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/**
* 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.tez;
import java.io.IOException;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hive.ql.exec.Utilities;
import org.apache.hadoop.hive.ql.io.HiveFileFormatUtils;
import org.apache.hadoop.hive.ql.io.HiveInputFormat;
import org.apache.hadoop.hive.ql.plan.MapWork;
import org.apache.hadoop.hive.ql.plan.PartitionDesc;
import org.apache.hadoop.mapred.FileSplit;
import org.apache.hadoop.mapred.InputSplit;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.split.TezGroupedSplit;
import org.apache.hadoop.mapred.split.TezMapredSplitsGrouper;
import org.apache.tez.dag.api.TaskLocationHint;
import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.Lists;
import com.google.common.collect.Multimap;
/**
* SplitGrouper is used to combine splits based on head room and locality. It
* also enforces restrictions around schema, file format and bucketing.
*/
public class SplitGrouper {
private static final Log LOG = LogFactory.getLog(SplitGrouper.class);
// TODO This needs to be looked at. Map of Map to Map... Made concurrent for now since split generation
// can happen in parallel.
private static final Map, Map> cache =
new ConcurrentHashMap<>();
private final TezMapredSplitsGrouper tezGrouper = new TezMapredSplitsGrouper();
/**
* group splits for each bucket separately - while evenly filling all the
* available slots with tasks
*/
public Multimap group(Configuration conf,
Multimap bucketSplitMultimap, int availableSlots, float waves)
throws IOException {
// figure out how many tasks we want for each bucket
Map bucketTaskMap =
estimateBucketSizes(availableSlots, waves, bucketSplitMultimap.asMap());
// allocate map bucket id to grouped splits
Multimap bucketGroupedSplitMultimap =
ArrayListMultimap. create();
// use the tez grouper to combine splits once per bucket
for (int bucketId : bucketSplitMultimap.keySet()) {
Collection inputSplitCollection = bucketSplitMultimap.get(bucketId);
InputSplit[] rawSplits = inputSplitCollection.toArray(new InputSplit[0]);
InputSplit[] groupedSplits =
tezGrouper.getGroupedSplits(conf, rawSplits, bucketTaskMap.get(bucketId),
HiveInputFormat.class.getName());
LOG.info("Original split size is " + rawSplits.length + " grouped split size is "
+ groupedSplits.length + ", for bucket: " + bucketId);
for (InputSplit inSplit : groupedSplits) {
bucketGroupedSplitMultimap.put(bucketId, inSplit);
}
}
return bucketGroupedSplitMultimap;
}
/**
* Create task location hints from a set of input splits
* @param splits the actual splits
* @return taskLocationHints - 1 per input split specified
* @throws IOException
*/
public List createTaskLocationHints(InputSplit[] splits) throws IOException {
List locationHints = Lists.newArrayListWithCapacity(splits.length);
for (InputSplit split : splits) {
String rack = (split instanceof TezGroupedSplit) ? ((TezGroupedSplit) split).getRack() : null;
if (rack == null) {
if (split.getLocations() != null) {
locationHints.add(TaskLocationHint.createTaskLocationHint(new HashSet(Arrays.asList(split
.getLocations())), null));
} else {
locationHints.add(TaskLocationHint.createTaskLocationHint(null, null));
}
} else {
locationHints.add(TaskLocationHint.createTaskLocationHint(null, Collections.singleton(rack)));
}
}
return locationHints;
}
/** Generate groups of splits, separated by schema evolution boundaries */
public Multimap generateGroupedSplits(JobConf jobConf,
Configuration conf,
InputSplit[] splits,
float waves, int availableSlots)
throws Exception {
return generateGroupedSplits(jobConf, conf, splits, waves, availableSlots, null, true);
}
/** Generate groups of splits, separated by schema evolution boundaries */
public Multimap generateGroupedSplits(JobConf jobConf,
Configuration conf,
InputSplit[] splits,
float waves, int availableSlots,
String inputName,
boolean groupAcrossFiles) throws
Exception {
MapWork work = populateMapWork(jobConf, inputName);
Multimap bucketSplitMultiMap =
ArrayListMultimap. create();
int i = 0;
InputSplit prevSplit = null;
for (InputSplit s : splits) {
// this is the bit where we make sure we don't group across partition
// schema boundaries
if (schemaEvolved(s, prevSplit, groupAcrossFiles, work)) {
++i;
prevSplit = s;
}
bucketSplitMultiMap.put(i, s);
}
LOG.info("# Src groups for split generation: " + (i + 1));
// group them into the chunks we want
Multimap groupedSplits =
this.group(jobConf, bucketSplitMultiMap, availableSlots, waves);
return groupedSplits;
}
/**
* get the size estimates for each bucket in tasks. This is used to make sure
* we allocate the head room evenly
*/
private Map estimateBucketSizes(int availableSlots, float waves,
Map> bucketSplitMap) {
// mapping of bucket id to size of all splits in bucket in bytes
Map bucketSizeMap = new HashMap();
// mapping of bucket id to number of required tasks to run
Map bucketTaskMap = new HashMap();
// compute the total size per bucket
long totalSize = 0;
boolean earlyExit = false;
for (int bucketId : bucketSplitMap.keySet()) {
long size = 0;
for (InputSplit s : bucketSplitMap.get(bucketId)) {
// the incoming split may not be a file split when we are re-grouping TezGroupedSplits in
// the case of SMB join. So in this case, we can do an early exit by not doing the
// calculation for bucketSizeMap. Each bucket will assume it can fill availableSlots * waves
// (preset to 0.5) for SMB join.
if (!(s instanceof FileSplit)) {
bucketTaskMap.put(bucketId, (int) (availableSlots * waves));
earlyExit = true;
continue;
}
FileSplit fsplit = (FileSplit) s;
size += fsplit.getLength();
totalSize += fsplit.getLength();
}
bucketSizeMap.put(bucketId, size);
}
if (earlyExit) {
return bucketTaskMap;
}
// compute the number of tasks
for (int bucketId : bucketSizeMap.keySet()) {
int numEstimatedTasks = 0;
if (totalSize != 0) {
// availableSlots * waves => desired slots to fill
// sizePerBucket/totalSize => weight for particular bucket. weights add
// up to 1.
numEstimatedTasks =
(int) (availableSlots * waves * bucketSizeMap.get(bucketId) / totalSize);
}
LOG.info("Estimated number of tasks: " + numEstimatedTasks + " for bucket " + bucketId);
if (numEstimatedTasks == 0) {
numEstimatedTasks = 1;
}
bucketTaskMap.put(bucketId, numEstimatedTasks);
}
return bucketTaskMap;
}
private static MapWork populateMapWork(JobConf jobConf, String inputName) {
MapWork work = null;
if (inputName != null) {
work = (MapWork) Utilities.getMergeWork(jobConf, inputName);
// work can still be null if there is no merge work for this input
}
if (work == null) {
work = Utilities.getMapWork(jobConf);
}
return work;
}
private boolean schemaEvolved(InputSplit s, InputSplit prevSplit, boolean groupAcrossFiles,
MapWork work) throws IOException {
boolean retval = false;
Path path = ((FileSplit) s).getPath();
PartitionDesc pd =
HiveFileFormatUtils.getPartitionDescFromPathRecursively(work.getPathToPartitionInfo(),
path, cache);
String currentDeserializerClass = pd.getDeserializerClassName();
Class currentInputFormatClass = pd.getInputFileFormatClass();
Class previousInputFormatClass = null;
String previousDeserializerClass = null;
if (prevSplit != null) {
Path prevPath = ((FileSplit) prevSplit).getPath();
if (!groupAcrossFiles) {
return !path.equals(prevPath);
}
PartitionDesc prevPD =
HiveFileFormatUtils.getPartitionDescFromPathRecursively(work.getPathToPartitionInfo(),
prevPath, cache);
previousDeserializerClass = prevPD.getDeserializerClassName();
previousInputFormatClass = prevPD.getInputFileFormatClass();
}
if ((currentInputFormatClass != previousInputFormatClass)
|| (!currentDeserializerClass.equals(previousDeserializerClass))) {
retval = true;
}
if (LOG.isDebugEnabled()) {
LOG.debug("Adding split " + path + " to src new group? " + retval);
}
return retval;
}
}
