sunhaibotb commented on a change in pull request #8124: [FLINK-11877] Implement the runtime handling of the InputSelectable interface URL: https://github.com/apache/flink/pull/8124#discussion_r276532049
########## File path: flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/io/StreamTwoInputSelectableProcessor.java ########## @@ -0,0 +1,434 @@ +/* + * 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.annotation.VisibleForTesting; +import org.apache.flink.api.common.typeutils.TypeSerializer; +import org.apache.flink.metrics.Counter; +import org.apache.flink.metrics.SimpleCounter; +import org.apache.flink.runtime.io.disk.iomanager.IOManager; +import org.apache.flink.runtime.io.network.partition.consumer.InputGate; +import org.apache.flink.runtime.metrics.groups.OperatorMetricGroup; +import org.apache.flink.streaming.api.operators.InputSelectable; +import org.apache.flink.streaming.api.operators.InputSelection; +import org.apache.flink.streaming.api.operators.TwoInputStreamOperator; +import org.apache.flink.streaming.api.watermark.Watermark; +import org.apache.flink.streaming.runtime.metrics.WatermarkGauge; +import org.apache.flink.streaming.runtime.streamrecord.StreamElement; +import org.apache.flink.streaming.runtime.streamrecord.StreamRecord; +import org.apache.flink.streaming.runtime.streamstatus.StreamStatus; +import org.apache.flink.streaming.runtime.streamstatus.StreamStatusMaintainer; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.io.IOException; +import java.util.ArrayList; +import java.util.Collection; +import java.util.List; +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.ExecutionException; +import java.util.concurrent.atomic.AtomicInteger; + +import static org.apache.flink.util.Preconditions.checkNotNull; +import static org.apache.flink.util.Preconditions.checkState; + +/** + * Input reader for {@link org.apache.flink.streaming.runtime.tasks.TwoInputSelectableStreamTask} + * in the case that the operator is InputSelectable. + * + * @param <IN1> The type of the records that arrive on the first input + * @param <IN2> The type of the records that arrive on the second input + */ +@Internal +public class StreamTwoInputSelectableProcessor<IN1, IN2> { + + private static final Logger LOG = LoggerFactory.getLogger(StreamTwoInputSelectableProcessor.class); + + private volatile boolean continuousProcessing = true; + + private final NetworkInput input1; + private final NetworkInput input2; + + private final Object lock; + + private final TwoInputStreamOperator<IN1, IN2, ?> streamOperator; + + private final InputSelectable inputSelector; + + private final AuxiliaryHandler auxiliaryHandler; + + private final CompletableFuture<Integer>[] listenFutures; + + private final boolean[] isFinished; + + private InputSelection inputSelection; + + private AtomicInteger availableInputsMask = new AtomicInteger(); Review comment: When reading with `ANY` mode, there are the following cases. 1. If two inputs are all available, take turns to read them (for fair reading). 2. If only one of the inputs is available, always read it until another input become available or itself becomes unavailable/finished. 3. If neither input is available, block to wait for any input to become available. Only using `BufferOrEvent#moreAvailable()` to update `int availableIntpusMask`, I think that there are some problems with the second case. Assuming that one of the inputs is unavailable at a certain moment and the corresponding bit mask in `availableInputsMask` is set to `0`, there are several possible ways to select which input to read. 1. We read the currently available input until it becomes unavailable or finished, but if the another input becomes available during this period, it will not be able to adjust to fair reading in time. 2. Always read with absolute fairness, that is, reading a record from the available input, then checking and waiting for the unavailable input to become available and reading it, but it is undoubtedly inefficient. I only thought of these ways. I didn't understand that way you said. ---------------------------------------------------------------- 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 With regards, Apache Git Services
