I created a very large CSR_matrix (~50 million rows), but when I try to split it into train and test sets, I get 'Segmentation Faults' error. They machine I am using has ~800gb RAM. I checked the RAM usage and found that it never reached the memory limit, so I do not anticipate it to be memory error. I tried different options, but so far no success. I am using Python 3.6.