import asyncio
import sys

@asyncio.coroutine
def test_pause_reading():
    chunk_size = 100

    code = '\n'.join((
        'import sys',
        'import time',
        'buffer = "x" * %s' % chunk_size,
        'for line in range(4):',
        '    sys.stdout.write(buffer)',
        '    sys.stdout.flush()',
        '    time.sleep(0.250)',
    ))
    proc = yield from asyncio.create_subprocess_exec(
                                 sys.executable, '-c', code,
                                 stdout=asyncio.subprocess.PIPE,
                                 limit=chunk_size // 2 - 1)

    stdout, stderr = yield from proc.communicate()

loop = asyncio.get_event_loop()
queue = asyncio.Queue()
loop.run_until_complete(test_pause_reading())
loop.close()