(accumulo) branch 2.1 updated: Fixes performance bug in GroupBalancer (#5432)

[kturner]

This is an automated email from the ASF dual-hosted git repository.

kturner pushed a commit to branch 2.1
in repository https://gitbox.apache.org/repos/asf/accumulo.git


The following commit(s) were added to refs/heads/2.1 by this push:
     new 14a7404e28 Fixes performance bug in GroupBalancer (#5432)
14a7404e28 is described below

commit 14a7404e2835ad0749f4d40567cd4141b58f7a0e
Author: Keith Turner <ktur...@apache.org>
AuthorDate: Thu Mar 27 11:44:46 2025 -0400

    Fixes performance bug in GroupBalancer (#5432)
    
    Code in GroupBalancer was calling
    `HashBasedTable.columnKeySet().removeAll(aList)`.  The Guava
    HashBasedTable code would iterator over all of its rows and columns and
    then call contains on the list passed in by GroupBalancer. So this code
    was doing `ROWS*COLS*LIST_SIZE` operations.   Changed the list to a
    hashset in this PR so now it only does `ROW*COLS` operations.
---
 .../java/org/apache/accumulo/core/spi/balancer/GroupBalancer.java    | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git 
a/core/src/main/java/org/apache/accumulo/core/spi/balancer/GroupBalancer.java 
b/core/src/main/java/org/apache/accumulo/core/spi/balancer/GroupBalancer.java
index dd41ef1c63..d96de4aced 100644
--- 
a/core/src/main/java/org/apache/accumulo/core/spi/balancer/GroupBalancer.java
+++ 
b/core/src/main/java/org/apache/accumulo/core/spi/balancer/GroupBalancer.java
@@ -25,6 +25,7 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
@@ -487,7 +488,7 @@ public abstract class GroupBalancer implements 
TabletBalancer {
     }
 
     ArrayList<Pair<String,TabletServerId>> serversGroupsToRemove = new 
ArrayList<>();
-    ArrayList<TabletServerId> serversToRemove = new ArrayList<>();
+    HashSet<TabletServerId> serversToRemove = new HashSet<>();
 
     for (TserverGroupInfo destTgi : tservers.values()) {
       if (surplusExtra.isEmpty()) {
@@ -611,7 +612,7 @@ public abstract class GroupBalancer implements 
TabletBalancer {
       }
     }
 
-    ArrayList<TabletServerId> emptyServers = new ArrayList<>();
+    HashSet<TabletServerId> emptyServers = new HashSet<>();
     ArrayList<Pair<String,TabletServerId>> emptyServerGroups = new 
ArrayList<>();
     for (TserverGroupInfo destTgi : tservers.values()) {
       if (extraSurplus.isEmpty()) {