claudevdm commented on code in PR #39896: URL: https://github.com/apache/beam/pull/39896#discussion_r3874012934
########## sdks/java/io/iceberg/src/main/java/org/apache/beam/sdk/io/iceberg/BoundedAsyncTasks.java: ########## @@ -0,0 +1,113 @@ +/* + * 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.beam.sdk.io.iceberg; + +import java.util.ArrayDeque; +import java.util.Deque; +import java.util.Iterator; +import java.util.concurrent.Callable; +import java.util.concurrent.ExecutorService; +import java.util.concurrent.Executors; +import java.util.concurrent.Future; +import java.util.function.Consumer; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.util.concurrent.ThreadFactoryBuilder; + +/** + * Runs tasks on a fixed thread pool while bounding how many are in flight. Results are handed to + * {@code onDone} on the caller's thread (from {@link #submit} and {@link #awaitAll}), so a DoFn can + * emit them without a thread-safe output. + */ +class BoundedAsyncTasks<T> { + private final ExecutorService executor; + private final int maxInFlight; + private final Deque<Future<T>> active = new ArrayDeque<>(); + + BoundedAsyncTasks(int threads, int maxInFlight) { + Preconditions.checkArgument(threads > 0, "threads must be positive, got: %s", threads); + Preconditions.checkArgument( + maxInFlight > 0, "maxInFlight must be positive, got: %s", maxInFlight); + this.executor = + Executors.newFixedThreadPool( + threads, + new ThreadFactoryBuilder() + .setDaemon(true) + .setNameFormat("iceberg-async-task-%d") + .build()); + this.maxInFlight = maxInFlight; + } + + /** + * Submits a task, first delivering any finished results. Blocks while {@code maxInFlight} tasks + * are outstanding. If a task failed, its exception is rethrown and every other outstanding task + * is cancelled. + */ + void submit(Callable<T> task, Consumer<T> onDone) throws Exception { + try { + drainFinished(onDone); + while (active.size() >= maxInFlight) { + Future<T> oldest = active.removeFirst(); + onDone.accept(oldest.get()); // blocks until the oldest task completes Review Comment: I'd like to avoid making too many changes in this PR to how it works. Will consider this as a follow up. Right now the all completed futures already drain before blocking, so this would only be an issue if there is tail latency on the oldest. -- 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. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
