Norris Lee created DRILL-2509:
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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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