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HBASE-26309 Balancer tends to move regions to the server at the end o… (#3812) 

Signed-off-by: Duo Zhang <zhangduo@apache.org>
This commit is contained in:
clarax 2021-11-02 19:27:46 -07:00 committed by GitHub
parent cc701e2c28
commit 0b7630bc1f
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5 changed files with 120 additions and 21 deletions
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7
hbase-server/src/main/java/org/apache/hadoop/hbase/master/balancer/BaseLoadBalancer.java
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@ -338,6 +338,7 @@ public abstract class BaseLoadBalancer implements LoadBalancer {
racks[entry.getValue()] = entry.getKey();
}
LOG.debug("Hosts are {} racks are {}", hostsToIndex, racksToIndex);
for (Entry<ServerName, List<RegionInfo>> entry : clusterState.entrySet()) {
int serverIndex = serversToIndex.get(entry.getKey().getAddress());
regionPerServerIndex = serverIndexToRegionsOffset[serverIndex];
@ -365,6 +366,7 @@ public abstract class BaseLoadBalancer implements LoadBalancer {
serversPerHost[i] = new int[serversPerHostList.get(i).size()];
for (int j = 0; j < serversPerHost[i].length; j++) {
serversPerHost[i][j] = serversPerHostList.get(i).get(j);
LOG.debug("server {} is on host {}",serversPerHostList.get(i).get(j), i);
}
if (serversPerHost[i].length > 1) {
multiServersPerHost = true;
@ -375,6 +377,7 @@ public abstract class BaseLoadBalancer implements LoadBalancer {
serversPerRack[i] = new int[serversPerRackList.get(i).size()];
for (int j = 0; j < serversPerRack[i].length; j++) {
serversPerRack[i][j] = serversPerRackList.get(i).get(j);
LOG.info("server {} is on rack {}",serversPerRackList.get(i).get(j), i);
}
}
@ -960,6 +963,10 @@ public abstract class BaseLoadBalancer implements LoadBalancer {
private Comparator<Integer> numRegionsComparator = Comparator.comparingInt(this::getNumRegions);
public Comparator<Integer> getNumRegionsComparator() {
return numRegionsComparator;
}
int getLowestLocalityRegionOnServer(int serverIndex) {
if (regionFinder != null) {
float lowestLocality = 1.0f;

54
hbase-server/src/main/java/org/apache/hadoop/hbase/master/balancer/LoadCandidateGenerator.java
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@ -18,13 +18,13 @@
package org.apache.hadoop.hbase.master.balancer;
import java.util.concurrent.ThreadLocalRandom;
import org.apache.yetus.audience.InterfaceAudience;
@InterfaceAudience.Private
class LoadCandidateGenerator extends CandidateGenerator {
@Override
BaseLoadBalancer.Cluster.Action generate(BaseLoadBalancer.Cluster cluster) {
@Override BaseLoadBalancer.Cluster.Action generate(BaseLoadBalancer.Cluster cluster) {
cluster.sortServersByRegionCount();
int thisServer = pickMostLoadedServer(cluster, -1);
int otherServer = pickLeastLoadedServer(cluster, thisServer);
@ -34,27 +34,53 @@ class LoadCandidateGenerator extends CandidateGenerator {
private int pickLeastLoadedServer(final BaseLoadBalancer.Cluster cluster, int thisServer) {
Integer[] servers = cluster.serverIndicesSortedByRegionCount;
int index = 0;
while (servers[index] == null || servers[index] == thisServer) {
index++;
if (index == servers.length) {
return -1;
int selectedIndex = -1;
double currentLargestRandom = -1;
for (int i = 0; i < servers.length; i++) {
if (servers[i] == null || servers[i] == thisServer) {
continue;
}
if (selectedIndex != -1 && cluster.getNumRegionsComparator().compare(servers[i],
servers[selectedIndex]) != 0) {
// Exhausted servers of the same region count
break;
}
// we don't know how many servers have the same region count, we will randomly select one
// using a simplified inline reservoir sampling by assignmening a random number to stream
// data and choose the greatest one. (http://gregable.com/2007/10/reservoir-sampling.html)
double currentRandom = ThreadLocalRandom.current().nextDouble();
if (currentRandom > currentLargestRandom) {
selectedIndex = i;
currentLargestRandom = currentRandom;
}
}
return servers[index];
return selectedIndex == -1 ? -1 : servers[selectedIndex];
}
private int pickMostLoadedServer(final BaseLoadBalancer.Cluster cluster, int thisServer) {
Integer[] servers = cluster.serverIndicesSortedByRegionCount;
int index = servers.length - 1;
while (servers[index] == null || servers[index] == thisServer) {
index--;
if (index < 0) {
return -1;
int selectedIndex = -1;
double currentLargestRandom = -1;
for (int i = servers.length - 1; i >= 0; i--) {
if (servers[i] == null || servers[i] == thisServer) {
continue;
}
if (selectedIndex != -1
&& cluster.getNumRegionsComparator().compare(servers[i], servers[selectedIndex]) != 0) {
// Exhausted servers of the same region count
break;
}
// we don't know how many servers have the same region count, we will randomly select one
// using a simplified inline reservoir sampling by assignmening a random number to stream
// data and choose the greatest one. (http://gregable.com/2007/10/reservoir-sampling.html)
double currentRandom = ThreadLocalRandom.current().nextDouble();
if (currentRandom > currentLargestRandom) {
selectedIndex = i;
currentLargestRandom = currentRandom;
}
}
return servers[index];
return selectedIndex == -1 ? -1 : servers[selectedIndex];
}
}

7
hbase-server/src/main/java/org/apache/hadoop/hbase/master/balancer/StochasticLoadBalancer.java
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@ -510,9 +510,10 @@ public class StochasticLoadBalancer extends BaseLoadBalancer {
plans = createRegionPlans(cluster);
LOG.info("Finished computing new moving plan. Computation took {} ms" +
" to try {} different iterations. Found a solution that moves " +
"{} regions; Going from a computed imbalance of {}" + " to a new imbalance of {}. ",
endTime - startTime, step, plans.size(), initCost / sumMultiplier,
currentCost / sumMultiplier);
"{} regions; Going from a computed imbalance of {}" +
" to a new imbalance of {}. funtionCost={}",
endTime - startTime, step, plans.size(),
initCost / sumMultiplier, currentCost / sumMultiplier, functionCost());
sendRegionPlansToRingBuffer(plans, currentCost, initCost, initFunctionTotalCosts, step);
return plans;

39
hbase-server/src/test/java/org/apache/hadoop/hbase/master/balancer/BalancerTestBase.java
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@ -571,7 +571,7 @@ public class BalancerTestBase {
List<ServerAndLoad> balancedCluster = reconcile(list, plans, serverMap);
// Print out the cluster loads to make debugging easier.
LOG.info("Mock Balance : " + printMock(balancedCluster));
LOG.info("Mock after Balance : " + printMock(balancedCluster));
if (assertFullyBalanced) {
assertClusterAsBalanced(balancedCluster);
@ -587,6 +587,43 @@ public class BalancerTestBase {
}
}
protected void testWithClusterWithIteration(Map<ServerName, List<RegionInfo>> serverMap,
RackManager rackManager, boolean assertFullyBalanced, boolean assertFullyBalancedForReplicas) {
List<ServerAndLoad> list = convertToList(serverMap);
LOG.info("Mock Cluster : " + printMock(list) + " " + printStats(list));
loadBalancer.setRackManager(rackManager);
// Run the balancer.
Map<TableName, Map<ServerName, List<RegionInfo>>> LoadOfAllTable =
(Map) mockClusterServersWithTables(serverMap);
List<RegionPlan> plans = loadBalancer.balanceCluster(LoadOfAllTable);
assertNotNull("Initial cluster balance should produce plans.", plans);
List<ServerAndLoad> balancedCluster = null;
// Run through iteration until done. Otherwise will be killed as test time out
while (plans != null && (assertFullyBalanced || assertFullyBalancedForReplicas)) {
// Apply the plan to the mock cluster.
balancedCluster = reconcile(list, plans, serverMap);
// Print out the cluster loads to make debugging easier.
LOG.info("Mock after balance: " + printMock(balancedCluster));
LoadOfAllTable = (Map) mockClusterServersWithTables(serverMap);
plans = loadBalancer.balanceCluster(LoadOfAllTable);
}
// Print out the cluster loads to make debugging easier.
LOG.info("Mock Final balance: " + printMock(balancedCluster));
if (assertFullyBalanced) {
assertNull("Given a requirement to be fully balanced, second attempt at plans should " +
"produce none.", plans);
}
if (assertFullyBalancedForReplicas) {
assertRegionReplicaPlacement(serverMap, rackManager);
}
}
protected Map<ServerName, List<RegionInfo>> createServerMap(int numNodes,
int numRegions,
int numRegionsPerServer,

34
hbase-server/src/test/java/org/apache/hadoop/hbase/master/balancer/TestStochasticLoadBalancerRegionReplicaWithRacks.java
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@ -17,6 +17,7 @@
*/
package org.apache.hadoop.hbase.master.balancer;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.hadoop.hbase.HBaseClassTestRule;
@ -38,6 +39,8 @@ public class TestStochasticLoadBalancerRegionReplicaWithRacks extends BalancerTe
private static class ForTestRackManager extends RackManager {
int numRacks;
Map<String, Integer> serverIndexes = new HashMap<String, Integer>();
int numServers = 0;
public ForTestRackManager(int numRacks) {
this.numRacks = numRacks;
@ -45,13 +48,18 @@ public class TestStochasticLoadBalancerRegionReplicaWithRacks extends BalancerTe
@Override
public String getRack(ServerName server) {
return "rack_" + (server.hashCode() % numRacks);
String key = server.getServerName();
if (!serverIndexes.containsKey(key)) {
serverIndexes.put(key, numServers++);
}
return "rack_" + serverIndexes.get(key) % numRacks;
}
}
@Test
public void testRegionReplicationOnMidClusterWithRacks() {
conf.setLong(StochasticLoadBalancer.MAX_STEPS_KEY, 10000000L);
conf.setLong(StochasticLoadBalancer.MAX_STEPS_KEY, 100000000L);
conf.setBoolean("hbase.master.balancer.stochastic.runMaxSteps", true);
conf.setFloat("hbase.master.balancer.stochastic.maxMovePercent", 1.0f);
conf.setLong("hbase.master.balancer.stochastic.maxRunningTime", 120 * 1000); // 120 sec
loadBalancer.setConf(conf);
@ -65,6 +73,26 @@ public class TestStochasticLoadBalancerRegionReplicaWithRacks extends BalancerTe
createServerMap(numNodes, numRegions, numRegionsPerServer, replication, numTables);
RackManager rm = new ForTestRackManager(numRacks);
testWithCluster(serverMap, rm, false, true);
testWithClusterWithIteration(serverMap, rm, true, true);
}
@Test
public void testRegionReplicationOnLargeClusterWithRacks() {
conf.setBoolean("hbase.master.balancer.stochastic.runMaxSteps", false);
conf.setLong(StochasticLoadBalancer.MAX_STEPS_KEY, 5000L);
conf.setFloat("hbase.master.balancer.stochastic.maxMovePercent", 1.0f);
conf.setLong("hbase.master.balancer.stochastic.maxRunningTime", 10 * 1000); // 10 sec
loadBalancer.onConfigurationChange(conf);
int numNodes = 100;
int numRegions = numNodes * 30;
int replication = 3; // 3 replicas per region
int numRegionsPerServer = 28;
int numTables = 1;
int numRacks = 4; // all replicas should be on a different rack
Map<ServerName, List<RegionInfo>> serverMap =
createServerMap(numNodes, numRegions, numRegionsPerServer, replication, numTables);
RackManager rm = new ForTestRackManager(numRacks);
testWithClusterWithIteration(serverMap, rm, true, true);
}
}