private void deleteSpillFiles() {
        for (UnsafeSorterSpillWriter spill : spillWriters) {
            try {
                spill.removeFile();
            } catch (IOException e) {
                logger.error("", e);
            }
        }
    }
Deletes any spill files created by this sorter.
indexr-query-opt/src/main/java/org/apache/spark/util/collection/unsafe/sort/UnsafeExternalSorter.java