python- how to display size of all variables

A bit more code, but works in Python 3 and gives a sorted, human readable output:

import sys
def sizeof_fmt(num, suffix='B'):
    ''' by Fred Cirera,  https://stackoverflow.com/a/1094933/1870254, modified'''
    for unit in ['','Ki','Mi','Gi','Ti','Pi','Ei','Zi']:
        if abs(num) < 1024.0:
            return "%3.1f %s%s" % (num, unit, suffix)
        num /= 1024.0
    return "%.1f %s%s" % (num, 'Yi', suffix)

for name, size in sorted(((name, sys.getsizeof(value)) for name, value in locals().items()),
                         key= lambda x: -x[1])[:10]:
    print("{:>30}: {:>8}".format(name, sizeof_fmt(size)))

Example output:

                  umis:   3.6 GiB
       barcodes_sorted:   3.6 GiB
          barcodes_idx:   3.6 GiB
              barcodes:   3.6 GiB
                  cbcs:   3.6 GiB
         reads_per_umi:   1.3 GiB
          umis_per_cbc:  59.1 MiB
         reads_per_cbc:  59.1 MiB
                   _40:  12.1 KiB
                     _:   1.6 KiB

You can iterate over both the key and value of a dictionary using .items()

from __future__ import print_function  # for Python2
import sys

local_vars = list(locals().items())
for var, obj in local_vars:
    print(var, sys.getsizeof(obj))