zhuzhurk commented on a change in pull request #13924:
URL: https://github.com/apache/flink/pull/13924#discussion_r602116115
##########
File path:
flink-runtime/src/test/java/org/apache/flink/runtime/io/network/partition/SortMergeResultPartitionTest.java
##########
@@ -161,17 +188,45 @@ private void recordDataWritten(
numBytesWritten[subpartition] += record.remaining();
}
+ private ByteBuffer getRandomData(int dataSize, Random random) {
Review comment:
nit: `getRandomData` -> `generateRandomData `
##########
File path:
flink-runtime/src/test/java/org/apache/flink/runtime/io/network/partition/SortMergeResultPartitionTest.java
##########
@@ -252,36 +306,24 @@ public void testReleaseWhileWriting() throws Exception {
@Test
public void testReleaseWhileReading() throws Exception {
Review comment:
I think this can be a UT of `SortMergeResultPartitionReadScheduler` and
then we can remove `SortMergeResultPartition#getReadScheduler()`.
##########
File path:
flink-runtime/src/test/java/org/apache/flink/runtime/io/network/partition/SortMergeResultPartitionTest.java
##########
@@ -336,12 +384,79 @@ private SortMergeResultPartition
createSortMergedPartition(
ResultPartitionType.BLOCKING,
numSubpartitions,
numSubpartitions,
- bufferSize,
+ readBufferPool,
+ readIOExecutor,
new ResultPartitionManager(),
fileChannelManager.createChannel().getPath(),
null,
() -> bufferPool);
sortMergedResultPartition.setup();
return sortMergedResultPartition;
}
+
+ private SortMergeResultPartition createSortMergeResultPartitionWithData()
throws Exception {
+ return createSortMergeResultPartitionWithData(readBufferPool);
+ }
+
+ private SortMergeResultPartition createSortMergeResultPartitionWithData(
+ BatchShuffleReadBufferPool readBufferPool) throws Exception {
+ int numBuffers = 10;
+ int numWriteBuffers = numBuffers / 2;
+
+ BufferPool bufferPool = globalPool.createBufferPool(numBuffers,
numBuffers);
+ SortMergeResultPartition partition =
+ createSortMergedPartition(10, bufferPool, readBufferPool);
+ assertEquals(numWriteBuffers,
bufferPool.bestEffortGetNumOfUsedBuffers());
+
+ int numDataBuffers = 2 * readBufferPool.getNumTotalBuffers();
+ for (int i = 0; i < numDataBuffers; ++i) {
+ partition.emitRecord(ByteBuffer.allocate(bufferSize), 0);
+ }
+ partition.finish();
+ partition.close();
+
+ assertEquals(16384, partition.getResultFile().getNumRegions());
Review comment:
Could we have a clear form to show how this number is computed?
##########
File path:
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/SortMergeResultPartitionReadScheduler.java
##########
@@ -0,0 +1,395 @@
+/*
+ * 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.runtime.util.FatalExitExceptionHandler;
+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.CompletableFuture;
+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.
+ */
+class SortMergeResultPartitionReadScheduler implements Runnable,
BufferRecycler {
+
+ private static final Logger LOG =
+
LoggerFactory.getLogger(SortMergeResultPartitionReadScheduler.class);
+
+ private final FatalExitExceptionHandler fatalErrorHandler = new
FatalExitExceptionHandler();
+
+ /** Lock used to synchronize multi-thread access to thread-unsafe fields.
*/
+ private final Object lock;
+
+ /**
+ * A {@link CompletableFuture} to be completed when this read scheduler
including all resources
+ * is released.
+ */
+ private final CompletableFuture<?> releaseFuture = new
CompletableFuture<>();
+
+ /** 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;
+
+ SortMergeResultPartitionReadScheduler(
+ 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 (the expected buffers
per request is 8M)
+ // buffers for data read. Currently, it is only an empirical value can
not be configured
+ this.maxRequestedBuffers = Math.max(1, 4 *
bufferPool.getNumBuffersPerRequest());
+
+ // initialize the buffer pool eagerly to avoid reporting errors like
OOM too late
+ bufferPool.initialize();
+ }
+
+ @Override
+ public synchronized void run() {
+ Queue<SortMergeSubpartitionReader> availableReaders =
getAvailableReaders();
+
+ Queue<MemorySegment> buffers = allocateBuffers(availableReaders);
+ int numBuffersAllocated = buffers.size();
+
+ Set<SortMergeSubpartitionReader> finishedReaders =
readData(availableReaders, buffers);
+
+ int numBuffersRead = numBuffersAllocated - buffers.size();
+ releaseBuffers(buffers);
+
+ removeFinishedAndFailedReaders(numBuffersRead, finishedReaders);
+ }
+
+ private Queue<MemorySegment> allocateBuffers(
+ Queue<SortMergeSubpartitionReader> availableReaders) {
+ if (availableReaders.isEmpty()) {
+ return new ArrayDeque<>();
+ }
+
+ try {
+ return new ArrayDeque<>(bufferPool.requestBuffers());
+ } catch (Throwable throwable) {
+ // do not fail the pending subpartitions if the TimeoutException
occurs and we are
+ // currently holding buffers, otherwise, fail all pending
subpartitions immediately
+ if (!(throwable instanceof TimeoutException) ||
numRequestedBuffers <= 0) {
Review comment:
Do you mean that `TimeoutException` is acceptable if this scheduler had
acquired some buffers before, because we just want to guarantee the first
request to be fulfilled within the timeout and secondary requests are just
best-effort?
If my understanding is correct, could we elaborate it here because I find it
is not very easy to get the idea.
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