Python printing inline with a sleep command

Question

Why is the following code

from __future__ import print_function
from time import sleep

def print_inline():
    print("Hello ", end='')
    sleep(5)
    print("World")

print_inline()

waits until the sleep is done to print Hello World, shouldn't print Hello then wait for 5 seconds and print World in the same line?

Answer 1

No, it shouldn't. "Hello" sits in the output buffer until there's a reason to flush it to the output device. In this case, that "reason" is the end of the program. If you want The delayed effect, add

import sys
sys.stdout.flush()

just before your sleep statement.

See also a more complete discussion here.

Answer 2

If you set the first print to:

print("Hello ", end='', flush=True)

this should print Hello, then sleep for 5, then print World.

Edit: this only works in Python 3, didn't see the Python 2.7 tag...