How wildfly resets properties set on connection when returned to connection pool

Question

I am doing jndi lookup for datasource configured in JBOSS

DataSource dataSource = (DataSource) new InitialContext().lookup(dataSourceStr);
return dataSource.getConnection();

Connection is closed by using try-with-resource. Once I get connection object I'm setting isolation property on it, I need it for my functionality.

connection.setTransactionIsolation(Connection.TRANSACTION_READ_UNCOMMITTED);//1

Once my operation is done I want to check what's isolation value present in connection for that I created connection object using similar mechanism given above and tested it's value which I found as TRANSACTION_READ_COMMITTED(2) which is default one and not which I had overriden. This is actually working as I wanted it to. I've not reset value to TRANSACTION_READ_COMMITTED(2) again once my operation is done but still it's getting reset to original TRANSACTION_READ_COMMITTED(2) when returned backed to pool. I m interested in knowing how this is happening/where can I look for more details.

I have kept only 1 connection in connection pool so I know when I accessed connection again I got the same connection object on which I had previously overriden value TRANSACTION_READ_UNCOMMITTED for isolation. I double checked it's by not closing connection thus it gave error when I tried to access it again.

My question is how connection value which was overriden is getting reset when it's getting back to pool?

Answer 1

could you please post the configuration of you DataSource?

This Behaviour is not specified by JBoss/WildFly it depends on the Implementation of DS you are using. So the behavior you are seeing can change between vendor specific implementations of DataSources.

For example if you are using postgres you could have a look on github.com/pgjdbc/pgjdbc/blob/… this is the listener which is fired when a pooled connection is closed.. but it seems postgres doesn't have such an "reset" behavior of it's pooled connections