We have an interesting trouble on http://adsoftheworld.com The hook_page_build implementations sometimes looses some value from cache.
Look at this image: http://www.diigo.com/item/image/2peqe/drbq
After
$implementations_cache = cache_get('module_implements', 'cache_bootstrap');
$cache = $implementations_cache->data['page_build'];
I get this array: block, panels_everywhere, rules, admin_menu
Without cache
$hook_info = module_hook_info();
$hook = 'page_build';
$implementations[$hook] = array();
$list = module_list(FALSE, FALSE, FALSE);
foreach ($list as $module) {
$include_file = isset($hook_info[$hook]['group']) && module_load_include('inc', $module, $module . '.' . $hook_info[$hook]['group']);
if (function_exists($module . '_' . $hook)) {
$implementations[$hook][$module] = $include_file ? $hook_info[$hook]['group'] : FALSE;
}
}
the $implementations['page_build'] are: block, metatag, panels_everywhere, toggle_page_elements, rules, admin_menu, admin_menu_toolbar.
We are using the latest dev memcache as cache backend.
As I see, only the _page_build hook is affected. I can't catch any event, which causes that, and I don't see any relevant in the log. Clear class registry fix it, but became wrong 1-2 times in a day.
Why are lost those values?
UPDATE on 01/18/13
added debug code to cache_set, I experienced the following:
This starts when a user load two pages close to same time:
user/%user/points 1358402424.7797
user/%user/subscriptions 1358402424.0462
Other hooks are affected: init, ctools_plugin_api, entity_view, flag_default_flag, element_info_alter, ctools_render_alter, page_build, form_alter
By the following modules: rate, a custom feature, metatag, metatag_opengraph, better_formats, admin_menu_toolbar, toggle_page_elements (this is a custom module)
The one thing, which is similar in these, these were added to the project relative later, but I'm not sure, these were the last modules.
I didn't see any relevant in system table too.
An additional speciality, but I think, it doesn't matter: This site uses a master-slave db environment with module autoslave.
