Github user sitalkedia commented on the pull request:

    https://github.com/apache/spark/pull/13107#issuecomment-219762996
  
    I am not 100% sure of the root cause, but I suspect this is happening when 
JVM is trying to allocate very large size buffer for pointer array. The issue 
might be because the JVM is not able to allocate large buffer in contiguous 
memory location on heap and since the unsafe operations assume contiguous 
memory location of the objects, any unsafe operation on large buffer results in 
memory corruption which manifests as TimSort issue. 
    
    Unfortunately, this issue is not reproducible consistently and I am not 
sure of the root cause. So I am not sure how can we have a regression test for 
it.
    
    Also, please note that this change itself is a no-op unless you override 
the default value of `numElementsForSpillThreshold`, which is `Long.MAX_VALUE`. 


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