New submission from Joe Borg:
I'm in need of an unbuffered stdin for Python3. Using the '-u' flag worked
fine in Python2. But, it seems, Python3's stdin is always buffered; as seen in
http://bugs.python.org/issue4705.
This is not always desirable. For example:
#!/bin/python3
import os, subprocess, time
with open("%s/unbuffered_test.log" % (os.getenv("HOME")), "w") as f:
with subprocess.Popen(["%s/unbuffered_test.sh" % (os.getenv("HOME"))],
stdin=subprocess.PIPE, stdout=f, stderr=f) as p:
p.stdin.write(bytes("test\n", encoding="utf-8"))
time.sleep(10)
Where unbuffered_test.sh is:
#!/bin/sh
read INPUT
echo $INPUT
exit 0
Running with -u in Python2 sees the log file populated before the 10 seconds
are up. This isn't the case in Python3. This making controlling applications,
using subprocess, basically impossible; without putting p.stdin.flush() after
each command (which does work in the example above).
I ran this example in Python3.3.2.
----------
messages: 196359
nosy: Joe.Borg
priority: normal
severity: normal
status: open
title: Python3 unbuffered stdin
versions: Python 3.1, Python 3.2, Python 3.3, Python 3.4, Python 3.5
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Python tracker <[email protected]>
<http://bugs.python.org/issue18868>
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