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https://issues.apache.org/jira/browse/DBCP-247?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Shlomo Swidler updated DBCP-247:
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Affects Version/s: 1.2.1
I think, based on googling, that the affected version is 1.2.1. Whatever
version of DBCP shipped with Tomcat 5.5, that's the one.
> ResultSet returned from Statement.getGeneratedKeys has non-delegating
> Connection
> --------------------------------------------------------------------------------
>
> Key: DBCP-247
> URL: https://issues.apache.org/jira/browse/DBCP-247
> Project: Commons Dbcp
> Issue Type: Bug
> Affects Versions: 1.2.1
> Environment: Ubuntu Linux 7.10, JDK 1.5, Tomcat 5.5, MySQL 5.0.45
> Reporter: Shlomo Swidler
> Priority: Minor
>
> We have a library that wraps a ResultSet and, when the client code calls
> ResultSet.close(), our library also closes the underlying Statement and
> Connection. This is very useful because it allows us to abstract out from the
> client code whether the Connection needs to be closed when you're done with
> the ResultSet (as when using DBCP) or not (as when running standalone, with
> classic MySQL JDBC driver connections).
> Here's a snippet of the library code:
> public class ResultSetWrapper {
> private ResultSet rs;
> public ResultSetWrapper(ResultSet rs) {
> this.rs = rs;
> }
> public boolean next() throws SQLException {
> return rs.next();
> }
> public int getInt(int fieldNum) throws SQLException {
> return rs.getInt(fieldNum);
> }
> // ... etc methods delegating to the underlying ResultSet
> public void close() throws SQLException {
> Statement st = rs.getStatement();
> Connection conn = st.getConnection();
> try {
> rs.close();
> } finally {
> try {
> st.close();
> } finally {
> conn.close(); // Here is where the problem lies
> }
> }
> }
> }
> Now, in order to test our code we are running with maxActive=1 and maxIdle=1,
> so we never actually use more than one JDBC connection.
> This works great when the ResultSetWrapper wraps a plain-old ResultSet
> returned from Statement.executeQuery().
> But when I wrap a ResultSet returned from Statement.getGeneratedKeys(), then
> the underlying JDBC connection is closed (at the "Here is where the problem
> lies" comment in ResultSetWrapper), not the DBCP DelegatingConnection. Here
> is an example:
> example database table:
> CREATE TABLE test (id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, name
> VARCHAR(50) NOT NULL);
> example test case:
> public class Test {
> private DataSource dataSource = null;
> public Test() {
> // initialize the DataSource
> // ...
> }
> public ResultSetWrapper wrapGeneratedKeysQuery() throws SQLException {
> Connection conn = dataSource.getConnection();
> Statement st = conn.createStatement();
> st.execute("INSERT INTO test (name) VALUES ('foo')");
> ResultSet rs = st.getGeneratedKeys();
> return new ResultSetWrapper(rs);
> }
> public ResultSetWrapper wrapPlainQuery() throws SQLException {
> Connection conn = dataSource.getConnection(); // Here is where we run out
> of connections in the pool
> Statement st = conn.createStatement();
> ResultSet rs = st.executeQuery("SELECT id FROM test LIMIT 1");
> ResultSetWrapper rsw = new ResultSetWrapper(rs);
> return rsw;
> }
> public static void test() throws Exception {
> Test t = new Test();
> ResultSetWrapper rsw = t.wrapGeneratedKeysQuery();
> rsw.next();
> rsw.getInt(1);
> rsw.close(); // This closes the underlying JDBC connection
> ResultSetWrapper rsw2 = t.wrapPlainQuery(); // throws an exception: DBCP
> connection pool is exhausted
> rsw2.next();
> rsw2.getInt(1);
> rsw2.close();
> }
> }
> The result: the DBCP connection is never returned to the pool. We run out of
> connections. wrapPlainQuery's getConnection fails because the pool (of 1
> connection) has been exhausted. The statement rsw.close() closed the
> underlying JDBC connection and didn't return the DBCP connection to the pool.
> The workaround is to always carry around within the ResultSetWrapper the
> "original" Connection upon which the query was executed. But this should not
> be necessary.
> Sorry, but I can't tell what version of DBCP I'm running. It's the one
> included in the Tomcat 5.5 bundle I'm running.
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