.
+ // 2) The target buffer has not been released from memory.
+ // So, just skip this round reading.
+ if (!cachedRegionManager.updateCachedRegionIfNeeded(firstBufferToLoad).isPresent()) {
+ return true;
+ }
+
+ moveFileOffsetToBuffer(firstBufferToLoad);
+
+ int numRemainingBuffersInRegion =
+ cachedRegionManager.getRemainingBuffersInRegion(firstBufferToLoad);
+
+ int indexToLoad;
+ int numLoaded = 0;
+ while (!buffers.isEmpty()
+ && numRemainingBuffersInRegion-- > 0
+ && (indexToLoad = bufferIndexManager.getNextToLoad()) >= 0) {
+ MemorySegment segment = buffers.poll();
+ Buffer buffer;
+ try {
+ if ((buffer = readFromByteChannel(dataFileChannel, headerBuf, segment, recycler))
+ == null) {
+ buffers.add(segment);
+ break;
+ }
+ } catch (Throwable throwable) {
+ buffers.add(segment);
+ throw throwable;
+ }
+
+ loadedBuffers.add(BufferIndexOrError.newBuffer(buffer, indexToLoad));
+ bufferIndexManager.updateLastLoaded(indexToLoad);
+ cachedRegionManager.updateBufferAndFileOffset(indexToLoad, dataFileChannel.position());
+ ++numLoaded;
+ }
+
+ if (loadedBuffers.size() <= numLoaded) {
+ notifier.notifyDataAvailableFromDisk();
+ }
+
+ return true;
+ }
+
+ public synchronized void fail(Throwable failureCause) {
+ checkState(!isFailed, "subpartition file reader has already failed.");
+ isFailed = true;
+ BufferIndexOrError bufferIndexOrError;
+ // empty from tail, in-case subpartition view consumes concurrently and gets the wrong order
+ while ((bufferIndexOrError = loadedBuffers.pollLast()) != null) {
+ if (!bufferIndexOrError.isError()) {
+ checkNotNull(bufferIndexOrError.buffer).recycleBuffer();
+ }
+ }
+
+ loadedBuffers.add(BufferIndexOrError.newError(failureCause));
+ notifier.notifyDataAvailableFromDisk();
+ }
+
+ /** Provides priority calculation logic for io scheduler. */
+ @Override
+ public int compareTo(HsSubpartitionFileReader that) {
+ return Long.compare(this.getNextOffsetToLoad(), that.getNextOffsetToLoad());
+ }
+
+ public void prepareForScheduling() {
+ updateConsumptionProgress();
+ }
+
+ // ------------------------------------------------------------------------
+ // Methods only for testing
+ // ------------------------------------------------------------------------
+
+ @VisibleForTesting
+ Deque<BufferIndexOrError> getLoadedBuffers() {
+ return loadedBuffers;
+ }
+
+ @VisibleForTesting
+ BufferIndexManager getBufferIndexManager() {
+ return bufferIndexManager;
+ }
+
+ // ------------------------------------------------------------------------
+ // Internal Methods
+ // ------------------------------------------------------------------------
+
+ private void moveFileOffsetToBuffer(int bufferIndex) throws IOException {
+ Tuple2<Integer, Long> indexAndOffset = cachedRegionManager.tryGetFileOffset(bufferIndex);
+ dataFileChannel.position(indexAndOffset.f1);
+ for (int i = 0; i < bufferIndex - indexAndOffset.f0; ++i) {
+ positionToNextBuffer(dataFileChannel, headerBuf);
+ }
+ dataFileChannel.position(indexAndOffset.f1);
+ }
+
+ /** Returns Long.MAX_VALUE if shouldn't load. */
+ private long getNextOffsetToLoad() {
+ int bufferIndex = bufferIndexManager.getNextToLoad();
+ if (bufferIndex < 0) {
+ return Long.MAX_VALUE;
+ } else {
+ return cachedRegionManager.getFileOffset(bufferIndex);
+ }
+ }
+
+ /** Indicates a buffer with index or an error. */
+ public static class BufferIndexOrError {
+ @Nullable public final Buffer buffer;
+ public final int index;
+ public final Throwable throwable;
+
+ private BufferIndexOrError(@Nullable Buffer buffer, int index, Throwable throwable) {
+ this.buffer = buffer;
+ this.index = index;
+ this.throwable = throwable;
+ }
+
+ public boolean isError() {
+ return buffer == null;
+ }
+
+ public Buffer.DataType getDataType() {
+ return buffer == null ? Buffer.DataType.NONE : buffer.getDataType();
+ }
+
+ private static BufferIndexOrError newError(Throwable throwable) {
+ return new BufferIndexOrError(null, -1, throwable);
+ }
+
+ private static BufferIndexOrError newBuffer(Buffer buffer, int index) {
+ return new BufferIndexOrError(checkNotNull(buffer), index, null);
+ }
+ }
+
+ /** Take care of buffer index consumed by the file reader. */
+ static class BufferIndexManager {
+ /** Index of the last buffer that has ever been loaded from file. */
+ private int lastLoaded = -1;
+ /** Index of the last buffer that has been consumed by downstream, to the best knowledge. */
+ private int lastConsumed = -1;
+
+ private void updateLastLoaded(int lastLoaded) {
+ checkState(this.lastLoaded <= lastLoaded);
+ this.lastLoaded = lastLoaded;
+ }
+
+ private void updateLastConsumed(int lastConsumed) {
+ this.lastConsumed = lastConsumed;
+ }
+
+ /** Returns a negative value if shouldn't load. */
+ int getNextToLoad() {
+ int nextToLoad = Math.max(lastLoaded, lastConsumed) + 1;
+ int maxToLoad = lastConsumed + MAX_BUFFERS_READ_AHEAD;
+ return nextToLoad <= maxToLoad ? nextToLoad : -1;
+ }
+ }
+
+ private static class CachedRegionManager {
Review Comment:
I refactored this class.
##########
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/hybrid/HsSubpartitionFileReader.java:
##########
@@ -0,0 +1,379 @@
+/*
+ * 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.flink.runtime.io.network.partition.hybrid;
+
+import org.apache.flink.annotation.VisibleForTesting;
+import org.apache.flink.api.java.tuple.Tuple2;
+import org.apache.flink.core.memory.MemorySegment;
+import org.apache.flink.runtime.io.network.buffer.Buffer;
+import org.apache.flink.runtime.io.network.buffer.BufferRecycler;
+import org.apache.flink.runtime.io.network.partition.BufferReaderWriterUtil;
+
+import javax.annotation.Nullable;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.util.Deque;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.Queue;
+import java.util.concurrent.LinkedBlockingDeque;
+
+import static org.apache.flink.runtime.io.network.partition.BufferReaderWriterUtil.positionToNextBuffer;
+import static org.apache.flink.runtime.io.network.partition.BufferReaderWriterUtil.readFromByteChannel;
+import static org.apache.flink.util.Preconditions.checkNotNull;
+import static org.apache.flink.util.Preconditions.checkState;
+
+/**
+ * This component is responsible for reading data from disk.
+ *
+ * <p>In order to access the disk as sequentially as possible {@link HsSubpartitionFileReader} need
+ * to be able to compare priorities.
+ */
+public class HsSubpartitionFileReader implements Comparable<HsSubpartitionFileReader> {
+ /**
+ * Prevent other consumers from starving. This default value needs to be tuning experimentally
+ * or introduced a configuration option.
+ */
+ public static final int MAX_BUFFERS_READ_AHEAD = 5;
+
+ private final ByteBuffer headerBuf = BufferReaderWriterUtil.allocatedHeaderBuffer();
+
+ private final int subpartitionId;
+
+ private final FileChannel dataFileChannel;
+
+ private final HsSubpartitionViewNotifier notifier;
+
+ private final CachedRegionManager cachedRegionManager;
+
+ private final BufferIndexManager bufferIndexManager;
+
+ private final Deque<BufferIndexOrError> loadedBuffers = new LinkedBlockingDeque<>();
+
+ private boolean isFailed;
+
+ public HsSubpartitionFileReader(
+ int subpartitionId,
+ FileChannel dataFileChannel,
+ HsSubpartitionViewNotifier notifier,
+ HsFileDataIndex dataIndex) {
+ this.subpartitionId = subpartitionId;
+ this.dataFileChannel = dataFileChannel;
+ this.notifier = notifier;
+ this.bufferIndexManager = new BufferIndexManager();
+ this.cachedRegionManager = new CachedRegionManager(subpartitionId, dataIndex);
+ }
+
+ /** Refresh downstream consumption progress for another round scheduling of reading. */
+ public void updateConsumptionProgress() {
+ bufferIndexManager.updateLastConsumed(notifier.getConsumingOffset());
+ }
+
+ @Override
+ public boolean equals(Object o) {
+ if (this == o) {
+ return true;
+ }
+ if (o == null || getClass() != o.getClass()) {
+ return false;
+ }
+ HsSubpartitionFileReader that = (HsSubpartitionFileReader) o;
+ return subpartitionId == that.subpartitionId;
+ }
+
+ @Override
+ public int hashCode() {
+ return Objects.hash(subpartitionId);
+ }
+
+ /**
+ * Read subpartition data into buffers.
+ *
+ * <p>This transfers the ownership of used buffers to this class. It's this class'
+ * responsibility to release the buffers using the recycler when no longer needed.
+ *
+ * <p>Calling this method does not always use up all the provided buffers. It's this class'
+ * decision when to stop reading. Currently, it stops reading when: 1) buffers are used up, or
+ * 2) reaches the end of the subpartition data within the region, or 3) enough data have been
+ * read ahead the downstream consuming offset.
+ */
+ public synchronized boolean readBuffers(Queue<MemorySegment> buffers, BufferRecycler recycler)
Review Comment:
By checking the code, I found that there is no need to return a value here. This part of the logic has been changed, you can review it again.
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