Flush output after each line for Python 3

[msabramo]

For some reason, output is getting buffered on Python 3.

Fixes GH-136

Cc: @jlirochon

[jlirochon]

Not totally fixed ?

    $ honcho start
    13:49:59 system | web.1 started (pid=21538)
    ^C13:51:53 system | SIGINT received
    13:51:53 system | sending SIGTERM to web.1 (pid 21538)
    13:51:53 system | web.1 stopped (rc=-15)

With PYTHONUNBUFFERED, there is one more line :

    $ PYTHONUNBUFFERED=1 honcho start
    13:52:19 system | web.1 started (pid=21552)
    13:52:19 web.1  | serving on http://0.0.0.0:8080
    ^C13:52:34 system | SIGINT received
    13:52:34 system | sending SIGTERM to web.1 (pid 21552)
    13:52:34 system | web.1 stopped (rc=-15)

[msabramo]

Hmm that could be because of honcho or it could be because of whatever process you're running. What does your Procfile look like?

I wonder what happens if you add PYTHONUNBUFFERED=1 to .env or Procfile?

[nickstenning]

I don't think this is the right fix. It looks like to me like the buffering is caused by the io.StreamWriter we're instantiating here, which is intended to ensure that sys.stdout is set to encode output as UTF-8.

We should be able to remove those lines without ill effect except that this will result in more people complaining about crashes when Honcho tries to emit unicode to terminals that don't have appropriate LANG settings. (e.g. #51)

At the moment Honcho is being a bit of a bad command-line citizen by actively ignoring the terminal encoding and just spitting out UTF-8. Perhaps the best solution would be to remove the lines which are causing this buffering and emit a warning (perhaps even a fatal error?) if sys.stdout.encoding != 'UTF-8'...

[msabramo]

Agreed. See https://github.com/nickstenning/honcho/pull/139 as a replacement for this PR.