Java tutorial
/** * * 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.util; import java.io.IOException; import java.io.InterruptedIOException; import java.util.List; import java.util.concurrent.ExecutorService; import java.util.concurrent.LinkedBlockingQueue; import java.util.concurrent.ThreadLocalRandom; import java.util.concurrent.ThreadPoolExecutor; import java.util.concurrent.TimeUnit; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.hbase.classification.InterfaceAudience; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.hbase.HConstants; import org.apache.hadoop.hbase.TableName; import org.apache.hadoop.hbase.client.Connection; import org.apache.hadoop.hbase.client.ConnectionFactory; import org.apache.hadoop.hbase.client.HConnection; import org.apache.hadoop.hbase.client.Row; import org.apache.hadoop.hbase.client.coprocessor.Batch; /** * Provides ability to create multiple HConnection instances and allows to process a batch of * actions using HConnection.processBatchCallback() */ @InterfaceAudience.Private public class MultiHConnection { private static final Log LOG = LogFactory.getLog(MultiHConnection.class); private HConnection[] hConnections; private final Object hConnectionsLock = new Object(); private int noOfConnections; private ExecutorService batchPool; /** * Create multiple HConnection instances and initialize a thread pool executor * @param conf configuration * @param noOfConnections total no of HConnections to create * @throws IOException */ public MultiHConnection(Configuration conf, int noOfConnections) throws IOException { this.noOfConnections = noOfConnections; synchronized (this.hConnectionsLock) { hConnections = new HConnection[noOfConnections]; for (int i = 0; i < noOfConnections; i++) { HConnection conn = (HConnection) ConnectionFactory.createConnection(conf); hConnections[i] = conn; } } createBatchPool(conf); } /** * Close the open connections and shutdown the batchpool */ public void close() { synchronized (hConnectionsLock) { if (hConnections != null) { for (Connection conn : hConnections) { if (conn != null) { try { conn.close(); } catch (IOException e) { LOG.info("Got exception in closing connection", e); } finally { conn = null; } } } hConnections = null; } } if (this.batchPool != null && !this.batchPool.isShutdown()) { this.batchPool.shutdown(); try { if (!this.batchPool.awaitTermination(10, TimeUnit.SECONDS)) { this.batchPool.shutdownNow(); } } catch (InterruptedException e) { this.batchPool.shutdownNow(); } } } /** * Randomly pick a connection and process the batch of actions for a given table * @param actions the actions * @param tableName table name * @param results the results array * @param callback * @throws IOException */ @SuppressWarnings("deprecation") public <R> void processBatchCallback(List<? extends Row> actions, TableName tableName, Object[] results, Batch.Callback<R> callback) throws IOException { // Currently used by RegionStateStore // A deprecated method is used as multiple threads accessing RegionStateStore do a single put // and htable is not thread safe. Alternative would be to create an Htable instance for each // put but that is not very efficient. // See HBASE-11610 for more details. try { hConnections[ThreadLocalRandom.current().nextInt(noOfConnections)].processBatchCallback(actions, tableName, this.batchPool, results, callback); } catch (InterruptedException e) { throw new InterruptedIOException(e.getMessage()); } } // Copied from ConnectionImplementation.getBatchPool() // We should get rid of this when HConnection.processBatchCallback is un-deprecated and provides // an API to manage a batch pool private void createBatchPool(Configuration conf) { // Use the same config for keep alive as in ConnectionImplementation.getBatchPool(); int maxThreads = conf.getInt("hbase.multihconnection.threads.max", 256); int coreThreads = conf.getInt("hbase.multihconnection.threads.core", 256); if (maxThreads == 0) { maxThreads = Runtime.getRuntime().availableProcessors() * 8; } if (coreThreads == 0) { coreThreads = Runtime.getRuntime().availableProcessors() * 8; } long keepAliveTime = conf.getLong("hbase.multihconnection.threads.keepalivetime", 60); LinkedBlockingQueue<Runnable> workQueue = new LinkedBlockingQueue<Runnable>(maxThreads * conf .getInt(HConstants.HBASE_CLIENT_MAX_TOTAL_TASKS, HConstants.DEFAULT_HBASE_CLIENT_MAX_TOTAL_TASKS)); ThreadPoolExecutor tpe = new ThreadPoolExecutor(coreThreads, maxThreads, keepAliveTime, TimeUnit.SECONDS, workQueue, Threads.newDaemonThreadFactory("MultiHConnection" + "-shared-")); tpe.allowCoreThreadTimeOut(true); this.batchPool = tpe; } }