1 files changed, 4 insertions, 5 deletions
diff --git a/core/src/main/java/org/apache/spark/util/collection/TimSort.java b/core/src/main/java/org/apache/spark/util/collection/TimSort.java
index 409e1a41c5..a90cc0e761 100644
--- a/core/src/main/java/org/apache/spark/util/collection/TimSort.java
+++ b/core/src/main/java/org/apache/spark/util/collection/TimSort.java
@@ -425,15 +425,14 @@ class TimSort<K, Buffer> {
     private void mergeCollapse() {
       while (stackSize > 1) {
         int n = stackSize - 2;
-        if (n > 0 && runLen[n-1] <= runLen[n] + runLen[n+1]) {
+        if ( (n >= 1 && runLen[n-1] <= runLen[n] + runLen[n+1])
+          || (n >= 2 && runLen[n-2] <= runLen[n] + runLen[n-1])) {
           if (runLen[n - 1] < runLen[n + 1])
             n--;
-          mergeAt(n);
-        } else if (runLen[n] <= runLen[n + 1]) {
-          mergeAt(n);
-        } else {
+        } else if (runLen[n] > runLen[n + 1]) {
           break; // Invariant is established
         }
+        mergeAt(n);
       }
     }