import os, threading, time, sys

if sys.platform == 'win32':
    timer = time.clock
else:
    timer = time.time

def send_in_chunks(f):
    try:
        for _ in range(LENGTH // len(chunk)):
            f.write(chunk)
    finally:
        f.close()

def recv(f, buf):
    try:
        buf.append(f.read())
    finally:
        f.close()

for i in range(10):
    chunk = b"X" * 4096
    MB = 1024**2
    LENGTH = 2**i*MB
    buf = []
    r, w = os.pipe()
    r, w = os.fdopen(r, 'rb', 0), os.fdopen(w, 'wb', 0)
    thread = threading.Thread(target=recv, args=(r, buf))

    time.sleep(1)
    start = timer()
    thread.start()
    send_in_chunks(w)
    thread.join()
    elapsed = timer() - start

    assert len(buf.pop()) == LENGTH
    print('amount = %.0f MB; time taken = %.3f secs; rate = %.2f MB/s' %
          (1.0*LENGTH/MB, elapsed, 1.0*LENGTH/MB/(elapsed+1e-9)))