From a4b4c75dcfdce362eeca1117be88ca803282a820 Mon Sep 17 00:00:00 2001
From: Christine Poerschke <cpoerschke@apache.org>
Date: Wed, 11 Nov 2015 17:52:00 +0000
Subject: [PATCH] LUCENE-6892: various lucene.index initialCapacity tweaks

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1713903 13f79535-47bb-0310-9956-ffa450edef68
---
 lucene/CHANGES.txt                                            | 3 +++
 lucene/core/src/java/org/apache/lucene/index/CodecReader.java | 2 +-
 lucene/core/src/java/org/apache/lucene/index/IndexWriter.java | 4 ++--
 .../core/src/java/org/apache/lucene/index/LogMergePolicy.java | 4 ++--
 lucene/core/src/java/org/apache/lucene/index/MultiFields.java | 4 ++--
 .../org/apache/lucene/index/SegmentDocValuesProducer.java     | 2 +-
 6 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/lucene/CHANGES.txt b/lucene/CHANGES.txt
index 299cbb21a58..304480681ba 100644
--- a/lucene/CHANGES.txt
+++ b/lucene/CHANGES.txt
@@ -203,6 +203,9 @@ Optimizations
 * LUCENE-6863: Optimized storage requirements of doc values fields when less
   than 1% of documents have a value. (Adrien Grand)
 
+* LUCENE-6892: various lucene.index initialCapacity tweaks
+  (Christine Poerschke)
+
 Bug Fixes
 
 * LUCENE-6817: ComplexPhraseQueryParser.ComplexPhraseQuery does not display 
diff --git a/lucene/core/src/java/org/apache/lucene/index/CodecReader.java b/lucene/core/src/java/org/apache/lucene/index/CodecReader.java
index aad92e24fa6..c879b9ed2bf 100644
--- a/lucene/core/src/java/org/apache/lucene/index/CodecReader.java
+++ b/lucene/core/src/java/org/apache/lucene/index/CodecReader.java
@@ -333,7 +333,7 @@ public abstract class CodecReader extends LeafReader implements Accountable {
   @Override
   public Collection<Accountable> getChildResources() {
     ensureOpen();
-    List<Accountable> resources = new ArrayList<>();
+    final List<Accountable> resources = new ArrayList<>(6);
     
     // terms/postings
     resources.add(Accountables.namedAccountable("postings", getPostingsReader()));
diff --git a/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java b/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java
index 523ac1821f3..22a2ffaebc3 100644
--- a/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java
+++ b/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java
@@ -2390,7 +2390,7 @@ public class IndexWriter implements Closeable, TwoPhaseCommit, Accountable {
    *  to match with a call to {@link IOUtils#close} in a
    *  finally clause. */
   private List<Lock> acquireWriteLocks(Directory... dirs) throws IOException {
-    List<Lock> locks = new ArrayList<>();
+    List<Lock> locks = new ArrayList<>(dirs.length);
     for(int i=0;i<dirs.length;i++) {
       boolean success = false;
       try {
@@ -3967,7 +3967,7 @@ public class IndexWriter implements Closeable, TwoPhaseCommit, Accountable {
       infoStream.message("IW", "merging " + segString(merge.segments));
     }
 
-    merge.readers = new ArrayList<>();
+    merge.readers = new ArrayList<>(sourceSegments.size());
 
     // This is try/finally to make sure merger's readers are
     // closed:
diff --git a/lucene/core/src/java/org/apache/lucene/index/LogMergePolicy.java b/lucene/core/src/java/org/apache/lucene/index/LogMergePolicy.java
index 5102e2bb66d..a8d4ed7177e 100644
--- a/lucene/core/src/java/org/apache/lucene/index/LogMergePolicy.java
+++ b/lucene/core/src/java/org/apache/lucene/index/LogMergePolicy.java
@@ -461,7 +461,7 @@ public abstract class LogMergePolicy extends MergePolicy {
 
     // Compute levels, which is just log (base mergeFactor)
     // of the size of each segment
-    final List<SegmentInfoAndLevel> levels = new ArrayList<>();
+    final List<SegmentInfoAndLevel> levels = new ArrayList<>(numSegments);
     final float norm = (float) Math.log(mergeFactor);
 
     final Collection<SegmentCommitInfo> mergingSegments = writer.getMergingSegments();
@@ -563,7 +563,7 @@ public abstract class LogMergePolicy extends MergePolicy {
         } else if (!anyTooLarge) {
           if (spec == null)
             spec = new MergeSpecification();
-          final List<SegmentCommitInfo> mergeInfos = new ArrayList<>();
+          final List<SegmentCommitInfo> mergeInfos = new ArrayList<>(end-start);
           for(int i=start;i<end;i++) {
             mergeInfos.add(levels.get(i).info);
             assert infos.contains(levels.get(i).info);
diff --git a/lucene/core/src/java/org/apache/lucene/index/MultiFields.java b/lucene/core/src/java/org/apache/lucene/index/MultiFields.java
index a0f0d50285f..9348009ab32 100644
--- a/lucene/core/src/java/org/apache/lucene/index/MultiFields.java
+++ b/lucene/core/src/java/org/apache/lucene/index/MultiFields.java
@@ -66,8 +66,8 @@ public final class MultiFields extends Fields {
         // already an atomic reader / reader with one leave
         return leaves.get(0).reader().fields();
       default:
-        final List<Fields> fields = new ArrayList<>();
-        final List<ReaderSlice> slices = new ArrayList<>();
+        final List<Fields> fields = new ArrayList<>(leaves.size());
+        final List<ReaderSlice> slices = new ArrayList<>(leaves.size());
         for (final LeafReaderContext ctx : leaves) {
           final LeafReader r = ctx.reader();
           final Fields f = r.fields();
diff --git a/lucene/core/src/java/org/apache/lucene/index/SegmentDocValuesProducer.java b/lucene/core/src/java/org/apache/lucene/index/SegmentDocValuesProducer.java
index 70d3e1a6903..ee0f4eae023 100644
--- a/lucene/core/src/java/org/apache/lucene/index/SegmentDocValuesProducer.java
+++ b/lucene/core/src/java/org/apache/lucene/index/SegmentDocValuesProducer.java
@@ -161,7 +161,7 @@ class SegmentDocValuesProducer extends DocValuesProducer {
 
   @Override
   public Collection<Accountable> getChildResources() {
-    List<Accountable> resources = new ArrayList<>();
+    final List<Accountable> resources = new ArrayList<>(dvProducers.size());
     for (Accountable producer : dvProducers) {
       resources.add(Accountables.namedAccountable("delegate", producer));
     }