How to use

FSClusterStats

in

org.apache.hadoop.hdfs.server.blockmanagement

/**
 * Determine if a datanode should be chosen based on current workload.
 *
 * @param node The target datanode
 * @return Return true if the datanode should be excluded, otherwise false
 */
boolean excludeNodeByLoad(DatanodeDescriptor node){
 final double maxLoad = considerLoadFactor *
   stats.getInServiceXceiverAverage();
 final int nodeLoad = node.getXceiverCount();
 if ((nodeLoad > maxLoad) && (maxLoad > 0)) {
  logNodeIsNotChosen(node, NodeNotChosenReason.NODE_TOO_BUSY,
    "(load: " + nodeLoad + " > " + maxLoad + ")");
  return true;
 }
 return false;
}

Node localNode = null;
boolean avoidStaleNodes = (stats != null
  && stats.isAvoidingStaleDataNodesForWrite());
boolean avoidLocalNode = (addBlockFlags != null
  && addBlockFlags.contains(AddBlockFlag.NO_LOCAL_WRITE)

private static int getNumDNInService(FSNamesystem fsn) {
 return fsn.getBlockManager().getDatanodeManager().getFSClusterStats()
  .getNumDatanodesInService();
}

private static double getInServiceXceiverAverage(FSNamesystem fsn) {
 return fsn.getBlockManager().getDatanodeManager().getFSClusterStats()
  .getInServiceXceiverAverage();
}

&& stats.isAvoidingStaleDataNodesForWrite();

.getInServiceXceiverAverage(), EPSILON);
.getInServiceXceiverAverage(), EPSILON);

  && stats.isAvoidingStaleDataNodesForWrite());
final Node localNode = chooseTarget(numOfReplicas, writer, excludedNodes,
  blocksize, maxNodesPerRack, results, avoidStaleNodes, storagePolicy,

final double maxLoad = 2.0 * stats.getInServiceXceiverAverage();
final int nodeLoad = node.getXceiverCount();
if (nodeLoad > maxLoad) {

  && stats.isAvoidingStaleDataNodesForWrite());
final Node localNode = chooseTarget(numOfReplicas, writer, excludedNodes,
  blocksize, maxNodesPerRack, results, avoidStaleNodes, storagePolicy,

final double maxLoad = 2.0 * stats.getInServiceXceiverAverage();
final int nodeLoad = node.getXceiverCount();
if (nodeLoad > maxLoad) {

&& stats.isAvoidingStaleDataNodesForWrite();

&& stats.isAvoidingStaleDataNodesForWrite();