tillrohrmann commented on a change in pull request #6898: [FLINK-10431] Extraction of scheduling-related code from SlotPool into preliminary Scheduler URL: https://github.com/apache/flink/pull/6898#discussion_r227453190
########## File path: flink-runtime/src/main/java/org/apache/flink/runtime/jobmaster/slotpool/LocationPreferenceSlotSelection.java ########## @@ -0,0 +1,111 @@ +/* + * 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.jobmaster.slotpool; + +import org.apache.flink.runtime.clusterframework.types.ResourceID; +import org.apache.flink.runtime.clusterframework.types.ResourceProfile; +import org.apache.flink.runtime.clusterframework.types.SlotProfile; +import org.apache.flink.runtime.jobmanager.scheduler.Locality; +import org.apache.flink.runtime.jobmaster.SlotInfo; +import org.apache.flink.runtime.taskmanager.TaskManagerLocation; + +import javax.annotation.Nonnull; + +import java.util.Collection; +import java.util.HashMap; +import java.util.List; +import java.util.Map; +import java.util.function.BiFunction; + +/** + * This class implements a {@link SlotSelectionStrategy} that is based on location preference hints. + */ +public class LocationPreferenceSlotSelection implements SlotSelectionStrategy { + + public static final LocationPreferenceSlotSelection INSTANCE = new LocationPreferenceSlotSelection(); + + private LocationPreferenceSlotSelection() { + } + + /** + * Calculates the candidate's locality score. + */ + private static final BiFunction<Integer, Integer, Integer> LOCALITY_EVALUATION_FUNCTION = + (localWeigh, hostLocalWeigh) -> localWeigh * 10 + hostLocalWeigh; + + @Nonnull + @Override + public SlotInfoAndLocality selectBestSlotForProfile( + @Nonnull List<SlotInfo> availableSlots, + @Nonnull SlotProfile slotProfile) { + + Collection<TaskManagerLocation> locationPreferences = slotProfile.getPreferredLocations(); + + if (availableSlots.isEmpty()) { + return SlotInfoAndLocality.of(null, Locality.UNKNOWN); + } + + final ResourceProfile resourceProfile = slotProfile.getResourceProfile(); + + // if we have no location preferences, we can only filter by the additional requirements. + if (locationPreferences.isEmpty()) { + for (SlotInfo candidate : availableSlots) { + if (candidate.getResourceProfile().isMatching(resourceProfile)) { + return SlotInfoAndLocality.of(candidate, Locality.UNCONSTRAINED); + } + } + return SlotInfoAndLocality.of(null, Locality.UNKNOWN); + } + + // we build up two indexes, one for resource id and one for host names of the preferred locations. + final Map<ResourceID, Integer> preferredResourceIDs = new HashMap<>(locationPreferences.size()); + final Map<String, Integer> preferredFQHostNames = new HashMap<>(locationPreferences.size()); + + for (TaskManagerLocation locationPreference : locationPreferences) { + preferredResourceIDs.merge(locationPreference.getResourceID(), 1, Integer::sum); + preferredFQHostNames.merge(locationPreference.getFQDNHostname(), 1, Integer::sum); + } + + SlotInfo bestCandidate = null; + Locality bestCandidateLocality = Locality.UNKNOWN; + int bestCandidateScore = Integer.MIN_VALUE; + + for (SlotInfo candidate : availableSlots) { + + if (candidate.getResourceProfile().isMatching(resourceProfile)) { + + // this gets candidate is local-weigh + Integer localWeigh = preferredResourceIDs.getOrDefault(candidate.getTaskManagerLocation().getResourceID(), 0); + + // this gets candidate is host-local-weigh + Integer hostLocalWeigh = preferredFQHostNames.getOrDefault(candidate.getTaskManagerLocation().getFQDNHostname(), 0); + + int candidateScore = LOCALITY_EVALUATION_FUNCTION.apply(localWeigh, hostLocalWeigh); + if (candidateScore > bestCandidateScore) { + bestCandidateScore = candidateScore; + bestCandidate = candidate; + bestCandidateLocality = localWeigh > 0 ? Locality.LOCAL : hostLocalWeigh > 0 ? Locality.HOST_LOCAL : Locality.NON_LOCAL; + } + } + } + + // at the end of the iteration, we return the candidate with best possible locality or null. + return SlotInfoAndLocality.of(bestCandidate, bestCandidateLocality); Review comment: This block could be separate method as well, e.g. `selectBestSlotByPreferredLocations` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
