org.apache.flink.runtime.operators.AllReduceDriver Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* 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,
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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.flink.runtime.operators;
import org.apache.flink.api.common.ExecutionConfig;
import org.apache.flink.metrics.Counter;
import org.apache.flink.runtime.operators.util.metrics.CountingCollector;
import org.apache.flink.util.Collector;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.flink.api.common.functions.ReduceFunction;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.api.common.typeutils.TypeSerializerFactory;
import org.apache.flink.runtime.operators.util.TaskConfig;
import org.apache.flink.util.MutableObjectIterator;
/**
* Reduce task which is executed by a Task Manager. The task has a
* single input and one or multiple outputs. It is provided with a ReduceFunction
* implementation.
*
* The AllReduceDriver creates an iterator over all records from its input.
* The elements are handed pairwise to the reduce()
method of the ReduceFunction.
*
* @see org.apache.flink.api.common.functions.ReduceFunction
*/
public class AllReduceDriver implements Driver, T> {
private static final Logger LOG = LoggerFactory.getLogger(AllReduceDriver.class);
private TaskContext, T> taskContext;
private MutableObjectIterator input;
private TypeSerializer serializer;
private boolean running;
private boolean objectReuseEnabled = false;
// ------------------------------------------------------------------------
@Override
public void setup(TaskContext, T> context) {
this.taskContext = context;
this.running = true;
}
@Override
public int getNumberOfInputs() {
return 1;
}
@Override
public Class> getStubType() {
@SuppressWarnings("unchecked")
final Class> clazz = (Class>) (Class) ReduceFunction.class;
return clazz;
}
@Override
public int getNumberOfDriverComparators() {
return 0;
}
// --------------------------------------------------------------------------------------------
@Override
public void prepare() throws Exception {
final TaskConfig config = this.taskContext.getTaskConfig();
if (config.getDriverStrategy() != DriverStrategy.ALL_REDUCE) {
throw new Exception("Unrecognized driver strategy for AllReduce driver: " + config.getDriverStrategy().name());
}
TypeSerializerFactory serializerFactory = this.taskContext.getInputSerializer(0);
this.serializer = serializerFactory.getSerializer();
this.input = this.taskContext.getInput(0);
ExecutionConfig executionConfig = taskContext.getExecutionConfig();
this.objectReuseEnabled = executionConfig.isObjectReuseEnabled();
if (LOG.isDebugEnabled()) {
LOG.debug("AllReduceDriver object reuse: " + (this.objectReuseEnabled ? "ENABLED" : "DISABLED") + ".");
}
}
@Override
public void run() throws Exception {
if (LOG.isDebugEnabled()) {
LOG.debug(this.taskContext.formatLogString("AllReduce preprocessing done. Running Reducer code."));
}
final Counter numRecordsIn = this.taskContext.getMetricGroup().counter("numRecordsIn");
final Counter numRecordsOut = this.taskContext.getMetricGroup().counter("numRecordsOut");
final ReduceFunction stub = this.taskContext.getStub();
final MutableObjectIterator input = this.input;
final TypeSerializer serializer = this.serializer;
final Collector collector = new CountingCollector<>(this.taskContext.getOutputCollector(), numRecordsOut);
T val1;
if ((val1 = input.next()) == null) {
return;
}
numRecordsIn.inc();
if (objectReuseEnabled) {
// We only need two objects. The first reference stores results and is
// eventually collected. New values are read into the second.
T val2 = serializer.createInstance();
T value = val1;
while (running && (val2 = input.next(val2)) != null) {
numRecordsIn.inc();
value = stub.reduce(value, val2);
// we must never read into the object returned
// by the user, so swap the reuse objects,
if (value == val2) {
T tmp = val1;
val1 = val2;
val2 = tmp;
}
}
collector.collect(value);
} else {
T val2;
while (running && (val2 = input.next()) != null) {
numRecordsIn.inc();
val1 = stub.reduce(val1, val2);
}
collector.collect(val1);
}
}
@Override
public void cleanup() {}
@Override
public void cancel() {
this.running = false;
}
}