How can I output the output of one python script to another python script

Question

I am stuck in the output pipeline of one script to another script (both are pythons).

This question is very similar, but (1) it does not give an answer (2), I have a slight difference. So, I thought the new question would be better.

Here is the problem.
Both scenarios are almost identical:

receiver.py

import sys
import time

for line in sys.stdin:
    sys.stdout.write(line)
    sys.stdout.flush()
    time.sleep(3)

replicator.py

import sys
import time

for line in sys.stdin:
    sys.stderr.write(line)
    sys.stderr.flush()
    time.sleep(3)

When I execute these scripts in bash or cmd one by one, everything is fine. Both of the examples below work, and I see the input text in the output:

Work: (one line is displayed every 3 seconds)

cat data.txt | python receiver.py
cat data.txt | python replicator.py

But as soon as I go from one script to another script, they stop working:

Doesn't work: (nothing appears until the end of the file)

cat data.txt | python receiver.py | python replicator.py

, script , !

:

cat data.txt | python receiver.py | cat -n
cat data.txt | python replicator.py | cat -n

, sleep(), :

:

time.sleep(0)

:

cat data.txt | python receiver.py | python replicator.py

- , ? . , .

UPDATE

, .
data.txt, .

receiver.py

import sys
import time
import datetime

for line in sys.stdin:
    sys.stdout.write(str(datetime.datetime.now().strftime("%H:%M:%S"))+'\t')
    sys.stdout.write(line)
    sys.stdout.flush()
    time.sleep(1)

data.txt

Line-A
Line-B
Line-C
Line-D

$> cat data.txt
Line-A
Line-B
Line-C
Line-D

$> cat data.txt | python receiver.py
09:05:44        Line-A
09:05:45        Line-B
09:05:46        Line-C
09:05:47        Line-D

$> cat data.txt | python receiver.py | python receiver.py
09:05:54        09:05:50        Line-A
09:05:55        09:05:51        Line-B
09:05:56        09:05:52        Line-C
09:05:57        09:05:53        Line-D

$> cat test.log | python receiver.py | sed -e "s/^/$(date +"%H:%M:%S") /"
09:17:55        09:17:55        Line-A
09:17:55        09:17:56        Line-B
09:17:55        09:17:57        Line-C
09:17:55        09:17:58        Line-D

$> cat test.log | python receiver.py | cat | python receiver.py
09:36:21        09:36:17        Line-A
09:36:22        09:36:18        Line-B
09:36:23        09:36:19        Line-C
09:36:24        09:36:20        Line-D

, python script , script , . .

, (sed ), . ?

Answer 1

File (for line in sys.stdin).

, :

import sys
import time
import datetime

while True:
    line = sys.stdin.readline()
    if not line:
       break
    sys.stdout.write(str(datetime.datetime.now().strftime("%H:%M:%S"))+'\t')
    sys.stdout.write(line)
    sys.stdout.flush()
    time.sleep(1)

:

$ cat data.txt | python receiver.py |  python receiver.py
09:43:46        09:43:46        Line-A
09:43:47        09:43:47        Line-B
09:43:48        09:43:48        Line-C
09:43:49        09:43:49        Line-D

... , file.readlines() File ( sys.stdin), . , file.readline() 1: .

: File Object Python 3