from cgi import FieldStorage
from io import BytesIO
from time import time

from psutil import virtual_memory


data = '&'.join(['a=']*3000000) # ~9MB
fp = BytesIO(data.encode('ascii'))
start = virtual_memory().used
field_storage = FieldStorage(
    fp=fp,
    environ={
        'REQUEST_METHOD': 'POST',
    },
    keep_blank_values=True,
)
print('Memory used: {} bytes'.format(virtual_memory().used - start))