deniskuzZ commented on code in PR #3303: URL: https://github.com/apache/hive/pull/3303#discussion_r887860283
########## ql/src/java/org/apache/hadoop/hive/ql/txn/compactor/CompactionHeartbeatService.java: ########## @@ -0,0 +1,256 @@ +/* + * 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.hive.ql.txn.compactor; + +import org.apache.commons.pool2.BasePooledObjectFactory; +import org.apache.commons.pool2.ObjectPool; +import org.apache.commons.pool2.PooledObject; +import org.apache.commons.pool2.impl.DefaultPooledObject; +import org.apache.commons.pool2.impl.GenericObjectPool; +import org.apache.commons.pool2.impl.GenericObjectPoolConfig; +import org.apache.hadoop.hive.conf.HiveConf; +import org.apache.hadoop.hive.metastore.HiveMetaStoreUtils; +import org.apache.hadoop.hive.metastore.IMetaStoreClient; +import org.apache.hadoop.hive.metastore.conf.MetastoreConf; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.NoSuchElementException; +import java.util.Objects; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.Executors; +import java.util.concurrent.Future; +import java.util.concurrent.ScheduledExecutorService; +import java.util.concurrent.TimeUnit; + +/** + * Singleton service responsible for heartbeating the compaction transactions. + */ +class CompactionHeartbeatService { + + + private static final Logger LOG = LoggerFactory.getLogger(CompactionHeartbeatService.class); + + private static volatile CompactionHeartbeatService INSTANCE; + + /** + * Return the singleton instance of this class. + * @param conf The {@link HiveConf} used to create the service. Used only during the firsst call + * @return Returns the singleton {@link CompactionHeartbeatService} + * @throws IllegalStateException Thrown when the service has already been shut down. + */ + static CompactionHeartbeatService getInstance(HiveConf conf) { + if (INSTANCE == null) { + synchronized (CompactionHeartbeatService.class) { + if (INSTANCE == null) { + LOG.debug("Initializing compaction txn heartbeater service."); + INSTANCE = new CompactionHeartbeatService(conf); + Runtime.getRuntime().addShutdownHook(new Thread(() -> { + try { + INSTANCE.shutdown(); + } catch (InterruptedException e) { + Thread.currentThread().interrupt(); + } + })); + } + } + } + if (INSTANCE.heartbeatExecutor.isShutdown()) { + throw new IllegalStateException("The CompactionHeartbeatService is already shut down!"); + } + return INSTANCE; + } + + private final ScheduledExecutorService heartbeatExecutor; + private final ObjectPool<IMetaStoreClient> clientPool; + private final long initialDelay; + private final long period; + private final ConcurrentHashMap<Long, TaskWrapper> tasks = new ConcurrentHashMap<>(30); + + /** + * Starts the heartbeat for the given transaction + * @param txnId The id of the compaction txn + * @param lockId The id of the lock associated with the txn + * @param tableName Required for logging only + * @throws IllegalStateException Thrown when the heartbeat for the given txn has already been started. + */ + void startHeartbeat(long txnId, long lockId, String tableName) { + if (tasks.containsKey(txnId)) { + throw new IllegalStateException("Heartbeat already started for TXN " + txnId); + } + LOG.info("Submitting heartbeat task for TXN {}", txnId); + CompactionHeartbeater heartbeater = new CompactionHeartbeater(txnId, lockId, tableName); + Future<?> submittedTask = heartbeatExecutor.scheduleAtFixedRate(heartbeater, initialDelay, period, TimeUnit.MILLISECONDS); + tasks.put(txnId, new TaskWrapper(heartbeater, submittedTask)); + } + + /** + * Stops the heartbeat for the given transaction + * @param txnId The id of the compaction txn + * @throws IllegalStateException Thrown when there is no {@link CompactionHeartbeater} task associated with the + * given txnId. + */ + void stopHeartbeat(long txnId) { + LOG.info("Stopping heartbeat task for TXN {}", txnId); + TaskWrapper wrapper = tasks.get(txnId); + if (wrapper == null) { + throw new IllegalStateException("No registered heartbeat found for TXN " + txnId); + } + wrapper.future.cancel(false); + try { + wrapper.heartbeater.waitUntilFinish(); Review Comment: should we gracefully wait for a certain time and then issue a force terminate ? -- This is an automated message from the Apache Git Service. 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