rkhachatryan commented on a change in pull request #10939: [FLINK-15750][network] Moving output flushing to the mailbox URL: https://github.com/apache/flink/pull/10939#discussion_r370702676
########## File path: flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/io/OutputFlusher.java ########## @@ -0,0 +1,125 @@ +/* + * 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.VisibleForTesting; +import org.apache.flink.runtime.io.network.api.writer.RecordWriter; +import org.apache.flink.streaming.api.operators.MailboxExecutor; +import org.apache.flink.util.FlinkException; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.ArrayList; +import java.util.concurrent.Future; + +/** + * A dedicated thread that periodically flushes the output buffers, to set upper latency bounds. + * + * <p>The thread is daemonic, because it is only a utility thread. + */ +public class OutputFlusher extends Thread { + /** Default name for the output flush thread, if no name with a task reference is given. */ + @VisibleForTesting + public static final String OUTPUT_FLUSH_THREAD_NAME = "OutputFlusher"; + + private static final Logger LOG = LoggerFactory.getLogger(OutputFlusher.class); + + private final RecordWriter<?> recordWriter; + private final long timeout; + private final MailboxExecutor mailboxExecutor; + + private volatile boolean running = true; + + public OutputFlusher( + RecordWriter<?> recordWriter, + String taskName, + long timeout, + MailboxExecutor mailboxExecutor) { + super(OUTPUT_FLUSH_THREAD_NAME + " for " + taskName); + this.recordWriter = recordWriter; + this.timeout = timeout; + this.mailboxExecutor = mailboxExecutor; + setDaemon(true); + } + + public void terminate() { + running = false; + interrupt(); + } + + @Override + public void run() { + try { + Future<?> future = null; + + while (running) { + try { + if (future != null) { + future.get(); + } + Thread.sleep(timeout); + } catch (InterruptedException e) { + // propagate this if we are still running, because it should not happen + // in that case + if (running) { + throw new Exception(e); + } + } + + recordWriter.flushAll(); + } + } catch (Throwable t) { + LOG.error("An exception happened while flushing the outputs", t); + mailboxExecutor.execute( + () -> { + throw new FlinkException("OutputFlusher thread has failed", t); + }, + "OutputFlusher"); + } + } + + /** + * Closeable collection of {@link OutputFlusher}. + */ + public static class OutputFlushers implements AutoCloseable { + private final ArrayList<OutputFlusher> outputFlushers = new ArrayList<>(); + + public void addOutputFlusher(OutputFlusher outputFlusher) { + outputFlushers.add(outputFlusher); + } + + public void close() { + for (OutputFlusher outputFlusher : outputFlushers) { + outputFlusher.terminate(); + try { + outputFlusher.join(); Review comment: nit: it would be faster to 1st terminate all flushers, then join ---------------------------------------------------------------- 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: [email protected] With regards, Apache Git Services
