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From ppadma <...@git.apache.org>
Subject [GitHub] drill pull request #758: DRILL-5287: Provide option to skip updates of ephem...
Date Fri, 24 Feb 2017 18:43:03 GMT
Github user ppadma commented on a diff in the pull request:

    https://github.com/apache/drill/pull/758#discussion_r103005063
  
    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/work/foreman/Foreman.java
---
    @@ -1010,7 +1010,9 @@ public void addToEventQueue(final QueryState newState, final Exception
exception
     
       private void recordNewState(final QueryState newState) {
         state = newState;
    -    queryManager.updateEphemeralState(newState);
    +    if (queryContext.getOptions().getOption(ExecConstants.ZK_QUERY_STATE_UPDATE)) {
    +      queryManager.updateEphemeralState(newState);
    +    }
    --- End diff --
    
    For long running queries, it may not make much difference. It adds latency of around ~50-60
msec for single query. However, with high concurrency, impact of contention because of zookeeper
updates is significant. Like I mentioned in the JIRA, for concurrency=100, the average query
response time for simple queries is 8 sec vs 0.2 sec with these updates disabled.  It does
not impact the query profile. Query profile gets updated and written at the end of the query
as usual.  This option affects only running queries. In Web UI, you will not see running queries
and their state.


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