From c081cfa0bae3b421126219f9394aaa2c3555ba3d Mon Sep 17 00:00:00 2001
From: Adrien Grand <jpountz@gmail.com>
Date: Mon, 13 Nov 2023 10:01:39 +0100
Subject: [PATCH] Use a serial merge scheduler to avoid race conditions when
 checking for hasPendingMerges().

Closes #12763
---
 .../src/test/org/apache/lucene/index/TestIndexWriter.java    | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java b/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java
index bd71fedb05e..f63a1ee6aef 100644
--- a/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java
+++ b/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java
@@ -2372,7 +2372,10 @@ public class TestIndexWriter extends LuceneTestCase {
 
   public void testHasUncommittedChanges() throws IOException {
     Directory dir = newDirectory();
-    IndexWriter writer = new IndexWriter(dir, newIndexWriterConfig(new MockAnalyzer(random())));
+    IndexWriter writer = new IndexWriter(dir,
+        newIndexWriterConfig(new MockAnalyzer(random()))
+        // Use a serial merge scheduler to avoid race conditions when checking for hasPendingMerges()
+        .setMergeScheduler(new SerialMergeScheduler()));
     assertTrue(
         writer.hasUncommittedChanges()); // this will be true because a commit will create an empty
     // index