SingleConnectionDataSource now closing on new instance - spring

Question

I have a small commandline utility. My code is simple I create a SingleConnectionDataSource and pass it along till it is needed and I do
ds.getConnection()
Uptil now it was working and I would get a connection and would use it but some months back this stopped working and threw an exception
Failed to obtain JDBC Connection; nested exception is java.sql.SQLException: Connection was closed in SingleConnectionDataSource. Check that user code checks should Close() before closing Connections, or set 'suppress Close' to 'true'
Now when i create the datasource I added
((SingleConnectionDataSource)db).setSuppressClose(true);
and now it works fine ( as the exception suggested)
My question is why did it stop working or how was it working before, why would it be closed even at first user. As per the java doc it is supposed to be
Implementation of SmartDataSource that wraps a single JDBC Connection
which is not closed after use.
So I should be the one closing it to begin with at the end of the process.
So technically, I have a question of why did i get the problem that i have already solved but i don't understand when did this start coming.
Edit -- It behaves like this on SQL server only and not Oracle.
Edit2 -- Sorry, In oracle it uses a different way so it works
JdbcTemplate template = new JdbcTemplate(dataSource);
So either use SuppressClose(true) or use JdbcTemplate

Answer 1

We would need to know your database and application server to answer definitively, but my guess is that one or the other was closing the connection after a timeout. Why are you trying to manage the connection to begin with however? Many application servers provide a connection pool.

Answer 2

This is a partial answer to my own question: why would it close the connection before first use?
in SingleConnectionDatasource getConnection calls
/**
* Initialize the underlying Connection via the DriverManager.
*/
public void initConnection() throws SQLException {
if (getUrl() == null) {
throw new IllegalStateException("'url' property is required for lazily initializing a Connection");
}
synchronized (this.connectionMonitor) {
closeConnection();
this.target = getConnectionFromDriver(getUsername(), getPassword());
prepareConnection(this.target);
if (logger.isDebugEnabled()) {
logger.debug("Established shared JDBC Connection: " + this.target);
}
this.connection = (isSuppressClose() ? getCloseSuppressingConnectionProxy(this.target) : this.target);
}
}
This basically, creates a closed connection to begin with. Which makes it more intriguing why did it work in the first place. This class has been with the same initConnection() method since its inception ( as far as I can see on github).