001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018package org.apache.hadoop.hbase.mapred; 019 020import java.io.IOException; 021import org.apache.hadoop.hbase.HBaseConfiguration; 022import org.apache.hadoop.hbase.TableName; 023import org.apache.hadoop.hbase.client.Connection; 024import org.apache.hadoop.hbase.client.ConnectionFactory; 025import org.apache.hadoop.hbase.client.RegionLocator; 026import org.apache.hadoop.hbase.io.ImmutableBytesWritable; 027import org.apache.hadoop.hbase.util.Bytes; 028import org.apache.hadoop.mapred.JobConf; 029import org.apache.hadoop.mapred.Partitioner; 030import org.apache.yetus.audience.InterfaceAudience; 031import org.slf4j.Logger; 032import org.slf4j.LoggerFactory; 033 034/** 035 * This is used to partition the output keys into groups of keys. Keys are grouped according to the 036 * regions that currently exist so that each reducer fills a single region so load is distributed. 037 * @param <K2> 038 * @param <V2> 039 */ 040@InterfaceAudience.Public 041public class HRegionPartitioner<K2, V2> implements Partitioner<ImmutableBytesWritable, V2> { 042 private static final Logger LOG = LoggerFactory.getLogger(HRegionPartitioner.class); 043 // Connection and locator are not cleaned up; they just die when partitioner is done. 044 private Connection connection; 045 private RegionLocator locator; 046 private byte[][] startKeys; 047 048 @Override 049 public void configure(JobConf job) { 050 try { 051 this.connection = ConnectionFactory.createConnection(HBaseConfiguration.create(job)); 052 TableName tableName = TableName.valueOf(job.get(TableOutputFormat.OUTPUT_TABLE)); 053 this.locator = this.connection.getRegionLocator(tableName); 054 } catch (IOException e) { 055 LOG.error(e.toString(), e); 056 } 057 058 try { 059 this.startKeys = this.locator.getStartKeys(); 060 } catch (IOException e) { 061 LOG.error(e.toString(), e); 062 } 063 } 064 065 @Override 066 public int getPartition(ImmutableBytesWritable key, V2 value, int numPartitions) { 067 byte[] region = null; 068 // Only one region return 0 069 if (this.startKeys.length == 1) { 070 return 0; 071 } 072 try { 073 // Not sure if this is cached after a split so we could have problems 074 // here if a region splits while mapping 075 region = locator.getRegionLocation(key.get()).getRegion().getStartKey(); 076 } catch (IOException e) { 077 LOG.error(e.toString(), e); 078 } 079 for (int i = 0; i < this.startKeys.length; i++) { 080 if (Bytes.compareTo(region, this.startKeys[i]) == 0) { 081 if (i >= numPartitions) { 082 // cover if we have less reduces then regions. 083 return (Integer.toString(i).hashCode() & Integer.MAX_VALUE) % numPartitions; 084 } 085 return i; 086 } 087 } 088 // if above fails to find start key that match we need to return something 089 return 0; 090 } 091}