Question

My stack is the uWSGI 1.2.2, bottle, and gevent 1.0b2. I am trying to do the following async.

1) serve a pixel image as fast as possible and close the connection
2) I then pass the query string to a function so I can use gevent to async write data to redis
3) Per the uwsgi doc at http://projects.unbit.it/uwsgi/wiki/Gevent I appear to doing it correct.
4) In the logs i get this error. I servers the pixel but…..

Traceback (most recent call last):
  File "/home/ubuntu/workspace/bottleServer.py", line 222, in upixel
    gevent.spawn(pixelRedisWrite,cookie_id,query_string,yield_time)
UnboundLocalError: local variable 'query_string' referenced before assignment
[pid: 28173|app: 0|req: 91/91] 120.28.191.173 () {40 vars in 1909 bytes} [Sat May 12 19:07:24 2012] GET /upixel?bid=eydhdmlkJzogJ2luZm9AYWRtYWdpYy5jby5qcCcsICdjcmlkJzogJzIwNzY3MDczNTE1JywgJ21hYm

So….why is this happening? The query string is there….

Here is how I launch uwsgi

sudo /usr/local/bin/uwsgi --loop gevent --socket :3031 --wsgi-file /home/ubuntu/workspace/bottleServer.py --master --async 10 --listen 100 --processes 1 





def pixelRedisWrite(ckid,qs,yield_time):
    pass


@route('/upixel/')
@route('/upixel')
def upixel():
    sw = stopwatch.Timer()

    if request.get_cookie('rtbhui'):
        cookie_id = request.get_cookie('rtbhui')
    else:
        cookie_id=str(uuid4())
        response.set_cookie('rtbhui', cookie_id , max_age=31556952*2, domain='rtb.rtbhui.com')

    cookie_id='test'
    response.content_type = 'image/gif'
    sw.stop()
    yield_time = int(sw.elapsed * 1000)
    if request.query.bid:
        query_string = base64.b64decode(request.query.bid)
        query_string = ast.literal_eval(query_string)
        #pixelRedisWrite(cookie_id,query_string,yield_time)
    yield pixel
    #print 'gggggg',query_string
    gevent.spawn(pixelRedisWrite,cookie_id,query_string,yield_time)


if __name__ == "__main__":
    # Interactive mode
    run(host='localhost', port=8080)
else:
    # Mod WSGI launch
    os.chdir(os.path.dirname(__file__))
    application = default_app()

Answer 1

This has nothing to do with gevent or uwsgi. You’re defining query_string only in certain case (when request.query.bid is true). If it’s not true, the variable is undefined and UnboundLocalError tells you that.