hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/scheduler/SnapshotBasedOverAllocationPolicy.java

/**
 * 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.hadoop.yarn.server.nodemanager.containermanager.scheduler;

import org.apache.hadoop.yarn.api.records.Resource;
import org.apache.hadoop.yarn.api.records.ResourceUtilization;
import org.apache.hadoop.yarn.server.api.records.ResourceThresholds;
import org.apache.hadoop.yarn.server.nodemanager.containermanager.monitor.ContainersMonitor;
import org.apache.hadoop.yarn.util.resource.Resources;

/**
 * An implementation of NMAllocationPolicy based on the
 * snapshot of the latest containers utilization to determine how much
 * resources are available * to launch containers when over-allocation
 * is turned on.
 */
public class SnapshotBasedOverAllocationPolicy
    extends NMAllocationPolicy {

  public SnapshotBasedOverAllocationPolicy(
      ResourceThresholds overAllocationThresholds,
      ContainersMonitor containersMonitor) {
    super(overAllocationThresholds, containersMonitor);
  }

  @Override
  public Resource getAvailableResources() {
    ResourceUtilization utilization =
        containersMonitor.getContainersUtilization(true).getUtilization();

    long memoryOverAllocationThresholdBytes =
        Math.round(
            ((double) overAllocationThresholds.getMemoryThreshold()) *
            containersMonitor.getPmemAllocatedForContainers());
    long memoryUtilizationBytes =
        ((long) utilization.getPhysicalMemory()) << 20;
    long memoryAvailable =
        memoryOverAllocationThresholdBytes - memoryUtilizationBytes;

    int vcoreAvailable = Math.round(
        (overAllocationThresholds.getCpuThreshold() - utilization.getCPU()) *
            containersMonitor.getVCoresAllocatedForContainers());

    return (memoryAvailable <= 0 || vcoreAvailable <= 0) ? Resources.none() :
        Resource.newInstance(memoryAvailable >> 20, vcoreAvailable);
  }
}