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Posted to reviews@spark.apache.org by GitBox <gi...@apache.org> on 2020/11/03 14:09:50 UTC
[GitHub] [spark] otterc commented on a change in pull request #30062: [SPARK-32916][SHUFFLE] Implementation of shuffle service that leverages push-based shuffle in YARN deployment mode
otterc commented on a change in pull request #30062:
URL: https://github.com/apache/spark/pull/30062#discussion_r516175694
##########
File path: common/network-shuffle/src/main/java/org/apache/spark/network/shuffle/protocol/PushBlockStream.java
##########
@@ -23,24 +23,31 @@
import org.apache.spark.network.protocol.Encoders;
// Needed by ScalaDoc. See SPARK-7726
-import static org.apache.spark.network.shuffle.protocol.BlockTransferMessage.Type;
/**
* Request to push a block to a remote shuffle service to be merged in push based shuffle.
* The remote shuffle service will also include this message when responding the push requests.
*/
public class PushBlockStream extends BlockTransferMessage {
+ public static final String SHUFFLE_PUSH_BLOCK_PREFIX = "shufflePush";
public final String appId;
- public final String blockId;
+ public final int shuffleId;
+ public final int mapIndex;
+ public final int reduceId;
// Similar to the chunkIndex in StreamChunkId, indicating the index of a block in a batch of
// blocks to be pushed.
public final int index;
+ public final String streamId;
Review comment:
The `streamId` is used for `StreamCallbackWithId.getID()` . The usage of the name `streamId` in `toString` and `decode` is a typo.
##########
File path: common/network-common/src/main/java/org/apache/spark/network/util/TransportConf.java
##########
@@ -363,4 +363,38 @@ public boolean useOldFetchProtocol() {
return conf.getBoolean("spark.shuffle.useOldFetchProtocol", false);
}
+ /**
+ * Class name of the implementation of MergedShuffleFileManager that merges the blocks
+ * pushed to it when push-based shuffle is enabled. Default implementation for merging the blocks
+ * remotely is 'org.apache.spark.network.shuffle.RemoteBlockPushResolver'.
+ * To turn off push-based shuffle at a cluster level, set the configuration to
+ * 'org.apache.spark.network.shuffle.ExternalBlockHandler$NoOpMergedShuffleFileManager'.
+ */
+ public String mergeShuffleFileManagerImpl() {
+ return conf.get("spark.shuffle.push.based.mergedShuffleFileManagerImpl",
+ "org.apache.spark.network.shuffle.RemoteBlockPushResolver");
Review comment:
Sure. I will change the default to be `NoOpMergedShuffleFileManager`.
cc. @Ngone51 @tgravescs
##########
File path: common/network-shuffle/src/main/java/org/apache/spark/network/shuffle/protocol/PushBlockStream.java
##########
@@ -23,24 +23,31 @@
import org.apache.spark.network.protocol.Encoders;
// Needed by ScalaDoc. See SPARK-7726
-import static org.apache.spark.network.shuffle.protocol.BlockTransferMessage.Type;
/**
* Request to push a block to a remote shuffle service to be merged in push based shuffle.
* The remote shuffle service will also include this message when responding the push requests.
*/
public class PushBlockStream extends BlockTransferMessage {
+ public static final String SHUFFLE_PUSH_BLOCK_PREFIX = "shufflePush";
public final String appId;
- public final String blockId;
+ public final int shuffleId;
+ public final int mapIndex;
+ public final int reduceId;
// Similar to the chunkIndex in StreamChunkId, indicating the index of a block in a batch of
// blocks to be pushed.
public final int index;
+ public final String streamId;
Review comment:
This is fixed.
##########
File path: common/network-shuffle/src/main/java/org/apache/spark/network/shuffle/RemoteBlockPushResolver.java
##########
@@ -0,0 +1,883 @@
+/*
+ * 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.spark.network.shuffle;
+
+import java.io.BufferedOutputStream;
+import java.io.DataOutputStream;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Objects;
+import com.google.common.base.Preconditions;
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
+import com.google.common.cache.Weigher;
+import com.google.common.collect.Maps;
+import com.google.common.primitives.Ints;
+import com.google.common.primitives.Longs;
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.Unpooled;
+import org.roaringbitmap.RoaringBitmap;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.spark.network.buffer.FileSegmentManagedBuffer;
+import org.apache.spark.network.buffer.ManagedBuffer;
+import org.apache.spark.network.client.StreamCallbackWithID;
+import org.apache.spark.network.protocol.Encoders;
+import org.apache.spark.network.shuffle.protocol.ExecutorShuffleInfo;
+import org.apache.spark.network.shuffle.protocol.FinalizeShuffleMerge;
+import org.apache.spark.network.shuffle.protocol.MergeStatuses;
+import org.apache.spark.network.shuffle.protocol.PushBlockStream;
+import org.apache.spark.network.util.JavaUtils;
+import org.apache.spark.network.util.NettyUtils;
+import org.apache.spark.network.util.TransportConf;
+
+/**
+ * An implementation of {@link MergedShuffleFileManager} that provides the most essential shuffle
+ * service processing logic to support push based shuffle.
+ */
+public class RemoteBlockPushResolver implements MergedShuffleFileManager {
+
+ private static final Logger logger = LoggerFactory.getLogger(RemoteBlockPushResolver.class);
+ @VisibleForTesting
+ static final String MERGE_MANAGER_DIR = "merge_manager";
+
+ private final ConcurrentMap<String, AppPathsInfo> appsPathInfo;
+ private final ConcurrentMap<AppShuffleId, Map<Integer, AppShufflePartitionInfo>> partitions;
+
+ private final Executor directoryCleaner;
+ private final TransportConf conf;
+ private final int minChunkSize;
+ private final ErrorHandler.BlockPushErrorHandler errorHandler;
+
+ @SuppressWarnings("UnstableApiUsage")
+ private final LoadingCache<File, ShuffleIndexInformation> indexCache;
+
+ @SuppressWarnings("UnstableApiUsage")
+ public RemoteBlockPushResolver(TransportConf conf) {
+ this.conf = conf;
+ this.partitions = Maps.newConcurrentMap();
+ this.appsPathInfo = Maps.newConcurrentMap();
+ this.directoryCleaner = Executors.newSingleThreadExecutor(
+ // Add `spark` prefix because it will run in NM in Yarn mode.
+ NettyUtils.createThreadFactory("spark-shuffle-merged-shuffle-directory-cleaner"));
+ this.minChunkSize = conf.minChunkSizeInMergedShuffleFile();
+ CacheLoader<File, ShuffleIndexInformation> indexCacheLoader =
+ new CacheLoader<File, ShuffleIndexInformation>() {
+ public ShuffleIndexInformation load(File file) throws IOException {
+ return new ShuffleIndexInformation(file);
+ }
+ };
+ indexCache = CacheBuilder.newBuilder()
+ .maximumWeight(conf.mergedIndexCacheSize())
+ .weigher((Weigher<File, ShuffleIndexInformation>) (file, indexInfo) -> indexInfo.getSize())
+ .build(indexCacheLoader);
+ this.errorHandler = new ErrorHandler.BlockPushErrorHandler();
+ }
+
+ /**
+ * Given the appShuffleId and reduceId that uniquely identifies a given shuffle partition of an
+ * application, retrieves the associated metadata. If not present and the corresponding merged
+ * shuffle does not exist, initializes the metadata.
+ */
+ private AppShufflePartitionInfo getOrCreateAppShufflePartitionInfo(
+ AppShuffleId appShuffleId,
+ int reduceId) {
+ Map<Integer, AppShufflePartitionInfo> shufflePartitions =
+ partitions.computeIfAbsent(appShuffleId, id -> Maps.newConcurrentMap());
Review comment:
I have made this change
##########
File path: common/network-shuffle/src/main/java/org/apache/spark/network/shuffle/RemoteBlockPushResolver.java
##########
@@ -0,0 +1,883 @@
+/*
+ * 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.spark.network.shuffle;
+
+import java.io.BufferedOutputStream;
+import java.io.DataOutputStream;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Objects;
+import com.google.common.base.Preconditions;
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
+import com.google.common.cache.Weigher;
+import com.google.common.collect.Maps;
+import com.google.common.primitives.Ints;
+import com.google.common.primitives.Longs;
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.Unpooled;
+import org.roaringbitmap.RoaringBitmap;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.spark.network.buffer.FileSegmentManagedBuffer;
+import org.apache.spark.network.buffer.ManagedBuffer;
+import org.apache.spark.network.client.StreamCallbackWithID;
+import org.apache.spark.network.protocol.Encoders;
+import org.apache.spark.network.shuffle.protocol.ExecutorShuffleInfo;
+import org.apache.spark.network.shuffle.protocol.FinalizeShuffleMerge;
+import org.apache.spark.network.shuffle.protocol.MergeStatuses;
+import org.apache.spark.network.shuffle.protocol.PushBlockStream;
+import org.apache.spark.network.util.JavaUtils;
+import org.apache.spark.network.util.NettyUtils;
+import org.apache.spark.network.util.TransportConf;
+
+/**
+ * An implementation of {@link MergedShuffleFileManager} that provides the most essential shuffle
+ * service processing logic to support push based shuffle.
+ */
+public class RemoteBlockPushResolver implements MergedShuffleFileManager {
+
+ private static final Logger logger = LoggerFactory.getLogger(RemoteBlockPushResolver.class);
+ @VisibleForTesting
+ static final String MERGE_MANAGER_DIR = "merge_manager";
+
+ private final ConcurrentMap<String, AppPathsInfo> appsPathInfo;
+ private final ConcurrentMap<AppShuffleId, Map<Integer, AppShufflePartitionInfo>> partitions;
+
+ private final Executor directoryCleaner;
+ private final TransportConf conf;
+ private final int minChunkSize;
+ private final ErrorHandler.BlockPushErrorHandler errorHandler;
+
+ @SuppressWarnings("UnstableApiUsage")
+ private final LoadingCache<File, ShuffleIndexInformation> indexCache;
+
+ @SuppressWarnings("UnstableApiUsage")
+ public RemoteBlockPushResolver(TransportConf conf) {
+ this.conf = conf;
+ this.partitions = Maps.newConcurrentMap();
+ this.appsPathInfo = Maps.newConcurrentMap();
+ this.directoryCleaner = Executors.newSingleThreadExecutor(
+ // Add `spark` prefix because it will run in NM in Yarn mode.
+ NettyUtils.createThreadFactory("spark-shuffle-merged-shuffle-directory-cleaner"));
+ this.minChunkSize = conf.minChunkSizeInMergedShuffleFile();
+ CacheLoader<File, ShuffleIndexInformation> indexCacheLoader =
+ new CacheLoader<File, ShuffleIndexInformation>() {
+ public ShuffleIndexInformation load(File file) throws IOException {
+ return new ShuffleIndexInformation(file);
+ }
+ };
+ indexCache = CacheBuilder.newBuilder()
+ .maximumWeight(conf.mergedIndexCacheSize())
+ .weigher((Weigher<File, ShuffleIndexInformation>) (file, indexInfo) -> indexInfo.getSize())
+ .build(indexCacheLoader);
+ this.errorHandler = new ErrorHandler.BlockPushErrorHandler();
+ }
+
+ /**
+ * Given the appShuffleId and reduceId that uniquely identifies a given shuffle partition of an
+ * application, retrieves the associated metadata. If not present and the corresponding merged
+ * shuffle does not exist, initializes the metadata.
+ */
+ private AppShufflePartitionInfo getOrCreateAppShufflePartitionInfo(
+ AppShuffleId appShuffleId,
+ int reduceId) {
+ Map<Integer, AppShufflePartitionInfo> shufflePartitions =
+ partitions.computeIfAbsent(appShuffleId, id -> Maps.newConcurrentMap());
+ return shufflePartitions.computeIfAbsent(reduceId, key -> {
+ // It only gets here when the key is not present in the map. This could either
+ // be the first time the merge manager receives a pushed block for a given application
+ // shuffle partition, or after the merged shuffle file is finalized. We handle these
+ // two cases accordingly by checking if the file already exists.
+ File dataFile = getMergedShuffleDataFile(appShuffleId, reduceId);
+ File indexFile = getMergedShuffleIndexFile(appShuffleId, reduceId);
+ File metaFile = getMergedShuffleMetaFile(appShuffleId, reduceId);
+ try {
+ if (dataFile.exists()) {
+ return null;
+ } else {
+ return new AppShufflePartitionInfo(appShuffleId, reduceId, dataFile, indexFile, metaFile);
+ }
+ } catch (IOException e) {
+ logger.error(
+ "Cannot create merged shuffle partition with data file {}, index file {}, and "
+ + "meta file {}", dataFile.getAbsolutePath(),
+ indexFile.getAbsolutePath(), metaFile.getAbsolutePath());
+ throw new RuntimeException(
+ String.format("Cannot initialize merged shuffle partition for appId %s shuffleId %s "
+ + "reduceId %s", appShuffleId.appId, appShuffleId.shuffleId, reduceId), e);
+ }
+ });
+ }
+
+ @Override
+ public MergedBlockMeta getMergedBlockMeta(String appId, int shuffleId, int reduceId) {
+ AppShuffleId appShuffleId = new AppShuffleId(appId, shuffleId);
+ File indexFile = getMergedShuffleIndexFile(appShuffleId, reduceId);
+ if (!indexFile.exists()) {
+ throw new RuntimeException(String.format(
+ "Merged shuffle index file %s not found", indexFile.getPath()));
+ }
+ int size = (int) indexFile.length();
+ // First entry is the zero offset
+ int numChunks = (size / Long.BYTES) - 1;
+ File metaFile = getMergedShuffleMetaFile(appShuffleId, reduceId);
+ if (!metaFile.exists()) {
+ throw new RuntimeException(String.format("Merged shuffle meta file %s not found",
+ metaFile.getPath()));
+ }
+ FileSegmentManagedBuffer chunkBitMaps =
+ new FileSegmentManagedBuffer(conf, metaFile, 0L, metaFile.length());
+ logger.trace(
+ "{} shuffleId {} reduceId {} num chunks {}", appId, shuffleId, reduceId, numChunks);
+ return new MergedBlockMeta(numChunks, chunkBitMaps);
+ }
+
+ @SuppressWarnings("UnstableApiUsage")
+ @Override
+ public ManagedBuffer getMergedBlockData(String appId, int shuffleId, int reduceId, int chunkId) {
+ AppShuffleId appShuffleId = new AppShuffleId(appId, shuffleId);
+ File dataFile = getMergedShuffleDataFile(appShuffleId, reduceId);
+ if (!dataFile.exists()) {
+ throw new RuntimeException(String.format("Merged shuffle data file %s not found",
+ dataFile.getPath()));
+ }
+ File indexFile = getMergedShuffleIndexFile(appShuffleId, reduceId);
+ try {
+ // If we get here, the merged shuffle file should have been properly finalized. Thus we can
+ // use the file length to determine the size of the merged shuffle block.
+ ShuffleIndexInformation shuffleIndexInformation = indexCache.get(indexFile);
+ ShuffleIndexRecord shuffleIndexRecord = shuffleIndexInformation.getIndex(chunkId);
+ return new FileSegmentManagedBuffer(
+ conf, dataFile, shuffleIndexRecord.getOffset(), shuffleIndexRecord.getLength());
+ } catch (ExecutionException e) {
+ throw new RuntimeException(String.format(
+ "Failed to open merged shuffle index file %s", indexFile.getPath()), e);
+ }
+ }
+
+ /**
+ * The logic here is consistent with
+ * org.apache.spark.storage.DiskBlockManager#getMergedShuffleFile
+ */
+ private File getFile(String appId, String filename) {
+ // TODO: Change the message when this service is able to handle NM restart
+ AppPathsInfo appPathsInfo = Preconditions.checkNotNull(appsPathInfo.get(appId),
+ "application " + appId + " is not registered or NM was restarted.");
+ File targetFile = ExecutorDiskUtils.getFile(appPathsInfo.activeLocalDirs,
+ appPathsInfo.subDirsPerLocalDir, filename);
+ logger.debug("Get merged file {}", targetFile.getAbsolutePath());
+ return targetFile;
+ }
+
+ private File getMergedShuffleDataFile(AppShuffleId appShuffleId, int reduceId) {
+ String fileName = String.format("%s.data", generateFileName(appShuffleId, reduceId));
+ return getFile(appShuffleId.appId, fileName);
+ }
+
+ private File getMergedShuffleIndexFile(AppShuffleId appShuffleId, int reduceId) {
+ String indexName = String.format("%s.index", generateFileName(appShuffleId, reduceId));
+ return getFile(appShuffleId.appId, indexName);
+ }
+
+ private File getMergedShuffleMetaFile(AppShuffleId appShuffleId, int reduceId) {
+ String metaName = String.format("%s.meta", generateFileName(appShuffleId, reduceId));
+ return getFile(appShuffleId.appId, metaName);
+ }
+
+ @Override
+ public String[] getMergedBlockDirs(String appId) {
+ AppPathsInfo appPathsInfo = Preconditions.checkNotNull(appsPathInfo.get(appId),
+ "application " + appId + " is not registered or NM was restarted.");
+ String[] activeLocalDirs = Preconditions.checkNotNull(appPathsInfo.activeLocalDirs,
+ "application " + appId
+ + " active local dirs list has not been updated by any executor registration");
+ return activeLocalDirs;
+ }
+
+ @Override
+ public void applicationRemoved(String appId, boolean cleanupLocalDirs) {
+ logger.info("Application {} removed, cleanupLocalDirs = {}", appId, cleanupLocalDirs);
+ // TODO: Change the message when this service is able to handle NM restart
+ AppPathsInfo appPathsInfo = Preconditions.checkNotNull(appsPathInfo.remove(appId),
+ "application " + appId + " is not registered or NM was restarted.");
+ Iterator<Map.Entry<AppShuffleId, Map<Integer, AppShufflePartitionInfo>>> iterator =
+ partitions.entrySet().iterator();
+ while (iterator.hasNext()) {
+ Map.Entry<AppShuffleId, Map<Integer, AppShufflePartitionInfo>> entry = iterator.next();
+ AppShuffleId appShuffleId = entry.getKey();
+ if (appId.equals(appShuffleId.appId)) {
+ iterator.remove();
+ for (AppShufflePartitionInfo partitionInfo : entry.getValue().values()) {
+ try {
+ partitionInfo.closeAllFiles();
+ } catch (IOException e) {
+ logger.error("Error closing merged shuffle files for appId {} shuffleId {} reduceId {}",
+ appId, partitionInfo.appShuffleId.shuffleId, partitionInfo.reduceId);
+ }
+ }
+ }
+ }
+ if (cleanupLocalDirs) {
+ Path[] dirs = Arrays.stream(appPathsInfo.activeLocalDirs)
+ .map(dir -> Paths.get(dir)).toArray(Path[]::new);
+ directoryCleaner.execute(() -> deleteExecutorDirs(dirs));
+ }
+ }
+
+ /**
+ * Serially delete local dirs, executed in a separate thread.
+ */
+ @VisibleForTesting
+ void deleteExecutorDirs(Path[] dirs) {
+ for (Path localDir : dirs) {
+ try {
+ if (Files.exists(localDir)) {
+ JavaUtils.deleteRecursively(localDir.toFile());
+ logger.debug("Successfully cleaned up directory: {}", localDir);
+ }
+ } catch (Exception e) {
+ logger.error("Failed to delete directory: {}", localDir, e);
+ }
+ }
+ }
+
+ @Override
+ public StreamCallbackWithID receiveBlockDataAsStream(PushBlockStream msg) {
+ // Retrieve merged shuffle file metadata
+ String[] blockIdParts = msg.blockId.split("_");
+ if (blockIdParts.length != 4 || !blockIdParts[0].equals("shuffle")) {
+ throw new IllegalArgumentException("Unexpected shuffle block id format: " + msg.blockId);
+ }
+ AppShuffleId appShuffleId = new AppShuffleId(msg.appId, Integer.parseInt(blockIdParts[1]));
+ int mapIndex = Integer.parseInt(blockIdParts[2]);
+ int reduceId = Integer.parseInt(blockIdParts[3]);
+ AppShufflePartitionInfo partitionInfoBeforeCheck =
+ getOrCreateAppShufflePartitionInfo(appShuffleId, reduceId);
+
+ // Here partitionInfo will be null in 2 cases:
+ // 1) The request is received for a block that has already been merged, this is possible due
+ // to the retry logic.
+ // 2) The request is received after the merged shuffle is finalized, thus is too late.
+ //
+ // For case 1, we will drain the data in the channel and just respond success
+ // to the client. This is required because the response of the previously merged
+ // block will be ignored by the client, per the logic in RetryingBlockFetcher.
+ // Note that the netty server should receive data for a given block id only from 1 channel
+ // at any time. The block should be pushed only from successful maps, thus there should be
+ // only 1 source for a given block at any time. Although the netty client might retry sending
+ // this block to the server multiple times, the data of the same block always arrives from the
+ // same channel thus the server should have already processed the previous request of this
+ // block before seeing it again in the channel. This guarantees that we can simply just
+ // check the bitmap to determine if a block is a duplicate or not.
+ //
+ // For case 2, we will also drain the data in the channel, but throw an exception in
+ // {@link org.apache.spark.network.client.StreamCallback#onComplete(String)}. This way,
+ // the client will be notified of the failure but the channel will remain active. Keeping
+ // the channel alive is important because the same channel could be reused by multiple map
+ // tasks in the executor JVM, which belongs to different stages. While one of the shuffles
+ // in these stages is finalized, the others might still be active. Tearing down the channel
+ // on the server side will disrupt these other on-going shuffle merges. It's also important
+ // to notify the client of the failure, so that it can properly halt pushing the remaining
+ // blocks upon receiving such failures to preserve resources on the server/client side.
+ //
+ // Speculative execution would also raise a possible scenario with duplicate blocks. Although
+ // speculative execution would kill the slower task attempt, leading to only 1 task attempt
+ // succeeding in the end, there is no guarantee that only one copy of the block will be
+ // pushed. This is due to our handling of block push process outside of the map task, thus
+ // it is possible for the speculative task attempt to initiate the block push process before
+ // getting killed. When this happens, we need to distinguish the duplicate blocks as they
+ // arrive. More details on this is explained in later comments.
+
+ // Track if the block is received after shuffle merge finalize
+ final boolean isTooLate = partitionInfoBeforeCheck == null;
+ // Check if the given block is already merged by checking the bitmap against the given map index
+ final AppShufflePartitionInfo partitionInfo = partitionInfoBeforeCheck != null
+ && partitionInfoBeforeCheck.mapTracker.contains(mapIndex) ? null : partitionInfoBeforeCheck;
+
+ return new StreamCallbackWithID() {
+ private int length = 0;
+ // This indicates that this stream got the opportunity to write the blocks to the merged file.
+ // Once this is set to true and the stream encounters a failure then it will take necessary
+ // action to overwrite any partial written data. This is reset to false when the stream
+ // completes without any failures.
+ private boolean isWriting = false;
+ // Use on-heap instead of direct ByteBuffer since these buffers will be GC'ed very quickly
+ private List<ByteBuffer> deferredBufs;
+
+ @Override
+ public String getID() {
+ return msg.blockId;
+ }
+
+ /**
+ * Write a ByteBuffer to the merged shuffle file. Here we keep track of the length of the
+ * block data written to file. In case of failure during writing block to file, we use the
+ * information tracked in partitionInfo to overwrite the corrupt block when writing the new
+ * block.
+ */
+ private void writeBuf(ByteBuffer buf) throws IOException {
+ while (buf.hasRemaining()) {
+ assert partitionInfo != null;
+ if (partitionInfo.isEncounteredFailure()) {
+ long updatedPos = partitionInfo.getPosition() + length;
+ logger.debug(
+ "{} shuffleId {} reduceId {} encountered failure current pos {} updated pos {}",
+ appShuffleId.appId, appShuffleId.shuffleId, reduceId, partitionInfo.getPosition(),
+ updatedPos);
+ length += partitionInfo.dataChannel.write(buf, updatedPos);
+ } else {
+ length += partitionInfo.dataChannel.write(buf);
+ }
+ }
+ }
+
+ /**
+ * There will be multiple streams of map blocks belonging to the same reduce partition. At any
+ * given point of time, only a single map stream can write its data to the merged file. Until
+ * this stream is completed, the other streams defer writing. This prevents corruption of
+ * merged data. This returns whether this stream is the active stream that can write to the
+ * merged file.
+ */
+ private boolean allowedToWrite() {
+ assert partitionInfo != null;
+ return partitionInfo.getCurrentMapIndex() < 0
+ || partitionInfo.getCurrentMapIndex() == mapIndex;
+ }
+
+ /**
+ * Returns if this is a duplicate block generated by speculative tasks. With speculative
+ * tasks, we could receive the same block from 2 different sources at the same time. One of
+ * them is going to be the first to set the currentMapIndex. When that block does so, it's
+ * going to see the currentMapIndex initially as -1. After it sets the currentMapIndex, it's
+ * going to write some data to disk, thus increasing the length counter. The other duplicate
+ * block is going to see the currentMapIndex already set to its mapIndex. However, it hasn't
+ * written any data yet. If the first block gets written completely and resets the
+ * currentMapIndex to -1 before the processing for the second block finishes, we can just
+ * check the bitmap to identify the second as a duplicate.
+ */
+ private boolean isDuplicateBlock() {
+ assert partitionInfo != null;
+ return (partitionInfo.getCurrentMapIndex() == mapIndex && length == 0)
+ || partitionInfo.mapTracker.contains(mapIndex);
+ }
+
+ /**
+ * This is only invoked when the stream is able to write. The stream first writes any deferred
+ * block parts buffered in memory.
+ */
+ private void writeAnyDeferredBufs() throws IOException {
+ assert partitionInfo != null;
+ if (deferredBufs != null && !deferredBufs.isEmpty()) {
+ for (ByteBuffer deferredBuf : deferredBufs) {
+ writeBuf(deferredBuf);
+ }
+ deferredBufs = null;
+ }
+ }
+
+ @Override
+ public void onData(String streamId, ByteBuffer buf) throws IOException {
+ // If partition info is null, ignore the requests. It could only be
+ // null either when a request is received after the shuffle file is
+ // finalized or when a request is for a duplicate block.
+ if (partitionInfo == null) {
+ return;
+ }
+ // When handling the block data using StreamInterceptor, it can help to reduce the amount
+ // of data that needs to be buffered in memory since it does not wait till the completion
+ // of the frame before handling the message, thus releasing the ByteBuf earlier. However,
+ // this also means it would chunk a block into multiple buffers. Here, we want to preserve
+ // the benefit of handling the block data using StreamInterceptor as much as possible while
+ // providing the guarantee that one block would be continuously written to the merged
+ // shuffle file before the next block starts. For each shuffle partition, we would track
+ // the current map index to make sure only block matching the map index can be written to
+ // disk. If one server thread sees the block being handled is the current block, it would
+ // directly write the block to disk. Otherwise, it would buffer the block chunks in memory.
+ // If the block becomes the current block before we see the end of it, we would then dump
+ // all buffered block data to disk and write the remaining portions of the block directly
+ // to disk as well. This way, we avoid having to buffer the entirety of every blocks in
+ // memory, while still providing the necessary guarantee.
+ synchronized (partitionInfo) {
+ Map<Integer, AppShufflePartitionInfo> shufflePartitions = partitions.get(appShuffleId);
+ // If the partitionInfo corresponding to (appId, shuffleId, reduceId) is no longer present
+ // then it means that the shuffle merge has already been finalized. We should thus ignore
+ // the data and just drain the remaining bytes of this message. This check should be
+ // placed inside the synchronized block to make sure that checking the key is still
+ // present and processing the data is atomic.
+ if (shufflePartitions == null || !shufflePartitions.containsKey(reduceId)) {
+ // TODO is it necessary to dereference deferredBufs?
+ deferredBufs = null;
+ return;
+ }
+ // Check whether we can write to disk
+ if (allowedToWrite()) {
+ isWriting = true;
+ // Identify duplicate block generated by speculative tasks. We respond success to
+ // the client in cases of duplicate even though no data is written.
+ if (isDuplicateBlock()) {
+ deferredBufs = null;
+ return;
+ }
+ logger.trace("{} shuffleId {} reduceId {} onData writable", appShuffleId.appId,
+ appShuffleId.shuffleId, reduceId);
+ if (partitionInfo.getCurrentMapIndex() < 0) {
+ partitionInfo.setCurrentMapIndex(mapIndex);
+ }
+
+ // If we got here, it's safe to write the block data to the merged shuffle file. We
+ // first write any deferred block.
+ writeAnyDeferredBufs();
+ writeBuf(buf);
+ // If we got here, it means we successfully write the current chunk of block to merged
+ // shuffle file. If we encountered failure while writing the previous block, we should
+ // reset the file channel position and the status of partitionInfo to indicate that we
+ // have recovered from previous disk write failure. However, we do not update the
+ // position tracked by partitionInfo here. That is only updated while the entire block
+ // is successfully written to merged shuffle file.
+ if (partitionInfo.isEncounteredFailure()) {
+ partitionInfo.dataChannel.position(partitionInfo.getPosition() + length);
+ partitionInfo.setEncounteredFailure(false);
+ }
+ } else {
+ logger.trace("{} shuffleId {} reduceId {} onData deferred", appShuffleId.appId,
+ appShuffleId.shuffleId, reduceId);
+ // If we cannot write to disk, we buffer the current block chunk in memory so it could
+ // potentially be written to disk later. We take our best effort without guarantee
+ // that the block will be written to disk. If the block data is divided into multiple
+ // chunks during TCP transportation, each #onData invocation is an attempt to write
+ // the block to disk. If the block is still not written to disk after all #onData
+ // invocations, the final #onComplete invocation is the last attempt to write the
+ // block to disk. If we still couldn't write this block to disk after this, we give up
+ // on this block push request and respond failure to client. We could potentially
+ // buffer the block longer or wait for a few iterations inside #onData or #onComplete
+ // to increase the chance of writing the block to disk, however this would incur more
+ // memory footprint or decrease the server processing throughput for the shuffle
+ // service. In addition, during test we observed that by randomizing the order in
+ // which clients sends block push requests batches, only ~0.5% blocks failed to be
+ // written to disk due to this reason. We thus decide to optimize for server
+ // throughput and memory usage.
+ if (deferredBufs == null) {
+ deferredBufs = new LinkedList<>();
+ }
+ // Write the buffer to the in-memory deferred cache. Since buf is a slice of a larger
+ // byte buffer, we cache only the relevant bytes not the entire large buffer to save
+ // memory.
+ ByteBuffer deferredBuf = ByteBuffer.allocate(buf.remaining());
+ deferredBuf.put(buf);
+ deferredBuf.flip();
+ deferredBufs.add(deferredBuf);
+ }
+ }
+ }
+
+ @Override
+ public void onComplete(String streamId) throws IOException {
+ logger.trace("{} shuffleId {} reduceId {} onComplete invoked", appShuffleId.appId,
+ appShuffleId.shuffleId, reduceId);
+ if (partitionInfo == null) {
+ if (isTooLate) {
+ // Throw an exception here so the block data is drained from channel and server
+ // responds RpcFailure to the client.
+ throw new RuntimeException(String.format("Block %s %s", msg.blockId,
+ ErrorHandler.BlockPushErrorHandler.TOO_LATE_MESSAGE_SUFFIX));
+ } else {
+ // For duplicate block that is received before the shuffle merge finalizes, the
+ // server should respond success to the client.
+ return;
+ }
+ }
+ // TODO should the merge manager check for the merge completion ratio here and finalize
+ // TODO shuffle merge if appropriate? So the merge manager can potentially finalize early
+ // TODO and the file channel can be closed even if finalize merge request is somehow not
+ // TODO received from the driver? If so, then we need to know # maps for this shuffle.
+
+ synchronized (partitionInfo) {
+ Map<Integer, AppShufflePartitionInfo> shufflePartitions = partitions.get(appShuffleId);
+ // When this request initially got to the server, the shuffle merge finalize request
+ // was not received yet. By the time we finish reading this message, the shuffle merge
+ // however is already finalized. We should thus respond RpcFailure to the client.
+ if (shufflePartitions == null || !shufflePartitions.containsKey(reduceId)) {
+ deferredBufs = null;
+ throw new RuntimeException(String.format("Block %s %s", msg.blockId,
+ ErrorHandler.BlockPushErrorHandler.TOO_LATE_MESSAGE_SUFFIX));
+ }
+ // Check if we can commit this block
+ if (allowedToWrite()) {
+ isWriting = true;
+ // Identify duplicate block generated by speculative tasks. We respond success to
+ // the client in cases of duplicate even though no data is written.
+ if (isDuplicateBlock()) {
+ deferredBufs = null;
+ return;
+ }
+ if (partitionInfo.getCurrentMapIndex() < 0) {
+ writeAnyDeferredBufs();
+ }
+ long updatedPos = partitionInfo.getPosition() + length;
+ boolean indexUpdated = false;
+ if (updatedPos - partitionInfo.getLastChunkOffset() >= minChunkSize) {
+ partitionInfo.updateChunkInfo(updatedPos, mapIndex);
+ indexUpdated = true;
+ }
+ partitionInfo.setPosition(updatedPos);
+ partitionInfo.setCurrentMapIndex(-1);
+
+ // update merged results
+ partitionInfo.blockMerged(mapIndex);
+ if (indexUpdated) {
+ partitionInfo.resetChunkTracker();
+ }
+ } else {
+ deferredBufs = null;
+ throw new RuntimeException(String.format("%s %s to merged shuffle",
+ ErrorHandler.BlockPushErrorHandler.BLOCK_APPEND_COLLISION_DETECTED_MSG_PREFIX,
+ msg.blockId));
+ }
+ }
+ isWriting = false;
+ }
+
+ @Override
+ public void onFailure(String streamId, Throwable throwable) throws IOException {
+ if (errorHandler.shouldLogError(throwable)) {
+ logger.error("Encountered issue when merging shuffle partition block {}", msg, throwable);
+ } else {
+ logger.debug("Encountered issue when merging shuffle partition block {}", msg, throwable);
+ }
+ // Only update partitionInfo if the failure corresponds to a valid request. If the
+ // request is too late, i.e. received after shuffle merge finalize, #onFailure will
+ // also be triggered, and we can just ignore. Also, if we couldn't find an opportunity
+ // to write the block data to disk, we should also ignore here.
+ Map<Integer, AppShufflePartitionInfo> shufflePartitions = partitions.get(appShuffleId);
+ if (isWriting && partitionInfo != null && shufflePartitions != null
+ && shufflePartitions.containsKey(reduceId)) {
+ synchronized (partitionInfo) {
+ logger.debug("{} shuffleId {} reduceId {} set encountered failure", appShuffleId.appId,
+ appShuffleId.shuffleId, reduceId);
+ partitionInfo.setCurrentMapIndex(-1);
+ partitionInfo.setEncounteredFailure(true);
+ }
+ }
+ }
+ };
+ }
+
+ @SuppressWarnings("SynchronizationOnLocalVariableOrMethodParameter")
+ @Override
+ public MergeStatuses finalizeShuffleMerge(FinalizeShuffleMerge msg) throws IOException {
+ logger.info("Finalizing shuffle {} from Application {}.", msg.shuffleId, msg.appId);
+ List<RoaringBitmap> bitmaps = new LinkedList<>();
+ List<Integer> reduceIds = new LinkedList<>();
+ List<Long> sizes = new LinkedList<>();
+ Map<Integer, AppShufflePartitionInfo> shufflePartitions =
Review comment:
There were some race conditions introduced when changed the map into a 2-level map. However, now all of them are addressed thanks to everyone's input. So, I don't think we need to introduce a wider lock. Please take another look at the current changes.
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