/**
* 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.hdfs.server.balancer;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Random;
import java.util.concurrent.TimeoutException;
import junit.framework.TestCase;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hdfs.DFSConfigKeys;
import org.apache.hadoop.hdfs.DFSTestUtil;
import org.apache.hadoop.hdfs.DFSUtil;
import org.apache.hadoop.hdfs.HdfsConfiguration;
import org.apache.hadoop.hdfs.MiniDFSCluster;
import org.apache.hadoop.hdfs.protocol.Block;
import org.apache.hadoop.hdfs.protocol.ClientProtocol;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
import org.apache.hadoop.hdfs.protocol.HdfsConstants.DatanodeReportType;
import org.apache.hadoop.hdfs.protocol.LocatedBlock;
import org.apache.hadoop.hdfs.server.datanode.SimulatedFSDataset;
import org.apache.hadoop.hdfs.server.namenode.NameNode;
/**
* This class tests if a balancer schedules tasks correctly.
*/
public class TestBalancer extends TestCase {
private static final Log LOG = LogFactory.getLog(
"org.apache.hadoop.hdfs.TestReplication");
final private static long CAPACITY = 500L;
final private static String RACK0 = "/rack0";
final private static String RACK1 = "/rack1";
final private static String RACK2 = "/rack2";
final static private String fileName = "/tmp.txt";
final static private Path filePath = new Path(fileName);
private MiniDFSCluster cluster;
ClientProtocol client;
static final long TIMEOUT = 20000L; //msec
static final double CAPACITY_ALLOWED_VARIANCE = 0.005; // 0.5%
static final double BALANCE_ALLOWED_VARIANCE = 0.11; // 10%+delta
static final int DEFAULT_BLOCK_SIZE = 10;
private static final Random r = new Random();
static {
Balancer.setBlockMoveWaitTime(1000L) ;
}
static void initConf(Configuration conf) {
conf.setLong(DFSConfigKeys.DFS_BLOCK_SIZE_KEY, DEFAULT_BLOCK_SIZE);
conf.setInt(DFSConfigKeys.DFS_BYTES_PER_CHECKSUM_KEY, DEFAULT_BLOCK_SIZE);
conf.setLong(DFSConfigKeys.DFS_HEARTBEAT_INTERVAL_KEY, 1L);
SimulatedFSDataset.setFactory(conf);
conf.setLong(DFSConfigKeys.DFS_BALANCER_MOVEDWINWIDTH_KEY, 2000L);
}
/* create a file with a length of <code>fileLen</code> */
private void createFile(long fileLen, short replicationFactor)
throws IOException {
FileSystem fs = cluster.getFileSystem();
DFSTestUtil.createFile(fs, filePath, fileLen,
replicationFactor, r.nextLong());
DFSTestUtil.waitReplication(fs, filePath, replicationFactor);
}
/* fill up a cluster with <code>numNodes</code> datanodes
* whose used space to be <code>size</code>
*/
private ExtendedBlock[] generateBlocks(Configuration conf, long size,
short numNodes) throws IOException {
cluster = new MiniDFSCluster.Builder(conf).numDataNodes(numNodes).build();
try {
cluster.waitActive();
client = DFSUtil.createNamenode(conf);
short replicationFactor = (short)(numNodes-1);
long fileLen = size/replicationFactor;
createFile(fileLen, replicationFactor);
List<LocatedBlock> locatedBlocks = client.
getBlockLocations(fileName, 0, fileLen).getLocatedBlocks();
int numOfBlocks = locatedBlocks.size();
ExtendedBlock[] blocks = new ExtendedBlock[numOfBlocks];
for(int i=0; i<numOfBlocks; i++) {
ExtendedBlock b = locatedBlocks.get(i).getBlock();
blocks[i] = new ExtendedBlock(b.getBlockPoolId(), b.getBlockId(), b
.getNumBytes(), b.getGenerationStamp());
}
return blocks;
} finally {
cluster.shutdown();
}
}
/* Distribute all blocks according to the given distribution */
static Block[][] distributeBlocks(ExtendedBlock[] blocks,
short replicationFactor, final long[] distribution) {
// make a copy
long[] usedSpace = new long[distribution.length];
System.arraycopy(distribution, 0, usedSpace, 0, distribution.length);
List<List<Block>> blockReports =
new ArrayList<List<Block>>(usedSpace.length);
Block[][] results = new Block[usedSpace.length][];
for(int i=0; i<usedSpace.length; i++) {
blockReports.add(new ArrayList<Block>());
}
for(int i=0; i<blocks.length; i++) {
for(int j=0; j<replicationFactor; j++) {
boolean notChosen = true;
while(notChosen) {
int chosenIndex = r.nextInt(usedSpace.length);
if( usedSpace[chosenIndex]>0 ) {
notChosen = false;
blockReports.get(chosenIndex).add(blocks[i].getLocalBlock());
usedSpace[chosenIndex] -= blocks[i].getNumBytes();
}
}
}
}
for(int i=0; i<usedSpace.length; i++) {
List<Block> nodeBlockList = blockReports.get(i);
results[i] = nodeBlockList.toArray(new Block[nodeBlockList.size()]);
}
return results;
}
static long sum(long[] x) {
long s = 0L;
for(long a : x) {
s += a;
}
return s;
}
/* we first start a cluster and fill the cluster up to a certain size.
* then redistribute blocks according the required distribution.
* Afterwards a balancer is running to balance the cluster.
*/
private void testUnevenDistribution(Configuration conf,
long distribution[], long capacities[], String[] racks) throws Exception {
int numDatanodes = distribution.length;
if (capacities.length != numDatanodes || racks.length != numDatanodes) {
throw new IllegalArgumentException("Array length is not the same");
}
// calculate total space that need to be filled
final long totalUsedSpace = sum(distribution);
// fill the cluster
ExtendedBlock[] blocks = generateBlocks(conf, totalUsedSpace,
(short) numDatanodes);
// redistribute blocks
Block[][] blocksDN = distributeBlocks(
blocks, (short)(numDatanodes-1), distribution);
// restart the cluster: do NOT format the cluster
conf.set(DFSConfigKeys.DFS_NAMENODE_SAFEMODE_THRESHOLD_PCT_KEY, "0.0f");
cluster = new MiniDFSCluster.Builder(conf).numDataNodes(numDatanodes)
.format(false)
.racks(racks)
.simulatedCapacities(capacities)
.build();
cluster.waitActive();
client = DFSUtil.createNamenode(conf);
for(int i = 0; i < blocksDN.length; i++)
cluster.injectBlocks(i, Arrays.asList(blocksDN[i]));
final long totalCapacity = sum(capacities);
runBalancer(conf, totalUsedSpace, totalCapacity);
cluster.shutdown();
}
/**
* Wait until heartbeat gives expected results, within CAPACITY_ALLOWED_VARIANCE,
* summed over all nodes. Times out after TIMEOUT msec.
* @param expectedUsedSpace
* @param expectedTotalSpace
* @throws IOException - if getStats() fails
* @throws TimeoutException
*/
private void waitForHeartBeat(long expectedUsedSpace, long expectedTotalSpace)
throws IOException, TimeoutException {
long timeout = TIMEOUT;
long failtime = (timeout <= 0L) ? Long.MAX_VALUE
: System.currentTimeMillis() + timeout;
while (true) {
long[] status = client.getStats();
double totalSpaceVariance = Math.abs((double)status[0] - expectedTotalSpace)
/ expectedTotalSpace;
double usedSpaceVariance = Math.abs((double)status[1] - expectedUsedSpace)
/ expectedUsedSpace;
if (totalSpaceVariance < CAPACITY_ALLOWED_VARIANCE
&& usedSpaceVariance < CAPACITY_ALLOWED_VARIANCE)
break; //done
if (System.currentTimeMillis() > failtime) {
throw new TimeoutException("Cluster failed to reached expected values of "
+ "totalSpace (current: " + status[0]
+ ", expected: " + expectedTotalSpace
+ "), or usedSpace (current: " + status[1]
+ ", expected: " + expectedUsedSpace
+ "), in more than " + timeout + " msec.");
}
try {
Thread.sleep(100L);
} catch(InterruptedException ignored) {
}
}
}
/**
* Wait until balanced: each datanode gives utilization within
* BALANCE_ALLOWED_VARIANCE of average
* @throws IOException
* @throws TimeoutException
*/
private void waitForBalancer(long totalUsedSpace, long totalCapacity)
throws IOException, TimeoutException {
long timeout = TIMEOUT;
long failtime = (timeout <= 0L) ? Long.MAX_VALUE
: System.currentTimeMillis() + timeout;
final double avgUtilization = ((double)totalUsedSpace) / totalCapacity;
boolean balanced;
do {
DatanodeInfo[] datanodeReport =
client.getDatanodeReport(DatanodeReportType.ALL);
assertEquals(datanodeReport.length, cluster.getDataNodes().size());
balanced = true;
for (DatanodeInfo datanode : datanodeReport) {
double nodeUtilization = ((double)datanode.getDfsUsed())
/ datanode.getCapacity();
if (Math.abs(avgUtilization - nodeUtilization) > BALANCE_ALLOWED_VARIANCE) {
balanced = false;
if (System.currentTimeMillis() > failtime) {
throw new TimeoutException(
"Rebalancing expected avg utilization to become "
+ avgUtilization + ", but on datanode " + datanode
+ " it remains at " + nodeUtilization
+ " after more than " + TIMEOUT + " msec.");
}
try {
Thread.sleep(100);
} catch (InterruptedException ignored) {
}
break;
}
}
} while (!balanced);
}
/** This test start a cluster with specified number of nodes,
* and fills it to be 30% full (with a single file replicated identically
* to all datanodes);
* It then adds one new empty node and starts balancing.
*
* @param conf - configuration
* @param capacities - array of capacities of original nodes in cluster
* @param racks - array of racks for original nodes in cluster
* @param newCapacity - new node's capacity
* @param newRack - new node's rack
* @throws Exception
*/
private void doTest(Configuration conf, long[] capacities, String[] racks,
long newCapacity, String newRack) throws Exception {
assertEquals(capacities.length, racks.length);
int numOfDatanodes = capacities.length;
cluster = new MiniDFSCluster.Builder(conf)
.numDataNodes(capacities.length)
.racks(racks)
.simulatedCapacities(capacities)
.build();
try {
cluster.waitActive();
client = DFSUtil.createNamenode(conf);
long totalCapacity = sum(capacities);
// fill up the cluster to be 30% full
long totalUsedSpace = totalCapacity*3/10;
createFile(totalUsedSpace/numOfDatanodes, (short)numOfDatanodes);
// start up an empty node with the same capacity and on the same rack
cluster.startDataNodes(conf, 1, true, null,
new String[]{newRack}, new long[]{newCapacity});
totalCapacity += newCapacity;
// run balancer and validate results
runBalancer(conf, totalUsedSpace, totalCapacity);
} finally {
cluster.shutdown();
}
}
private void runBalancer(Configuration conf,
long totalUsedSpace, long totalCapacity) throws Exception {
waitForHeartBeat(totalUsedSpace, totalCapacity);
// start rebalancing
final List<InetSocketAddress> namenodes =new ArrayList<InetSocketAddress>();
namenodes.add(NameNode.getServiceAddress(conf, true));
final int r = Balancer.run(namenodes, Balancer.Parameters.DEFALUT, conf);
assertEquals(Balancer.ReturnStatus.SUCCESS.code, r);
waitForHeartBeat(totalUsedSpace, totalCapacity);
LOG.info("Rebalancing with default ctor.");
waitForBalancer(totalUsedSpace, totalCapacity);
}
/** one-node cluster test*/
private void oneNodeTest(Configuration conf) throws Exception {
// add an empty node with half of the CAPACITY & the same rack
doTest(conf, new long[]{CAPACITY}, new String[]{RACK0}, CAPACITY/2, RACK0);
}
/** two-node cluster test */
private void twoNodeTest(Configuration conf) throws Exception {
doTest(conf, new long[]{CAPACITY, CAPACITY}, new String[]{RACK0, RACK1},
CAPACITY, RACK2);
}
/** test using a user-supplied conf */
public void integrationTest(Configuration conf) throws Exception {
initConf(conf);
oneNodeTest(conf);
}
/** Test a cluster with even distribution,
* then a new empty node is added to the cluster*/
public void testBalancer0() throws Exception {
Configuration conf = new HdfsConfiguration();
initConf(conf);
oneNodeTest(conf);
twoNodeTest(conf);
}
/** Test unevenly distributed cluster */
public void testBalancer1() throws Exception {
Configuration conf = new HdfsConfiguration();
initConf(conf);
testUnevenDistribution(conf,
new long[] {50*CAPACITY/100, 10*CAPACITY/100},
new long[]{CAPACITY, CAPACITY},
new String[] {RACK0, RACK1});
}
public void testBalancer2() throws Exception {
Configuration conf = new HdfsConfiguration();
initConf(conf);
testBalancerDefaultConstructor(conf, new long[] { CAPACITY, CAPACITY },
new String[] { RACK0, RACK1 }, CAPACITY, RACK2);
}
private void testBalancerDefaultConstructor(Configuration conf,
long[] capacities, String[] racks, long newCapacity, String newRack)
throws Exception {
int numOfDatanodes = capacities.length;
assertEquals(numOfDatanodes, racks.length);
cluster = new MiniDFSCluster.Builder(conf)
.numDataNodes(capacities.length)
.racks(racks)
.simulatedCapacities(capacities)
.build();
try {
cluster.waitActive();
client = DFSUtil.createNamenode(conf);
long totalCapacity = sum(capacities);
// fill up the cluster to be 30% full
long totalUsedSpace = totalCapacity * 3 / 10;
createFile(totalUsedSpace / numOfDatanodes, (short) numOfDatanodes);
// start up an empty node with the same capacity and on the same rack
cluster.startDataNodes(conf, 1, true, null, new String[] { newRack },
new long[] { newCapacity });
totalCapacity += newCapacity;
// run balancer and validate results
runBalancer(conf, totalUsedSpace, totalCapacity);
} finally {
cluster.shutdown();
}
}
/**
* @param args
*/
public static void main(String[] args) throws Exception {
TestBalancer balancerTest = new TestBalancer();
balancerTest.testBalancer0();
balancerTest.testBalancer1();
balancerTest.testBalancer2();
}
}