Hello,
I am using Commons DBCP to pool my sqlserver database connections.
Sometimes there is just an hourglass cursor when trying to access my
application - looks like there are no free connections available.
Am I doing anything wrong in my code? Should I be closing the
datasource, for example? Please see below.
Class for retrieving datasource:
package mypackage.name.here
import javax.sql.*;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.*;
import org.apache.commons.dbcp.*;
import org.apache.commons.pool.*;
import org.apache.commons.pool.impl.*;
public class DatabaseUtil {
static PoolingDataSource dataSource = null;
public static final String DB_PROPERTIES =
"myextension.properties";
// Returns a DataSource that implements connection pooling
public static synchronized DataSource getDataSource(String
configDir) throws Exception {
if (dataSource == null){
Properties p = new Properties();
try{
File cfg = new File(configDir, DB_PROPERTIES);
p.load(new FileInputStream(cfg));
} catch (IOException e) {
System.out.println(e);
}
String type = p.getProperty("dbType");
String url = p.getProperty("url");
String ip = p.getProperty("dbIP");
String name = p.getProperty("dbName");
String port = p.getProperty("dbPort");
String sid = p.getProperty("dbSid");
String fullUrl = null;
if (type.trim().equals("ms")){
// MSSQL
fullUrl = url+ip+"/"+name;
} else {
// ORACLE
fullUrl = url+ip+":"+port+":"+sid;
}
BasicDataSource ds = new BasicDataSource();
ds.setUrl(fullUrl);
ds.setDriverClassName(p.getProperty("driver"));
ds.setUsername(p.getProperty("usr"));
ds.setPassword(EncDoc.decode(p.getProperty("pass") ));
ds.setMaxActive(100);
// Create a PoolableDataSource
ObjectPool connectionPool = new GenericObjectPool(null);
ConnectionFactory connectionFactory = new
DataSourceConnectionFactory(ds);
PoolableObjectFactory poolableConnectionFactory = new
PoolableConnectionFactory(connectionFactory, connectionPool, null,
null, false, true);
dataSource = new PoolingDataSource(connectionPool);
}
return dataSource;
}
}
Sample JSP page:
...
DataSource dataSource = DatabaseUtil.getDataSource(configDir);
Connection myConnect = null;
Statement myStatement = null;
ResultSet myResults = null;
try{
myConnect = dataSource.getConnection();
myStatement = myConnect.createStatement();
...
myQuery = "select count (*) as 'total' from admin where courseID =
'"+courseID+"'";
myStatement.executeQuery(myQuery);
myResults = myStatement.getResultSet();
while (myResults.next()) count = myResults.getInt("total");
...
}catch (SQLException e) {
out.println("SQL Error: <br><br>"+e);
} finally {
try { myResults.close(); } catch(Exception e) {}
try { myStatement.close(); } catch(Exception e) { }
try { myConnect.close(); } catch(Exception e) { }
}
Thanks all.
downlode@.gmail.com wrote:
> Hello,
> I am using Commons DBCP to pool my sqlserver database connections.
> Sometimes there is just an hourglass cursor when trying to access my
> application - looks like there are no free connections available.
> Am I doing anything wrong in my code? Should I be closing the
> datasource, for example? Please see below.
Hi. The JSP code is excellent. Very safe and sure to close
the connection. I am not knowledgeable about that pool
implementation. I would suggest getting a full thread dump
of the JVM during that hang, and see what is waiting on what.
Can you find out how many JSPs are running concurrently
when such a hang is happening? If the pool implementation
ever calls DriverManager calls, it may be the cause. DriverManager
calls are all class-synchronized, and lots of JDBC drivers
make those calls under the covers, so any one long-running
DriverManager call (getConnection()) can halt all other JDBC
in the whole JVM...
Joe Weinstein at BEA Systems
> Class for retrieving datasource:
>
> package mypackage.name.here
> import javax.sql.*;
> import java.io.File;
> import java.io.FileInputStream;
> import java.io.IOException;
> import java.util.*;
> import org.apache.commons.dbcp.*;
> import org.apache.commons.pool.*;
> import org.apache.commons.pool.impl.*;
> public class DatabaseUtil {
> static PoolingDataSource dataSource = null;
> public static final String DB_PROPERTIES =
> "myextension.properties";
>
> // Returns a DataSource that implements connection pooling
> public static synchronized DataSource getDataSource(String
> configDir) throws Exception {
> if (dataSource == null){
> Properties p = new Properties();
> try{
> File cfg = new File(configDir, DB_PROPERTIES);
> p.load(new FileInputStream(cfg));
> } catch (IOException e) {
> System.out.println(e);
> }
> String type = p.getProperty("dbType");
> String url = p.getProperty("url");
> String ip = p.getProperty("dbIP");
> String name = p.getProperty("dbName");
> String port = p.getProperty("dbPort");
> String sid = p.getProperty("dbSid");
> String fullUrl = null;
> if (type.trim().equals("ms")){
> // MSSQL
> fullUrl = url+ip+"/"+name;
> } else {
> // ORACLE
> fullUrl = url+ip+":"+port+":"+sid;
> }
> BasicDataSource ds = new BasicDataSource();
> ds.setUrl(fullUrl);
> ds.setDriverClassName(p.getProperty("driver"));
> ds.setUsername(p.getProperty("usr"));
> ds.setPassword(EncDoc.decode(p.getProperty("pass") ));
> ds.setMaxActive(100);
> // Create a PoolableDataSource
> ObjectPool connectionPool = new GenericObjectPool(null);
> ConnectionFactory connectionFactory = new
> DataSourceConnectionFactory(ds);
> PoolableObjectFactory poolableConnectionFactory = new
> PoolableConnectionFactory(connectionFactory, connectionPool, null,
> null, false, true);
> dataSource = new PoolingDataSource(connectionPool);
> }
> return dataSource;
> }
> }
>
> Sample JSP page:
> ...
> DataSource dataSource = DatabaseUtil.getDataSource(configDir);
> Connection myConnect = null;
> Statement myStatement = null;
> ResultSet myResults = null;
> try{
> myConnect = dataSource.getConnection();
> myStatement = myConnect.createStatement();
> ...
> myQuery = "select count (*) as 'total' from admin where courseID =
> '"+courseID+"'";
> myStatement.executeQuery(myQuery);
> myResults = myStatement.getResultSet();
> while (myResults.next()) count = myResults.getInt("total");
> ...
> }catch (SQLException e) {
> out.println("SQL Error: <br><br>"+e);
> } finally {
> try { myResults.close(); } catch(Exception e) {}
> try { myStatement.close(); } catch(Exception e) { }
> try { myConnect.close(); } catch(Exception e) { }
> }
>
> Thanks all.
>
|||Joe Weinstein wrote:
>
> downlode@.gmail.com wrote:
>
> Hi. The JSP code is excellent. Very safe and sure to close
> the connection.
Actually, the one extra thing I might try, is to make the
connection and it's subobjects method-level objects. If the
JSP is typically one instantiated class, any multiple threads
executing it could overwrite the connection reference and
leak connections instead of having them all closed.
Joe
> I am not knowledgeable about that pool
> implementation. I would suggest getting a full thread dump
> of the JVM during that hang, and see what is waiting on what.
> Can you find out how many JSPs are running concurrently
> when such a hang is happening? If the pool implementation
> ever calls DriverManager calls, it may be the cause. DriverManager
> calls are all class-synchronized, and lots of JDBC drivers
> make those calls under the covers, so any one long-running
> DriverManager call (getConnection()) can halt all other JDBC
> in the whole JVM...
> Joe Weinstein at BEA Systems
>
|||Hi,
I'm not sure how I would go about making the connection a method-level
object in this scenario. Would I create a new class with a
getConnection() type method for creating and returning the connection?
Thanks,
Mike
> Actually, the one extra thing I might try, is to make the
> connection and it's subobjects method-level objects. If the
> JSP is typically one instantiated class, any multiple threads
> executing it could overwrite the connection reference and
> leak connections instead of having them all closed.
> Joe
|||downlode@.gmail.com wrote:
[vbcol=seagreen]
> Hi,
> I'm not sure how I would go about making the connection a method-level
> object in this scenario. Would I create a new class with a
> getConnection() type method for creating and returning the connection?
> Thanks,
> Mike
>
Hi. You could do that, or you could just make sure the scope of
the connection variable was within a block in the code, eg:
DataSource dataSource = DatabaseUtil.getDataSource(configDir);
try {
Connection myConnect = null; // ensure these have per-thread scope
Statement myStatement = null;
ResultSet myResults = null;
try{
myConnect = dataSource.getConnection();
myStatement = myConnect.createStatement();
...
myQuery = "select count (*) as 'total' from admin where courseID =
'"+courseID+"'";
myStatement.executeQuery(myQuery);
myResults = myStatement.getResultSet();
while (myResults.next()) count = myResults.getInt("total");
...
}catch (SQLException e) {
out.println("SQL Error: <br><br>"+e);
} finally {
try { myResults.close(); } catch(Exception e) {}
try { myStatement.close(); } catch(Exception e) { }
try { myConnect.close(); } catch(Exception e) { }
}
}
finally {}
|||OK, got you.
Thanks again.
Mike
