How to flush the STDOUT buffer in Python so that the content wrote to STDOUT is shown immediately?
flush library function on
sys.stdout which is the STDOUT:
import sys sys.stdout.flush()
From python doc:
flush() Flush the write buffers of the stream if applicable. This does nothing for read-only and non-blocking streams.
If you can’t change the code while you can change the
python interpreter options used, you can give it
-u Force stdin, stdout and stderr to be totally unbuffered. On systems where it matters, also put stdin, stdout and stderr in binary mode. Note that there is internal buffering in xreadlines(), readlines() and file-object iterators ("for line in sys.stdin") which is not influenced by this option. To work around this, you will want to use "sys.stdin.readline()" inside a "while 1:" loop.
If you can’t change the interpreter options either, there is another way too by setting the environment variable
PYTHONUNBUFFERED If this is set to a non-empty string it is equivalent to specifying the -u option.
Reference: python2.7 manual