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From "Norris Lee (JIRA)" <j...@apache.org>
Subject [jira] [Created] (DRILL-2509) Drill Client threading issue with m_pendingRequests
Date Fri, 20 Mar 2015 18:14:40 GMT
Norris Lee created DRILL-2509:
---------------------------------

             Summary: Drill Client threading issue with m_pendingRequests
                 Key: DRILL-2509
                 URL: https://issues.apache.org/jira/browse/DRILL-2509
             Project: Apache Drill
          Issue Type: Bug
          Components: Client - C++
    Affects Versions: 0.7.0
            Reporter: Norris Lee
            Assignee: Norris Lee
             Fix For: 0.9.0


1.       (Thread 1) 1st query receives the last record batch (no data, only contains the query
state. Eg. QueryResult_QueryState_COMPLETED) and calls processQueryResult. At this moment,
it grabs the lock. Assume m_pendingRequests = 1.
2.       (Thread 1) processQueryStatusResult is called and drops m_pendingRequests to 0. The
lock is still held at this point.
3.       (Thread 1) It returns from processQueryStatusResult, immediately followed by returning
from processQueryResult. At this point the lock is released.
4.       (Thread 2) SubmitQuery for the next query sees the lock has been freed so it swoops
in and grabs the lock. It bumps m_pendingRequests up to 1 and sets sendResusts=true since
it sees that m_pendingRequests was previously 0, causing it to call getNextResult
5.       (Thread 1) After returning from processQueryResult, it sees that m_pendingRequests
is now set to 1 so it calls getNextResult
6.       So now 2 threads end up calling getNextResult. For whatever reason, the server then
sends a record batch with no data, has_rpc_type = false, and rpc_type = 0, leading to throwing
a ERR_QRY_INVRPCTYPE error.




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