Author: cutting
Date: Mon Apr 16 13:35:23 2007
New Revision: 529389
URL: http://svn.apache.org/viewvc?view=rev&rev=529389
Log:
HADOOP-1155. Improve NetworkTopology's algorithm for finding nearby nodes.
Contributed by Hairong Kuang.
Modified:
lucene/hadoop/trunk/CHANGES.txt
lucene/hadoop/trunk/src/java/org/apache/hadoop/dfs/FSNamesystem.java
lucene/hadoop/trunk/src/java/org/apache/hadoop/net/NetworkTopology.java
lucene/hadoop/trunk/src/test/org/apache/hadoop/net/TestNetworkTopology.java
Modified: lucene/hadoop/trunk/CHANGES.txt
URL:
http://svn.apache.org/viewvc/lucene/hadoop/trunk/CHANGES.txt?view=diff&rev=529389&r1=529388&r2=529389
==============================================================================
--- lucene/hadoop/trunk/CHANGES.txt (original)
+++ lucene/hadoop/trunk/CHANGES.txt Mon Apr 16 13:35:23 2007
@@ -210,6 +210,9 @@
63. HADOOP-1258. Fix TestCheckpoint test case to wait for
MiniDFSCluster to be active. (Nigel Daley via tomwhite)
+64. HADOOP-1155. Improve NetworkTopology's algorithm for finding
+ nearby nodes, used by HDFS. (Hairong Kuang via cutting)
+
Release 0.12.3 - 2007-04-06
Modified: lucene/hadoop/trunk/src/java/org/apache/hadoop/dfs/FSNamesystem.java
URL:
http://svn.apache.org/viewvc/lucene/hadoop/trunk/src/java/org/apache/hadoop/dfs/FSNamesystem.java?view=diff&rev=529389&r1=529388&r2=529389
==============================================================================
--- lucene/hadoop/trunk/src/java/org/apache/hadoop/dfs/FSNamesystem.java
(original)
+++ lucene/hadoop/trunk/src/java/org/apache/hadoop/dfs/FSNamesystem.java Mon
Apr 16 13:35:23 2007
@@ -626,7 +626,7 @@
blocksMap.nodeIterator( blocks[i] ); it.hasNext(); ) {
machineSets[i][ numNodes++ ] = it.next();
}
- clusterMap.sortByDistance( client, machineSets[i] );
+ clusterMap.pseudoSortByDistance( client, machineSets[i] );
}
}
@@ -3120,13 +3120,13 @@
throws NotEnoughReplicasException {
DatanodeDescriptor result;
do {
- DatanodeDescriptor[] selectedNodes =
+ List<DatanodeDescriptor> selectedNodes =
chooseRandom(1, nodes, excludedNodes);
- if(selectedNodes.length == 0 ) {
+ if(selectedNodes.size() == 0 ) {
throw new NotEnoughReplicasException(
"Not able to place enough replicas" );
}
- result = (DatanodeDescriptor)(selectedNodes[0]);
+ result = (DatanodeDescriptor)(selectedNodes.get(0));
} while( !isGoodTarget( result, blocksize, maxNodesPerRack, results));
results.add(result);
return result;
@@ -3143,13 +3143,13 @@
throws NotEnoughReplicasException {
boolean toContinue = true;
do {
- DatanodeDescriptor[] selectedNodes =
+ List<DatanodeDescriptor> selectedNodes =
chooseRandom(numOfReplicas, nodes, excludedNodes);
- if(selectedNodes.length < numOfReplicas) {
+ if(selectedNodes.size() < numOfReplicas) {
toContinue = false;
}
- for(int i=0; i<selectedNodes.length; i++) {
- DatanodeDescriptor result = (DatanodeDescriptor)(selectedNodes[i]);
+ for(int i=0; i<selectedNodes.size(); i++) {
+ DatanodeDescriptor result =
(DatanodeDescriptor)(selectedNodes.get(i));
if( isGoodTarget( result, blocksize, maxNodesPerRack, results)) {
numOfReplicas--;
results.add(result);
@@ -3166,7 +3166,7 @@
/* Randomly choose <i>numOfNodes</i> nodes from <i>scope</i>.
* @return the choosen nodes
*/
- private DatanodeDescriptor[] chooseRandom(int numOfReplicas,
+ private List<DatanodeDescriptor> chooseRandom(int numOfReplicas,
String nodes,
List<DatanodeDescriptor> excludedNodes) {
List<DatanodeDescriptor> results =
@@ -3183,8 +3183,7 @@
numOfReplicas--;
}
}
- return (DatanodeDescriptor[])results.toArray(
- new DatanodeDescriptor[results.size()]);
+ return results;
}
/* judge if a node is a good target.
Modified:
lucene/hadoop/trunk/src/java/org/apache/hadoop/net/NetworkTopology.java
URL:
http://svn.apache.org/viewvc/lucene/hadoop/trunk/src/java/org/apache/hadoop/net/NetworkTopology.java?view=diff&rev=529389&r1=529388&r2=529389
==============================================================================
--- lucene/hadoop/trunk/src/java/org/apache/hadoop/net/NetworkTopology.java
(original)
+++ lucene/hadoop/trunk/src/java/org/apache/hadoop/net/NetworkTopology.java Mon
Apr 16 13:35:23 2007
@@ -19,6 +19,7 @@
import java.util.ArrayList;
import java.util.Collection;
+import java.util.HashMap;
import java.util.Comparator;
import java.util.List;
import java.util.Random;
@@ -300,6 +301,7 @@
InnerNode clusterMap = new InnerNode( InnerNode.ROOT ); // the root
private int numOfRacks = 0; // rack counter
+ private HashMap<String, Node> rackMap = new HashMap<String, Node>();
public NetworkTopology() {
}
@@ -322,6 +324,7 @@
if( clusterMap.add( node) ) {
if( rack == null ) {
numOfRacks++;
+ rackMap.put(node.getNetworkLocation(), node.getParent());
}
}
LOG.debug("NetworkTopology became:\n" + this.toString());
@@ -339,6 +342,7 @@
InnerNode rack = (InnerNode)getNode(node.getNetworkLocation());
if(rack == null) {
numOfRacks--;
+ rackMap.remove(node.getNetworkLocation());
}
}
LOG.debug("NetworkTopology became:\n" + this.toString());
@@ -369,6 +373,12 @@
*/
public synchronized Node getNode( String loc ) {
loc = NodeBase.normalize(loc);
+ // optimize searching rack node by looking up the rackMap
+ Node node = rackMap.get(loc);
+ if( node != null ) {
+ return node;
+ }
+ // otherwise slower search
if(!NodeBase.ROOT.equals(loc))
loc = loc.substring(1);
return clusterMap.getLoc( loc );
@@ -440,11 +450,7 @@
return false;
}
- if( node1 == node2 || node1.equals(node2)) {
- return true;
- }
-
- return node1.getParent()==node2.getParent();
+ return node1.getParent()==node2.getParent();
}
final private static Random r = new Random();
@@ -546,24 +552,47 @@
return tree.toString();
}
- /* Set and used only inside sortByDistance.
- * This saves an allocation each time we sort.
+ /** Sort nodes array by their distances to <i>reader</i>
+ * It linearly scans the array, if a local node is found, swap it with
+ * the first element of the array.
+ * If a local rack node is found, swap it with the first element following
+ * the local node.
+ * It leaves the rest nodes untouched.
*/
- private DatanodeDescriptor distFrom = null;
- private final Comparator<DatanodeDescriptor> nodeDistanceComparator =
- new Comparator<DatanodeDescriptor>() {
- public int compare(DatanodeDescriptor n1, DatanodeDescriptor n2) {
- return getDistance(distFrom, n1) - getDistance(distFrom, n2);
+ public synchronized void pseudoSortByDistance(
+ DatanodeDescriptor reader, DatanodeDescriptor[] nodes ) {
+ if (reader == null ) return; // no need to sort
+
+ DatanodeDescriptor tempNode;
+ int tempIndex = 0;
+ int localRackNode = -1;
+ //scan the array to find the local node & local rack node
+ for(int i=0; i<nodes.length; i++) {
+ if(tempIndex == 0 && reader == nodes[i]) { //local node
+ //swap the local node and the node at position 0
+ if( i != 0 ) {
+ tempNode = nodes[tempIndex];
+ nodes[tempIndex] = nodes[i];
+ nodes[i] = tempNode;
+ }
+ tempIndex=1;
+ if(localRackNode != -1 ) {
+ if(localRackNode == 0) {
+ localRackNode = i;
+ }
+ break;
+ }
+ } else if(localRackNode == -1 && isOnSameRack(reader, nodes[i])) {
//local rack
+ localRackNode = i;
+ if(tempIndex != 0 ) break;
}
- };
+ }
- /** Sorts nodes array by their distances to <i>reader</i>. */
- public synchronized void sortByDistance( final DatanodeDescriptor reader,
- DatanodeDescriptor[] nodes ) {
- if(reader != null && contains(reader)) {
- distFrom = reader;
- Arrays.sort( nodes, nodeDistanceComparator );
- distFrom = null;
+ // swap the local rack node and the node at position tempIndex
+ if(localRackNode != -1 && localRackNode != tempIndex ) {
+ tempNode = nodes[tempIndex];
+ nodes[tempIndex] = nodes[localRackNode];
+ nodes[localRackNode] = tempNode;
}
}
}
Modified:
lucene/hadoop/trunk/src/test/org/apache/hadoop/net/TestNetworkTopology.java
URL:
http://svn.apache.org/viewvc/lucene/hadoop/trunk/src/test/org/apache/hadoop/net/TestNetworkTopology.java?view=diff&rev=529389&r1=529388&r2=529389
==============================================================================
--- lucene/hadoop/trunk/src/test/org/apache/hadoop/net/TestNetworkTopology.java
(original)
+++ lucene/hadoop/trunk/src/test/org/apache/hadoop/net/TestNetworkTopology.java
Mon Apr 16 13:35:23 2007
@@ -25,7 +25,7 @@
}
}
- public void testContains() {
+ public void testContains() throws Exception {
for(int i=0; i<dataNodes.length; i++) {
assertTrue( cluster.contains(dataNodes[i]));
}
@@ -53,6 +53,46 @@
assertEquals(cluster.getDistance(dataNodes[0], dataNodes[6]), 6);
}
+ public void testPseudoSortByDistance() throws Exception {
+ DatanodeDescriptor[] testNodes = new DatanodeDescriptor[3];
+
+ // array contains both local node & local rack node
+ testNodes[0] = dataNodes[1];
+ testNodes[1] = dataNodes[2];
+ testNodes[2] = dataNodes[0];
+ cluster.pseudoSortByDistance(dataNodes[0], testNodes );
+ assertTrue(testNodes[0] == dataNodes[0]);
+ assertTrue(testNodes[1] == dataNodes[1]);
+ assertTrue(testNodes[2] == dataNodes[2]);
+
+ // array contains local node
+ testNodes[0] = dataNodes[1];
+ testNodes[1] = dataNodes[3];
+ testNodes[2] = dataNodes[0];
+ cluster.pseudoSortByDistance(dataNodes[0], testNodes );
+ assertTrue(testNodes[0] == dataNodes[0]);
+ assertTrue(testNodes[1] == dataNodes[1]);
+ assertTrue(testNodes[2] == dataNodes[3]);
+
+ // array contains local rack node
+ testNodes[0] = dataNodes[5];
+ testNodes[1] = dataNodes[3];
+ testNodes[2] = dataNodes[1];
+ cluster.pseudoSortByDistance(dataNodes[0], testNodes );
+ assertTrue(testNodes[0] == dataNodes[1]);
+ assertTrue(testNodes[1] == dataNodes[3]);
+ assertTrue(testNodes[2] == dataNodes[5]);
+
+ // array contains neither local node & local rack node
+ testNodes[0] = dataNodes[5];
+ testNodes[1] = dataNodes[3];
+ testNodes[2] = dataNodes[2];
+ cluster.pseudoSortByDistance(dataNodes[0], testNodes );
+ assertTrue(testNodes[0] == dataNodes[5]);
+ assertTrue(testNodes[1] == dataNodes[3]);
+ assertTrue(testNodes[2] == dataNodes[2]);
+ }
+
public void testRemove() throws Exception {
for(int i=0; i<dataNodes.length; i++) {
cluster.remove( dataNodes[i] );
