From 801b822972726c31637b235459f2b7a0aea93b29 Mon Sep 17 00:00:00 2001
From: Zhang Chao <80152403@qq.com>
Date: Tue, 4 Jun 2024 13:03:09 +0800
Subject: [PATCH] Avoid unnecessary memory allocation in
 PackedLongValues#Iterator (#13439)

We always allocate a long array of page size for a new PackedLongValues#Iterator instance, which is not necessary when packing a small number of values. this is more evident in the scenario of high-frequency flush operations
---
 lucene/CHANGES.txt                                             | 3 ++-
 .../java/org/apache/lucene/util/packed/PackedLongValues.java   | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/lucene/CHANGES.txt b/lucene/CHANGES.txt
index 0544165a86f..b89aa865a81 100644
--- a/lucene/CHANGES.txt
+++ b/lucene/CHANGES.txt
@@ -249,7 +249,8 @@ Improvements
 
 Optimizations
 ---------------------
-(No changes)
+
+* GITHUB#13439: Avoid unnecessary memory allocation in PackedLongValues#Iterator. (Zhang Chao)
 
 Bug Fixes
 ---------------------
diff --git a/lucene/core/src/java/org/apache/lucene/util/packed/PackedLongValues.java b/lucene/core/src/java/org/apache/lucene/util/packed/PackedLongValues.java
index cda57f0fb4c..e996c2d52e1 100644
--- a/lucene/core/src/java/org/apache/lucene/util/packed/PackedLongValues.java
+++ b/lucene/core/src/java/org/apache/lucene/util/packed/PackedLongValues.java
@@ -138,7 +138,7 @@ public class PackedLongValues extends LongValues implements Accountable {
     int currentCount; // number of entries of the current page
 
     Iterator() {
-      currentValues = new long[pageMask + 1];
+      currentValues = new long[(int) Math.min(size, pageMask + 1)];
       vOff = pOff = 0;
       fillBlock();
     }