# Read and write a huge file.
import sys

def write_file(end = 126, loops = 150, fname='bigfile'):
    fh = open(fname, 'w')
    buff = 'A' * end
    for k in range(loops):
        for t in range(end+1):
            fh.write(buff[:t]+'\n')
    fh.close()

def read_file(end = 126, fname = 'bigfile'):
    fh = open(fname, 'r')
    offset = 0
    loops = 0
    for rec in fh:
        if offset != len(rec.strip()):
            print 'Error at loop:', loops
            print 'Expected record length:', offset
            print 'Actual record length:', len(rec.strip())
            sys.exit(0)
        offset += 1
        if offset > end:
            offset = 0
            loops += 1
            if not loops % 10000: print loops
    fh.close()

if __name__ == '__main__':
    write_file(loops=1500000)
    read_file()