svn commit: r1031480 - /lucene/dev/trunk/lucene/src/java/org/apache/lucene/index/IndexWriter.java

[mi...@apache.org]

Author: mikemccand
Date: Fri Nov  5 09:01:51 2010
New Revision: 1031480

URL: http://svn.apache.org/viewvc?rev=1031480&view=rev
Log:
add comment explaining why flush isn't sync'd

Modified:
    lucene/dev/trunk/lucene/src/java/org/apache/lucene/index/IndexWriter.java

Modified: lucene/dev/trunk/lucene/src/java/org/apache/lucene/index/IndexWriter.java
URL: http://svn.apache.org/viewvc/lucene/dev/trunk/lucene/src/java/org/apache/lucene/index/IndexWriter.java?rev=1031480&r1=1031479&r2=1031480&view=diff
==============================================================================
--- lucene/dev/trunk/lucene/src/java/org/apache/lucene/index/IndexWriter.java (original)
+++ lucene/dev/trunk/lucene/src/java/org/apache/lucene/index/IndexWriter.java Fri Nov  5 09:01:51 2010
@@ -3229,6 +3229,14 @@ public class IndexWriter implements Clos
    *  be flushed
    */
   protected final void flush(boolean triggerMerge, boolean flushDocStores, boolean flushDeletes) throws CorruptIndexException, IOException {
+
+    // NOTE: this method cannot be sync'd because
+    // maybeMerge() in turn calls mergeScheduler.merge which
+    // in turn can take a long time to run and we don't want
+    // to hold the lock for that.  In the case of
+    // ConcurrentMergeScheduler this can lead to deadlock
+    // when it stalls due to too many running merges.
+
     // We can be called during close, when closing==true, so we must pass false to ensureOpen:
     ensureOpen(false);
     if (doFlush(flushDocStores, flushDeletes) && triggerMerge)