memcached：item在缓存中不可用(memcached: item is not available in cache)

 我有memcached的问题。 我使用带有模板'question_％d_％d'的字符串键存储值。 我记得： 
 
STAT bytes 13307757 
STAT limit_maxbytes 134217728
 
 但这是我的应用程序的日志： 
 
2012-01-03 16:40:42,896 Get question for key question_4_1045: cache miss
2012-01-03 18:03:10,270 Get question for key question_4_1045: cache miss
2012-01-03 22:26:16,454 Get question for key question_4_1045: cache miss
2012-01-04 02:01:54,639 Get question for key question_4_1045: cache miss
2012-01-04 02:45:03,647 Get question for key question_4_1045: cache miss
2012-01-04 02:46:55,880 Get question for key question_4_1045: cache hit
2012-01-04 02:51:55,606 Get question for key question_4_1045: cache miss
 
 所以我们可以看到，使用相同密钥的两个顺序调用导致两个缓存未命中，并且只从缓存中获取一次值。 
 
 为什么memcached从缓存中删除我的数据，即使有足够的空间？ 有可能解决它吗？ 
 
 我试图检查我的memcached日志文件（根据配置文件是/var/log/memcached.log），但它是空的。 谢谢！ 
 
 UPD：Django缓存设置： 
 
CACHES = {
    'default': {
        'BACKEND': 'django.core.cache.backends.memcached.MemcachedCache',
        'LOCATION': '127.0.0.1:11211',
        'TIMEOUT': 259200,
    }
}

CACHE_BACKEND = 'memcached://127.0.0.1:11211/'
 
 吸气： 
 
from django.core.cache import cache    
def get_question(level, random_num):
        key = 'question_' + unicode(level) + '_' + unicode(random_num)
        question = cache.get(key)
        if question is None:
            question = Question.objects.filter(level=level).order_by('id')[random_num]
            cache.set(key, question)
            log_message('Get question for key %s: cache miss' % key)
        else:
            log_message('Get question for key %s: cache hit' % key)
        return question

I have an issue with memcached. I store values using string key with template 'question_%d_%d'. I have enought memory:
 
STAT bytes 13307757 
STAT limit_maxbytes 134217728
 
but here is a log of my application:
 
2012-01-03 16:40:42,896 Get question for key question_4_1045: cache miss
2012-01-03 18:03:10,270 Get question for key question_4_1045: cache miss
2012-01-03 22:26:16,454 Get question for key question_4_1045: cache miss
2012-01-04 02:01:54,639 Get question for key question_4_1045: cache miss
2012-01-04 02:45:03,647 Get question for key question_4_1045: cache miss
2012-01-04 02:46:55,880 Get question for key question_4_1045: cache hit
2012-01-04 02:51:55,606 Get question for key question_4_1045: cache miss
 
so we can see, that two sequential calls with the same key lead to two cache misses, and only once value is fetched from cache.
 
Why memcached removes my data from cache, even if there is enough space? Is it possible to fix it?
 
I tried to check my memcached log file (according to config file it is /var/log/memcached.log), but it is empty. Thanks! 
 
UPD: Django cache settings:
 
CACHES = {
    'default': {
        'BACKEND': 'django.core.cache.backends.memcached.MemcachedCache',
        'LOCATION': '127.0.0.1:11211',
        'TIMEOUT': 259200,
    }
}

CACHE_BACKEND = 'memcached://127.0.0.1:11211/'
 
getter:
 
from django.core.cache import cache    
def get_question(level, random_num):
        key = 'question_' + unicode(level) + '_' + unicode(random_num)
        question = cache.get(key)
        if question is None:
            question = Question.objects.filter(level=level).order_by('id')[random_num]
            cache.set(key, question)
            log_message('Get question for key %s: cache miss' % key)
        else:
            log_message('Get question for key %s: cache hit' % key)
        return question

原文：https://stackoverflow.com/questions/8724337