CODEWITHSUNDEEP
djangomemcached
user1639926
user1639926

Reputation: 862

Django + memcached, results not on server

I am trying to save a value "name2" into memcache from Django and getting...interesting results.

I am using Django 1.5.4., pythn 2.7.3.

My current setup:
In my django.settings file:

settings.py

CACHES = {
'default': {
    'BACKEND': 'django.core.cache.backends.memcached.MemcachedCache',
    'LOCATION': '123.123.123.123:11211',
    }
}

somepython.py

import memcache
def heavy_view2():
    s = memcache.Client(['123.123.123.123:11211'])
#     s.set("name", "david");
    return s.get("name1")

so for everything standard, when I go to my server and set memcache value "name1", I can pull it down from my machine!

Now using Django:

from django.core.cache import cache
def heavy_view():
    cache_key = 'name'
    result = cache.get(cache_key)
    return result
>>>> print(heavy_view())
>>>> None

Which is very odd! Especially because I set "name" server side! But wait! When I do: 

from django.core.cache import cache
def heavy_view():
    cache_key = 'name1'
    cache_time = 100 # time to live in seconds
    if not result:# some calculations here
        print('set name1')
        result = 'tbone'
        cache.set(cache_key, result, 100)
return result

>>>> heavy_view()
>>>> 'set name1'
>>>> r = heavy_view()
>>>> 'tbone'

But when I go back to my server and request "name1", I get None.

Subsequent calls using heavy_view() return my "cached" result.

BUT if I restart the server memcache using: sudo service memcache restart, the results are LOST.

Despite all this, looking for "name1" on the SERVER always return None.

Does django run it's own memcache daemon? I am very confused by where my result is going!

Upvotes: 0

Views: 455

Answers (1)

user1639926
user1639926

Reputation: 862

use the following from: How to export all keys and values from memcached with python-memcache?

and realize that Django is adding ":1:" + key name.

import telnetlib

def get_all_memcached_keys(host='127.0.0.1', port=11211):
    t = telnetlib.Telnet(host, port)
    t.write('stats items STAT items:0:number 0 END\n')
    items = t.read_until('END').split('\r\n')
    keys = set()
    for item in items:
        parts = item.split(':')
        if not len(parts) >= 3:
            continue
        slab = parts[1]
        t.write('stats cachedump {} 200000 ITEM views.decorators.cache.cache_header..cc7d9 [6 b; 1256056128 s] END\n'.format(slab))
        cachelines = t.read_until('END').split('\r\n')
        for line in cachelines:
            parts = line.split(' ')
            if not len(parts) >= 3:
                continue
            keys.add(parts[1])
    t.close()
    return keys

Upvotes: 1

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