From 040127f946d719562d35f05a06d745d0788f9f3c Mon Sep 17 00:00:00 2001
From: luyuncheng <luyuncheng@bytedance.com>
Date: Tue, 6 Jun 2023 17:58:28 +0800
Subject: [PATCH] Reduce numDeletesToMerge in softdelete merge

---
 .../java/org/apache/lucene/index/MergePolicy.java   | 10 +++++++++-
 .../org/apache/lucene/index/TieredMergePolicy.java  | 13 +++++++++++--
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/lucene/core/src/java/org/apache/lucene/index/MergePolicy.java b/lucene/core/src/java/org/apache/lucene/index/MergePolicy.java
index 3eb527edb196..6b90b10836ed 100644
--- a/lucene/core/src/java/org/apache/lucene/index/MergePolicy.java
+++ b/lucene/core/src/java/org/apache/lucene/index/MergePolicy.java
@@ -741,8 +741,16 @@ public boolean useCompoundFile(
    * non-deleted documents is set.
    */
   protected long size(SegmentCommitInfo info, MergeContext mergeContext) throws IOException {
-    long byteSize = info.sizeInBytes();
     int delCount = mergeContext.numDeletesToMerge(info);
+    return size(info, delCount);
+  }
+
+  /**
+   * Return the byte size of the provided {@link SegmentCommitInfo}, pro-rated by percentage of
+   * non-deleted documents is set.
+   */
+  protected final long size(SegmentCommitInfo info, int delCount) throws IOException {
+    long byteSize = info.sizeInBytes();
     assert assertDelCount(delCount, info);
     double delRatio =
         info.info.maxDoc() <= 0 ? 0d : (double) delCount / (double) info.info.maxDoc();
diff --git a/lucene/core/src/java/org/apache/lucene/index/TieredMergePolicy.java b/lucene/core/src/java/org/apache/lucene/index/TieredMergePolicy.java
index 304bbdd2e57a..b4f3bb340dd2 100644
--- a/lucene/core/src/java/org/apache/lucene/index/TieredMergePolicy.java
+++ b/lucene/core/src/java/org/apache/lucene/index/TieredMergePolicy.java
@@ -915,13 +915,14 @@ public MergeSpecification findForcedDeletesMerges(SegmentInfos infos, MergeConte
     final Set<SegmentCommitInfo> merging = mergeContext.getMergingSegments();
 
     boolean haveWork = false;
+    List<SegmentSizeAndDocs> sortedInfos = new ArrayList<>();
     for (SegmentCommitInfo info : infos) {
       int delCount = mergeContext.numDeletesToMerge(info);
       assert assertDelCount(delCount, info);
+      sortedInfos.add(new SegmentSizeAndDocs(info, size(info, delCount), delCount));
       double pctDeletes = 100. * ((double) delCount) / info.info.maxDoc();
       if (pctDeletes > forceMergeDeletesPctAllowed && !merging.contains(info)) {
         haveWork = true;
-        break;
       }
     }
 
@@ -929,7 +930,15 @@ public MergeSpecification findForcedDeletesMerges(SegmentInfos infos, MergeConte
       return null;
     }
 
-    List<SegmentSizeAndDocs> sortedInfos = getSortedBySegmentSize(infos, mergeContext);
+    sortedInfos.sort(
+        (o1, o2) -> {
+          // Sort by largest size:
+          int cmp = Long.compare(o2.sizeInBytes, o1.sizeInBytes);
+          if (cmp == 0) {
+            cmp = o1.name.compareTo(o2.name);
+          }
+          return cmp;
+        });
 
     Iterator<SegmentSizeAndDocs> iter = sortedInfos.iterator();
     while (iter.hasNext()) {