It turns out that the issue was not with django or gevent or redis, rather chrome was queueing the connections. If I use two different browsers the code works as expected.
Using Redis to synchronize requests in Django
문제
I am trying to synchronize incoming connections using Redis lpush/blpop
.
For example, one user attempts to load the page, and his connection blocks via blpop
.
As soon as a second user starts loading the page they lpush
, releasing the first connection.
Instead the first blpop
seems to block the entire server and the second connection never enters the view.
Here is a minimal example of what I'm trying:
views.py:
from django.http import HttpResponse
import redis
r = redis.StrictRedis()
def two_view(request):
print('Starting request')
if r.get('waiting') == '1':
print('Someone is waiting')
r.set('waiting', 0)
print('Pushing key')
r.lpush('waiting_key', 1)
return HttpResponse('Released lock, we both go')
else:
print('Nobody is waiting.')
r.set('waiting', 1)
print('Begin waiting for other')
r.blpop('waiting_key')
return HttpResponse('set waiting higher, to: {}'.format(r.get('waiting')))
manage.py:
#!/usr/bin/env python
from gevent import monkey
monkey.patch_all()
import os
import sys
if __name__ == "__main__":
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "basic.settings")
from django.core.management import execute_from_command_line
execute_from_command_line(sys.argv)
urls.py:
from django.conf.urls import patterns, include, url
from django.contrib import admin
from views import two_view
admin.autodiscover()
urlpatterns = patterns('',
url(r'^admin/', include(admin.site.urls)),
url(r'^$', two_view),
)
And the output when I point two tabs at it:
(env)Vincents-MacBook-Pro:basic vkhougaz$ python manage.py runserver
Validating models...
0 errors found
April 04, 2014 - 02:38:34
Django version 1.6.2, using settings 'basic.settings'
Starting development server at http://127.0.0.1:8000/
Quit the server with CONTROL-C.
Starting request
Nobody is waiting.
Begin waiting for other
And both tabs never finish loading.
Here is a working example of what I am trying to do:
import redis
from gevent import monkey
import gevent
monkey.patch_all(thread=False)
from time import sleep
conpol = redis.ConnectionPool()
def do_lock_thing_1():
r = redis.StrictRedis(connection_pool=conpol)
print('starting thing 1')
r.blpop('k')
print('finishing thing 1')
def do_lock_thing_2():
r = redis.StrictRedis(connection_pool=conpol)
print('starting thing 2')
sleep(1)
r.lpush('k', 1)
print('finishing thing 2')
r2 = redis.StrictRedis(connection_pool=conpol)
r2.delete('k')
t1 = gevent.spawn(do_lock_thing_1)
t2 = gevent.spawn(do_lock_thing_2)
gevent.joinall([t1, t2])
And the output:
starting thing 1
starting thing 2
<1 second delay>
finishing thing 2
finishing thing 1
What am I missing?
해결책
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