[jira] [Commented] (CALCITE-5099) ResultSetEnumerable.enumeratorBasedOnStatement cause the backend connection leak

[itxiangkui (Jira)]

    [ 
https://issues.apache.org/jira/browse/CALCITE-5099?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17524036#comment-17524036
 ] 

itxiangkui commented on CALCITE-5099:
-------------------------------------

We have extended JdbcSchema and JdbcCatalogSchema in order to connect to the 
back-end mysql database.
At the same time, HikariDataSource was used to replace the original 
BasicDataSource. When the connection pool leak detection of HikariDataSource 
was activated, a connection leak was detected.

{code:java}
java.lang.Exception: Apparent connection leak detected
        at 
com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:128)
        at 
org.apache.calcite.runtime.ResultSetEnumerable.enumeratorBasedOnStatement(ResultSetEnumerable.java:267)
        at 
org.apache.calcite.runtime.ResultSetEnumerable.enumerator(ResultSetEnumerable.java:257)
        at 
org.apache.calcite.linq4j.AbstractEnumerable.iterator(AbstractEnumerable.java:33)
        at 
org.apache.calcite.jdbc.CalciteMetaImpl.fetch(CalciteMetaImpl.java:674)
        at 
org.apache.calcite.avatica.remote.LocalService.apply(LocalService.java:245)
        at 
org.apache.calcite.avatica.remote.Service$FetchRequest.accept(Service.java:1395)
        at 
org.apache.calcite.avatica.remote.Service$FetchRequest.accept(Service.java:1362)
        at 
org.apache.calcite.avatica.remote.AbstractHandler.apply(AbstractHandler.java:94)
        at 
org.apache.calcite.avatica.remote.JsonHandler.apply(JsonHandler.java:52)
        at 
org.apache.calcite.avatica.server.AvaticaJsonHandler.handle(AvaticaJsonHandler.java:133)
        at 
org.eclipse.jetty.server.handler.HandlerList.handle(HandlerList.java:59)
        at 
org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
        at org.eclipse.jetty.server.Server.handle(Server.java:500)
        at 
org.eclipse.jetty.server.HttpChannel.lambda$handle$1(HttpChannel.java:383)
        at org.eclipse.jetty.server.HttpChannel.dispatch(HttpChannel.java:547)
        at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:375)
        at 
org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:270)
        at 
org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:311)
        at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:103)
        at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:117)
        at 
org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:336)
        at 
org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:313)
        at 
org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:171)
        at 
org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:129)
        at 
org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:388)
        at 
org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:806)
        at 
org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:938)
        at java.lang.Thread.run(Thread.java:748)
{code}

Navigating to the snippet is


{code:java}
  private Enumerator<T> enumeratorBasedOnStatement() {
    Connection connection = null;
    Statement statement = null;
    try {
      connection = dataSource.getConnection();
      statement = connection.createStatement();
      setTimeoutIfPossible(statement);
      if (statement.execute(sql)) {
        final ResultSet resultSet = statement.getResultSet();
        statement = null;
        connection = null;
        return new ResultSetEnumerator<>(resultSet, rowBuilderFactory);
      } else {
        Integer updateCount = statement.getUpdateCount();
        //noinspection unchecked
        return Linq4j.singletonEnumerator((T) updateCount);
      }
    } catch (SQLException e) {
      throw Static.RESOURCE.exceptionWhilePerformingQueryOnJdbcSubSchema(sql)
          .ex(e);
    } finally {
      closeIfPossible(connection, statement);
    }
  }
{code}


obviously when you set:
*statement = null;*
*connection = null;*
the connection may leak,closeIfPossible(connection, statement); will close a 
null connection





> ResultSetEnumerable.enumeratorBasedOnStatement  cause the backend connection 
> leak
> ---------------------------------------------------------------------------------
>
>                 Key: CALCITE-5099
>                 URL: https://issues.apache.org/jira/browse/CALCITE-5099
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 1.30.0
>            Reporter: itxiangkui
>            Priority: Major
>




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