clarax commented on a change in pull request #3575:
URL: https://github.com/apache/hbase/pull/3575#discussion_r686554888
##########
File path:
hbase-balancer/src/main/java/org/apache/hadoop/hbase/master/balancer/RegionReplicaCandidateGenerator.java
##########
@@ -39,42 +44,37 @@
* @param regionIndexToPrimaryIndex Cluster.regionsIndexToPrimaryIndex
* @return a regionIndex for the selected primary or -1 if there is no
co-locating
*/
- int selectCoHostedRegionPerGroup(int[] primariesOfRegionsPerGroup, int[]
regionsPerGroup,
- int[] regionIndexToPrimaryIndex) {
- int currentPrimary = -1;
- int currentPrimaryIndex = -1;
- int selectedPrimaryIndex = -1;
+ int selectCoHostedRegionPerGroup(HashMap<Integer, ArrayList<Integer>>
primariesOfRegionsPerGroup,
+ Collection<Integer> regionsPerGroup, int[] regionIndexToPrimaryIndex) {
+
double currentLargestRandom = -1;
- // primariesOfRegionsPerGroup is a sorted array. Since it contains the
primary region
- // ids for the regions hosted in server, a consecutive repetition means
that replicas
- // are co-hosted
- for (int j = 0; j <= primariesOfRegionsPerGroup.length; j++) {
- int primary = j < primariesOfRegionsPerGroup.length ?
primariesOfRegionsPerGroup[j] : -1;
- if (primary != currentPrimary) { // check for whether we see a new
primary
- int numReplicas = j - currentPrimaryIndex;
- if (numReplicas > 1) { // means consecutive primaries, indicating
co-location
- // decide to select this primary region id or not
- double currentRandom = ThreadLocalRandom.current().nextDouble();
- // we don't know how many region replicas are co-hosted, we will
randomly select one
- // using reservoir sampling
(http://gregable.com/2007/10/reservoir-sampling.html)
- if (currentRandom > currentLargestRandom) {
- selectedPrimaryIndex = currentPrimary;
- currentLargestRandom = currentRandom;
- }
+ Map.Entry<Integer, ArrayList<Integer>> selectedPrimaryIndexEntry = null;
+
+ // primariesOfRegionsPerGroup is a hashmap of count of primary index on a
server. a count > 1
+ // means that replicas are co-hosted
+ for(Map.Entry<Integer, ArrayList<Integer>> pair :
primariesOfRegionsPerGroup.entrySet()) {
+ if (pair.getValue().size() > 1) { // indicating co-location
+ // decide to select this primary region id or not
+ double currentRandom = ThreadLocalRandom.current().nextDouble();
+ // we don't know how many region replicas are co-hosted, we will
randomly select one
+ // using reservoir sampling
(http://gregable.com/2007/10/reservoir-sampling.html)
+ if (currentRandom > currentLargestRandom) {
+ selectedPrimaryIndexEntry = pair;
+ currentLargestRandom = currentRandom;
}
- currentPrimary = primary;
- currentPrimaryIndex = j;
}
}
- // we have found the primary id for the region to move. Now find the
actual regionIndex
- // with the given primary, prefer to move the secondary region.
- for (int regionIndex : regionsPerGroup) {
- if (selectedPrimaryIndex == regionIndexToPrimaryIndex[regionIndex]) {
+ if (selectedPrimaryIndexEntry == null) {
+ return -1;
+ }
+
+ // we have found the primary id and the set of regions for the region to
move.
+ // now to return one of the secondary
+ for (Integer regionIndex : selectedPrimaryIndexEntry.getValue()) {
Review comment:
we store the region indexes of all colocated replicas here so we don't
need to do O(n) look up on regionIndexToPrimaryIndex.
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: issues-unsubscr...@hbase.apache.org
For queries about this service, please contact Infrastructure at:
us...@infra.apache.org
