[GitHub] [incubator-nemo] jaehwan0214 commented on a change in pull request #304: [NEMO-394] Exchange data via shared memory

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

jaehwan0214 commented on a change in pull request #304:
URL: https://github.com/apache/incubator-nemo/pull/304#discussion_r519580659



##########
File path: runtime/executor/src/main/java/org/apache/nemo/runtime/executor/task/MultiThreadParentTaskDataFetcher.java
##########
@@ -127,14 +129,19 @@ private void fetchDataLazily() {
                   watermarkWithIndex.getIndex(), watermarkWithIndex.getWatermark());
               }
             } else {
+              if (element instanceof Finishmark) {
+                isFinishMarkProduced = true;
+              }
               // data element
               elementQueue.offer(element);
             }
           }
-
           // This iterator is finished.
           countBytesSynchronized(iterator);
-          elementQueue.offer(Finishmark.getInstance());
+          // If the current iterator hasn't produced finish mark, put it into the global queue.
+          if (!isFinishMarkProduced) {

Review comment:
       When the local output context closes, it produces a finish mark. In this case, the data fetcher receives a finish mark from the iterator. Then, the data fetcher shouldn't produce another finish mark when the iterator is finished. 




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