[jira] [Commented] (ACCUMULO-2757) millions of zookeeper watches

["John Vines (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ACCUMULO-2757?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15875094#comment-15875094 ] 

John Vines commented on ACCUMULO-2757:
--------------------------------------

So, I've spotted issues caused by this in the wild today, it expresses itself like https://issues.apache.org/jira/browse/ZOOKEEPER-706

> millions of zookeeper watches
> -----------------------------
>
>                 Key: ACCUMULO-2757
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-2757
>             Project: Accumulo
>          Issue Type: Improvement
>          Components: client, master, tserver
>         Environment: very large clusters
>            Reporter: Eric Newton
>            Assignee: Eric Newton
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> I recently learned how to get the number of watches in a zookeeper node.
> {noformat}
> $ echo wchp | nc localhost 2181
> {noformat}
> There are a surprising number of watches supporting table configuration.  A single tserver accumulo instance with one data table is using 872 watches.  Large clusters, even with many zookeepers, can have millions of watches.
> We may need to watch a single notification node, or serialize the table configs into a single node per table.  That would accomplish ACCUMULO-1568, too.



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