"While working on a proper complexity analysis of the algorithm, we realised that there was an error in the last paper reporting such a bug (http://envisage-project.eu/wp-content/uploads/2015/02/sortin...). This implies that the correction implemented in the Java source code (changing Timsort stack size) is wrong and that it is still possible to make it break. This is explained in full details in our analysis: https://arxiv.org/pdf/1805.08612.pdf"

There are likely a million ways malformed input can make a java server throw an exception; that's typically how java handles malformed input. It just gets caught and returned as an error to the client.

  arrayToSort[sum] = 1;

Use:

  Integer[] arrayToSort = new Integer[2000000000];

    Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 49
        at java.util.ComparableTimSort.pushRun(Unknown Source)
        at java.util.ComparableTimSort.sort(Unknown Source)
        at java.util.Arrays.sort(Unknown Source)
        at Test.main(Test.java:80)

    arrayToSort[sum] = 1;

    >>> a=[0]*sum(rls)
    >>> sum=-1
    >>> for i in rls:
    ...   sum += i
    ...   a[sum] = 1
    ... 
    >>> a.sort()
    >>> 

Worst-case complexity.

Also, I needed to bump my JVM heap up to 16GB (not 9GB as recommended), just to run it.