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Cache-Memcached-Fast-0.14
River stage two • 31 direct dependents • 40 total dependents

Changes for version 0.14 - 2009-02-07

  • improve Ketama distribution. The change is incompatible with Ketama implementation in previous versions.
  • Changes since 0.13:
  • Change calculation of Ketama points for a given server to get mapping ratios closer to server weight ratios. New Ketama mode is compatible with nginx's module memcached_hash (http://openhack.ru/nginx-patched/wiki/MemcachedHash) version 0.4, which has the same change, and is incompatible with earlier versions of both named and this module.
  • Add script/ketama-distr.pl to compute server's share of continuum. Real-world example:
    • script/ketama-distr.pl --ketama_points=150 \ --server=10.0.143.4:11211 \ --server=10.0.143.6:11211 \ --server=10.0.143.7:11211 \ --server=10.0.143.8:11211
  • outputs:
    • Old: server 1: 10.0.143.4:11211 total = 671585356 (15.64%) server 2: 10.0.143.6:11211 total = 601117590 (14.00%) server 3: 10.0.143.7:11211 total = 1771239512 (41.24%) server 4: 10.0.143.8:11211 total = 1251024837 (29.13%)
    • New: server 1: 10.0.143.4:11211 total = 1057134262 (24.61%) server 2: 10.0.143.6:11211 total = 1111432463 (25.88%) server 3: 10.0.143.7:11211 total = 1017280856 (23.69%) server 4: 10.0.143.8:11211 total = 1109119714 (25.82%)
    • Continuum array size = 4800 bytes
  • I.e. "Old" is what we were getting before the change, and "New" is what we are getting now. "Continuum array size" is how much memory is used to store the continuum array. Try this script on your servers to see your distribution, and possibly to tweak ketama_points and/or server weights to get a better one.
  • Fix RT#41077 (http://rt.cpan.org/Ticket/Display.html?id=41077): implement disconnect_all(). Patch is by norbi.nix.hu, with minor corrections---thanks!.

Documentation

ketama-distr.pl
compute relative distribution of keys.

Modules

Cache::Memcached::Fast
Perl client for memcached, in C language

Other files