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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"JDBC driver: Closing a Connection does not close its Statement(s), potentially leading to exceptions related to memory leaks","articleBody":"### Describe the bug, including details regarding any error messages, version, and platform.\n\nAccording to the JDBC specification 4.3 available at https://download.oracle.com/otn-pub/jcp/jdbc-4_3-mrel3-eval-spec/jdbc4.3-fr-spec.pdf, chapter 9.6.4.1:\n\n\u003e All Statement objects created from a given\nConnection object will be closed when the close method for the Connection\nobject is called.\n\nIn the Flight SQL JDBC driver closing a Connection does not automatically close the Statement instances obtained via that Connection, making it non compliant with the standard.\n\nDue to this non compliance, on closing a Connection that has a Statement with one or more ResultSet that haven't been fully consumed, we get an exception on `Connection.close()`\n\nCode to reproduce:\n\n`\n    try {\n\n      // Establish connection\n\n      Connection connection = DriverManager.getConnection(jdbcUrl, properties);\n      System.out.println(\"Connected to Arrow Flight SQL server\");\n\n      Statement stmt = connection.createStatement();\n      // my_table needs to have some rows for the bug to manifest itself\n      ResultSet rs = stmt.executeQuery(\"SELECT * FROM my_table\");\n      // adding this close will eliminate the memory leak, without needing to close the Statement\n      // rs.close();\n\n      // with stmt.close() we get no memory leak, even if we didn't close the ResultSet\n      //stmt.close();\n\n      connection.close();\n      System.out.println(\"\\nConnection closed\");\n\n    } catch (Exception e) {\n      System.err.println(\"Error: \" + e.getMessage());\n      e.printStackTrace();\n    }\n\n`\n\nResulting in the following exception and stack trace\n\n\n```\nDec 14, 2025 5:36:23 PM org.apache.arrow.driver.jdbc.shaded.org.apache.arrow.memory.BaseAllocator close\nSEVERE: Memory was leaked by query. Memory leaked: (32)\nAllocator(flight-client) 0/32/32/9223372036854775807 (res/actual/peak/limit)\n\nError: Failed to clean up client resources.\njava.sql.SQLException: Failed to clean up client resources.\n\tat org.apache.arrow.driver.jdbc.client.ArrowFlightSqlClientHandler.close(ArrowFlightSqlClientHandler.java:269)\n\tat org.apache.arrow.driver.jdbc.ArrowFlightConnection.close(ArrowFlightConnection.java:178)\n\tat MemoryLeak.main(MemoryLeak.java:136)\nCaused by: java.lang.IllegalStateException: Memory was leaked by query. Memory leaked: (32)\nAllocator(flight-client) 0/32/32/9223372036854775807 (res/actual/peak/limit)\n\n\tat org.apache.arrow.driver.jdbc.shaded.org.apache.arrow.memory.BaseAllocator.close(BaseAllocator.java:504)\n\tat org.apache.arrow.driver.jdbc.shaded.org.apache.arrow.flight.FlightClient.close(FlightClient.java:744)\n\tat org.apache.arrow.driver.jdbc.shaded.org.apache.arrow.util.AutoCloseables.close(AutoCloseables.java:97)\n\tat org.apache.arrow.driver.jdbc.shaded.org.apache.arrow.util.AutoCloseables.close(AutoCloseables.java:75)\n\tat org.apache.arrow.driver.jdbc.shaded.org.apache.arrow.flight.sql.FlightSqlClient.close(FlightSqlClient.java:1137)\n\tat org.apache.arrow.driver.jdbc.shaded.org.apache.arrow.util.AutoCloseables.close(AutoCloseables.java:97)\n\tat org.apache.arrow.driver.jdbc.shaded.org.apache.arrow.util.AutoCloseables.close(AutoCloseables.java:75)\n\tat org.apache.arrow.driver.jdbc.client.ArrowFlightSqlClientHandler.close(ArrowFlightSqlClientHandler.java:267)\n\t... 2 more\n\n\n```\n\nWhile a user of the driver with good defensive programming practice would open the ResultSet and/or Statement in a try-with block, the driver should still follow the standard and not produce this Exception.\n\nI believe this bug has been here since the creation of the driver, but I have confirmed that it occurs for both version 17.0.0 and 18.3.0 of the driver.\n\n\n\n\n","author":{"url":"https://github.com/ennuite","@type":"Person","name":"ennuite"},"datePublished":"2025-12-14T17:49:03.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/932/arrow-java/issues/932"}