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HBASE-3586 Improve the selection of regions to balance 

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1078020 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Andrew Kyle Purtell 2011-03-04 15:51:07 +00:00
parent b986aacbb6
commit b5365c49aa
2 changed files with 20 additions and 1 deletions
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2
CHANGES.txt
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@ -88,6 +88,8 @@ Release 0.91.0 - Unreleased
HBASE-3564 DemoClient.pl - a demo client in Perl
HBASE-3560 the hbase-default entry of "hbase.defaults.for.version"
causes tests not to run via not-maven
HBASE-3586 Improve the selection of regions to balance (Ted Yu via Andrew
Purtell)
TASK
HBASE-3559 Move report of split to master OFF the heartbeat channel

19
src/main/java/org/apache/hadoop/hbase/master/LoadBalancer.java
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@ -21,6 +21,7 @@ package org.apache.hadoop.hbase.master;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
@ -59,6 +60,17 @@ public class LoadBalancer {
private static final Log LOG = LogFactory.getLog(LoadBalancer.class);
private static final Random rand = new Random();
static class RegionPlanComparator implements Comparator<RegionPlan> {
@Override
public int compare(RegionPlan l, RegionPlan r) {
long diff = r.getRegionInfo().getRegionId() - l.getRegionInfo().getRegionId();
if (diff < 0) return -1;
if (diff > 0) return 1;
return 0;
}
}
static RegionPlanComparator rpComparator = new RegionPlanComparator();
/**
* Generate a global load balancing plan according to the specified map of
* server information to the most loaded regions of each server.
@ -77,6 +89,8 @@ public class LoadBalancer {
* <li>Iterate down the most loaded servers, shedding regions from each so
* each server hosts exactly <b>MAX</b> regions. Stop once you reach a
* server that already has &lt;= <b>MAX</b> regions.
* <p>
* Order the regions to move from most recent to least.
*
* <li>Iterate down the least loaded servers, assigning regions so each server
* has exactly </b>MIN</b> regions. Stop once you reach a server that
@ -184,7 +198,8 @@ public class LoadBalancer {
List<HRegionInfo> regions = server.getValue();
int numToOffload = Math.min(regionCount - max, regions.size());
int numTaken = 0;
for (HRegionInfo hri: regions) {
for (int i = regions.size() - 1; i >= 0; i--) {
HRegionInfo hri = regions.get(i);
// Don't rebalance meta regions.
if (hri.isMetaRegion()) continue;
regionsToMove.add(new RegionPlan(hri, serverInfo, null));
@ -194,6 +209,8 @@ public class LoadBalancer {
serverBalanceInfo.put(serverInfo,
new BalanceInfo(numToOffload, (-1)*numTaken));
}
// put young regions at the beginning of regionsToMove
Collections.sort(regionsToMove, rpComparator);
// Walk down least loaded, filling each to the min
int serversUnderloaded = 0; // number of servers that get new regions