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From sudheeshkatkam <...@git.apache.org>
Subject [GitHub] drill pull request: DRILL-4446: Support mandatory work assignment ...
Date Thu, 07 Apr 2016 22:38:00 GMT
Github user sudheeshkatkam commented on a diff in the pull request:

    https://github.com/apache/drill/pull/403#discussion_r58956969
  
    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/planner/fragment/HardAffinityFragmentParallelizer.java
---
    @@ -0,0 +1,134 @@
    +/**
    + * 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
    + * <p/>
    + * http://www.apache.org/licenses/LICENSE-2.0
    + * <p/>
    + * 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.drill.exec.planner.fragment;
    +
    +import com.google.common.collect.Lists;
    +import com.google.common.collect.Maps;
    +import org.apache.drill.exec.physical.EndpointAffinity;
    +import org.apache.drill.exec.physical.PhysicalOperatorSetupException;
    +import org.apache.drill.exec.proto.CoordinationProtos.DrillbitEndpoint;
    +import org.slf4j.Logger;
    +
    +import java.util.Collection;
    +import java.util.List;
    +import java.util.Map;
    +import java.util.Map.Entry;
    +
    +/**
    + * Implementation of {@link FragmentParallelizer} where fragment requires running on
a given set of endpoints. Width
    + * per node is depended on the affinity to the endpoint and total width (calculated using
costs)
    + */
    +public class HardAffinityFragmentParallelizer implements FragmentParallelizer {
    +  private static final Logger logger = org.slf4j.LoggerFactory.getLogger(HardAffinityFragmentParallelizer.class);
    +
    +  public static final HardAffinityFragmentParallelizer INSTANCE = new HardAffinityFragmentParallelizer();
    +
    +  private static String EOL = System.getProperty("line.separator");
    +
    +  private HardAffinityFragmentParallelizer() { /* singleton */}
    +
    +  @Override
    +  public void parallelizeFragment(final Wrapper fragmentWrapper, final ParallelizationParameters
parameters,
    +      final Collection<DrillbitEndpoint> activeEndpoints) throws PhysicalOperatorSetupException
{
    +
    +    final Stats stats = fragmentWrapper.getStats();
    +    final ParallelizationInfo pInfo = stats.getParallelizationInfo();
    +
    +    // Go through the affinity map and extract the endpoints that have mandatory assignment
requirement
    +    final Map<DrillbitEndpoint, EndpointAffinity> endpointPool = Maps.newHashMap();
    +    for(Entry<DrillbitEndpoint, EndpointAffinity> entry : pInfo.getEndpointAffinityMap().entrySet())
{
    +      if (entry.getValue().isAssignmentRequired()) {
    +        endpointPool.put(entry.getKey(), entry.getValue());
    +      }
    +    }
    +
    +    // Step 1: Find the width taking into various parameters
    +    // 1.1. Find the parallelization based on cost. Use max cost of all operators in
this fragment; this is consistent
    +    //      with the calculation that ExcessiveExchangeRemover uses.
    +    int width = (int) Math.ceil(stats.getMaxCost() / parameters.getSliceTarget());
    +
    +    // 1.2. Make sure the width is at least the number of endpoints that require an assignment
    +    width = Math.max(endpointPool.size(), width);
    +
    +    // 1.3. Cap the parallelization width by fragment level width limit and system level
per query width limit
    +    width = Math.max(1, Math.min(width, pInfo.getMaxWidth()));
    +    checkAndThrow(endpointPool.size() <= width, logger,
    +        "Number of mandatory endpoints ({}) that require an assignment is more than the
allowed fragment max " +
    +            "width ({}).", endpointPool.size(), pInfo.getMaxWidth());
    +
    +    // 1.4 Cap the parallelization width by global max query width
    +    width = Math.max(1, Math.min(width, parameters.getMaxGlobalWidth()));
    +    checkAndThrow(endpointPool.size() <= width, logger,
    +        "Number of mandatory endpoints ({}) that require an assignment is more than the
allowed global query " +
    +            "width ({}).", endpointPool.size(), parameters.getMaxGlobalWidth());
    +
    +    // 1.5 Cap the parallelization width by max allowed parallelization per node
    +    width = Math.max(1, Math.min(width, endpointPool.size()*parameters.getMaxWidthPerNode()));
    +
    +    // Step 2: Select the endpoints
    +    final Map<DrillbitEndpoint, Integer> endpoints = Maps.newHashMap();
    +
    +    // 2.1 First add each endpoint from the pool once so that the mandatory assignment
requirement is fulfilled.
    +    for(Entry<DrillbitEndpoint, EndpointAffinity> entry : endpointPool.entrySet())
{
    +      endpoints.put(entry.getKey(), 1);
    +    }
    +    int totalAssigned = endpoints.size();
    +
    +    // 2.2 Assign the remaining slots to endpoints proportional to the affinity of each
endpoint
    +    int remainingSlots = width - endpoints.size();
    +    while (remainingSlots > 0) {
    +      for(EndpointAffinity epAf : endpointPool.values()) {
    +        final int moreAllocation = (int) Math.ceil(epAf.getAffinity() * remainingSlots);
    +        int currentAssignments = endpoints.get(epAf.getEndpoint());
    +        for(int i=0;
    +            i < moreAllocation &&  totalAssigned < width && currentAssignments
< parameters.getMaxWidthPerNode();
    +            i++) {
    +          totalAssigned++;
    +          currentAssignments++;
    +        }
    +        endpoints.put(epAf.getEndpoint(), currentAssignments);
    +      }
    +      final int previousRemainingSlots = remainingSlots;
    +      remainingSlots = width - totalAssigned;
    +      if (previousRemainingSlots == remainingSlots) {
    +        logger.error("Can't parallelize fragment: " +
    +            "Every mandatory node has exhausted the maximum width per node limit." +
EOL +
    +            "Endpoint pool: {}" + EOL + "Assignment so far: {}" + EOL + "Width: {}",
endpointPool, endpoints, width);
    +        throw new PhysicalOperatorSetupException("Can not parallelize fragment.");
    +      }
    +    }
    +
    +    final List<DrillbitEndpoint> assignedEndpoints = Lists.newArrayList();
    +    for(Entry<DrillbitEndpoint, Integer> entry : endpoints.entrySet()) {
    +      for(int i=0; i < entry.getValue(); i++) {
    +        assignedEndpoints.add(entry.getKey());
    +      }
    +    }
    +
    +    fragmentWrapper.setWidth(width);
    +    fragmentWrapper.assignEndpoints(assignedEndpoints);
    +  }
    +
    +  private static void checkAndThrow(final boolean expr, final Logger logger, final String
errMsg, Object... args)
    --- End diff --
    
    checkOrThrow?


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