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Fix another deadlock which can occur while acquiring merge buffers (#…
…16372) (#16427) Fixes a deadlock while acquiring merge buffers Co-authored-by: Laksh Singla <lakshsingla@gmail.com>
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227
...ing/src/test/java/org/apache/druid/query/groupby/GroupByResourcesReservationPoolTest.java
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| /* | ||
| * 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; | ||
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|
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| 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.error.DruidException; | ||
| 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.Ignore; | ||
| import org.junit.Test; | ||
|
|
||
| import java.nio.ByteBuffer; | ||
| import java.util.concurrent.CountDownLatch; | ||
| import java.util.concurrent.ExecutorService; | ||
|
|
||
| public class GroupByResourcesReservationPoolTest | ||
| { | ||
|
|
||
| /** | ||
| * CONFIG + QUERY require exactly 1 merge buffer to succeed if 'willMergeRunners' is true while allocating the resources | ||
| */ | ||
| private static final GroupByQueryConfig CONFIG = new GroupByQueryConfig(); | ||
| private static final GroupByQuery QUERY = GroupByQuery.builder() | ||
| .setInterval(Intervals.ETERNITY) | ||
| .setDataSource("foo") | ||
| .setDimensions( | ||
| ImmutableList.of( | ||
| new DefaultDimensionSpec("dim2", "_d0") | ||
| ) | ||
| ) | ||
| .setGranularity(Granularities.ALL) | ||
| .setContext( | ||
| ImmutableMap.of("timeout", 0) | ||
| ) // Query can block indefinitely | ||
| .build(); | ||
|
|
||
| /** | ||
| * 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 | ||
| */ | ||
| @Ignore( | ||
| "Isn't run as a part of CI since it sleeps for 5 seconds. Callers must run the test manually if any changes are made " | ||
| + "to the corresponding class" | ||
| ) | ||
| @Test(timeout = 100_000L) | ||
| public void testInterleavedReserveAndRemove() | ||
| { | ||
| ExecutorService executor = Execs.multiThreaded(3, "group-by-resources-reservation-pool-test-%d"); | ||
|
|
||
| // Sanity checks that the query will acquire exactly one merge buffer. This safeguards the test being useful in | ||
| // case the merge buffer acquisition code changes to acquire less than one merge buffer (the test would be | ||
| // useless in that case) or more than one merge buffer (the test would incorrectly fail in that case) | ||
| Assert.assertEquals( | ||
| 1, | ||
| GroupByQueryResources.countRequiredMergeBufferNumForMergingQueryRunner(CONFIG, QUERY) | ||
| + GroupByQueryResources.countRequiredMergeBufferNumForToolchestMerge(QUERY) | ||
| ); | ||
|
|
||
| // Blocking pool with a single buffer, which means only one of the queries can succeed at a time | ||
| BlockingPool<ByteBuffer> mergeBufferPool = new DefaultBlockingPool<>(() -> ByteBuffer.allocate(100), 1); | ||
| GroupByResourcesReservationPool groupByResourcesReservationPool = | ||
| new GroupByResourcesReservationPool(mergeBufferPool, CONFIG); | ||
|
|
||
| // Latch indicating that the first thread has called reservationPool.reserve() | ||
| CountDownLatch reserveCalledByFirstThread = new CountDownLatch(1); | ||
| // Latch indicating that the second thread has called reservationPool.reserve() | ||
| CountDownLatch reserveCalledBySecondThread = new CountDownLatch(1); | ||
| // Latch indicating that all the threads have been completed successfully. Main thread waits on this latch before exiting | ||
| CountDownLatch threadsCompleted = new CountDownLatch(2); | ||
|
|
||
| // THREAD 1 | ||
| executor.submit(() -> { | ||
|
|
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| QueryResourceId queryResourceId1 = new QueryResourceId("test-id-1") | ||
| { | ||
| @Override | ||
| public int hashCode() | ||
| { | ||
| // IMPORTANT ASSUMPTION: For the test to be useful, it assumes that under the hood we are using a | ||
| // ConcurrentHashMap<QueryResourceId, GroupByResources> (or a concurrent map with similar implementation) that | ||
| // implements granular locking of the nodes | ||
| // The hashCode of the queryResourceId used in Thread1 and Thread2 is the same. Therefore, both the queryIds | ||
| // would be guarded by the same lock | ||
| return 10; | ||
| } | ||
|
|
||
| @Override | ||
| public boolean equals(Object o) | ||
| { | ||
| return super.equals(o); | ||
| } | ||
| }; | ||
| groupByResourcesReservationPool.reserve(queryResourceId1, QUERY, true); | ||
| reserveCalledByFirstThread.countDown(); | ||
| try { | ||
| reserveCalledBySecondThread.await(); | ||
| } | ||
| catch (InterruptedException e) { | ||
| Assert.fail("Interrupted while waiting for second reserve call to be made"); | ||
| } | ||
| groupByResourcesReservationPool.clean(queryResourceId1); | ||
| threadsCompleted.countDown(); | ||
| }); | ||
|
|
||
| // THREAD 2 | ||
| executor.submit(() -> { | ||
| try { | ||
| reserveCalledByFirstThread.await(); | ||
| } | ||
| catch (InterruptedException e) { | ||
| Assert.fail("Interrupted while waiting for first reserve call to be made"); | ||
| } | ||
|
|
||
| QueryResourceId queryResourceId2 = new QueryResourceId("test-id-2") | ||
| { | ||
| @Override | ||
| public int hashCode() | ||
| { | ||
| return 10; | ||
| } | ||
|
|
||
| @Override | ||
| public boolean equals(Object o) | ||
| { | ||
| return super.equals(o); | ||
| } | ||
| }; | ||
|
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| // Since the reserve() call is blocking, we need to execute it separately, so that we can count down the latch | ||
| // and inform Thread1 the reserve call has been made by this thread | ||
| executor.submit(() -> { | ||
| groupByResourcesReservationPool.reserve(queryResourceId2, QUERY, true); | ||
| threadsCompleted.countDown(); | ||
| }); | ||
| try { | ||
| // This sleep call "ensures" that the statment pool.reserve(queryResourceId2) is called before we release the | ||
| // latch (that will cause Thread1 to release the acquired resources). It still doesn't guarantee the previous | ||
| // statement, however that's the best we can do, given that reserve() is blocking | ||
| Thread.sleep(5_000); | ||
| } | ||
| catch (InterruptedException e) { | ||
| Assert.fail("Interrupted while sleeping"); | ||
| } | ||
| reserveCalledBySecondThread.countDown(); | ||
| }); | ||
|
|
||
| try { | ||
| threadsCompleted.await(); | ||
| } | ||
| catch (InterruptedException e) { | ||
| Assert.fail("Interrupted while waiting for the threads to complete"); | ||
| } | ||
| } | ||
|
|
||
| @Test | ||
| public void testMultipleSimultaneousAllocationAttemptsFail() | ||
| { | ||
| BlockingPool<ByteBuffer> mergeBufferPool = new DefaultBlockingPool<>(() -> ByteBuffer.allocate(100), 1); | ||
| GroupByResourcesReservationPool groupByResourcesReservationPool = | ||
| new GroupByResourcesReservationPool(mergeBufferPool, CONFIG); | ||
| QueryResourceId queryResourceId = new QueryResourceId("test-id"); | ||
|
|
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| groupByResourcesReservationPool.reserve(queryResourceId, QUERY, true); | ||
|
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| Assert.assertThrows( | ||
| DruidException.class, | ||
| () -> groupByResourcesReservationPool.reserve(queryResourceId, QUERY, true) | ||
| ); | ||
| } | ||
|
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||
| @Test | ||
| public void testMultipleSequentialAllocationAttemptsSucceed() | ||
| { | ||
| BlockingPool<ByteBuffer> mergeBufferPool = new DefaultBlockingPool<>(() -> ByteBuffer.allocate(100), 1); | ||
| GroupByResourcesReservationPool groupByResourcesReservationPool = | ||
| new GroupByResourcesReservationPool(mergeBufferPool, CONFIG); | ||
| QueryResourceId queryResourceId = new QueryResourceId("test-id"); | ||
|
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| groupByResourcesReservationPool.reserve(queryResourceId, QUERY, true); | ||
| GroupByQueryResources oldResources = groupByResourcesReservationPool.fetch(queryResourceId); | ||
|
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| // Cleanup the resources | ||
| groupByResourcesReservationPool.clean(queryResourceId); | ||
|
|
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| // Repeat the calls | ||
| groupByResourcesReservationPool.reserve(queryResourceId, QUERY, true); | ||
| GroupByQueryResources newResources = groupByResourcesReservationPool.fetch(queryResourceId); | ||
| Assert.assertNotNull(newResources); | ||
|
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| Assert.assertNotSame(oldResources, newResources); | ||
| } | ||
| } |