org.apache.flink.runtime.operators.chaining.ChainedReduceCombineDriver Maven / Gradle / Ivy

/*
 * 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.flink.runtime.operators.chaining;

import org.apache.flink.api.common.functions.Function;
import org.apache.flink.api.common.functions.ReduceFunction;
import org.apache.flink.api.common.functions.util.FunctionUtils;
import org.apache.flink.api.common.typeutils.TypeComparator;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.core.memory.MemorySegment;
import org.apache.flink.runtime.jobgraph.tasks.AbstractInvokable;
import org.apache.flink.runtime.memory.MemoryManager;
import org.apache.flink.runtime.operators.BatchTask;
import org.apache.flink.runtime.operators.DriverStrategy;
import org.apache.flink.runtime.operators.hash.InPlaceMutableHashTable;
import org.apache.flink.runtime.operators.sort.FixedLengthRecordSorter;
import org.apache.flink.runtime.operators.sort.InMemorySorter;
import org.apache.flink.runtime.operators.sort.NormalizedKeySorter;
import org.apache.flink.runtime.operators.sort.QuickSort;
import org.apache.flink.util.Collector;
import org.apache.flink.util.MutableObjectIterator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.EOFException;
import java.io.IOException;
import java.util.List;

/**
 * Chained version of ReduceCombineDriver.
 */
public class ChainedReduceCombineDriver extends ChainedDriver {

	private static final Logger LOG = LoggerFactory.getLogger(ChainedReduceCombineDriver.class);

	/** Fix length records with a length below this threshold will be in-place sorted, if possible. */
	private static final int THRESHOLD_FOR_IN_PLACE_SORTING = 32;


	private AbstractInvokable parent;

	private TypeSerializer serializer;

	private TypeComparator comparator;

	private ReduceFunction reducer;

	private DriverStrategy strategy;

	private InMemorySorter sorter;

	private QuickSort sortAlgo = new QuickSort();

	private InPlaceMutableHashTable table;

	private InPlaceMutableHashTable.ReduceFacade reduceFacade;

	private List memory;

	private volatile boolean running;

	// ------------------------------------------------------------------------

	@Override
	public Function getStub() {
		return reducer;
	}

	@Override
	public String getTaskName() {
		return taskName;
	}

	@Override
	public void setup(AbstractInvokable parent) {
		this.parent = parent;
		running = true;

		strategy = config.getDriverStrategy();

		reducer = BatchTask.instantiateUserCode(config, userCodeClassLoader, ReduceFunction.class);
		FunctionUtils.setFunctionRuntimeContext(reducer, getUdfRuntimeContext());
	}

	@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.getInputSerializer(0, userCodeClassLoader).getSerializer();
		comparator = config.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(serializer, comparator.duplicate(), memory);
				} else {
					sorter = new NormalizedKeySorter(serializer, comparator.duplicate(), memory);
				}
				break;
			case HASHED_PARTIAL_REDUCE:
				table = new InPlaceMutableHashTable(serializer, comparator, memory);
				table.open();
				reduceFacade = table.new ReduceFacade(reducer, outputCollector, objectReuseEnabled);
				break;
		}
	}

	@Override
	public void collect(T record) {
		try {
			switch (strategy) {
				case SORTED_PARTIAL_REDUCE:
					collectSorted(record);
					break;
				case HASHED_PARTIAL_REDUCE:
					collectHashed(record);
					break;
			}
		} catch (Exception ex) {
			throw new ExceptionInChainedStubException(taskName, ex);
		}
	}

	private void collectSorted(T record) throws Exception {
		// try writing to the sorter first
		if (!sorter.write(record)) {
			// it didn't succeed; sorter is full

			// do the actual sorting, combining, and data writing
			sortAndCombine();
			sorter.reset();

			// write the value again
			if (!sorter.write(record)) {
				throw new IOException("Cannot write record to fresh sort buffer. Record too large.");
			}
		}
	}

	private void collectHashed(T record) throws Exception {
		try {
			reduceFacade.updateTableEntryWithReduce(record);
		} catch (EOFException ex) {
			// the table has run out of memory
			reduceFacade.emitAndReset();
			// try again
			reduceFacade.updateTableEntryWithReduce(record);
		}
	}

	private void sortAndCombine() throws Exception {
		final InMemorySorter sorter = this.sorter;

		if (!sorter.isEmpty()) {
			sortAlgo.sort(sorter);

			final TypeSerializer serializer = this.serializer;
			final TypeComparator comparator = this.comparator;
			final ReduceFunction function = this.reducer;
			final Collector output = this.outputCollector;
			final MutableObjectIterator input = sorter.getIterator();

			if (objectReuseEnabled) {
				// We only need two objects. The first reference stores results and is
				// eventually collected. New values are read into the second.
				//
				// The output value must have the same key fields as the input values.

				T reuse1 = input.next();
				T reuse2 = serializer.createInstance();

				T value = reuse1;

				// iterate over key groups
				while (running && value != null) {
					comparator.setReference(value);

					// iterate within a key group
					while ((reuse2 = input.next(reuse2)) != null) {
						if (comparator.equalToReference(reuse2)) {
							// same group, reduce
							value = function.reduce(value, reuse2);

							// we must never read into the object returned
							// by the user, so swap the reuse objects
							if (value == reuse2) {
								T tmp = reuse1;
								reuse1 = reuse2;
								reuse2 = tmp;
							}
						} else {
							// new key group
							break;
						}
					}

					output.collect(value);

					// swap the value from the new key group into the first object
					T tmp = reuse1;
					reuse1 = reuse2;
					reuse2 = tmp;

					value = reuse1;
				}
			} else {
				T value = input.next();

				// iterate over key groups
				while (running && value != null) {
					comparator.setReference(value);
					T res = value;

					// iterate within a key group
					while ((value = input.next()) != null) {
						if (comparator.equalToReference(value)) {
							// same group, reduce
							res = function.reduce(res, value);
						} else {
							// new key group
							break;
						}
					}

					output.collect(res);
				}
			}
		}
	}

	@Override
	public void close() {
		// send the final batch
		try {
			switch (strategy) {
				case SORTED_PARTIAL_REDUCE:
					sortAndCombine();
					break;
				case HASHED_PARTIAL_REDUCE:
					reduceFacade.emit();
					break;
			}
		} catch (Exception ex2) {
			throw new ExceptionInChainedStubException(taskName, ex2);
		}

		outputCollector.close();
	}

	@Override
	public void closeTask() throws Exception {
		if (sorter != null) {
			sorter.dispose();
		}
		if (table != null) {
			table.close();
		}
		parent.getEnvironment().getMemoryManager().release(memory);
		BatchTask.closeUserCode(reducer);
	}

	@Override
	public void cancelTask() {
		running = false;

		try {
			if (sorter != null) {
				sorter.dispose();
			}
			if (table != null) {
				table.close();
			}
		} catch (Exception e) {
			// may happen during concurrent modification
		}

		parent.getEnvironment().getMemoryManager().release(memory);
	}
}