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From "Pranay Singh (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-5142 EventSequence displays negative elapsed time.
Date Tue, 17 Oct 2017 21:55:54 GMT
Pranay Singh has posted comments on this change. ( http://gerrit.cloudera.org:8080/8215 )

Change subject: IMPALA-5142 EventSequence displays negative elapsed time.
......................................................................


Patch Set 1:

(1 comment)

http://gerrit.cloudera.org:8080/#/c/8215/1//COMMIT_MSG
Commit Message:

http://gerrit.cloudera.org:8080/#/c/8215/1//COMMIT_MSG@22
PS1, Line 22: value.
> That's right since the code not synchronized we can read a garbage start_ w
In the thread doing ClientRequestState::ClientRequestState()

a) When the function AddEventSequence() is called, an EventSequence with the  name is looked
for, if found then the EventSequence is returned else a new event sequence gets created.

b) Then after the query_events->Start(0 resets the monotonic time for the EventSequence,
so say in this case a matching name for "Query Timeline" was found

In another thread which is done doing AdmissionController::AdmitQuery(QuerySchedule* schedule)
in the mean time will have ScopedEvent destroyed for the same EventSequence and since they
are not serialized we may hit upon this issue.

/// Utility class to mark an event when the object is destroyed.                         

class ScopedEvent {                                                                      

  .....                                                                                  
       
  /// Mark the event when the object is destroyed                                        

  ~ScopedEvent() {                                                                       

    event_sequence_->MarkEvent(label_);     --->                                   
          
  }                                                                                      

   
};



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I8c944396d96473b17b453da3e913ffc56680a896
Gerrit-Change-Number: 8215
Gerrit-PatchSet: 1
Gerrit-Owner: Pranay Singh
Gerrit-Reviewer: Dan Hecht <dhecht@cloudera.com>
Gerrit-Reviewer: Pranay Singh
Gerrit-Comment-Date: Tue, 17 Oct 2017 21:55:54 +0000
Gerrit-HasComments: Yes

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