Fri, 10 Apr 2026 12:25:57 +0000 https://bugs.horde.org/ticket/7086 Consider consistent hashing for Horde_Memcache I don't know enough about how pecl/memcache handles multiple memcache servers to know if this is redundant, but if it's not already using consistent hashing, we should have at least an option to manage the array of memcache servers ourselves, and do that to spread keys around. In addition, we could use this same code to implement multiple-write, where we write data to 2 memcache servers instead of one, to decrease thrashing or cache misses if a server drops out. A good explanation: http://www.spiteful.com/2008/03/17/programmers-toolbox-part-3-consistent-hashing/ A potential implementation (I'll be adding one to the Horde_Support package hopefully within a few days as well): http://code.google.com/p/flexihash/ Mon, 21 Jul 2008 03:30:37 +0000 https://bugs.horde.org/ticket/7086#t47658 Memcache already has internal consistent hashing. When adding server(s) to the pool, a certain percentage of keys from the existing servers are moved to the new server. When removing server(s), the lost keys are redistributed to the remaining servers. Mon, 21 Jul 2008 04:37:16 +0000 https://bugs.horde.org/ticket/7086#t47660 To clarify, this is internally done by the PECL memcache driver. As of memcache 2.2.0, a new PHP ini setting was added: "memcache.hash_strategy" = {standard, consistent} However, 'consistent' did not become the default until 3.0.0. So I guess it may be useful to set this automatically if using memcache 2.2+. No need to make it a config option however. Mon, 21 Jul 2008 04:54:02 +0000 https://bugs.horde.org/ticket/7086#t47661 Version 3.0 also added key redundancy. Mon, 21 Jul 2008 04:55:08 +0000 https://bugs.horde.org/ticket/7086#t47662 Changes have been made in CVS for this ticket: http://cvs.horde.org/diff.php/framework/Memcache/lib/Horde/Memcache.php?r1=1.3&r2=1.4&ty=u Mon, 21 Jul 2008 05:05:34 +0000 https://bugs.horde.org/ticket/7086#t47663 Changes have been made in CVS for this ticket: http://cvs.horde.org/diff.php/framework/Memcache/lib/Horde/Memcache.php?r1=1.1.2.3&r2=1.1.2.4&ty=u Mon, 21 Jul 2008 05:08:24 +0000 https://bugs.horde.org/ticket/7086#t47664 For the way we use memcache, key redundancy doesn't makes sense. The overhead in keeping cache information on multiple servers on every request is not worth the gains we might get in the (rare) event a memcache server is removed from the pool. Since our memcache data is not entirely based on underlying DB/SQL data, B thrashing issues are reduced. Mon, 21 Jul 2008 17:33:19 +0000 https://bugs.horde.org/ticket/7086#t47688