Parameshwara,
On 8/2/25 1:54 AM, Parameshwara Bhat wrote:
I am working on a task of migrating a running a JSP/JSF application on
tomcat-6.0 to tomcat 9.0
My installation of tomcat-9.0.87 is on Opensuse-Leap-15.6. Database is
postgresql 17, using postgresql-42.7.7.jar for driver.
I am able to run legacy application on tomcat-9.0.87 after making
following changes ( picked up from tomcat-9.0 docs) to application's
connection code.
It's unclear what changes you made. You have only posted one code snippet.
try {
InitialContext cxt = new InitialContext();
/*if ( cxt == null ) {
throw new Exception("Uh oh -- no context!");
}*/
DataSource ds = (DataSource) cxt.lookup(
"java:/comp/env/jdbc/public_PostgreSQL" );
/*if ( ds == null ) {
throws new Exception("Data source not found!");
}*/
try {
this.con = ds.getConnection();
Doing this kind of thing in a JSP is probably going to cause all kinds
of problems. "This kind of thing" is defined as "setting a class
member's value during request processing". Note that only a single
instance of the JSP's backing Java class will be created, and all
requests running in all threads will be sharing this connection object
and the this.conn reference to it.
} catch (SQLException ex) {
ex.printStackTrace();
}
} catch (NamingException e) {
e.printStackTrace();
}
/* this.con = DriverManager.getConnection(url, username,
password); */
My context.xml content is below.
<?xml version="1.0" encoding="UTF-8"?>
<Context path="/ERP">
<Resource auth="Container"
driverClassName="org.postgresql.Driver" maxTotal="40" maxIdle="20"
maxWaitMillis="-1" name="jdbc/public_PostgreSQL"
password="kapital" type="javax.sql.DataSource"
url="jdbc:postgresql://localhost:5444/das" username="das"/>
</Context>
I am able to run application only after making maxTotal="40" from
maxTotal="20" ; maxIdle="20" from maxIdle="10". Corresponding values for
tomcat 6 running installation are maxActive="20", maxIdle="10".
With maxTotal="40" and maxIdle="20", I am able to barely run once. If I
log out and try to login again, application can never login. In fact, I
was able to login even once only after changing to maxTotal="40" and
maxIdle="20". Otherwise application would be forever stuck at login,
never able to enter application. I am able to login the first time I
login and never afterwards. I have to kill tomcat-9.0.87 and
restart,then I am able to login again.
My guess is, pooled connections to database are not released to be re-used.
I will thank any help to understand and resolve this. I have read
documentation before making changes to DB connection, but I might have
missed nuances.
You should enable tracking of "abandoned connections" and also enable
logging of those abandoned connections as well. I would highly recommend
in a development environment setting your maxTotal to 1 (yes, ONE) as
this will make it very very obvious if you have any connection leaks in
your application, or if you have pool-related deadlocks hiding in there
as well.
This blog post is relevant but may require some adaptation to use within
a JSP setting:
https://blog.christopherschultz.net/2009/03/16/properly-handling-pooled-jdbc-connections/
-chris
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