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https://issues.apache.org/jira/browse/ZOOKEEPER-2770?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16086643#comment-16086643
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ASF GitHub Bot commented on ZOOKEEPER-2770:
-------------------------------------------

Github user karanmehta93 commented on a diff in the pull request:

    https://github.com/apache/zookeeper/pull/307#discussion_r127363108
  
    --- Diff: 
src/java/main/org/apache/zookeeper/server/quorum/QuorumPeerConfig.java ---
    @@ -61,6 +61,7 @@
     
         private static boolean standaloneEnabled = true;
         private static boolean reconfigEnabled = false;
    +    private static int warnThreshold = 10000;
    --- End diff --
    
    I suggest having to turn on logging by default. Won't hurt much as such. 
People can opt out if they want. Its similar to usual stats collection IMO.


> ZooKeeper slow operation log
> ----------------------------
>
>                 Key: ZOOKEEPER-2770
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2770
>             Project: ZooKeeper
>          Issue Type: Improvement
>            Reporter: Karan Mehta
>            Assignee: Karan Mehta
>         Attachments: ZOOKEEPER-2770.001.patch, ZOOKEEPER-2770.002.patch, 
> ZOOKEEPER-2770.003.patch
>
>
> ZooKeeper is a complex distributed application. There are many reasons why 
> any given read or write operation may become slow: a software bug, a protocol 
> problem, a hardware issue with the commit log(s), a network issue. If the 
> problem is constant it is trivial to come to an understanding of the cause. 
> However in order to diagnose intermittent problems we often don't know where, 
> or when, to begin looking. We need some sort of timestamped indication of the 
> problem. Although ZooKeeper is not a datastore, it does persist data, and can 
> suffer intermittent performance degradation, and should consider implementing 
> a 'slow query' log, a feature very common to services which persist 
> information on behalf of clients which may be sensitive to latency while 
> waiting for confirmation of successful persistence.
> Log the client and request details if the server discovers, when finally 
> processing the request, that the current time minus arrival time of the 
> request is beyond a configured threshold. 
> Look at the HBase {{responseTooSlow}} feature for inspiration. 



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