virajjasani commented on pull request #2523: URL: https://github.com/apache/hbase/pull/2523#issuecomment-707605198
We used to have 2 types of hot config reload: 1. `_switch` commands (e.g `balancer_switch`) which uses znode to update config on/off values and hence, even after master failover, new active master would be able to read config value from znode and stay up-to-date even in the presence of stale config value on hbase-site. 2. `ConfigurationObserver` with implementation of `onConfigurationChange()`, which requires operator to update new config value on all desired servers e.g all masters (active + backup) and then utilize config reload commands `update_config` or `update_config_all`. Since I haven't used (looking forward to dig deeper) `PropagatingConfigurationObserver`, one question is, does it also require updating configs on disk to make sure if master fails-over, next active master reloads config from disk or we have some rendezvous like ZK being used under the hood that ensures config change on disk is not mandatory? I am also not a fan of using another new znode, just trying to understand the crux of hot reload of config and it's impact related to stale config value presence on backup master. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
