org.apache.pig.backend.hadoop.executionengine.mapReduceLayer

Class JobControlCompiler

java.lang.Object

org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.JobControlCompiler

public class JobControlCompiler
extends Object

This is compiler class that takes an MROperPlan and converts it into a JobControl object with the relevant dependency info maintained. The JobControl Object is made up of Jobs each of which has a JobConf. The MapReduceOper corresponds to a Job and the getJobCong method returns the JobConf that is configured as per the MapReduceOper

Comparator Design

A few words on how comparators are chosen. In almost all cases we use raw comparators (the one exception being when the user provides a comparison function for order by). For order by queries the PigTYPERawComparator functions are used, where TYPE is Int, Long, etc. These comparators are null aware and asc/desc aware. The first byte of each of the NullableTYPEWritable classes contains info on whether the value is null. Asc/desc is written as an array into the JobConf with the key pig.sortOrder so that it can be read by each of the comparators as part of their setConf call.

For non-order by queries, PigTYPEWritableComparator classes are used. These are all just type specific instances of WritableComparator.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	JobControlCompiler.PigBagWritableComparator
static class	JobControlCompiler.PigBigDecimalWritableComparator
static class	JobControlCompiler.PigBigIntegerWritableComparator
static class	JobControlCompiler.PigBooleanWritableComparator
static class	JobControlCompiler.PigCharArrayWritableComparator
static class	JobControlCompiler.PigDateTimeWritableComparator
static class	JobControlCompiler.PigDBAWritableComparator
static class	JobControlCompiler.PigDoubleWritableComparator
static class	JobControlCompiler.PigFloatWritableComparator
static class	JobControlCompiler.PigGroupingBagWritableComparator
static class	JobControlCompiler.PigGroupingBigDecimalWritableComparator
static class	JobControlCompiler.PigGroupingBigIntegerWritableComparator
static class	JobControlCompiler.PigGroupingBooleanWritableComparator
static class	JobControlCompiler.PigGroupingCharArrayWritableComparator
static class	JobControlCompiler.PigGroupingDateTimeWritableComparator
static class	JobControlCompiler.PigGroupingDBAWritableComparator
static class	JobControlCompiler.PigGroupingDoubleWritableComparator
static class	JobControlCompiler.PigGroupingFloatWritableComparator
static class	JobControlCompiler.PigGroupingIntWritableComparator
static class	JobControlCompiler.PigGroupingLongWritableComparator
static class	JobControlCompiler.PigGroupingPartitionWritableComparator
static class	JobControlCompiler.PigGroupingTupleWritableComparator
static class	JobControlCompiler.PigIntWritableComparator
static class	JobControlCompiler.PigLongWritableComparator
static class	JobControlCompiler.PigSecondaryKeyGroupComparator
static class	JobControlCompiler.PigTupleWritableComparator
static class	JobControlCompiler.PigWritableComparator

Field Summary

Fields

Modifier and Type	Field and Description
static String	BIG_JOB_LOG_MSG
static String	END_OF_INP_IN_MAP
HashMap<String,ArrayList<Pair<String,Long>>>	globalCounters
static String	LOG_DIR
static String	PIG_MAP_COUNTER
static String	PIG_MAP_RANK_NAME
static String	PIG_MAP_SEPARATOR
static String	PIG_MAP_STORES We will serialize the POStore(s) present in map and reduce in lists in the Hadoop Conf.
static String	PIG_REDUCE_STORES
static String	SMALL_JOB_LOG_MSG

Constructor Summary

Constructors

Constructor and Description
JobControlCompiler(PigContext pigContext, org.apache.hadoop.conf.Configuration conf)
JobControlCompiler(PigContext pigContext, org.apache.hadoop.conf.Configuration conf, org.apache.hadoop.conf.Configuration defaultConf)

Method Summary

Modifier and Type	Method and Description
void	adjustNumReducers(MROperPlan plan, MapReduceOper mro, org.apache.hadoop.mapreduce.Job nwJob) Adjust the number of reducers based on the default_parallel, requested parallel and estimated parallel.
org.apache.hadoop.mapred.jobcontrol.JobControl	compile(MROperPlan plan, String grpName) Compiles all jobs that have no dependencies removes them from the plan and returns.
static void	configureCompression(org.apache.hadoop.conf.Configuration conf)
static int	estimateNumberOfReducers(org.apache.hadoop.mapreduce.Job job, MapReduceOper mapReducerOper) Looks up the estimator from REDUCER_ESTIMATOR_KEY and invokes it to find the number of reducers to use.
static org.apache.hadoop.fs.Path	getCacheStagingDir(org.apache.hadoop.conf.Configuration conf)
static org.apache.hadoop.fs.Path	getFromCache(PigContext pigContext, org.apache.hadoop.conf.Configuration conf, URL url)
Map<org.apache.hadoop.mapred.jobcontrol.Job,MapReduceOper>	getJobMroMap() Gets the map of Job and the MR Operator
List<POStore>	getStores(org.apache.hadoop.mapred.jobcontrol.Job job) Returns all store locations of a previously compiled job
void	moveResults(List<org.apache.hadoop.mapred.jobcontrol.Job> completedJobs) Moves all the results of a collection of MR jobs to the final output directory.
void	reset() Resets the state
static void	setOutputFormat(org.apache.hadoop.mapreduce.Job job)
int	updateMROpPlan(List<org.apache.hadoop.mapred.jobcontrol.Job> completeFailedJobs)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOG_DIR

public static final String LOG_DIR

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Constant Field Values

END_OF_INP_IN_MAP

public static final String END_OF_INP_IN_MAP

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Constant Field Values

PIG_MAP_COUNTER

public static final String PIG_MAP_COUNTER

See Also:

Constant Field Values

PIG_MAP_RANK_NAME

public static final String PIG_MAP_RANK_NAME

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Constant Field Values

PIG_MAP_SEPARATOR

public static final String PIG_MAP_SEPARATOR

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Constant Field Values

globalCounters

public HashMap<String,ArrayList<Pair<String,Long>>> globalCounters

SMALL_JOB_LOG_MSG

public static final String SMALL_JOB_LOG_MSG

See Also:

Constant Field Values

BIG_JOB_LOG_MSG

public static final String BIG_JOB_LOG_MSG

See Also:

Constant Field Values

PIG_MAP_STORES

public static final String PIG_MAP_STORES

We will serialize the POStore(s) present in map and reduce in lists in the Hadoop Conf. In the case of Multi stores, we could deduce these from the map plan and reduce plan but in the case of single store, we remove the POStore from the plan - in either case, we serialize the POStore(s) so that PigOutputFormat and PigOutputCommiter can get the POStore(s) in the same way irrespective of whether it is multi store or single store.

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Constant Field Values

PIG_REDUCE_STORES

public static final String PIG_REDUCE_STORES

See Also:

Constant Field Values

Constructor Detail

JobControlCompiler

public JobControlCompiler(PigContext pigContext,
                          org.apache.hadoop.conf.Configuration conf)

JobControlCompiler

public JobControlCompiler(PigContext pigContext,
                          org.apache.hadoop.conf.Configuration conf,
                          org.apache.hadoop.conf.Configuration defaultConf)

Method Detail

getStores

public List<POStore> getStores(org.apache.hadoop.mapred.jobcontrol.Job job)

Returns all store locations of a previously compiled job

reset

public void reset()

Resets the state

getJobMroMap

public Map<org.apache.hadoop.mapred.jobcontrol.Job,MapReduceOper> getJobMroMap()

Gets the map of Job and the MR Operator

moveResults

public void moveResults(List<org.apache.hadoop.mapred.jobcontrol.Job> completedJobs)
                 throws IOException

Moves all the results of a collection of MR jobs to the final output directory. Some of the results may have been put into a temp location to work around restrictions with multiple output from a single map reduce job. This method should always be called after the job execution completes.

Throws:

IOException

compile

public org.apache.hadoop.mapred.jobcontrol.JobControl compile(MROperPlan plan,
                                                              String grpName)
                                                       throws JobCreationException

Compiles all jobs that have no dependencies removes them from the plan and returns. Should be called with the same plan until exhausted.

Parameters:

plan - - The MROperPlan to be compiled

grpName - - The name given to the JobControl

Returns:

JobControl object - null if no more jobs in plan

Throws:

JobCreationException

updateMROpPlan

public int updateMROpPlan(List<org.apache.hadoop.mapred.jobcontrol.Job> completeFailedJobs)

configureCompression

public static void configureCompression(org.apache.hadoop.conf.Configuration conf)

adjustNumReducers

public void adjustNumReducers(MROperPlan plan,
                              MapReduceOper mro,
                              org.apache.hadoop.mapreduce.Job nwJob)
                       throws IOException

Adjust the number of reducers based on the default_parallel, requested parallel and estimated parallel. For sampler jobs, we also adjust the next job in advance to get its runtime parallel as the number of partitions used in the sampler.

Parameters:

plan - the MR plan

mro - the MR operator

nwJob - the current job

Throws:

IOException

estimateNumberOfReducers

public static int estimateNumberOfReducers(org.apache.hadoop.mapreduce.Job job,
                                           MapReduceOper mapReducerOper)
                                    throws IOException

Looks up the estimator from REDUCER_ESTIMATOR_KEY and invokes it to find the number of reducers to use. If REDUCER_ESTIMATOR_KEY isn't set, defaults to InputSizeReducerEstimator.

Parameters:

job -

mapReducerOper -

Throws:

IOException

getCacheStagingDir

public static org.apache.hadoop.fs.Path getCacheStagingDir(org.apache.hadoop.conf.Configuration conf)
                                                    throws IOException

Throws:

IOException

getFromCache

public static org.apache.hadoop.fs.Path getFromCache(PigContext pigContext,
                                                     org.apache.hadoop.conf.Configuration conf,
                                                     URL url)
                                              throws IOException

Throws:

IOException

setOutputFormat

public static void setOutputFormat(org.apache.hadoop.mapreduce.Job job)