[GitHub] davisp opened a new pull request #886: Fix cluster upgrades when deploying ddoc_cache

[gi...@git.apache.org]

davisp opened a new pull request #886: Fix cluster upgrades when deploying ddoc_cache
URL: https://github.com/apache/couchdb/pull/886
 
 
   ## Overview
   
   As it turns out I made a bit of a mistake when I forgot that the old
   ddoc_cache implementation had an ets_lru process registered as
   ddoc_cache_lru. These cast messages were causing that process to crash.
   If a cluster had enough design document activity and enough nodes this
   would cause nodes with the old ddoc_cache implementation to reboot the
   entire VM. This was a cascading failure due to the ets_lru process
   restarting frequently enough that it brought down the entire ddoc_cache
   application.
   
   ## Testing recommendations
   
   Try a rolling reboot upgrade of a large cluster with significant write load on design documents.
   
   ## Checklist
   
   - [x] Code is written and works correctly;
   - [x] Changes are covered by tests;
   - [ ] Documentation reflects the changes;
   
 
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