gianm commented on code in PR #16372: URL: https://github.com/apache/druid/pull/16372#discussion_r1588038254
########## processing/src/main/java/org/apache/druid/query/groupby/GroupByResourcesReservationPool.java: ########## @@ -104,18 +104,23 @@ public GroupByResourcesReservationPool( } /** - * Reserves appropriate resources, and maps it to the queryResourceId (usually the query's resource id) in the internal map + * Reserves appropriate resources, and maps it to the queryResourceId (usually the query's resource id) in the internal map. + * This is a blocking call, and can block upto the given query's timeout Review Comment: up to (spelling) ########## processing/src/test/java/org/apache/druid/query/groupby/GroupByResourcesReservationPoolTest.java: ########## @@ -0,0 +1,174 @@ +/* + * 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.druid.query.groupby; + +import com.google.common.collect.ImmutableList; +import com.google.common.collect.ImmutableMap; +import org.apache.druid.collections.BlockingPool; +import org.apache.druid.collections.DefaultBlockingPool; +import org.apache.druid.java.util.common.Intervals; +import org.apache.druid.java.util.common.concurrent.Execs; +import org.apache.druid.java.util.common.granularity.Granularities; +import org.apache.druid.query.QueryResourceId; +import org.apache.druid.query.dimension.DefaultDimensionSpec; +import org.junit.Assert; +import org.junit.Test; + +import java.nio.ByteBuffer; +import java.util.concurrent.CountDownLatch; +import java.util.concurrent.ExecutorService; + +public class GroupByResourcesReservationPoolTest +{ + + /** + * This test confirms that the interleaved GroupByResourcesReservationPool.reserve() and GroupByResourcesReservationPool.clean() + * between multiple threads succeed. It is specifically designed to test the case when the operations are interleaved in the + * following manner: + * <p> + * THREAD1 THREAD2 + * pool.reserve(query1) + * pool.reserve(query2) + * pool.clean(query1) + * <p> + * This test assumes a few things about the implementation of the interfaces, which are laid out in the comments. + * <p> + * The test should complete under 10 seconds, and the majority of the time would be consumed by waiting for the thread + * that sleeps for 5 seconds Review Comment: I don't think we should add new unit tests that have sleeps; the test suite takes long enough to run already. They are also a sign of a test that is not robust. Is it possible to rewrite this test to not use a sleep? If not, I'd suggest having it be `@Ignore` so it doesn't run on every test suite run. Then include a comment in the code of `GroupByResourcesReservationPool` itself that says if a future developer is changing the logic, they should run this test manually to ensure they aren't introducing a deadlock. ########## processing/src/main/java/org/apache/druid/query/groupby/GroupByResourcesReservationPool.java: ########## @@ -104,18 +104,23 @@ public GroupByResourcesReservationPool( } /** - * Reserves appropriate resources, and maps it to the queryResourceId (usually the query's resource id) in the internal map + * Reserves appropriate resources, and maps it to the queryResourceId (usually the query's resource id) in the internal map. + * This is a blocking call, and can block upto the given query's timeout */ public void reserve(QueryResourceId queryResourceId, GroupByQuery groupByQuery, boolean willMergeRunner) { if (queryResourceId == null) { throw DruidException.defensive("Query resource id must be populated"); } + GroupByQueryResources resources = + GroupingEngine.prepareResource(groupByQuery, mergeBufferPool, willMergeRunner, groupByQueryConfig); + pool.compute(queryResourceId, (id, existingResource) -> { if (existingResource != null) { + resources.close(); Review Comment: Rather than risk `resources.close()` holding the `compute` lock for too long, how about using `pool.putIfAbsent` instead, and then if `putIfAbsent` returns nonnull (signifying there was some existing resource), then call `resources.close()` and throw the defensive exception. -- This is an automated message from the Apache Git Service. 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