Github user JoshRosen commented on a diff in the pull request:
https://github.com/apache/spark/pull/9793#discussion_r45804928
--- Diff:
core/src/main/java/org/apache/spark/util/collection/unsafe/sort/UnsafeExternalSorter.java
---
@@ -489,10 +495,6 @@ public void loadNext() throws IOException {
}
upstream = nextUpstream;
nextUpstream = null;
-
- assert(inMemSorter != null);
--- End diff --
Ah, I see that `getSortedIterator()`'s contract specifies that the caller
should call `cleanupResources()` after consuming the iterator:
```
/**
* Returns a sorted iterator. It is the caller's responsibility to call
`cleanupResources()`
* after consuming this iterator.
*/
```
Even if we're merging an in-memory iterator with a bunch of on-disk spills,
there isn't an advantage to trying to free the in-memory iterator's array as
soon as we hit the end of that in-memory iterator, since in expectation I think
that we would hit the end of that iterator at about the same time that we hit
the end of the other iterators / the merged iterator as a whole.
Therefore, LGTM.
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