Question

I want to read a large file (>5GB), line by line, without loading its entire contents into memory. I cannot use readlines() since it creates a very large list in memory.

Answer 1

Use a for loop on a file object to read it line-by-line. Use with open(...) to let a context manager ensure that the file is closed after reading:

with open("log.txt") as infile:
    for line in infile:
        print(line)