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From laurentgo <...@git.apache.org>
Subject [GitHub] drill pull request #858: DRILL-3640: Support JDBC Statement.setQueryTimeout(...
Date Wed, 21 Jun 2017 18:20:12 GMT
Github user laurentgo commented on a diff in the pull request:

    https://github.com/apache/drill/pull/858#discussion_r123327453
  
    --- Diff: exec/jdbc/src/main/java/org/apache/drill/jdbc/impl/DrillStatementImpl.java ---
    @@ -38,8 +44,12 @@
     // methods for compatibility.)
     class DrillStatementImpl extends AvaticaStatement implements DrillStatement,
                                                                  DrillRemoteStatement {
    +  //Not using the DrillbitContext's ExecutorService as this is threadPool is light-weight
(threads wake up to cancel tasks) but needs a low response time
    +  private static ExecutorService queryTimeoutTaskPool = Executors.newCachedThreadPool(new
NamedThreadFactory("q-timeout-"));
    --- End diff --
    
    DrillCursor is handling all the logic of executing queries, and waiting for results. It
has access to the connection and the statement, so you would know the timeout (if set). In
the cursor, we are using a lock for the first message, and a blocking queue for the batches,
but when waiting on those, there's no timeout set. Instead we could use query timeout (or
the remaining time left since the beginning of the execution) and throws SqlTimeoutException
when the locks throws TimeoutException themselves.
    
    In that scenario, no thread pool involved (except the one for I/O but it was already existing)


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