org.apache.hadoop.hive.ql.optimizer.SetReducerParallelism Maven / Gradle / Ivy
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package org.apache.hadoop.hive.ql.optimizer;
import java.util.Collection;
import java.util.EnumSet;
import java.util.Stack;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.hive.conf.HiveConf;
import org.apache.hadoop.hive.ql.exec.Operator;
import org.apache.hadoop.hive.ql.exec.ReduceSinkOperator;
import org.apache.hadoop.hive.ql.exec.Utilities;
import org.apache.hadoop.hive.ql.lib.Node;
import org.apache.hadoop.hive.ql.lib.SemanticNodeProcessor;
import org.apache.hadoop.hive.ql.lib.NodeProcessorCtx;
import org.apache.hadoop.hive.ql.parse.OptimizeTezProcContext;
import org.apache.hadoop.hive.ql.parse.SemanticException;
import org.apache.hadoop.hive.ql.plan.ExprNodeDesc.ExprNodeDescEqualityWrapper;
import org.apache.hadoop.hive.ql.plan.OperatorDesc;
import org.apache.hadoop.hive.ql.plan.ReduceSinkDesc;
import org.apache.hadoop.hive.ql.stats.StatsUtils;
import static org.apache.hadoop.hive.ql.plan.ReduceSinkDesc.ReducerTraits.AUTOPARALLEL;
import static org.apache.hadoop.hive.ql.plan.ReduceSinkDesc.ReducerTraits.UNIFORM;
import static org.apache.hadoop.hive.ql.plan.ReduceSinkDesc.ReducerTraits.FIXED;
/**
* SetReducerParallelism determines how many reducers should
* be run for a given reduce sink.
*/
public class SetReducerParallelism implements SemanticNodeProcessor {
private static final Logger LOG = LoggerFactory.getLogger(SetReducerParallelism.class.getName());
@SuppressWarnings("unchecked")
@Override
public Object process(Node nd, Stack stack,
NodeProcessorCtx procContext, Object... nodeOutputs)
throws SemanticException {
OptimizeTezProcContext context = (OptimizeTezProcContext) procContext;
ReduceSinkOperator sink = (ReduceSinkOperator) nd;
ReduceSinkDesc desc = sink.getConf();
long bytesPerReducer = context.conf.getLongVar(HiveConf.ConfVars.BYTESPERREDUCER);
int maxReducers = context.conf.getIntVar(HiveConf.ConfVars.MAXREDUCERS);
int constantReducers = context.conf.getIntVar(HiveConf.ConfVars.HADOOPNUMREDUCERS);
if (context.visitedReduceSinks.contains(sink)) {
// skip walking the children
LOG.debug("Already processed reduce sink: " + sink.getName());
return true;
}
context.visitedReduceSinks.add(sink);
if (desc.getNumReducers() <= 0) {
if (constantReducers > 0) {
LOG.info("Parallelism for reduce sink "+sink+" set by user to "+constantReducers);
desc.setNumReducers(constantReducers);
} else {
long numberOfBytes = 0;
// we need to add up all the estimates from the siblings of this reduce sink
for (Operator sibling:
sink.getChildOperators().get(0).getParentOperators()) {
if (sibling.getStatistics() != null) {
numberOfBytes = StatsUtils.safeAdd(
numberOfBytes, sibling.getStatistics().getDataSize());
} else {
LOG.warn("No stats available from: "+sibling);
}
}
int numReducers = Utilities.estimateReducers(numberOfBytes, bytesPerReducer,
maxReducers, false);
LOG.info("Set parallelism for reduce sink "+sink+" to: "+numReducers);
desc.setNumReducers(numReducers);
final Collection keyCols = ExprNodeDescEqualityWrapper.transform(desc.getKeyCols());
final Collection partCols = ExprNodeDescEqualityWrapper.transform(desc.getPartitionCols());
if (keyCols != null && keyCols.equals(partCols)) {
desc.setReducerTraits(EnumSet.of(UNIFORM, AUTOPARALLEL));
} else {
desc.setReducerTraits(EnumSet.of(AUTOPARALLEL));
}
}
} else {
LOG.info("Number of reducers determined to be: "+desc.getNumReducers());
desc.setReducerTraits(EnumSet.of(FIXED)); // usually controlled by bucketing
}
return false;
}
}