[GitHub] [hive] pgaref commented on a change in pull request #1067: HIVE-23627: Review of GroupByOperator

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

pgaref commented on a change in pull request #1067:
URL: https://github.com/apache/hive/pull/1067#discussion_r436072669



##########
File path: ql/src/java/org/apache/hadoop/hive/ql/exec/GroupByOperator.java
##########
@@ -990,24 +955,17 @@ private void flushHashTable(boolean complete) throws HiveException {
     // changed in the future
 
     if (complete) {
-      Iterator<Map.Entry<KeyWrapper, AggregationBuffer[]>> iter = hashAggregations
-          .entrySet().iterator();
-      while (iter.hasNext()) {
-        Map.Entry<KeyWrapper, AggregationBuffer[]> m = iter.next();
-        forward(m.getKey().getKeyArray(), m.getValue());
+      for (Map.Entry<KeyWrapper, AggregationBuffer[]> entry : hashAggregations.entrySet()) {
+        forward(entry.getKey().getKeyArray(), entry.getValue());
       }
-      hashAggregations.clear();
       hashAggregations = null;
-      if (LOG.isInfoEnabled()) {
-        LOG.info("Hash Table completed flushed");
-      }
+      LOG.info("Hash Table completed flushed");
       return;
     }
 
     int oldSize = hashAggregations.size();
-    if (LOG.isInfoEnabled()) {
-      LOG.info("Hash Tbl flush: #hash table = " + oldSize);
-    }
+    LOG.info("Hash Tbl flush: #hash table = " + oldSize);

Review comment:
       The problem is string concatenation does a lot of work without knowing if it is needed or not -- {} format does not!
   http://slf4j.org/faq.html#logging_performance




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