Question

I have a server that is trying to stream some content to a client (which is Kenneth Reitz excellent requests library) – (Props to toastdriven.com for code below). Note that in a browser, it works as expected.

from gevent import monkey
monkey.patch_all()

import datetime
import time
from gevent import Greenlet
from gevent import pywsgi
from gevent import queue

import json

def current_time(body):
    current = start = datetime.datetime.now()
    end = start + datetime.timedelta(seconds=60)

    while current < end:
        current = datetime.datetime.now()
        message = json.dumps({'time': current.strftime("%Y-%m-%d %I:%M:%S")})
        body.put(message)
        time.sleep(1)

    body.put('</body></html>')
    body.put(StopIteration)

def handle(environ, start_response):
    start_response('200 OK', [('Content-Type', 'text/html')])
    body = queue.Queue()
    g = Greenlet.spawn(current_time, body)
    return body

server = pywsgi.WSGIServer(('127.0.0.1', 1234), handle)
print "Serving on http://127.0.0.1:1234..."
server.serve_forever()

And a client:

import sys
import requests
import json

my_config = {'verbose': sys.stdout}
r = requests.get('http://127.0.0.1:1234/', config=my_config)

for line in r.iter_lines():
    print json.loads(line)

I dont’ understand why the json lines arent’ showing up in the terminal (OSX). When I ctrl-c the responses are dumped to the screen.

If I do:

for line in r.iter_content()

I get the json, a character on each line, streamed as expected.

Any ideas?

Answer 1

Your client is probably running in a terminal window that is buffered. After each print, try adding sys.stdout.flush() to flush the output buffer.