Exhausted memory with many roles enable

Please explain a bit your use-case. Do you have any scheme on how the roles are assigned to users? Are there any role-combinations which never will occure? Can you formulate (in words) a set of rules which role combinations are to be expected?

Authcache Enum tries to discover every possible authcache key. It does this by enumerating every combination of roles. In order to solve your problem it might be enough to limit the number of combinations.

Maybe this is possible by determining the maximum of existing role combinations instead of blindly work with all the combinations which are theoretical possible. I.e. select the user with the most roles and only build combinations of roles up to that number. However, this obviously will not work if there is at least one user having (nearly) all roles assigned.

In order to asses whether restricting the cardinality would solve the problem in your case, please save the following PHP snipped into a file in your websites root directory and run it once, then post the result here:

define('DRUPAL_ROOT', getcwd());
require_once DRUPAL_ROOT . '/includes/bootstrap.inc';
drupal_bootstrap(DRUPAL_BOOTSTRAP_FULL);

$roles = array_keys(authcache_get_roles());

$t0 = microtime(TRUE);
$k_max = db_query('SELECT MAX(k) FROM (SELECT DISTINCT count(rid) AS k FROM {users_roles} WHERE rid IN (:roles) GROUP BY uid) AS cardinalities', array(':roles' => $roles))->fetchField();
$t1 = microtime(TRUE);
$dt = ($t1 - $t0);

print "k_max=${k_max};dt=${dt}";

The output should look similar to this:
k_max=2;dt=0.00018405914306641

Hello,

I got a similar error message in my system:

PHP Fatal error: Out of memory (allocated 1695023104) (tried to allocate 36 bytes) in C:\\...\\sites\\all\\modules\\authcache\\modules\\authcache_enum\\authcache_enum.comb.inc on line 29, referer: ...

... so I tried to patch the authcache.module with the patch from here "https://www.drupal.org/node/1963756" but the code is different, so now way to do this. (Checked with current DEV-version from 2015-01-02)

.. and I run your PHP code on my site, here is the result: k_max=119;dt=0.015625

Thanks for helping
Matroschker

@Matroschker these numbers indicate that there are at least 119 authcache enabled roles at the site in question. Is this really true?

Hi znerol,

yes it's true. But I checked this also with 45 roles - the same effect.

Matroschker

Can you estimate how many users you have per role-combination?

znerol,

not really. We have ~10 roles which defines the permissions for the kind of worker and a lot of product roles, which we use to give access to special content.
Can you explain why it is necessary that all roles, an user have, must selected in the authcache configuration that the caching works?

Matroschker

I'd like to point out the following things about Authcache;

1. When assessing caching performance, the cache hit/miss ratio is the key-indicator.
2. Hence it is most effective on sites where a big number of users share a small number of role combinations.
3. On sites where there are not many users sharing role combinations, the cache-hit/miss ratio will be poor. This is because each role-combination will generate a distinct cache-key, i.e. one page will be cached separately for each group of users (where group = users with common role combination).
4. It cannot speed up a slow backend. If your users mainly edit content, then do not use it.

As a rule of thumb if you end up selecting more than a small number of roles (perhaps at most 10) in Authcache, then you most probably should not use it at all.

Ok, thank you for these information, we will consider these.
Can you recommend another cache modul?
PS: We have no free content only content which is available for authenticated users.

Thank you.

Perhaps post this question to the High Performance group on groups.drupal.org.

Now we could solve the performance issue on our site with an update of PHP to version 5.6 to enable built in OpCache and an enabled Memcached and Memcached Storage.

Thank you for your help.
(Drupal 7.34)

I have multiple roles but would like the option to select authenticated users (no other roles) and authorized user (any other roles). The latter would just cache anyone who is has the authenticated user role regardless of any other roles they might have.

@SocialNicheGuru This is not something which could be solved safely in a generic way, but it can be achieved by customizing the Customizing authcache key calculation as explained in Authcache 2 tuning guide - optimize cache-hit ratio.

k_max=4;dt=0.025913953781128

I've also run into this but I resolved to not cache for most of the roles as the people who have these roles are few and they are unlikely to get a good cache hit ratio anyway.

Patch supplied in related issue #2443049-19: Performance issue with cache expiration