wsry commented on a change in pull request #13924: URL: https://github.com/apache/flink/pull/13924#discussion_r601187940
########## File path: flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/SortMergeResultPartitionReader.java ########## @@ -0,0 +1,350 @@ +/* + * 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; + +import org.apache.flink.annotation.VisibleForTesting; +import org.apache.flink.core.memory.MemorySegment; +import org.apache.flink.runtime.io.disk.BatchShuffleReadBufferPool; +import org.apache.flink.runtime.io.network.buffer.BufferRecycler; +import org.apache.flink.util.IOUtils; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import javax.annotation.concurrent.GuardedBy; + +import java.io.IOException; +import java.nio.channels.FileChannel; +import java.nio.file.Path; +import java.nio.file.StandardOpenOption; +import java.util.ArrayDeque; +import java.util.ArrayList; +import java.util.Collection; +import java.util.Collections; +import java.util.HashSet; +import java.util.List; +import java.util.PriorityQueue; +import java.util.Queue; +import java.util.Set; +import java.util.concurrent.Executor; +import java.util.concurrent.TimeoutException; + +import static org.apache.flink.util.Preconditions.checkNotNull; +import static org.apache.flink.util.Preconditions.checkState; + +/** + * Data reader for {@link SortMergeResultPartition} which can read data for all downstream tasks + * consuming the corresponding {@link SortMergeResultPartition}. It always tries to read shuffle + * data in order of file offset, which maximums the sequential read so can improve the blocking + * shuffle performance. + */ +public class SortMergeResultPartitionReader implements Runnable, BufferRecycler { + + private static final Logger LOG = LoggerFactory.getLogger(SortMergeResultPartitionReader.class); + + /** Lock used to synchronize multi-thread access to thread-unsafe fields. */ + private final Object lock; + + /** Buffer pool from which to allocate buffers for shuffle data reading. */ + private final BatchShuffleReadBufferPool bufferPool; + + /** Executor to run the shuffle data reading task. */ + private final Executor ioExecutor; + + /** Maximum number of buffers can be allocated by this partition reader. */ + private final int maxRequestedBuffers; + + /** All failed subpartition readers to be released. */ + @GuardedBy("lock") + private final Set<SortMergeSubpartitionReader> failedReaders = new HashSet<>(); + + /** All readers waiting to read data of different subpartitions. */ + @GuardedBy("lock") + private final Set<SortMergeSubpartitionReader> allReaders = new HashSet<>(); + + /** File channel shared by all subpartitions to read data from. */ + @GuardedBy("lock") + private FileChannel dataFileChannel; + + /** File channel shared by all subpartitions to read index from. */ + @GuardedBy("lock") + private FileChannel indexFileChannel; + + /** Number of buffers already allocated and still not recycled by this partition reader. */ + @GuardedBy("lock") + private int numRequestedBuffers; + + /** + * Whether the data reading task is currently running or not. This flag is used when trying to + * submit the data reading task. + */ + @GuardedBy("lock") + private boolean isRunning; + + /** Whether this reader has been released or not. */ + @GuardedBy("lock") + private boolean isReleased; + + public SortMergeResultPartitionReader( + BatchShuffleReadBufferPool bufferPool, Executor ioExecutor, Object lock) { + this.lock = checkNotNull(lock); + this.bufferPool = checkNotNull(bufferPool); + this.ioExecutor = checkNotNull(ioExecutor); + // one partition reader can consume at most 32M buffers for data read, it is only an + // empirical value which can not be configured currently + this.maxRequestedBuffers = Math.max(1, 4 * bufferPool.getNumBuffersPerRequest()); + + bufferPool.initialize(); + } + + @Override + public synchronized void run() { + Set<SortMergeSubpartitionReader> finishedReaders = new HashSet<>(); + Queue<SortMergeSubpartitionReader> availableReaders = getAvailableReaders(); + + Queue<MemorySegment> buffers = new ArrayDeque<>(); + if (!availableReaders.isEmpty()) { + try { + buffers.addAll(bufferPool.requestBuffers()); + } catch (Throwable throwable) { + // this can happen only when the buffer pool is destroyed or buffer request timeout + if (!(throwable instanceof TimeoutException) || numRequestedBuffers <= 0) { + failSubpartitionReaders(availableReaders, throwable); + LOG.error("Failed to request buffers for data reading.", throwable); Review comment: Though no data is read, the following removeFinishedAndFailedReaders should not be skiped. If timeout happen and no buffer is hold, all readers will be failed and if some buffers are hold, we just trigger next request. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
