AHeise commented on a change in pull request #11507: [FLINK-16587] Add basic CheckpointBarrierHandler for unaligned checkpoint URL: https://github.com/apache/flink/pull/11507#discussion_r402909258
########## File path: flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/io/CheckpointBarrierUnaligner.java ########## @@ -0,0 +1,242 @@ +/* + * 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.streaming.runtime.io; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.runtime.checkpoint.channel.ChannelStateWriter; +import org.apache.flink.runtime.checkpoint.channel.InputChannelInfo; +import org.apache.flink.runtime.io.network.api.CancelCheckpointMarker; +import org.apache.flink.runtime.io.network.api.CheckpointBarrier; +import org.apache.flink.runtime.io.network.buffer.Buffer; +import org.apache.flink.runtime.jobgraph.tasks.AbstractInvokable; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import javax.annotation.Nullable; + +import java.util.Arrays; +import java.util.concurrent.CompletableFuture; + +import static org.apache.flink.util.Preconditions.checkNotNull; + +/** + * {@link CheckpointBarrierUnaligner} is used for triggering checkpoint while reading the first barrier + * and keeping track of the number of received barriers and consumed barriers. + */ +@Internal +public class CheckpointBarrierUnaligner extends CheckpointBarrierHandler { + + private static final Logger LOG = LoggerFactory.getLogger(CheckpointBarrierUnaligner.class); + + private final String taskName; + + /** + * Tag the state of which input channel has read the barrier. If one channel has read the barrier by task, + * the respective in-flight input buffers should be empty when triggering unaligned checkpoint. + */ + private final boolean[] barrierConsumedChannels; + + /** + * Tag the state of which input channel has received the barrier. Until the barrier of a specific channel is + * received, all new buffers need to be persisted after unaligned checkpointing has been started. + */ + private final boolean[] barrierReceivedChannels; + + /** + * Contains the offsets of the channel indices for each gate when flattening the channels of all gates. + * + * <p>For example, consider 3 gates with 4 channels, {@code gateChannelOffsets = [0, 4, 8]}. + */ + private final int[] gateChannelOffsets; + + /** + * The number of input channels which has read the barrier by task. + */ + private int numBarriersReceived; + + /** + * The checkpoint id to guarantee that we would trigger only one checkpoint when reading the same barrier from + * different channels. + */ + private long currentCheckpointId = -1L; + + private final ChannelStateWriter channelStateWriter; + + private CompletableFuture<?> allBarriersReceivedFuture; + + CheckpointBarrierUnaligner( + int[] numberOfInputChannelsPerGate, + ChannelStateWriter channelStateWriter, + String taskName, + @Nullable AbstractInvokable toNotifyOnCheckpoint) { + super(toNotifyOnCheckpoint); + + this.taskName = taskName; + this.channelStateWriter = checkNotNull(channelStateWriter); + + final int numGates = numberOfInputChannelsPerGate.length; + + gateChannelOffsets = new int[numGates]; + for (int index = 1; index < numGates; index++) { + gateChannelOffsets[index] = gateChannelOffsets[index - 1] + numberOfInputChannelsPerGate[index - 1]; + } + + final int totalNumChannels = gateChannelOffsets[numGates - 1] + numberOfInputChannelsPerGate[numGates - 1]; + barrierConsumedChannels = new boolean[totalNumChannels]; + Arrays.fill(barrierConsumedChannels, true); + barrierReceivedChannels = new boolean[totalNumChannels]; + Arrays.fill(barrierReceivedChannels, true); + } + + @Override + public void releaseBlocksAndResetBarriers() { + } + + /** + * For unaligned checkpoint, it never blocks processing from the task aspect. + * + * <p>For PoC, we do not consider the possibility that the unaligned checkpoint would + * not perform due to the max configured unaligned checkpoint size. + */ + @Override + public boolean isBlocked(int channelIndex) { + return false; + } + + /** + * We still need to trigger checkpoint while reading the first barrier from one channel, because this might happen + * earlier than the previous async trigger via mailbox by netty thread. And the {@link AbstractInvokable} has the + * deduplication logic to guarantee trigger checkpoint only once finally. + * + * <p>Note this is also suitable for the trigger case of local input channel. + */ + @Override + public synchronized boolean processBarrier( + CheckpointBarrier receivedBarrier, + int channelIndex, + long bufferedBytes) { + long barrierId = receivedBarrier.getId(); + if (checkNewCheckpoint(barrierId)) { + notifyCheckpointAsync(receivedBarrier, bufferedBytes, 0); + } + barrierConsumedChannels[channelIndex] = true; + return false; + } + + @Override + public boolean processCancellationBarrier(CancelCheckpointMarker cancelBarrier) { + return false; + } + + @Override + public boolean processEndOfPartition() { + return false; + } + + @Override + public long getLatestCheckpointId() { + return currentCheckpointId; + } + + @Override + public long getAlignmentDurationNanos() { + return 0; + } + + @Override + public String toString() { + return String.format("%s: last checkpoint: %d", taskName, currentCheckpointId); + } + + @Override + public void checkpointSizeLimitExceeded(long maxBufferedBytes) { + } + + @Override + protected boolean isBarrierConsumed(long checkpointId, int channelIndex) { + if (checkpointId < currentCheckpointId) { + return true; + } + if (checkpointId > currentCheckpointId) { + return false; + } + return barrierConsumedChannels[channelIndex]; + } + + public CompletableFuture<?> getAllBarriersReceivedFuture(long checkpointId) { Review comment: Please double-check the threading model and look for potential concurrency issues. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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