diff --git a/indexing-service/src/main/java/io/druid/indexing/common/index/YeOldePlumberSchool.java b/indexing-service/src/main/java/io/druid/indexing/common/index/YeOldePlumberSchool.java
index ff9f1549607..de3aa720219 100644
--- a/indexing-service/src/main/java/io/druid/indexing/common/index/YeOldePlumberSchool.java
+++ b/indexing-service/src/main/java/io/druid/indexing/common/index/YeOldePlumberSchool.java
@@ -40,6 +40,7 @@ import io.druid.segment.IndexIO;
 import io.druid.segment.IndexMerger;
 import io.druid.segment.QueryableIndex;
 import io.druid.segment.SegmentUtils;
+import io.druid.segment.incremental.IncrementalIndex;
 import io.druid.segment.indexing.DataSchema;
 import io.druid.segment.indexing.RealtimeTuningConfig;
 import io.druid.segment.loading.DataSegmentPusher;
@@ -219,14 +220,14 @@ public class YeOldePlumberSchool implements PlumberSchool
           log.info("Spilling index[%d] with rows[%d] to: %s", indexToPersist.getCount(), rowsToPersist, dirToPersist);
 
           try {
-
+            final IncrementalIndex index = indexToPersist.getIndex();
             IndexMerger.persist(
                 indexToPersist.getIndex(),
                 dirToPersist
             );
 
             indexToPersist.swapSegment(null);
-
+            index.close();
             metrics.incrementRowOutputCount(rowsToPersist);
 
             spilled.add(dirToPersist);
diff --git a/processing/src/main/java/io/druid/query/GroupByParallelQueryRunner.java b/processing/src/main/java/io/druid/query/GroupByParallelQueryRunner.java
index 43e65b9e49a..98b6ae7d9f5 100644
--- a/processing/src/main/java/io/druid/query/GroupByParallelQueryRunner.java
+++ b/processing/src/main/java/io/druid/query/GroupByParallelQueryRunner.java
@@ -28,6 +28,7 @@ import com.google.common.collect.Lists;
 import com.google.common.collect.Ordering;
 import com.metamx.common.Pair;
 import com.metamx.common.guava.Accumulator;
+import com.metamx.common.guava.ResourceClosingSequence;
 import com.metamx.common.guava.Sequence;
 import com.metamx.common.guava.Sequences;
 import com.metamx.common.logger.Logger;
@@ -140,7 +141,12 @@ public class GroupByParallelQueryRunner implements QueryRunner<Row>
       }
     }
 
-    return Sequences.simple(indexAccumulatorPair.lhs.iterableWithPostAggregations(null));
+    return new ResourceClosingSequence<Row>(
+        Sequences.simple(
+            indexAccumulatorPair.lhs
+                                .iterableWithPostAggregations(null)
+        ), indexAccumulatorPair.lhs
+    );
   }
 
 }
diff --git a/processing/src/main/java/io/druid/query/groupby/GroupByQueryQueryToolChest.java b/processing/src/main/java/io/druid/query/groupby/GroupByQueryQueryToolChest.java
index 1cec9a993c7..6a5845b3ef1 100644
--- a/processing/src/main/java/io/druid/query/groupby/GroupByQueryQueryToolChest.java
+++ b/processing/src/main/java/io/druid/query/groupby/GroupByQueryQueryToolChest.java
@@ -29,6 +29,7 @@ import com.google.inject.Inject;
 import com.metamx.common.Pair;
 import com.metamx.common.guava.Accumulator;
 import com.metamx.common.guava.ConcatSequence;
+import com.metamx.common.guava.ResourceClosingSequence;
 import com.metamx.common.guava.Sequence;
 import com.metamx.common.guava.Sequences;
 import com.metamx.emitter.service.ServiceMetricEvent;
@@ -62,10 +63,13 @@ public class GroupByQueryQueryToolChest extends QueryToolChest<Row, GroupByQuery
   {
   };
   private static final String GROUP_BY_MERGE_KEY = "groupByMerge";
-  private static final Map<String, Object> NO_MERGE_CONTEXT = ImmutableMap.<String, Object>of(GROUP_BY_MERGE_KEY, "false");
+  private static final Map<String, Object> NO_MERGE_CONTEXT = ImmutableMap.<String, Object>of(
+      GROUP_BY_MERGE_KEY,
+      "false"
+  );
   private final Supplier<GroupByQueryConfig> configSupplier;
-  private GroupByQueryEngine engine; // For running the outer query around a subquery
   private final StupidPool<ByteBuffer> bufferPool;
+  private GroupByQueryEngine engine; // For running the outer query around a subquery
 
 
   @Inject
@@ -99,16 +103,15 @@ public class GroupByQueryQueryToolChest extends QueryToolChest<Row, GroupByQuery
 
   private Sequence<Row> mergeGroupByResults(final GroupByQuery query, QueryRunner<Row> runner)
   {
-
     Sequence<Row> result;
-
     // If there's a subquery, merge subquery results and then apply the aggregator
     DataSource dataSource = query.getDataSource();
     if (dataSource instanceof QueryDataSource) {
       GroupByQuery subquery;
       try {
         subquery = (GroupByQuery) ((QueryDataSource) dataSource).getQuery();
-      } catch (ClassCastException e) {
+      }
+      catch (ClassCastException e) {
         throw new UnsupportedOperationException("Subqueries must be of type 'group by'");
       }
       Sequence<Row> subqueryResult = mergeGroupByResults(subquery, runner);
@@ -118,11 +121,10 @@ public class GroupByQueryQueryToolChest extends QueryToolChest<Row, GroupByQuery
     } else {
       result = runner.run(query);
     }
-
-    return postAggregate(query, makeIncrementalIndex(query, result));
+    final IncrementalIndex index = makeIncrementalIndex(query, result);
+    return new ResourceClosingSequence<Row>(postAggregate(query, index), index);
   }
 
-
   private Sequence<Row> postAggregate(final GroupByQuery query, IncrementalIndex index)
   {
     Sequence<Row> sequence = Sequences.map(
@@ -135,7 +137,7 @@ public class GroupByQueryQueryToolChest extends QueryToolChest<Row, GroupByQuery
             final MapBasedRow row = (MapBasedRow) input;
             return new MapBasedRow(
                 query.getGranularity()
-                    .toDateTime(row.getTimestampFromEpoch()),
+                     .toDateTime(row.getTimestampFromEpoch()),
                 row.getEvent()
             );
           }
@@ -156,7 +158,6 @@ public class GroupByQueryQueryToolChest extends QueryToolChest<Row, GroupByQuery
     return rows.accumulate(indexAccumulatorPair.lhs, indexAccumulatorPair.rhs);
   }
 
-
   @Override
   public Sequence<Row> mergeSequences(Sequence<Sequence<Row>> seqOfSequences)
   {
diff --git a/server/src/main/java/io/druid/segment/realtime/plumber/RealtimePlumber.java b/server/src/main/java/io/druid/segment/realtime/plumber/RealtimePlumber.java
index cbe8b597b9f..26b4cc45509 100644
--- a/server/src/main/java/io/druid/segment/realtime/plumber/RealtimePlumber.java
+++ b/server/src/main/java/io/druid/segment/realtime/plumber/RealtimePlumber.java
@@ -39,6 +39,7 @@ import io.druid.segment.IndexMerger;
 import io.druid.segment.QueryableIndex;
 import io.druid.segment.QueryableIndexSegment;
 import io.druid.segment.Segment;
+import io.druid.segment.incremental.IncrementalIndex;
 import io.druid.segment.indexing.DataSchema;
 import io.druid.segment.indexing.RealtimeTuningConfig;
 import io.druid.segment.loading.DataSegmentPusher;
@@ -713,14 +714,15 @@ public class RealtimePlumber implements Plumber
             indexToPersist.getIndex(),
             new File(computePersistDir(schema, interval), String.valueOf(indexToPersist.getCount()))
         );
-
+        IncrementalIndex index = indexToPersist.getIndex();
         indexToPersist.swapSegment(
             new QueryableIndexSegment(
                 indexToPersist.getSegment().getIdentifier(),
                 IndexIO.loadIndex(persistedFile)
             )
         );
-
+        //TODO: can there be some races here ?
+        index.close();
         return numRows;
       }
       catch (IOException e) {