Hi
I am managing an
application that uses the Postgres backend. Of late we have started
getting connection refused errors every now and then. We have not been
able to identify the cause of this. Any hints or known bugs that I should
be aware of? Thanks for any help extended!
Regards
Srinivas
Here is the
environment I work in:
Application is a Java app residing on a web server and
is running on Tomcat.
Versions:
jdk:
1.5.0_02
Tomcat
5.5.23
Web server:
httpd-2.0.52-28.ent.centos4
Kernel: Linux
version 2.6.9-42.0.10.ELsmp (mockbuild <at> builder5.centos.org)
(gcc version 3.4.6 20060404 (Red Hat 3.4.6-3)) #1 SMP Tue Feb 27 09:40:21 EST
2007
Postgres: 8.1.8 (64 bit version) -
postgresql-libs-8.1.8-1PGDG
postgresql-8.1.8-1PGDG
postgresql-server-8.1.8-1PGDG
postgresql-contrib-8.1.8-1PGDG
We use the JDBC2
driver that comes with Postgres.
The specific error
we get is:
CDBConnectionPool.newConnection() : SQLException=
org.postgresql.util.PSQLException: Connection refused. Check that the hostname
and port are correct and that the postmaster is accepting TCP/IP
connections.
Our
CDBConnectionPool class as below (this is a class that we have implemented to
establish BD connections):
import
java.sql.Connection;
import java.sql.DriverManager;
import
java.sql.SQLException;
import java.util.Enumeration;
import
java.util.Hashtable;
import java.util.Vector;
class
CDBConnectionPool
{
public synchronized Connection
getConnection(String stIPAddress,String stPort,String stDataBaseName, String
stUser,String stPassword,String stDBType)
{
Connection
con = null;
try
{
con =
newConnection(stIPAddress,stPort,stDataBaseName,stDBType,stUser,stPassword);
}
catch(Exception
e)
{
Logger.toLog("CONNECTION",stDataBaseName,"CDBConnectionPool.getConnection:Exception="+e);
}
return
con;
}
private
Connection newConnection(String stIPAddress,String stPort,String
stDataBaseName,String stDBType,String stUser,String
stPassword)
{
Connection con =
null;
try
{
String stURL =
"";
String stClassName = "";
if
(stDBType.equals("ORACLE"))
{
stURL
= "jdbc:oracle:thin: <at> "+ stIPAddress + ":" + stPort + ":" + stDataBaseName
;
stClassName =
"oracle.jdbc.driver.OracleDriver";
}
else
if(stDBType.equals("POSTGRES"))
{
stURL
=
"jdbc:postgresql://"+stIPAddress+":"+stPort+"/"+stDataBaseName;
stClassName
=
"org.postgresql.Driver";
}
else
if(stDBType.equals("MS-SQL2000"))
{
stURL
=
"jdbc:microsoft:sqlserver://"+stIPAddress+":"+stPort+";DatabaseName="+stDataBaseName;
stClassName
=
"com.microsoft.jdbc.sqlserver.SQLServerDriver";
}
else
if(stDBType.equals("SYBASE"))
{
stURL
=
"jdbc:sybase:Tds:"+stIPAddress+":"+stPort+"/"+stDataBaseName;
stClassName
=
"com.sybase.jdbc2.jdbc.SybDriver";
}
else
if(stDBType.equals("DB2"))
{
stURL =
"jdbc:db2://"+stIPAddress+":"+stPort+"/"+stDataBaseName;
stClassName =
"COM.ibm.db2.jdbc.net.DB2Driver";
}
Class.forName(stClassName);
con =
DriverManager.getConnection(stURL,stUser,stPassword);
}
catch(SQLException
sqle)
{
if(sqle.toString().indexOf("too many
clients")>=0)
{
Logger.toLog("CONNECTION",stDataBaseName,"CDBConnectionPool.newConnection()
: Maxmimum connections Reached. Waiting for connections to
freeup.");
con =
newConnection(stIPAddress,stPort,stDataBaseName,stDBType,stUser,stPassword);
}
else
{
Logger.toLog("CONNECTION",stDataBaseName,"CDBConnectionPool.newConnection()
: SQLException= " +
sqle);
}
}
catch(ClassNotFoundException
e)
{
Logger.toLog("CONNECTION",stDataBaseName,"CDBConnectionPool.newConnection()
: ClassNotFoundException = " +
e.getCause());
}
catch(Exception e)
{
Logger.toLog("CONNECTION",stDataBaseName,"CDBConnectionPool.newConnection()
: Exception= " + e);
}
return
con;
}
public void
freeConnection(Connection con,String
stDataBaseName)
{
try
{
con.close();
}catch(Exception
e){Logger.toLog("CONNECTION",stDataBaseName,"CDBConnectionPool.freeConnection :
Exception= " + e);}
}
}
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