GetConnection() and close() bottlenecks

Question

Hi all
When loadtesting our Weblogic 6.1 app with a SQL Server 2000 db I have found
that the primary bottleneck are calls to Connection.getConnection() and
Connection.close(). Often calls to these methods (15%) take about one second
and about 1% of the time they can take more than 20 seconds. The cpu % of
the appserver and dbserver never seems to go above about 30% as calls to
getConnection() and close() seem to be just blocking a lot of the time.
Also, the number of connections in use never seems to increas to more than
half the max allowed so its not running out of available db connections.
I am using a standard connection pool and TX datasource and have a cached
reference to my initial context and datasource so its not JNDI that is
causing the delays.
I'm wondering why the obtaining and closing of connections is taking so long
under load. Is anyone else experiencing these problems?
My config.xml looks like
<JDBCTxDataSource JNDIName="datasource-trading" Name="datasource-trading"
PoolName="trading" Targets="tradingserver"/>
<JDBCConnectionPool DriverName="weblogic.jdbc.mssqlserver4.Driver"
InitialCapacity="10" MaxCapacity="20" Name="trading"
Properties="user=trading;password=thepassword" Targets="tradingserver"
TestConnectionsOnRelease="true" TestConnectionsOnReserve="true"
TestTableName="application"
URL="jdbc:weblogic:mssqlserver4:localhost:1433"/>
The application test table contains 2 rows.
My singleton class that handles getting/closing connections looks something
like
public class ConnectionPoolManager {
private static InitialContext _context = null;
private static DataSource _datasource = null;
private static final String J2EE_DATASOURCE = "datasource-trading";
private static Context getContext() throws NamingException {
if (_context == null) _context = new InitialContext();
return _context;
public static DataSource getDataSource() throws NamingException {
if (_datasource == null) _datasource = (DataSource)
getContext().lookup.J2EE_DATASOURCE);
return _datasource;
public static Connection getConnection() throws SQLException {
Connection c = null;
try {
c = getDataSource().getConnection();
catch (NamingException ex) {
throw new SQLException("Unable to locate DataSource " +
J2EE_DATASOURCE);
c.setAutoCommit(false);
return c;
public static void releaseConnection(Connection con) {
if( con != null ) {
try {
con.rollback();
con.close();
} catch (SQLException e) {
throw new RuntimeException("Unable to release database
connection to the pool. " + e.getMessage());
Can anyone see any obvious reasons why the getting and returning connections
to the pool is taking so long? This is driving me crazy and delyaing my
project from being deployed live.
Thanks
Matt

Answer 1

Thanks Joe. I'll make the recommended changes and see how it goes.
"Joe Weinstein" <[email protected]> wrote in message
news:[email protected]...
>
>
Matt Krevs wrote:
Thanks Joe
- I've tried turning off test-connections-on-release and it does
decrease
times a little (generally a few milliseconds). I'll make sure its turnedoff
from now on.
- The application table is never updated
- All code runs in the same jvm
- I have used SQL Profiler during loadtesting and the longest durationof
any queries is about 2 seconds. I'm really stuck on why there is 1% ofthe
time an additional 18+ seconds
In your opinion, what would typically cause a close() or getConnection()to
take 20 seconds+? I've also found that rollback() can also take thislong
>
If rollback is included, then it's the DBMS taking it's own sweet time torespond.
GetConnection() should be instantaneous from a pool that has connectionsavailable,
except for the time it takes to do the test query, so the DBMS is againimplicated.
Close() calls rollback() if the connection is autoCommit(false). Close()also closes
any result sets or statements you have left...
If you turn of test-on-reserve, (even just for a test), it will removeall
the extra client-dbms communication, and will implicate the DBMScompletely if the
problem is still there, and you have enough connections in the pool.Lastly,
you might try this code for obtaining pool connections: (it may be faster)
// You can make one and re-use indefinitely
Driver d = new weblogic.jdbc.pool.Driver();
Connection c = d.connect("jdbc:weblogic:pool:YOURPOOLNAME", null );
Joe
Matt
"Joe Weinstein" <[email protected]> wrote in message
news:[email protected]...
Matt Krevs wrote:
Hi all
When loadtesting our Weblogic 6.1 app with a SQL Server 2000 db I have
found
that the primary bottleneck are calls to Connection.getConnection() and
Connection.close(). Often calls to these methods (15%) take about onesecond
and about 1% of the time they can take more than 20 seconds. The cpu %of
the appserver and dbserver never seems to go above about 30% as calls
to
getConnection() and close() seem to be just blocking a lot of the time.
Also, the number of connections in use never seems to increas to morethan
half the max allowed so its not running out of available db
connections.
>>>>
I am using a standard connection pool and TX datasource and have acached
reference to my initial context and datasource so its not JNDI that is
causing the delays.
I'm wondering why the obtaining and closing of connections is taking solong
under load. Is anyone else experiencing these problems?
My config.xml looks like
<JDBCTxDataSource JNDIName="datasource-trading"Name="datasource-trading"
PoolName="trading" Targets="tradingserver"/>
<JDBCConnectionPool DriverName="weblogic.jdbc.mssqlserver4.Driver"
InitialCapacity="10" MaxCapacity="20" Name="trading"
Properties="user=trading;password=thepassword" Targets="tradingserver"
TestConnectionsOnRelease="true" TestConnectionsOnReserve="true"
TestTableName="application"
URL="jdbc:weblogic:mssqlserver4:localhost:1433"/>
The application test table contains 2 rows.
My singleton class that handles getting/closing connections lookssomething
like
public class ConnectionPoolManager {
private static InitialContext _context = null;
private static DataSource _datasource = null;
private static final String J2EE_DATASOURCE = "datasource-trading";
private static Context getContext() throws NamingException {
if (_context == null) _context = new InitialContext();
return _context;
public static DataSource getDataSource() throws NamingException {
if (_datasource == null) _datasource = (DataSource)
getContext().lookup.J2EE_DATASOURCE);
return _datasource;
public static Connection getConnection() throws SQLException {
Connection c = null;
try {
c = getDataSource().getConnection();
catch (NamingException ex) {
throw new SQLException("Unable to locate DataSource " +
J2EE_DATASOURCE);
c.setAutoCommit(false);
return c;
public static void releaseConnection(Connection con) {
if( con != null ) {
try {
con.rollback();
con.close();
} catch (SQLException e) {
throw new RuntimeException("Unable to release database
connection to the pool. " + e.getMessage());
Can anyone see any obvious reasons why the getting and returningconnections
to the pool is taking so long? This is driving me crazy and delyaing my
project from being deployed live.
Thanks
MattHi. You should turn off test-connections-on-release. That can waste
time.
Does your application ever update the application table? Does this code
and it's clients run in the server?
Joe
>