- LUCENE-388: optimize maybeMergeSegments() to speed up indexing.

git-svn-id: https://svn.apache.org/repos/asf/lucene/java/trunk@431153 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -121,6 +121,9 @@ Optimizations
      during segment merges (e.g. during indexing or optimizing), thus improving
      performance . (Michael Busch via Otis Gospodnetic)
 
+  4. LUCENE-388: Changes to maybeMergeSegments() to improve indexing speed.
+     (Paul Smith via Otis Gospodnetic)
+
 Release 2.0.0 2006-05-26
 
 API Changes

src/java/org/apache/lucene/index/IndexWriter.java

@@ -110,6 +110,7 @@ public class IndexWriter {
   private SegmentInfos segmentInfos = new SegmentInfos(); // the segments
   private final Directory ramDirectory = new RAMDirectory(); // for temp segs
 
+  private long bufferedDocCount = 0;
   private Lock writeLock;
 
   private int termIndexInterval = DEFAULT_TERM_INDEX_INTERVAL;
@@ -509,6 +510,7 @@ public class IndexWriter {
     dw.addDocument(segmentName, doc);
     synchronized (this) {
       segmentInfos.addElement(new SegmentInfo(segmentName, 1, ramDirectory));
+      bufferedDocCount++;
       maybeMergeSegments();
     }
   }
@@ -691,6 +693,15 @@ public class IndexWriter {
 
   /** Incremental segment merger.  */
   private final void maybeMergeSegments() throws IOException {
+    /**
+     *  do not bother checking the segment details to determine
+     *  if we should merge, but instead honour the maxBufferedDocs(minMergeDocs)
+     *  property to ensure we do not spend time checking for merge conditions
+     *  
+     */
+    if(bufferedDocCount<minMergeDocs) {
+        return;
+    }
     long targetMergeDocs = minMergeDocs;
     while (targetMergeDocs <= maxMergeDocs) {
       // find segments smaller than current target size
@@ -741,6 +752,8 @@ public class IndexWriter {
 
     int mergedDocCount = merger.merge();
 
+    bufferedDocCount -= mergedDocCount; // update bookkeeping about how many docs we have buffered
+    
     if (infoStream != null) {
       infoStream.println(" into "+mergedName+" ("+mergedDocCount+" docs)");
     }