| /* |
| * 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.hadoop.hbase.regionserver; |
| |
| import java.util.concurrent.CompletableFuture; |
| import java.util.concurrent.TimeUnit; |
| import java.util.function.Supplier; |
| import java.util.stream.Stream; |
| import org.apache.hadoop.hbase.HBaseClassTestRule; |
| import org.apache.hadoop.hbase.client.RegionInfo; |
| import org.apache.hadoop.hbase.client.RegionInfoBuilder; |
| import org.apache.hadoop.hbase.testclassification.LargeTests; |
| import org.apache.hadoop.hbase.testclassification.RegionServerTests; |
| import org.junit.ClassRule; |
| import org.junit.Test; |
| import org.junit.experimental.categories.Category; |
| |
| /** |
| * Test for the tangled mess that is static initialization of our our {@link RegionInfo} and |
| * {@link RegionInfoBuilder}, as reported on HBASE-24896. The condition being tested can only be |
| * reproduced the first time a JVM loads the classes under test. Thus, this test is marked as a |
| * {@link LargeTests} because, under their current configuration, tests in that category are run |
| * in their own JVM instances. |
| */ |
| @SuppressWarnings("deprecation") |
| @Category({ RegionServerTests.class, LargeTests.class}) |
| public class TestRegionInfoStaticInitialization { |
| @ClassRule |
| public static final HBaseClassTestRule CLASS_RULE = |
| HBaseClassTestRule.forClass(TestRegionInfoStaticInitialization.class); |
| |
| @Test |
| public void testParallelStaticInitialization() throws Exception { |
| // The JVM loads symbols lazily. These suppliers reference two symbols that, before this patch, |
| // are mutually dependent and expose a deadlock in the loading of symbols from RegionInfo and |
| // RegionInfoBuilder. |
| final Supplier<RegionInfo> retrieveUNDEFINED = () -> RegionInfo.UNDEFINED; |
| final Supplier<RegionInfo> retrieveMetaRegionInfo = |
| () -> RegionInfoBuilder.FIRST_META_REGIONINFO; |
| |
| // The test runs multiple threads that reference these mutually dependent symbols. In order to |
| // express this bug, these threads need to access these symbols at roughly the same time, so |
| // that the classloader is asked to materialize these symbols concurrently. These Suppliers are |
| // run on threads that have already been allocated, managed by the system's ForkJoin pool. |
| final CompletableFuture<?>[] futures = Stream.of( |
| retrieveUNDEFINED, retrieveMetaRegionInfo, retrieveUNDEFINED, retrieveMetaRegionInfo) |
| .map(CompletableFuture::supplyAsync) |
| .toArray(CompletableFuture<?>[]::new); |
| |
| // Loading classes should be relatively fast. 5 seconds is an arbitrary choice of timeout. It |
| // was chosen under the assumption that loading these symbols should complete much faster than |
| // this window. |
| CompletableFuture.allOf(futures).get(5, TimeUnit.SECONDS); |
| } |
| } |