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From "Bryan Pendleton (JIRA)" <derby-...@db.apache.org>
Subject [jira] Commented: (DERBY-557) Client driver gets OutOfMemoryError when re-executing statement without closing ResultSet
Date Sat, 11 Feb 2006 23:40:28 GMT
    [ http://issues.apache.org/jira/browse/DERBY-557?page=comments#action_12366046 ] 

Bryan Pendleton commented on DERBY-557:
---------------------------------------

This change looks good to me. The patch applies cleanly to the current trunk. I read through
the test code and thought it was fine. With your patch applied, I ran

java -Dframework=DerbyNetClient  -Dverbose=true org.apache.derbyTesting.functionTests.harness.RunTest
jdbcapi/derbyStress.java

and got the expected results (test passed, with the new print statement appearing in the output
as expected).


> Client driver gets OutOfMemoryError when re-executing statement without closing ResultSet
> -----------------------------------------------------------------------------------------
>
>          Key: DERBY-557
>          URL: http://issues.apache.org/jira/browse/DERBY-557
>      Project: Derby
>         Type: Bug
>   Components: Network Client
>     Versions: 10.1.1.0, 10.1.2.0, 10.2.0.0
>     Reporter: Knut Anders Hatlen
>     Assignee: Knut Anders Hatlen
>     Priority: Minor
>      Fix For: 10.1.2.0, 10.2.0.0, 10.1.1.2
>  Attachments: DERBY-557-regression-test.diff, DERBY-557-regression-test.stat, DERBY-557.diff,
DERBY-557.stat, derbyall_report.txt
>
> When re-executing a statement without closing the old ResultSet, some of the old ResultSet's
resources are not released, and the network client will eventually get an OutOfMemoryError.
> Example:
> 	Connection c = DriverManager.getConnection("jdbc:derby://localhost/mydb");
> 	PreparedStatement ps = c.prepareStatement("select * from sys.systables");
> 	while (true) {
> 		ResultSet rs = ps.executeQuery();
> 	}
> This code will run for some time and then throw an OutOfMemoryError. Same thing happens
with Statement instead of PreparedStatement. If rs.close() is added in the loop, the code
works. Explicitly closing the ResultSet should not be necessary according to this quote from
the JDBC 3.0 spec:
>   For Select statements, the statement is complete when the associated result set is
closed. The result set is closed as soon as one of the following occurs:
>      - all of the rows have been retrieved
>      - the associated Statement object is re-executed
>      - another Statement object is executed on the same connection

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