Flask Hello

hello.py

# Simple http server to test concurrency or load balancing or whatever,
# specifying numprocs greater than 1 will run that many instances of the
# flask app in subprocesses on incrementing ports beginning with the one specified
# Run:
#    sudo pip install flask
#    python hello.py [PORT-NUM] [NUMPROCS]

from flask import Flask
import os
import signal
import subprocess
import sys

app = Flask(__name__)

@app.route('/')
def hello_world():
    return "Hello from {0}".format(os.getpid())

def run_multi_in_subprocs(numprocs, starting_port):
    procs = []
    for port in xrange(starting_port, starting_port + numprocs):
        procs.append(subprocess.Popen(['python', __file__, str(port)]))

    def cleanup_for_exit(signal, frame):
        print "Caught SIGINT, killing {0} subproccesses and exiting".format(len(procs))
        [p.kill() for p in procs]
        sys.exit(0)

    signal.signal(signal.SIGINT, cleanup_for_exit)
    signal.pause()


if __name__ == '__main__':
    port = int(sys.argv[1]) if len(sys.argv) > 1 else 5000
    numprocs = int(sys.argv[2]) if len(sys.argv) > 2 else 1

    if numprocs == 1:
    	app.run(host='0.0.0.0', port=int(port))
    else:
        run_multi_in_subprocs(numprocs, port)