[GitHub] milleruntime commented on a change in pull request #759: Only requeue compaction when there was activity

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milleruntime commented on a change in pull request #759: Only requeue compaction when there was activity
URL: https://github.com/apache/accumulo/pull/759#discussion_r232075086
 
 

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 File path: server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/CompactionRunner.java
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 @@ -41,12 +41,18 @@ public void run() {
       return;
     }
 
-    tablet.majorCompact(reason, queued);
+    CompactionStats stats = tablet.majorCompact(reason, queued);
 
-    // if there is more work to be done, queue another major compaction
-    synchronized (tablet) {
-      if (reason == MajorCompactionReason.NORMAL && tablet.needsMajorCompaction(reason))
-        tablet.initiateMajorCompaction(reason);
+    // Some compaction strategies may always return true for shouldCompact() because they need to
+    // make blocking calls to gather information. Without the following check these strategies would
+    // endlessly requeue. So only check if a subsequent compaction is needed if the previous
+    // compaction actually did something.
+    if (stats != null && stats.getEntriesRead() > 0) {
 
 Review comment:
   Won't this prevent compactions from happening when `stats.getEntriesRead() == 0`?

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