Is output buffering enabled by default in Python's interpreter for
If the answer is positive, what are all the ways to disable it?
Suggestions so far:
-ucommand line switch
sys.stdoutin an object that flushes after every write
sys.stdout = os.fdopen(sys.stdout.fileno(), 'w', 0)
Is there any other way to set some global flag in
sys.stdout programmatically during execution?
You can skip buffering for a whole python process using "python -u" (or#!/usr/bin/env python -u etc) or by setting the environment variable PYTHONUNBUFFERED.
You could also replace sys.stdout with some other stream like wrapper which does a flush after every call.
class Unbuffered(object): def __init__(self, stream): self.stream = stream def write(self, data): self.stream.write(data) self.stream.flush() def writelines(self, datas): self.stream.writelines(datas) self.stream.flush() def __getattr__(self, attr): return getattr(self.stream, attr) import sys sys.stdout = Unbuffered(sys.stdout) print 'Hello'
I would rather put my answer in How to flush output of Python print? or in Python's print function that flushes the buffer when it's called?, but since they were marked as duplicates of this one (what I do not agree), I'll answer it here.
Since Python 3.3 print() supports the keyword argument "flush" (see documentation):
print('Hello World!', flush=True)