[drupal-devel] [bug] fuzzy cache flushes cache too frequently

[Jeremy]

Issue status update for 
http://drupal.org/node/29274
Post a follow up: 
http://drupal.org/project/comments/add/29274

 Project:      Drupal
 Version:      cvs
 Component:    base system
 Category:     bug reports
 Priority:     normal
 Assigned to:  Jeremy at kerneltrap.org
 Reported by:  Jeremy at kerneltrap.org
 Updated by:   Jeremy at kerneltrap.org
 Status:       patch (code needs review)
 Attachment:   http://drupal.org/files/issues/cache_3.patch (7.15 KB)

Based on a brief conversation with Dries, here is an updated version of
this patch.  


Configuration is simplified by removing all references to "strict" and
"loose" caches.  Instead, the cache is either "disabled" or "enabled". 
Additionally, the site administrator can now configure the "minimum
cache lifetime", the minimum amount of time cached data will remain
cached.


The patch updates the system.module and bootstrap.inc.




Jeremy at kerneltrap.org



Previous comments:
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Sun, 21 Aug 2005 00:20:39 +0000 : Jeremy at kerneltrap.org

Attachment: http://drupal.org/files/issues/bootstrap.inc_7.patch (2.08 KB)

The "fuzzy cache" mechanism is supposed to enforce a minimum time before
the cache table is flushed.  Logical errors in the fuzzy cache
implementation are leading to the cache table being flushed more
frequently.


With this patch and the fuzzy cache enabled, when an event leads to
cache_clear_all() being called:
 - the cache is invalidated for the current user (simulating the cache
being cleared for that user)
 - a 5 minutes timer is started


Once five minutes passes, the cache is finally cleared for all users. 
Thus, with this patch the cache should never be cleared more than once
every five minutes.  Testing needs to be done to determine if 5 minutes
is a long enough delay.  Optionally, this delay time could be made
configurable.




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Sun, 21 Aug 2005 00:21:01 +0000 : Jeremy at kerneltrap.org

Patch needs review.




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Sun, 21 Aug 2005 23:06:47 +0000 : chx

Jeremy, I love this patch. Can't wait for Dries to install and test on
drupal.org -- alas I can't test as I do not have a site with enough
visitors...