org.apache.kylin.engine.mr.common.MapReduceUtil Maven / Gradle / Ivy
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package org.apache.kylin.engine.mr.common;
import java.io.IOException;
import java.util.Map;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.kylin.common.KylinConfig;
import org.apache.kylin.cube.CubeInstance;
import org.apache.kylin.cube.CubeSegment;
import org.apache.kylin.cube.cuboid.CuboidScheduler;
import org.apache.kylin.cube.model.CubeDesc;
import org.apache.kylin.job.exception.JobException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class MapReduceUtil {
private static final Logger logger = LoggerFactory.getLogger(MapReduceUtil.class);
/**
* @return reducer number for calculating hll
*/
public static int getCuboidHLLCounterReducerNum(CubeInstance cube) {
int nCuboids = cube.getCuboidScheduler().getAllCuboidIds().size();
int shardBase = (nCuboids - 1) / cube.getConfig().getHadoopJobPerReducerHLLCuboidNumber() + 1;
int hllMaxReducerNumber = cube.getConfig().getHadoopJobHLLMaxReducerNumber();
if (shardBase > hllMaxReducerNumber) {
shardBase = hllMaxReducerNumber;
}
return shardBase;
}
/**
* @param cuboidScheduler specified can provide more flexibility
* */
public static int getLayeredCubingReduceTaskNum(CubeSegment cubeSegment, CuboidScheduler cuboidScheduler,
double totalMapInputMB, int level)
throws ClassNotFoundException, IOException, InterruptedException, JobException {
CubeDesc cubeDesc = cubeSegment.getCubeDesc();
KylinConfig kylinConfig = cubeDesc.getConfig();
double perReduceInputMB = kylinConfig.getDefaultHadoopJobReducerInputMB();
double reduceCountRatio = kylinConfig.getDefaultHadoopJobReducerCountRatio();
logger.info("Having per reduce MB " + perReduceInputMB + ", reduce count ratio " + reduceCountRatio + ", level "
+ level);
CubeStatsReader cubeStatsReader = new CubeStatsReader(cubeSegment, cuboidScheduler, kylinConfig);
double parentLayerSizeEst, currentLayerSizeEst, adjustedCurrentLayerSizeEst;
if (level == -1) {
//merge case
double estimatedSize = cubeStatsReader.estimateCubeSize();
adjustedCurrentLayerSizeEst = estimatedSize > totalMapInputMB ? totalMapInputMB : estimatedSize;
logger.debug("estimated size {}, input size {}, adjustedCurrentLayerSizeEst: {}", estimatedSize,
totalMapInputMB, adjustedCurrentLayerSizeEst);
} else if (level == 0) {
//base cuboid case TODO: the estimation could be very WRONG because it has no correction
adjustedCurrentLayerSizeEst = cubeStatsReader.estimateLayerSize(0);
logger.debug("adjustedCurrentLayerSizeEst: {}", adjustedCurrentLayerSizeEst);
} else {
parentLayerSizeEst = cubeStatsReader.estimateLayerSize(level - 1);
currentLayerSizeEst = cubeStatsReader.estimateLayerSize(level);
adjustedCurrentLayerSizeEst = totalMapInputMB / parentLayerSizeEst * currentLayerSizeEst;
logger.debug(
"totalMapInputMB: {}, parentLayerSizeEst: {}, currentLayerSizeEst: {}, adjustedCurrentLayerSizeEst: {}",
totalMapInputMB, parentLayerSizeEst, currentLayerSizeEst, adjustedCurrentLayerSizeEst);
}
// number of reduce tasks
int numReduceTasks = (int) Math.round(adjustedCurrentLayerSizeEst / perReduceInputMB * reduceCountRatio + 0.99);
// adjust reducer number for cube which has DISTINCT_COUNT measures for better performance
if (cubeDesc.hasMemoryHungryMeasures()) {
logger.debug("Multiply reducer num by 4 to boost performance for memory hungry measures");
numReduceTasks = numReduceTasks * 4;
}
// at least 1 reducer by default
numReduceTasks = Math.max(kylinConfig.getHadoopJobMinReducerNumber(), numReduceTasks);
// no more than 500 reducer by default
numReduceTasks = Math.min(kylinConfig.getHadoopJobMaxReducerNumber(), numReduceTasks);
return numReduceTasks;
}
public static int getInmemCubingReduceTaskNum(CubeSegment cubeSeg, CuboidScheduler cuboidScheduler)
throws IOException {
KylinConfig kylinConfig = cubeSeg.getConfig();
Map cubeSizeMap = new CubeStatsReader(cubeSeg, cuboidScheduler, kylinConfig).getCuboidSizeMap();
double totalSizeInM = 0;
for (Double cuboidSize : cubeSizeMap.values()) {
totalSizeInM += cuboidSize;
}
double perReduceInputMB = kylinConfig.getDefaultHadoopJobReducerInputMB();
double reduceCountRatio = kylinConfig.getDefaultHadoopJobReducerCountRatio();
// number of reduce tasks
int numReduceTasks = (int) Math.round(totalSizeInM / perReduceInputMB * reduceCountRatio);
// at least 1 reducer by default
numReduceTasks = Math.max(kylinConfig.getHadoopJobMinReducerNumber(), numReduceTasks);
// no more than 500 reducer by default
numReduceTasks = Math.min(kylinConfig.getHadoopJobMaxReducerNumber(), numReduceTasks);
logger.info("Having total map input MB " + Math.round(totalSizeInM));
logger.info("Having per reduce MB " + perReduceInputMB);
logger.info("Setting " + Reducer.Context.NUM_REDUCES + "=" + numReduceTasks);
return numReduceTasks;
}
}
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