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ASF GitHub Bot commented on FLINK-8547: --------------------------------------- Github user zhijiangW commented on a diff in the pull request: https://github.com/apache/flink/pull/5400#discussion_r167582763 --- Diff: flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/io/BufferBlocker.java --- @@ -0,0 +1,61 @@ +/* + * 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.io.network.partition.consumer.BufferOrEvent; + +import java.io.IOException; + +/** + * The buffer blocker takes the buffers and events from a data stream and adds them in a sequence. + * After a number of elements have been added, the blocker can "roll over": It presents the added + * elements as a readable sequence, and creates a new sequence. + */ +@Internal +public interface BufferBlocker { + + /** + * Adds a buffer or event to the blocker. + * + * @param boe The buffer or event to be added into the blocker. + */ + void add(BufferOrEvent boe) throws IOException; + + /** + * Starts a new sequence of buffers and event and returns the current sequence of buffers for reading. + * This method returns {@code null}, if nothing was added since the creation, or the last call to this method. + * + * @param newBuffer only works for {@link BufferSpiller} implements currently. + * @return The readable sequence of buffers and events, or 'null', if nothing was added. + */ + BufferOrEventSequence rollOver(boolean newBuffer) throws IOException; --- End diff -- sure > Implement CheckpointBarrierHandler not to spill data for exactly-once based > on credit-based flow control > -------------------------------------------------------------------------------------------------------- > > Key: FLINK-8547 > URL: https://issues.apache.org/jira/browse/FLINK-8547 > Project: Flink > Issue Type: Sub-task > Components: Network > Affects Versions: 1.5.0 > Reporter: zhijiang > Assignee: zhijiang > Priority: Major > > Currently in exactly-once mode, the {{BarrierBuffer}} would block inputs with > barriers until all inputs have received the barrier for a given checkpoint. > To avoid back-pressuring the input streams which may cause distributed > deadlocks, the {{BarrierBuffer}} has to spill the data in disk files to > recycle the buffers for blocked channels. > > Based on credit-based flow control, every channel has exclusive buffers, so > it is no need to spill data for avoiding deadlock. Then we implement a new > {{CheckpointBarrierHandler}} for only buffering the data for blocked channels > for better performance. > > And this new {{CheckpointBarrierHandler}} can also be configured to use or > not in order to rollback the original mode for unexpected risks. -- This message was sent by Atlassian JIRA (v7.6.3#76005)