[GitHub] [lucene-solr] jpountz commented on a change in pull request #1912: LUCENE-9535: Try to do larger flushes.

[GitBox <gi...@apache.org>]

jpountz commented on a change in pull request #1912:
URL: https://github.com/apache/lucene-solr/pull/1912#discussion_r526737612



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File path: lucene/core/src/java/org/apache/lucene/index/DocumentsWriterPerThreadPool.java
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@@ -112,19 +110,12 @@ private synchronized DocumentsWriterPerThread newWriter() {
   DocumentsWriterPerThread getAndLock() {
     synchronized (this) {
       ensureOpen();
-      // Important that we are LIFO here! This way if number of concurrent indexing threads was once high,
-      // but has now reduced, we only use a limited number of DWPTs. This also guarantees that if we have suddenly
-      // a single thread indexing
-      final Iterator<DocumentsWriterPerThread> descendingIterator = freeList.descendingIterator();
-      while (descendingIterator.hasNext()) {
-        DocumentsWriterPerThread perThread = descendingIterator.next();
-        if (perThread.tryLock()) {
-          descendingIterator.remove();
-          return perThread;
-        }
+      DocumentsWriterPerThread dwpt = freeList.poll(DocumentsWriterPerThread::tryLock);
+      if (dwpt == null) {
+        // DWPT is already locked before return by this method:

Review comment:
       > making me think the "allocate a new DWPT" case has something to do with the locking semantics.
   
   Hmm, this is exactly what my understanding is. :) To me the comment wat about highlighting that `newWriter()` implicitly takes the lock on the DWPT it creates?




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