/**
* 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.exec.mr;
import java.io.IOException;
import java.lang.management.ManagementFactory;
import java.lang.management.MemoryMXBean;
import java.net.URLClassLoader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.hive.ql.exec.MapredContext;
import org.apache.hadoop.hive.ql.exec.Operator;
import org.apache.hadoop.hive.ql.exec.Utilities;
import org.apache.hadoop.hive.ql.exec.mr.ExecMapper.ReportStats;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.plan.ReduceWork;
import org.apache.hadoop.hive.ql.plan.TableDesc;
import org.apache.hadoop.hive.serde2.Deserializer;
import org.apache.hadoop.hive.serde2.SerDeException;
import org.apache.hadoop.hive.serde2.SerDeUtils;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorFactory;
import org.apache.hadoop.io.BytesWritable;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.MapReduceBase;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reducer;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.util.ReflectionUtils;
import org.apache.hadoop.util.StringUtils;
/**
* ExecReducer is the generic Reducer class for Hive. Together with ExecMapper it is
* the bridge between the map-reduce framework and the Hive operator pipeline at
* execution time. It's main responsibilities are:
*
* - Load and setup the operator pipeline from XML
* - Run the pipeline by transforming key, value pairs to records and forwarding them to the operators
* - Sending start and end group messages to separate records with same key from one another
* - Catch and handle errors during execution of the operators.
*
*/
public class ExecReducer extends MapReduceBase implements Reducer {
private static final Logger LOG = LoggerFactory.getLogger("ExecReducer");
private static final boolean isInfoEnabled = LOG.isInfoEnabled();
private static final boolean isTraceEnabled = LOG.isTraceEnabled();
private static final String PLAN_KEY = "__REDUCE_PLAN__";
// Input value serde needs to be an array to support different SerDe
// for different tags
private final Deserializer[] inputValueDeserializer = new Deserializer[Byte.MAX_VALUE];
private final Object[] valueObject = new Object[Byte.MAX_VALUE];
private final List<Object> row = new ArrayList<Object>(Utilities.reduceFieldNameList.size());
// TODO: move to DynamicSerDe when it's ready
private Deserializer inputKeyDeserializer;
private JobConf jc;
private OutputCollector<?, ?> oc;
private Operator<?> reducer;
private Reporter rp;
private boolean abort = false;
private boolean isTagged = false;
private TableDesc keyTableDesc;
private TableDesc[] valueTableDesc;
private ObjectInspector[] rowObjectInspector;
// runtime objects
private transient Object keyObject;
private transient BytesWritable groupKey;
@Override
public void configure(JobConf job) {
rowObjectInspector = new ObjectInspector[Byte.MAX_VALUE];
ObjectInspector[] valueObjectInspector = new ObjectInspector[Byte.MAX_VALUE];
ObjectInspector keyObjectInspector;
if (isInfoEnabled) {
try {
LOG.info("conf classpath = "
+ Arrays.asList(((URLClassLoader) job.getClassLoader()).getURLs()));
LOG.info("thread classpath = "
+ Arrays.asList(((URLClassLoader) Thread.currentThread()
.getContextClassLoader()).getURLs()));
} catch (Exception e) {
LOG.info("cannot get classpath: " + e.getMessage());
}
}
jc = job;
ReduceWork gWork = Utilities.getReduceWork(job);
reducer = gWork.getReducer();
reducer.setParentOperators(null); // clear out any parents as reducer is the
// root
isTagged = gWork.getNeedsTagging();
try {
keyTableDesc = gWork.getKeyDesc();
inputKeyDeserializer = ReflectionUtils.newInstance(keyTableDesc
.getDeserializerClass(), null);
SerDeUtils.initializeSerDe(inputKeyDeserializer, null, keyTableDesc.getProperties(), null);
keyObjectInspector = inputKeyDeserializer.getObjectInspector();
valueTableDesc = new TableDesc[gWork.getTagToValueDesc().size()];
for (int tag = 0; tag < gWork.getTagToValueDesc().size(); tag++) {
// We should initialize the SerDe with the TypeInfo when available.
valueTableDesc[tag] = gWork.getTagToValueDesc().get(tag);
inputValueDeserializer[tag] = ReflectionUtils.newInstance(
valueTableDesc[tag].getDeserializerClass(), null);
SerDeUtils.initializeSerDe(inputValueDeserializer[tag], null,
valueTableDesc[tag].getProperties(), null);
valueObjectInspector[tag] = inputValueDeserializer[tag]
.getObjectInspector();
ArrayList<ObjectInspector> ois = new ArrayList<ObjectInspector>();
ois.add(keyObjectInspector);
ois.add(valueObjectInspector[tag]);
rowObjectInspector[tag] = ObjectInspectorFactory
.getStandardStructObjectInspector(Utilities.reduceFieldNameList, ois);
}
} catch (Exception e) {
throw new RuntimeException(e);
}
MapredContext.init(false, new JobConf(jc));
// initialize reduce operator tree
try {
LOG.info(reducer.dump(0));
reducer.initialize(jc, rowObjectInspector);
} catch (Throwable e) {
abort = true;
if (e instanceof OutOfMemoryError) {
// Don't create a new object if we are already out of memory
throw (OutOfMemoryError) e;
} else {
throw new RuntimeException("Reduce operator initialization failed", e);
}
}
}
@Override
public void reduce(Object key, Iterator values, OutputCollector output,
Reporter reporter) throws IOException {
if (reducer.getDone()) {
return;
}
if (oc == null) {
// propagate reporter and output collector to all operators
oc = output;
rp = reporter;
reducer.setReporter(rp);
MapredContext.get().setReporter(reporter);
}
try {
BytesWritable keyWritable = (BytesWritable) key;
byte tag = 0;
if (isTagged) {
// remove the tag from key coming out of reducer
// and store it in separate variable.
int size = keyWritable.getSize() - 1;
tag = keyWritable.get()[size];
keyWritable.setSize(size);
}
if (!keyWritable.equals(groupKey)) {
// If a operator wants to do some work at the beginning of a group
if (groupKey == null) { // the first group
groupKey = new BytesWritable();
} else {
// If a operator wants to do some work at the end of a group
if (isTraceEnabled) {
LOG.trace("End Group");
}
reducer.endGroup();
}
try {
keyObject = inputKeyDeserializer.deserialize(keyWritable);
} catch (Exception e) {
throw new HiveException(
"Hive Runtime Error: Unable to deserialize reduce input key from "
+ Utilities.formatBinaryString(keyWritable.get(), 0,
keyWritable.getSize()) + " with properties "
+ keyTableDesc.getProperties(), e);
}
groupKey.set(keyWritable.get(), 0, keyWritable.getSize());
if (isTraceEnabled) {
LOG.trace("Start Group");
}
reducer.startGroup();
reducer.setGroupKeyObject(keyObject);
}
// System.err.print(keyObject.toString());
while (values.hasNext()) {
BytesWritable valueWritable = (BytesWritable) values.next();
// System.err.print(who.getHo().toString());
try {
valueObject[tag] = inputValueDeserializer[tag].deserialize(valueWritable);
} catch (SerDeException e) {
throw new HiveException(
"Hive Runtime Error: Unable to deserialize reduce input value (tag="
+ tag
+ ") from "
+ Utilities.formatBinaryString(valueWritable.get(), 0,
valueWritable.getSize()) + " with properties "
+ valueTableDesc[tag].getProperties(), e);
}
row.clear();
row.add(keyObject);
row.add(valueObject[tag]);
try {
reducer.process(row, tag);
} catch (Exception e) {
String rowString = null;
try {
rowString = SerDeUtils.getJSONString(row, rowObjectInspector[tag]);
} catch (Exception e2) {
rowString = "[Error getting row data with exception " +
StringUtils.stringifyException(e2) + " ]";
}
throw new HiveException("Hive Runtime Error while processing row (tag="
+ tag + ") " + rowString, e);
}
}
} catch (Throwable e) {
abort = true;
if (e instanceof OutOfMemoryError) {
// Don't create a new object if we are already out of memory
throw (OutOfMemoryError) e;
} else {
LOG.error(StringUtils.stringifyException(e));
throw new RuntimeException(e);
}
}
}
@Override
public void close() {
// No row was processed
if (oc == null && isTraceEnabled) {
LOG.trace("Close called without any rows processed");
}
try {
if (groupKey != null) {
// If a operator wants to do some work at the end of a group
if (isTraceEnabled) {
LOG.trace("End Group");
}
reducer.endGroup();
}
reducer.close(abort);
ReportStats rps = new ReportStats(rp, jc);
reducer.preorderMap(rps);
} catch (Exception e) {
if (!abort) {
// signal new failure to map-reduce
LOG.error("Hit error while closing operators - failing tree");
throw new RuntimeException("Hive Runtime Error while closing operators: "
+ e.getMessage(), e);
}
} finally {
MapredContext.close();
Utilities.clearWorkMap(jc);
}
}
}