m-trieu commented on code in PR #27593: URL: https://github.com/apache/beam/pull/27593#discussion_r1274437354
########## runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/WindmillStreamPool.java: ########## @@ -0,0 +1,178 @@ +/* + * 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.runners.dataflow.worker.windmill; + +import java.util.ArrayList; +import java.util.List; +import java.util.Map; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.ThreadLocalRandom; +import java.util.function.Supplier; +import javax.annotation.concurrent.ThreadSafe; +import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.annotations.VisibleForTesting; +import org.joda.time.Duration; +import org.joda.time.Instant; + +/** + * Pool of homogeneous streams to Windmill. + * + * <p>The pool holds a fixed total number of streams, and keeps each stream open for a specified + * time to allow for better load-balancing. + */ +@ThreadSafe +public class WindmillStreamPool<StreamT extends WindmillServerStub.WindmillStream> { + + private final Duration streamTimeout; + private final Supplier<StreamT> streamSupplier; + private final List<WindmillStreamPool.StreamData<StreamT>> streams; + private final Map<StreamT, StreamData<StreamT>> holds; + + private WindmillStreamPool( + Duration streamTimeout, + Supplier<StreamT> streamSupplier, + List<WindmillStreamPool.StreamData<StreamT>> streams, + ConcurrentHashMap<StreamT, StreamData<StreamT>> holds) { + this.streams = streams; + this.streamTimeout = streamTimeout; + this.streamSupplier = streamSupplier; + this.holds = holds; + } + + public static <StreamT extends WindmillServerStub.WindmillStream> + WindmillStreamPool<StreamT> create( + int numStreams, Duration streamTimeout, Supplier<StreamT> streamSupplier) { + return new WindmillStreamPool<>( + streamTimeout, streamSupplier, emptyStreamList(numStreams), new ConcurrentHashMap<>()); + } + + /** + * Return a list of the given capacity populated with null. This list is used to load balance + * {@link WindmillStreamPool#getStream()} requests. It never grows in size and must be filled to + * capacity since the random used to grab a random stream is bound by the size of the list. + */ + @SuppressWarnings("nullness") Review Comment: ack yea, i tried this route. unfortunately if you annotate the list as nullable, it only checks allows that the list itself is null and will throw the following error if we are trying to call `add(null)` > error: [argument] incompatible argument for parameter arg0 of add. streamz.add(null); ^ found : null (NullType) required: @Initialized @NonNull StreamData<StreamT extends @Initialized @NonNull WindmillStream> ` i added a StreamLoadBalancer helper class to handle this using `Map<Integer, Stream>` with the key space bounded to the `capacity` which is `numStreams`. so now we don't have to deal with `null` -- 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]
