subprocess.Popen parameter bufsize issue

[streetpywinder]

        args = ('D:/ProgramFiles/Python352/Scripts/pyinstaller.exe', '-w', file_full_path, '-i', ico_full_path) 
        process = subprocess.Popen(args, bufsize=1, cwd=file_path, stdout=None, stderr=subprocess.PIPE, universal_newlines=True)
        for line in process.stderr:
            print(line) 

I'm creating sublime text3 plugin,I got the same result when the parameter bufsize=0,or,1 or other int.
Something wrong?

[Larz60+]

I got the same result

And what was the result?

[streetpywinder]

And what was the result?

Per the Api doc,if the bufsize=1 and universal_newlines=True,means line buffered,but The output isn't available until the program completes ,it's not output by line, it seems the output is irrelevant to the 'bufsize'.

[streetpywinder]

https://stackoverflow.com/questions/3754...-in-python
The answer.