[GitHub] [accumulo] ctubbsii commented on issue #1443: Fixes #1220 - Removes ZooKeeper watches on table configs when table is deleted.

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ctubbsii commented on issue #1443: Fixes #1220  -  Removes ZooKeeper watches on table configs when table is deleted.
URL: https://github.com/apache/accumulo/pull/1443#issuecomment-561853321
 
 
   > I have verified with my Uno instance and the ZooKeeper four letter command 'wchp' that this pull request does indeed remove all of the ZooKeeper watches related to an individual table when that table is deleted.
   
   Because of https://issues.apache.org/jira/browse/ZOOKEEPER-1274, that command doesn't give a full picture of the watches (it doesn't show child watches), which concerns me a bit.
   
   > @ctubbsii Below is output you see when you run **master branch** then the 'wchp' command shown below after a createtable command and then after a deletetable command in the Uno shell.
   
   I see that it does have fewer data watches, and have no doubt of this. My main concern is that the way we use ZooCache, these watches might be important and may have negative consequences if removed. Although it fixes the problem of leaving watches around when the table is deleted, it may make it so ZooCache misses when a new node is created. This is somewhat a drop in the bucket, though. The number of watches is still `O(m*n*p)`, albeit with a slightly smaller `p`. I think this scale problem and the watches on non-existing nodes issue are both resolved by a simpler solution to consolidate configs into a single node, which (as I said above), I'm going to try to look into, picking up my previous investigation into that.

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