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https://issues.apache.org/jira/browse/IMPALA-6735?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Alexander Behm resolved IMPALA-6735.
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Resolution: Not A Bug
> Inconsistent query submission, start, and end times in query profile
> --------------------------------------------------------------------
>
> Key: IMPALA-6735
> URL: https://issues.apache.org/jira/browse/IMPALA-6735
> Project: IMPALA
> Issue Type: Bug
> Components: Backend
> Affects Versions: Impala 2.11.0
> Reporter: Alexander Behm
> Priority: Major
> Labels: supportability
>
> We've sometimes observed inconsistencies in the following runtime profile
> entrues:
> * Query submitted (timeline event)
> * Start Time (info string, not a timeline event)
> * End Time (into string, not a timeline event)
> Here is one inconsistent example:
> {code}
> Query submitted at : 2018-03-22 10:27:57
> Start Time : 2018-03-22 10:28:05.883997000
> End Time : 2018-03-22 10:28:05.915566000
> {code}
> Based on the backend code it should not be possible that "Start Time" happens
> after "Query submitted". The relevant code snipped is in impala-server.cc
> ImpalaServer::ExecuteInternal():
> {code}
> ...
> // Sets the Start Time
> request_state->reset(new ClientRequestState(query_ctx, exec_env_,
> exec_env_->frontend(),
> this, session_state));
> // Sets the query submitted time
> (*request_state)->query_events()->MarkEvent("Query submitted");
> ...
> {code}
> One possible explanation could be that these events get the current time from
> different functions:
> * The timeline events use our MonotonicStopWatch
> * The "Start Time" and "End Time" use UnixMicros() from our own time.h
> It's not clear that these produce consistent timings.
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