org.apache.flink.runtime.operators.sort.FixedLengthRecordSorter Java Examples

@Override
public void openTask() throws Exception {
	// open the stub first
	final Configuration stubConfig = this.config.getStubParameters();
	BatchTask.openUserCode(this.combiner, stubConfig);

	// ----------------- Set up the sorter -------------------------

	// instantiate the serializer / comparator
	final TypeSerializerFactory<IN> serializerFactory = this.config.getInputSerializer(0, this.userCodeClassLoader);
	final TypeComparatorFactory<IN> sortingComparatorFactory = this.config.getDriverComparator(0, this.userCodeClassLoader);
	final TypeComparatorFactory<IN> groupingComparatorFactory = this.config.getDriverComparator(1, this.userCodeClassLoader);
	
	this.serializer = serializerFactory.getSerializer();

	TypeComparator<IN> sortingComparator = sortingComparatorFactory.createComparator();
	this.groupingComparator = groupingComparatorFactory.createComparator();
	
	MemoryManager memManager = this.parent.getEnvironment().getMemoryManager();
	final int numMemoryPages = memManager.computeNumberOfPages(this.config.getRelativeMemoryDriver());
	this.memory = memManager.allocatePages(this.parent, numMemoryPages);

	// instantiate a fix-length in-place sorter, if possible, otherwise the out-of-place sorter
	if (sortingComparator.supportsSerializationWithKeyNormalization() &&
		this.serializer.getLength() > 0 && this.serializer.getLength() <= THRESHOLD_FOR_IN_PLACE_SORTING)
	{
		this.sorter = new FixedLengthRecordSorter<IN>(this.serializer, sortingComparator.duplicate(), this.memory);
	} else {
		this.sorter = new NormalizedKeySorter<IN>(this.serializer, sortingComparator.duplicate(), this.memory);
	}

	if (LOG.isDebugEnabled()) {
		LOG.debug("SynchronousChainedCombineDriver object reuse: " + (this.objectReuseEnabled ? "ENABLED" : "DISABLED") + ".");
	}
}
 

@Override
public void openTask() throws Exception {
	// open the stub first
	final Configuration stubConfig = this.config.getStubParameters();
	BatchTask.openUserCode(this.reducer, stubConfig);

	// ----------------- Set up the sorter -------------------------

	// instantiate the serializer / comparator
	final TypeSerializerFactory<IN> serializerFactory = this.config.getInputSerializer(0, this.userCodeClassLoader);
	final TypeComparatorFactory<IN> sortingComparatorFactory = this.config.getDriverComparator(0, this.userCodeClassLoader);
	final TypeComparatorFactory<IN> groupingComparatorFactory = this.config.getDriverComparator(1, this.userCodeClassLoader);
	this.serializer = serializerFactory.getSerializer();
	
	TypeComparator<IN> sortingComparator = sortingComparatorFactory.createComparator();
	this.groupingComparator = groupingComparatorFactory.createComparator();

	MemoryManager memManager = this.parent.getEnvironment().getMemoryManager();
	final int numMemoryPages = memManager.computeNumberOfPages(this.config.getRelativeMemoryDriver());
	this.memory = memManager.allocatePages(this.parent, numMemoryPages);

	// instantiate a fix-length in-place sorter, if possible, otherwise the out-of-place sorter
	if (sortingComparator.supportsSerializationWithKeyNormalization() &&
		this.serializer.getLength() > 0 && this.serializer.getLength() <= THRESHOLD_FOR_IN_PLACE_SORTING)
	{
		this.sorter = new FixedLengthRecordSorter<IN>(this.serializer, sortingComparator.duplicate(), memory);
	} else {
		this.sorter = new NormalizedKeySorter<IN>(this.serializer, sortingComparator.duplicate(), memory);
	}

	if (LOG.isDebugEnabled()) {
		LOG.debug("SynchronousChainedCombineDriver object reuse: " + (this.objectReuseEnabled ? "ENABLED" : "DISABLED") + ".");
	}
}
 

@Override
public void openTask() throws Exception {
	// open the stub first
	final Configuration stubConfig = config.getStubParameters();
	BatchTask.openUserCode(reducer, stubConfig);

	// instantiate the serializer / comparator
	serializer = config.<T>getInputSerializer(0, userCodeClassLoader).getSerializer();
	comparator = config.<T>getDriverComparator(0, userCodeClassLoader).createComparator();

	MemoryManager memManager = parent.getEnvironment().getMemoryManager();
	final int numMemoryPages = memManager.computeNumberOfPages(config.getRelativeMemoryDriver());
	memory = memManager.allocatePages(parent, numMemoryPages);

	LOG.debug("ChainedReduceCombineDriver object reuse: " + (objectReuseEnabled ? "ENABLED" : "DISABLED") + ".");

	switch (strategy) {
		case SORTED_PARTIAL_REDUCE:
			// instantiate a fix-length in-place sorter, if possible, otherwise the out-of-place sorter
			if (comparator.supportsSerializationWithKeyNormalization() &&
				serializer.getLength() > 0 && serializer.getLength() <= THRESHOLD_FOR_IN_PLACE_SORTING) {
				sorter = new FixedLengthRecordSorter<T>(serializer, comparator.duplicate(), memory);
			} else {
				sorter = new NormalizedKeySorter<T>(serializer, comparator.duplicate(), memory);
			}
			break;
		case HASHED_PARTIAL_REDUCE:
			table = new InPlaceMutableHashTable<T>(serializer, comparator, memory);
			table.open();
			reduceFacade = table.new ReduceFacade(reducer, outputCollector, objectReuseEnabled);
			break;
	}
}
 

@Override
public void prepare() throws Exception {
	final DriverStrategy driverStrategy = this.taskContext.getTaskConfig().getDriverStrategy();
	if (driverStrategy != DriverStrategy.SORTED_GROUP_COMBINE){
		throw new Exception("Invalid strategy " + driverStrategy + " for group reduce combiner.");
	}
	
	

	final TypeSerializerFactory<IN> serializerFactory = this.taskContext.getInputSerializer(0);
	this.serializer = serializerFactory.getSerializer();

	final TypeComparator<IN> sortingComparator = this.taskContext.getDriverComparator(0);
	
	this.groupingComparator = this.taskContext.getDriverComparator(1);
	this.combiner = this.taskContext.getStub();
	this.output = this.taskContext.getOutputCollector();

	MemoryManager memManager = this.taskContext.getMemoryManager();
	final int numMemoryPages = memManager.computeNumberOfPages(this.taskContext.getTaskConfig().getRelativeMemoryDriver());
	this.memory = memManager.allocatePages(this.taskContext.getContainingTask(), numMemoryPages);

	// instantiate a fix-length in-place sorter, if possible, otherwise the out-of-place sorter
	if (sortingComparator.supportsSerializationWithKeyNormalization() &&
			this.serializer.getLength() > 0 && this.serializer.getLength() <= THRESHOLD_FOR_IN_PLACE_SORTING)
	{
		this.sorter = new FixedLengthRecordSorter<IN>(this.serializer, sortingComparator.duplicate(), memory);
	} else {
		this.sorter = new NormalizedKeySorter<IN>(this.serializer, sortingComparator.duplicate(), memory);
	}

	ExecutionConfig executionConfig = taskContext.getExecutionConfig();
	this.objectReuseEnabled = executionConfig.isObjectReuseEnabled();

	if (LOG.isDebugEnabled()) {
		LOG.debug("GroupReduceCombineDriver object reuse: {}.", (this.objectReuseEnabled ? "ENABLED" : "DISABLED"));
	}
}
 

@Override
public void openTask() throws Exception {
	// open the stub first
	final Configuration stubConfig = this.config.getStubParameters();
	BatchTask.openUserCode(this.combiner, stubConfig);

	// ----------------- Set up the sorter -------------------------

	// instantiate the serializer / comparator
	final TypeSerializerFactory<IN> serializerFactory = this.config.getInputSerializer(0, this.userCodeClassLoader);
	final TypeComparatorFactory<IN> sortingComparatorFactory = this.config.getDriverComparator(0, this.userCodeClassLoader);
	final TypeComparatorFactory<IN> groupingComparatorFactory = this.config.getDriverComparator(1, this.userCodeClassLoader);
	
	this.serializer = serializerFactory.getSerializer();

	TypeComparator<IN> sortingComparator = sortingComparatorFactory.createComparator();
	this.groupingComparator = groupingComparatorFactory.createComparator();
	
	MemoryManager memManager = this.parent.getEnvironment().getMemoryManager();
	final int numMemoryPages = memManager.computeNumberOfPages(this.config.getRelativeMemoryDriver());
	this.memory = memManager.allocatePages(this.parent, numMemoryPages);

	// instantiate a fix-length in-place sorter, if possible, otherwise the out-of-place sorter
	if (sortingComparator.supportsSerializationWithKeyNormalization() &&
		this.serializer.getLength() > 0 && this.serializer.getLength() <= THRESHOLD_FOR_IN_PLACE_SORTING)
	{
		this.sorter = new FixedLengthRecordSorter<IN>(this.serializer, sortingComparator.duplicate(), this.memory);
	} else {
		this.sorter = new NormalizedKeySorter<IN>(this.serializer, sortingComparator.duplicate(), this.memory);
	}

	if (LOG.isDebugEnabled()) {
		LOG.debug("SynchronousChainedCombineDriver object reuse: " + (this.objectReuseEnabled ? "ENABLED" : "DISABLED") + ".");
	}
}
 

@Override
public void openTask() throws Exception {
	// open the stub first
	final Configuration stubConfig = this.config.getStubParameters();
	BatchTask.openUserCode(this.reducer, stubConfig);

	// ----------------- Set up the sorter -------------------------

	// instantiate the serializer / comparator
	final TypeSerializerFactory<IN> serializerFactory = this.config.getInputSerializer(0, this.userCodeClassLoader);
	final TypeComparatorFactory<IN> sortingComparatorFactory = this.config.getDriverComparator(0, this.userCodeClassLoader);
	final TypeComparatorFactory<IN> groupingComparatorFactory = this.config.getDriverComparator(1, this.userCodeClassLoader);
	this.serializer = serializerFactory.getSerializer();
	
	TypeComparator<IN> sortingComparator = sortingComparatorFactory.createComparator();
	this.groupingComparator = groupingComparatorFactory.createComparator();

	MemoryManager memManager = this.parent.getEnvironment().getMemoryManager();
	final int numMemoryPages = memManager.computeNumberOfPages(this.config.getRelativeMemoryDriver());
	this.memory = memManager.allocatePages(this.parent, numMemoryPages);

	// instantiate a fix-length in-place sorter, if possible, otherwise the out-of-place sorter
	if (sortingComparator.supportsSerializationWithKeyNormalization() &&
		this.serializer.getLength() > 0 && this.serializer.getLength() <= THRESHOLD_FOR_IN_PLACE_SORTING)
	{
		this.sorter = new FixedLengthRecordSorter<IN>(this.serializer, sortingComparator.duplicate(), memory);
	} else {
		this.sorter = new NormalizedKeySorter<IN>(this.serializer, sortingComparator.duplicate(), memory);
	}

	if (LOG.isDebugEnabled()) {
		LOG.debug("SynchronousChainedCombineDriver object reuse: " + (this.objectReuseEnabled ? "ENABLED" : "DISABLED") + ".");
	}
}
 

@Override
public void openTask() throws Exception {
	// open the stub first
	final Configuration stubConfig = config.getStubParameters();
	BatchTask.openUserCode(reducer, stubConfig);

	// instantiate the serializer / comparator
	serializer = config.<T>getInputSerializer(0, userCodeClassLoader).getSerializer();
	comparator = config.<T>getDriverComparator(0, userCodeClassLoader).createComparator();

	MemoryManager memManager = parent.getEnvironment().getMemoryManager();
	final int numMemoryPages = memManager.computeNumberOfPages(config.getRelativeMemoryDriver());
	memory = memManager.allocatePages(parent, numMemoryPages);

	LOG.debug("ChainedReduceCombineDriver object reuse: " + (objectReuseEnabled ? "ENABLED" : "DISABLED") + ".");

	switch (strategy) {
		case SORTED_PARTIAL_REDUCE:
			// instantiate a fix-length in-place sorter, if possible, otherwise the out-of-place sorter
			if (comparator.supportsSerializationWithKeyNormalization() &&
				serializer.getLength() > 0 && serializer.getLength() <= THRESHOLD_FOR_IN_PLACE_SORTING) {
				sorter = new FixedLengthRecordSorter<T>(serializer, comparator.duplicate(), memory);
			} else {
				sorter = new NormalizedKeySorter<T>(serializer, comparator.duplicate(), memory);
			}
			break;
		case HASHED_PARTIAL_REDUCE:
			table = new InPlaceMutableHashTable<T>(serializer, comparator, memory);
			table.open();
			reduceFacade = table.new ReduceFacade(reducer, outputCollector, objectReuseEnabled);
			break;
	}
}
 

@Override
public void prepare() throws Exception {
	final DriverStrategy driverStrategy = this.taskContext.getTaskConfig().getDriverStrategy();
	if (driverStrategy != DriverStrategy.SORTED_GROUP_COMBINE){
		throw new Exception("Invalid strategy " + driverStrategy + " for group reduce combiner.");
	}
	
	

	final TypeSerializerFactory<IN> serializerFactory = this.taskContext.getInputSerializer(0);
	this.serializer = serializerFactory.getSerializer();

	final TypeComparator<IN> sortingComparator = this.taskContext.getDriverComparator(0);
	
	this.groupingComparator = this.taskContext.getDriverComparator(1);
	this.combiner = this.taskContext.getStub();
	this.output = this.taskContext.getOutputCollector();

	MemoryManager memManager = this.taskContext.getMemoryManager();
	final int numMemoryPages = memManager.computeNumberOfPages(this.taskContext.getTaskConfig().getRelativeMemoryDriver());
	this.memory = memManager.allocatePages(this.taskContext.getContainingTask(), numMemoryPages);

	// instantiate a fix-length in-place sorter, if possible, otherwise the out-of-place sorter
	if (sortingComparator.supportsSerializationWithKeyNormalization() &&
			this.serializer.getLength() > 0 && this.serializer.getLength() <= THRESHOLD_FOR_IN_PLACE_SORTING)
	{
		this.sorter = new FixedLengthRecordSorter<IN>(this.serializer, sortingComparator.duplicate(), memory);
	} else {
		this.sorter = new NormalizedKeySorter<IN>(this.serializer, sortingComparator.duplicate(), memory);
	}

	ExecutionConfig executionConfig = taskContext.getExecutionConfig();
	this.objectReuseEnabled = executionConfig.isObjectReuseEnabled();

	if (LOG.isDebugEnabled()) {
		LOG.debug("GroupReduceCombineDriver object reuse: {}.", (this.objectReuseEnabled ? "ENABLED" : "DISABLED"));
	}
}
 

@Override
public void openTask() throws Exception {
	// open the stub first
	final Configuration stubConfig = this.config.getStubParameters();
	BatchTask.openUserCode(this.combiner, stubConfig);

	// ----------------- Set up the sorter -------------------------

	// instantiate the serializer / comparator
	final TypeSerializerFactory<IN> serializerFactory = this.config.getInputSerializer(0, this.userCodeClassLoader);
	final TypeComparatorFactory<IN> sortingComparatorFactory = this.config.getDriverComparator(0, this.userCodeClassLoader);
	final TypeComparatorFactory<IN> groupingComparatorFactory = this.config.getDriverComparator(1, this.userCodeClassLoader);
	
	this.serializer = serializerFactory.getSerializer();

	TypeComparator<IN> sortingComparator = sortingComparatorFactory.createComparator();
	this.groupingComparator = groupingComparatorFactory.createComparator();
	
	MemoryManager memManager = this.parent.getEnvironment().getMemoryManager();
	final int numMemoryPages = memManager.computeNumberOfPages(this.config.getRelativeMemoryDriver());
	this.memory = memManager.allocatePages(this.parent, numMemoryPages);

	// instantiate a fix-length in-place sorter, if possible, otherwise the out-of-place sorter
	if (sortingComparator.supportsSerializationWithKeyNormalization() &&
		this.serializer.getLength() > 0 && this.serializer.getLength() <= THRESHOLD_FOR_IN_PLACE_SORTING)
	{
		this.sorter = new FixedLengthRecordSorter<IN>(this.serializer, sortingComparator.duplicate(), this.memory);
	} else {
		this.sorter = new NormalizedKeySorter<IN>(this.serializer, sortingComparator.duplicate(), this.memory);
	}

	if (LOG.isDebugEnabled()) {
		LOG.debug("SynchronousChainedCombineDriver object reuse: " + (this.objectReuseEnabled ? "ENABLED" : "DISABLED") + ".");
	}
}
 

@Override
public void openTask() throws Exception {
	// open the stub first
	final Configuration stubConfig = config.getStubParameters();
	BatchTask.openUserCode(reducer, stubConfig);

	// instantiate the serializer / comparator
	serializer = config.<T>getInputSerializer(0, userCodeClassLoader).getSerializer();
	comparator = config.<T>getDriverComparator(0, userCodeClassLoader).createComparator();

	MemoryManager memManager = parent.getEnvironment().getMemoryManager();
	final int numMemoryPages = memManager.computeNumberOfPages(config.getRelativeMemoryDriver());
	memory = memManager.allocatePages(parent, numMemoryPages);

	LOG.debug("ChainedReduceCombineDriver object reuse: " + (objectReuseEnabled ? "ENABLED" : "DISABLED") + ".");

	switch (strategy) {
		case SORTED_PARTIAL_REDUCE:
			// instantiate a fix-length in-place sorter, if possible, otherwise the out-of-place sorter
			if (comparator.supportsSerializationWithKeyNormalization() &&
				serializer.getLength() > 0 && serializer.getLength() <= THRESHOLD_FOR_IN_PLACE_SORTING) {
				sorter = new FixedLengthRecordSorter<T>(serializer, comparator.duplicate(), memory);
			} else {
				sorter = new NormalizedKeySorter<T>(serializer, comparator.duplicate(), memory);
			}
			break;
		case HASHED_PARTIAL_REDUCE:
			table = new InPlaceMutableHashTable<T>(serializer, comparator, memory);
			table.open();
			reduceFacade = table.new ReduceFacade(reducer, outputCollector, objectReuseEnabled);
			break;
	}
}
 

@Override
public void prepare() throws Exception {
	final DriverStrategy driverStrategy = this.taskContext.getTaskConfig().getDriverStrategy();
	if (driverStrategy != DriverStrategy.SORTED_GROUP_COMBINE){
		throw new Exception("Invalid strategy " + driverStrategy + " for group reduce combiner.");
	}
	
	

	final TypeSerializerFactory<IN> serializerFactory = this.taskContext.getInputSerializer(0);
	this.serializer = serializerFactory.getSerializer();

	final TypeComparator<IN> sortingComparator = this.taskContext.getDriverComparator(0);
	
	this.groupingComparator = this.taskContext.getDriverComparator(1);
	this.combiner = this.taskContext.getStub();
	this.output = this.taskContext.getOutputCollector();

	MemoryManager memManager = this.taskContext.getMemoryManager();
	final int numMemoryPages = memManager.computeNumberOfPages(this.taskContext.getTaskConfig().getRelativeMemoryDriver());
	this.memory = memManager.allocatePages(this.taskContext.getContainingTask(), numMemoryPages);

	// instantiate a fix-length in-place sorter, if possible, otherwise the out-of-place sorter
	if (sortingComparator.supportsSerializationWithKeyNormalization() &&
			this.serializer.getLength() > 0 && this.serializer.getLength() <= THRESHOLD_FOR_IN_PLACE_SORTING)
	{
		this.sorter = new FixedLengthRecordSorter<IN>(this.serializer, sortingComparator.duplicate(), memory);
	} else {
		this.sorter = new NormalizedKeySorter<IN>(this.serializer, sortingComparator.duplicate(), memory);
	}

	ExecutionConfig executionConfig = taskContext.getExecutionConfig();
	this.objectReuseEnabled = executionConfig.isObjectReuseEnabled();

	if (LOG.isDebugEnabled()) {
		LOG.debug("GroupReduceCombineDriver object reuse: {}.", (this.objectReuseEnabled ? "ENABLED" : "DISABLED"));
	}
}
 

@Override
public void prepare() throws Exception {
	final Counter numRecordsOut = taskContext.getMetricGroup().getIOMetricGroup().getNumRecordsOutCounter();

	strategy = taskContext.getTaskConfig().getDriverStrategy();

	// instantiate the serializer / comparator
	final TypeSerializerFactory<T> serializerFactory = taskContext.getInputSerializer(0);
	comparator = taskContext.getDriverComparator(0);
	serializer = serializerFactory.getSerializer();
	reducer = taskContext.getStub();
	output = new CountingCollector<>(this.taskContext.getOutputCollector(), numRecordsOut);

	MemoryManager memManager = taskContext.getMemoryManager();
	final int numMemoryPages = memManager.computeNumberOfPages(
		taskContext.getTaskConfig().getRelativeMemoryDriver());
	memory = memManager.allocatePages(taskContext.getContainingTask(), numMemoryPages);

	ExecutionConfig executionConfig = taskContext.getExecutionConfig();
	objectReuseEnabled = executionConfig.isObjectReuseEnabled();

	if (LOG.isDebugEnabled()) {
		LOG.debug("ReduceCombineDriver object reuse: " + (objectReuseEnabled ? "ENABLED" : "DISABLED") + ".");
	}

	switch (strategy) {
		case SORTED_PARTIAL_REDUCE:
			// instantiate a fix-length in-place sorter, if possible, otherwise the out-of-place sorter
			if (comparator.supportsSerializationWithKeyNormalization() &&
				serializer.getLength() > 0 && serializer.getLength() <= THRESHOLD_FOR_IN_PLACE_SORTING) {
				sorter = new FixedLengthRecordSorter<T>(serializer, comparator.duplicate(), memory);
			} else {
				sorter = new NormalizedKeySorter<T>(serializer, comparator.duplicate(), memory);
			}
			break;
		case HASHED_PARTIAL_REDUCE:
			table = new InPlaceMutableHashTable<T>(serializer, comparator, memory);
			reduceFacade = table.new ReduceFacade(reducer, output, objectReuseEnabled);
			break;
		default:
			throw new Exception("Invalid strategy " + taskContext.getTaskConfig().getDriverStrategy() + " for reduce combiner.");
	}
}
 

@Override
public void prepare() throws Exception {
	final Counter numRecordsOut = taskContext.getMetricGroup().getIOMetricGroup().getNumRecordsOutCounter();

	strategy = taskContext.getTaskConfig().getDriverStrategy();

	// instantiate the serializer / comparator
	final TypeSerializerFactory<T> serializerFactory = taskContext.getInputSerializer(0);
	comparator = taskContext.getDriverComparator(0);
	serializer = serializerFactory.getSerializer();
	reducer = taskContext.getStub();
	output = new CountingCollector<>(this.taskContext.getOutputCollector(), numRecordsOut);

	MemoryManager memManager = taskContext.getMemoryManager();
	final int numMemoryPages = memManager.computeNumberOfPages(
		taskContext.getTaskConfig().getRelativeMemoryDriver());
	memory = memManager.allocatePages(taskContext.getContainingTask(), numMemoryPages);

	ExecutionConfig executionConfig = taskContext.getExecutionConfig();
	objectReuseEnabled = executionConfig.isObjectReuseEnabled();

	if (LOG.isDebugEnabled()) {
		LOG.debug("ReduceCombineDriver object reuse: " + (objectReuseEnabled ? "ENABLED" : "DISABLED") + ".");
	}

	switch (strategy) {
		case SORTED_PARTIAL_REDUCE:
			// instantiate a fix-length in-place sorter, if possible, otherwise the out-of-place sorter
			if (comparator.supportsSerializationWithKeyNormalization() &&
				serializer.getLength() > 0 && serializer.getLength() <= THRESHOLD_FOR_IN_PLACE_SORTING) {
				sorter = new FixedLengthRecordSorter<T>(serializer, comparator.duplicate(), memory);
			} else {
				sorter = new NormalizedKeySorter<T>(serializer, comparator.duplicate(), memory);
			}
			break;
		case HASHED_PARTIAL_REDUCE:
			table = new InPlaceMutableHashTable<T>(serializer, comparator, memory);
			reduceFacade = table.new ReduceFacade(reducer, output, objectReuseEnabled);
			break;
		default:
			throw new Exception("Invalid strategy " + taskContext.getTaskConfig().getDriverStrategy() + " for reduce combiner.");
	}
}
 

@Override
public void prepare() throws Exception {
	final Counter numRecordsOut = taskContext.getMetricGroup().getIOMetricGroup().getNumRecordsOutCounter();

	strategy = taskContext.getTaskConfig().getDriverStrategy();

	// instantiate the serializer / comparator
	final TypeSerializerFactory<T> serializerFactory = taskContext.getInputSerializer(0);
	comparator = taskContext.getDriverComparator(0);
	serializer = serializerFactory.getSerializer();
	reducer = taskContext.getStub();
	output = new CountingCollector<>(this.taskContext.getOutputCollector(), numRecordsOut);

	MemoryManager memManager = taskContext.getMemoryManager();
	final int numMemoryPages = memManager.computeNumberOfPages(
		taskContext.getTaskConfig().getRelativeMemoryDriver());
	memory = memManager.allocatePages(taskContext.getContainingTask(), numMemoryPages);

	ExecutionConfig executionConfig = taskContext.getExecutionConfig();
	objectReuseEnabled = executionConfig.isObjectReuseEnabled();

	if (LOG.isDebugEnabled()) {
		LOG.debug("ReduceCombineDriver object reuse: " + (objectReuseEnabled ? "ENABLED" : "DISABLED") + ".");
	}

	switch (strategy) {
		case SORTED_PARTIAL_REDUCE:
			// instantiate a fix-length in-place sorter, if possible, otherwise the out-of-place sorter
			if (comparator.supportsSerializationWithKeyNormalization() &&
				serializer.getLength() > 0 && serializer.getLength() <= THRESHOLD_FOR_IN_PLACE_SORTING) {
				sorter = new FixedLengthRecordSorter<T>(serializer, comparator.duplicate(), memory);
			} else {
				sorter = new NormalizedKeySorter<T>(serializer, comparator.duplicate(), memory);
			}
			break;
		case HASHED_PARTIAL_REDUCE:
			table = new InPlaceMutableHashTable<T>(serializer, comparator, memory);
			reduceFacade = table.new ReduceFacade(reducer, output, objectReuseEnabled);
			break;
		default:
			throw new Exception("Invalid strategy " + taskContext.getTaskConfig().getDriverStrategy() + " for reduce combiner.");
	}
}