Use CDL to block threads to avoid flaky tests. (#14116)

* Use CDL to block threads to avoid flaky tests. * Update CHANGES.txt
apache · Jan 9, 2025 · ee65e8f · ee65e8f
1 parent 2756cd9
commit ee65e8f
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diff --git a/lucene/CHANGES.txt b/lucene/CHANGES.txt
@@ -68,8 +68,11 @@ Bug Fixes
 
 Other
 ---------------------
+
 * GITHUB#14081: Fix urls describing why NIOFS is not recommended for Windows (Marcel Yeonghyeon Ko)
 
+* GITHUB#14116 Use CDL to block threads to avoid flaky tests. (Ao Li)
+
 ======================= Lucene 10.1.0 =======================
 
 API Changes

diff --git a/lucene/core/src/test/org/apache/lucene/index/TestConcurrentMergeScheduler.java b/lucene/core/src/test/org/apache/lucene/index/TestConcurrentMergeScheduler.java
@@ -418,7 +418,6 @@ protected void doMerge(MergeSource mergeSource, MergePolicy.OneMerge merge)
     dir.close();
   }
 
-  @SuppressForbidden(reason = "Thread sleep")
   public void testIntraMergeThreadPoolIsLimitedByMaxThreads() throws IOException {
     ConcurrentMergeScheduler mergeScheduler = new ConcurrentMergeScheduler();
     MergeScheduler.MergeSource mergeSource =
@@ -475,11 +474,12 @@ public void merge(MergePolicy.OneMerge merge) throws IOException {
       Executor executor = mergeScheduler.intraMergeExecutor;
       AtomicInteger threadsExecutedOnPool = new AtomicInteger();
       AtomicInteger threadsExecutedOnSelf = new AtomicInteger();
-      for (int i = 0; i < 4; i++) {
+      CountDownLatch latch = new CountDownLatch(1);
+      final int totalThreads = 4;
+      for (int i = 0; i < totalThreads; i++) {
         mergeScheduler.mergeThreads.add(
             mergeScheduler.new MergeThread(mergeSource, merge) {
               @Override
-              @SuppressForbidden(reason = "Thread sleep")
               public void run() {
                 executor.execute(
                     () -> {
@@ -489,7 +489,7 @@ public void run() {
                         threadsExecutedOnPool.incrementAndGet();
                       }
                       try {
-                        Thread.sleep(100);
+                        latch.await();
                       } catch (InterruptedException e) {
                         throw new RuntimeException(e);
                       }
@@ -500,6 +500,10 @@ public void run() {
       for (ConcurrentMergeScheduler.MergeThread thread : mergeScheduler.mergeThreads) {
         thread.start();
       }
+      while (threadsExecutedOnSelf.get() + threadsExecutedOnPool.get() < totalThreads) {
+        Thread.yield();
+      }
+      latch.countDown();
       mergeScheduler.sync();
       assertEquals(3, threadsExecutedOnSelf.get());
       assertEquals(1, threadsExecutedOnPool.get());