Check For Websocket Data

[limitedAtonement]

The handler in examples/clock.py looks like this:

@sock.route('/clock')
def clock(ws):
    client_list.append(ws)
    while True:
        data = ws.receive()
        if data == 'stop':
            break
    client_list.remove(ws)

When terminating the server, the termination is held up because of the blocking call on ws.receive(). It would be better if we could do something like

@sock.route('/clock')
def clock(ws):
    client_list.append(ws)
    while keep_running():
        if ws.available():
            data = ws.receive()
            if data == 'stop':
                break
        else:
            time.sleep(.5)
    client_list.remove(ws)

keep_running can be set up to return False if a SIG_TERM was sent or whatever.

Is there any way to get this type of non-blocking behavior?

[miguelgrinberg]

What happens when SIGTERM is received varies depending on the web server that you are using. A proper handling of SIGTERM by the web server would close all open handles, which would in turn raise an exception on the receive() call. Not sure what web server you are using, but I would prefer to not add code in this package to compensate for web servers that don't do this correctly.

[limitedAtonement]

A just response. I'm using gunicorn (without gevent and eventlet at the moment). I'll see what it takes to get gunicorn to close IO handles on SIGTERM.