JDBC Exception in JNDI lookup

[Joe San]

Guys,

I have a Datasource configured in the tomcat config.xml and the appropriate resource-ref elements in the web.xml of my web app. When I tried to run my app by trying to connect to the database, I get the following error:

The dataspource obtained is.... org.apache.tomcat.dbcp.dbcp.BasicDataSource@c26b16
org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'null'
        at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1150)
        at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:880)
        at de.dpwn.fcap.core.service.user.impl.UserServiceImpl.sayHallo(UserServiceImpl.java:29)
        at org.apache.jsp.pages.welcome_jsp._jspService(welcome_jsp.java:79)
        at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
        at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:331)
        at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
        at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:873)
        at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
        at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
        at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
        at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
        at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.NullPointerException
        at sun.jdbc.odbc.JdbcOdbcDriver.getProtocol(JdbcOdbcDriver.java:507)
        at sun.jdbc.odbc.JdbcOdbcDriver.knownURL(JdbcOdbcDriver.java:476)
        at sun.jdbc.odbc.JdbcOdbcDriver.acceptsURL(JdbcOdbcDriver.java:307)
        at java.sql.DriverManager.getDriver(DriverManager.java:253)
        at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1143)
        ... 23 more

Any ideas as to what is going on??

Here is my context.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!--
  Licensed to the Apache Software Foundation (ASF) under one or more
  contributor license agreements.  See the NOTICE file distributed with
  this work for additional information regarding copyright ownership.
  The ASF licenses this file to You under the Apache License, Version 2.0
  (the "License"); you may not use this file except in compliance with
  the License.  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
-->
<!-- The contents of this file will be loaded for each web application -->
<Context path="/FCAP" docBase="FCAP" debug="5" reloadable="true" crossContext="true">

    <!-- Default set of monitored resources 
    <WatchedResource>WEB-INF/web.xml</WatchedResource> -->
	
    <!-- Uncomment this to disable session persistence across Tomcat restarts -->
    <!--
    <Manager pathname="" />
    -->
    <resource name="jdbc/MyDB" auth="Container" type="javax.sql.DataSource" 
removeAbandoned="true" removeAbandonedTimeout="30" maxActive="100" maxIdle="30" 
    	      maxWait="10000" username="fcap" password="fcap" 
driverClassName="oracle.jdbc.driver.OracleDriver" url="jdbc:oracle:thin:@localhost:1521:MYDBSCHEMA"/>    

</Context>

My web.xml snippet:

 <resource-ref>
      <description>DB Connection Pooling</description>
      <res-ref-name>jdbc/MyDB</res-ref-name>
      <res-type>javax.sql.DataSource</res-type>
      <res-auth>Container</res-auth>
 </resource-ref> 

[Joe San]

I even have the classes12.jar in the lib folder of my Tomcat installation.

[Karthik Shiraly]

Just an idea, haven't tried this out myself: Can you change driverClassName to "oracle.jdbc.OracleDriver" and try. The FAQ mentions that "oracle.jdbc.driver.*" is a deprecated package from a couple of years now...

[Misha Ver]

Jothi Shankar Kumar wrote:I even have the classes12.jar in the lib folder of my Tomcat installation.

Which Tomcat version you are using? Is it on Window, Linux?

[Tim Holloway]

Is this a duplicate? I responded to a post just like this very recently, and my recommendation was to check the URL very carefully.

And, for the record, an old Oracle driver class is probably OK here, since classes12.jar is an old driver jar. It was superseded in Oracle 9i.

[Michael Peremsky]

Make sure the jar file for the connector is in your classpath. e.g. tomcat/lib/odbc...jar

[Joe San]

Tim Holloway wrote:Is this a duplicate? I responded to a post just like this very recently, and my recommendation was to check the URL very carefully.

And, for the record, an old Oracle driver class is probably OK here, since classes12.jar is an old driver jar. It was superseded in Oracle 9i.

I saw your other post and I guess the database url what I have configured is correct. Which driver jar file should I have to use? classes12.jar or ojdbc.jar?? I'm using Oracle 10g and Tomcat 5.5.28 and JDK 1.4 as my environment.

[Joe San]

Karthik Shiraly wrote:Just an idea, haven't tried this out myself: Can you change driverClassName to "oracle.jdbc.OracleDriver" and try. The FAQ mentions that "oracle.jdbc.driver.*" is a deprecated package from a couple of years now...

Even tried this but still the same exception.

[Joe San]

It looks to me like the DataSource configuration was accepted, but then later when it is trying to create the Connection object, it fails.

[Jaikiran Pai]

It's a NullPointerException while creating a connection from datasource:

 The dataspource obtained is.... org.apache.tomcat.dbcp.dbcp.BasicDataSource@c26b16  
 org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'null'  

As Tim said, it looks like some issue with the URL and driver class being used.

de.dpwn.fcap.core.service.user.impl.UserServiceImpl.sayHallo(UserServiceImpl.java:29)

Post the code which is doing the lookup of the datasource and obtaining the connection.

[Joe San]

I had a look at the BasicDataSource.java and like you just said, it looks like the url is null as printed in the exception.

This is how I do the lookup for the DataSource:

    public String sayHallo() {
        try {
            InitialContext initialContext = new InitialContext();
            datasource = (DataSource) initialContext.lookup( "java:/comp/env/jdbc/MyDB" );
            if ( datasource == null ) {
                System.out.println("We are about to run into a shit...");
            }
            System.out.println("The datasource obtained is.... " + datasource); //The datasource gets printed here...
            Connection conn = null;
            try {
                conn = datasource.getConnection();
            }
            catch (Exception sex) {
                System.out.println("An exception has occurred when trying to get a Connection object and the 
                                              cause for the exception is " + sex.getCause());
                sex.printStackTrace();
            }

            java.sql.Statement st = conn.createStatement();
            ResultSet rs = null;
            rs = st.executeQuery("select * from DIVISION");
            while (rs.next()) {
                System.out.println("The first value is " + rs.getString(1));
                System.out.println("The second value is " + rs.getString(2));
            }

        }
        catch (NamingException ne) {
            ne.printStackTrace();
        }
        catch (Exception sex) {
            sex.printStackTrace();            
        }
        return "Hi from user service";  //To change body of implemented methods use File | Settings | File Templates.
    }

[Jaikiran Pai]

Jothi Shankar Kumar wrote:

            datasource = (DataSource) initialContext.lookup( "java:/comp/env/jdbc/dbTest" );

    }

You are looking up a completely different datasource and not the one whose configurations you posted:

<resource name="jdbc/MyDB" auth="Container" type="javax.sql.DataSource"   
 removeAbandoned="true" removeAbandonedTimeout="30" maxActive="100" maxIdle="30"   
               maxWait="10000" username="fcap" password="fcap"   
 driverClassName="oracle.jdbc.driver.OracleDriver" url="jdbc:oracle:thin:@localhost:1521:MYDBSCHEMA"/>

 <resource-ref>  
       <description>DB Connection Pooling</description>  
       <res-ref-name>jdbc/MyDB</res-ref-name>  
      <res-type>javax.sql.DataSource</res-type>  
       <res-auth>Container</res-auth>  
  </resource-ref>  

You should be using :

datasource = (DataSource) initialContext.lookup( "java:/comp/env/jdbc/MyDB" );

[Joe San]

That was my typo there....I checked the lookup names and they all point to MyDB. So that is not the cause.

[Joe San]

Any ideas??

[Joe San]

I tried the same sample using plain JDBC and it worked. I simply cannot understand why it would not work with Tomcat DBCP??

Tried the following...

import java.sql.*;

 public class JDBCSample {

 public static void main( String args[]) {

 String connectionURL = "jdbc:oracle:thin:@localhost:1521:MYDBSCHEMA";
 // Change the connection string according to your db, ip, username and password
       Connection con = null;
 try {

        // Load the Driver class.
        Class.forName("oracle.jdbc.OracleDriver");
        // If you are using any other database then load the right driver here.

     System.out.println("The URL is *************************************** $$$$$$$$$$$$$$$$$$$$$$$$ " + connectionURL);

        //Create the connection using the static getConnection method
        con = DriverManager.getConnection (connectionURL, "fcap", "fcap");

     System.out.println("The connection obtained is *************************************** " + con);

        //Create a Statement class to execute the SQL statement
        Statement stmt = con.createStatement();

        //Execute the SQL statement and get the results in a Resultset
        ResultSet rs = stmt.executeQuery("select * from division");

        // Iterate through the ResultSet, displaying two values
        // for each row using the getString method

        while (rs.next())
            System.out.println("Name= " + rs.getString(1) + " Date= " + rs.getString(2));
    }
    catch (SQLException e) {
        e.printStackTrace();
    }
    catch (Exception e) {
        e.printStackTrace();
    }
    finally {
        // Close the connection
     try {
         con.close();
     } catch (SQLException e) {
         e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
     }
 }
    }
    }

[Joe San]

Do we have to configure this in the server.xml or in the context.xml??? This is really getting annoying to make DBCP configured in Tomcat.

[Misha Ver]

Jothi Shankar Kumar wrote:Do we have to configure this in the server.xml or in the context.xml??? This is really getting annoying to make DBCP configured in Tomcat.

For Tomcat 5, unlike Tomcat 4.x, it is NOT recommended to place <Context> elements directly in the server.xml file. This is because it makes modifying the Context configuration more invasive since the main conf/server.xml file cannot be reloaded without restarting Tomcat.

http://tomcat.apache.org/tomcat-5.5-doc/config/context.html

[Jaikiran Pai]

Jothi, see if this thread helps https://coderanch.com/t/490267/Tomcat/t-get-connection-from-DataSource

[Joe San]

I do not understand the cause for this exception. It says the root cause is a NullPointerException...

The Context obtained is ******************************** org.apache.naming.NamingContext@31fb31
The datasource obtained is.... org.apache.tomcat.dbcp.dbcp.BasicDataSource@162522b
An exception has occurred when trying to get a Connection object and the cause for the exception is java.lang.NullPointerException
org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'null'
        at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1150)
        at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:880)
        at de.dpwn.fcap.core.service.user.impl.UserServiceImpl.sayHallo(UserServiceImpl.java:33)
        at org.apache.jsp.pages.welcome_jsp._jspService(welcome_jsp.java:79)
        at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
        at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:331)
        at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
        at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:873)
        at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
        at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
        at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
        at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
        at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.NullPointerException
        at sun.jdbc.odbc.JdbcOdbcDriver.getProtocol(JdbcOdbcDriver.java:507)
        at sun.jdbc.odbc.JdbcOdbcDriver.knownURL(JdbcOdbcDriver.java:476)
        at sun.jdbc.odbc.JdbcOdbcDriver.acceptsURL(JdbcOdbcDriver.java:307)
        at java.sql.DriverManager.getDriver(DriverManager.java:253)
        at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1143)
        ... 23 more

Any idea as to where I could find the ...23 more???

And below is the method that I'm executing:

public String sayHallo() {
        try {            
            Context initContext = new InitialContext();
            Context envContext  = (Context)initContext.lookup("java:/comp/env");
            System.out.println("The Context obtained is ******************************** " + envContext);
            DataSource dataSource = (DataSource)envContext.lookup("jdbc/dbTest");
            if ( dataSource == null ) {
                System.out.println("We are about to run into a shit...");
            }
            System.out.println("The datasource obtained is.... " + dataSource);
            Connection conn = null;
            try {
                conn = dataSource.getConnection();
            }
            catch (Exception sex) {
                System.out.println("An exception has occurred when trying to get a Connection object " +
                        "and the cause for the exception is " + sex.getCause());
                sex.printStackTrace();
            }

            //java.sql.Statement st = conn.createStatement();
            ResultSet rs = null;
            //rs = st.executeQuery("select * from DIVISION");
            //while (rs.next()) {
                //System.out.println("The first value is " + rs.getString(1));
                //System.out.println("The second value is " + rs.getString(2));
            //}

        }
        catch (NamingException ne) {
            ne.printStackTrace();
        }
        catch (Exception sex) {
            sex.printStackTrace();            
        }
        return "Hi from user service";  //To change body of implemented methods use File | Settings | File Templates.
    }

[Tim Holloway]

Now do you see why I hate this message?

Just a moment... Just a moment...

WHY is the stack tracking indicating a NullPointerException in the jdbc-odbc bridge driver??? This was supposed to be an native Oracle connection!!!

[Karthik Shiraly]

Hi Jothi,

Please change <resource> to <Resource> in your context.xml and check if it works. I get this error when I use <resource> because it's not a valid tag in context.xml, but <Resource> is. I think the JNDI lookup works because it's created out of the web.xml <resource-ref>, but then Tomcat simply ignores the erroneous <resource> tag and is unable to find the associated Resource.

Cheers
Karthik

[Joe San]

Karthik Shiraly wrote:Hi Jothi,

Please change <resource> to <Resource> in your context.xml and check if it works. I get this error when I use <resource> because it's not a valid tag in context.xml, but <Resource> is. I think the JNDI lookup works because it's created out of the web.xml <resource-ref>, but then Tomcat simply ignores the erroneous <resource> tag and is unable to find the associated Resource.

Cheers
Karthik

Man... Thank you really very very much. It was my mistake to have it small (like <resource>) and I changed it to (<Resource>) and it worked.

[Karthik Shiraly]

You're welcome! Now I see the value of DTDs...

[Jaikiran Pai]

Jothi Shankar Kumar wrote:

Man... Thank you really very very much. It was my mistake to have it small (like <resource>) and I changed it to (<Resource>) and it worked.

That is really weird for 2 reasons:

1) The xml validation should have failed. But I guess, that's disabled by default?
2) With that wrongly configured "resource", Tomcat was able to return a DataSource instance to the code, but wasn't able to create a connection on a call to getConnection(). Instead I would have expected the lookup of the datasource to fail.

Anyway, good to know that it's resolved.

[Joe San]

Jaikiran Pai wrote:

Jothi Shankar Kumar wrote:

Man... Thank you really very very much. It was my mistake to have it small (like <resource>) and I changed it to (<Resource>) and it worked.

That is really weird for 2 reasons:

1) The xml validation should have failed. But I guess, that's disabled by default?
2) With that wrongly configured "resource", Tomcat was able to return a DataSource instance to the code, but wasn't able to create a connection on a call to getConnection(). Instead I would have expected the lookup of the datasource to fail.

Anyway, good to know that it's resolved.

Do you know how to get this xml validation enabled??

[Joe San]

So I'm just putting up the complete list of items that one should do to get JDBC connection pooling working in Tomcat 5.5.28, Oracle 10g, JDK 1.4

Under "apache-tomcat-5.5.28\conf", edit the context.xml to look lie this as below:

<?xml version="1.0" encoding="UTF-8"?>
<!--
  Licensed to the Apache Software Foundation (ASF) under one or more
  contributor license agreements.  See the NOTICE file distributed with
  this work for additional information regarding copyright ownership.
  The ASF licenses this file to You under the Apache License, Version 2.0
  (the "License"); you may not use this file except in compliance with
  the License.  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
-->
<!-- The contents of this file will be loaded for each web application -->
<Context path="/MYPROJECT" docBase="MYPROJECT" debug="5" 
reloadable="true" crossContext="true">

    <!-- Default set of monitored resources 
    <WatchedResource>WEB-INF/web.xml</WatchedResource> -->
	
    <!-- Uncomment this to disable session persistence across Tomcat restarts -->
    <!--
    <Manager pathname="" />
    -->
    <Resource name="jdbc/dbTest" auth="Container" 
factory="org.apache.tomcat.dbcp.dbcp.BasicDataSourceFactory" 
type="javax.sql.DataSource" driverClassName="oracle.jdbc.OracleDriver" 
url="jdbc:oracle:thin:@localhost:1521:MYSID" username="owner" 
password="owner" removeAbandoned="true" 
removeAbandonedTimeout="30" maxWait="10000" 
maxActive="100" maxIdle="30" />    

</Context>

Next in the web.xml of your project (for me it is MYPROJECT) add the following lines:

 <resource-ref>
      <description>DB Connection Pooling</description>
      <res-ref-name>jdbc/dbTest</res-ref-name>
      <res-type>javax.sql.DataSource</res-type>
      <res-auth>Container</res-auth>
 </resource-ref> 

Next, in your code, do the following to get a reference to the connection pooled Connection object:

            Context initContext = new InitialContext();
            Context envContext  = (Context)initContext.lookup("java:/comp/env");
            System.out.println("The Context obtained is ******************************** " + envContext);
            DataSource dataSource = (DataSource)envContext.lookup("jdbc/dbTest");
            if ( dataSource == null ) {
                System.out.println("We are about to run into a shit...");
            }
            System.out.println("The datasource obtained is.... " + dataSource);
            Connection conn = null;
            try {
                conn = dataSource.getConnection();
            }
            catch (Exception sex) {
                System.out.println("An exception has occurred when trying to get a Connection object " +
                        "and the cause for the exception is " + sex.getCause());
                sex.printStackTrace();
            }

Hope it works for everyone else who would require Connection Pooling configured in Tomcat.

[Jaikiran Pai]

Jothi Shankar Kumar wrote:
Do you know how to get this xml validation enabled??

There's a xmlValidation attribute in the Host element of server.xml:

<Host name="localhost" appBase="webapps"

       unpackWARs="true" autoDeploy="true"

       xmlValidation="false" xmlNamespaceAware="false">

which is by default set to false. Try setting those to true.

[Tim Holloway]

I don't think that will help. I believe it's for indicating validation of the web.xml files in WARs.

The problem with validating server.xml is that not all of the elements in server.xml are rigidly defined. Notable offenders include option attributes for the database connection pool definition.

DTDs are all-or-nothing, which is why things like server.xml and Ant build files don't validate (and have no formal DTDs). XML schemas were designed (among other reasons) to help out in this regard, but unless I missed something, there's no xsd for Tomcat's server.xml.

Failing machine validation, I'm afraid you're just going to have to eyeball it.

[Jaikiran Pai]

Tim Holloway wrote:I don't think that will help. I believe it's for indicating validation of the web.xml files in WARs.

I see. I wasn't aware of that.

[Joe San]

Obtaining the Connection from the JNDI tree is now fine. I have another question here...What do I do with the obtained Connections after I have performed my work??? Do I have to explicitly close them by myself??

[Tim Holloway]

Jothi Shankar Kumar wrote:Obtaining the Connection from the JNDI tree is now fine. I have another question here...What do I do with the obtained Connections after I have performed my work??? Do I have to explicitly close them by myself??

Most definitely! If you don't, they'll leak.

The actual Connection is wrapped by the pool manager. The wrapping version of the connection returns the connection to the pool, so if you don't explicitly close, you'll exhaust the pool.

The Connection itself isn't actually closed, since the whole point of a Connection Pool is to keep connections ready to use with minimal overhead.

[Joe San]

So the Connection object that I obtain by calling dataSource.getConnection() actually returns me a kind of a proxy to the actual Connection object. How will the original Connection object be notified that I have closed the proxy Connection object???

[Tim Holloway]

Jothi Shankar Kumar wrote:So the Connection object that I obtain by calling dataSource.getConnection() actually returns me a kind of a proxy to the actual Connection object. How will the original Connection object be notified that I have closed the proxy Connection object???

It won't, and it won't care. The Connection that's being proxied will remain open and will be handed out again and again. Which makes it important that you set your connections to known states before using them. You might be able to depend on the Connection pool resetting some values, but unless you've specifically declared options, don't count on it. Especially for auto-commit.

I think, however, that an attempt to close a pooled connection while it's actively in use is going to throw an exception. It should, at any rate.