Thanks Stevie for the reply...you know what, I'm using
struts framework for display & user request Controllers (Action
servlet & Action classes). So, I can't possibly have single instance for Controllers.
From the Action class, I'm making call to the singleton POJO class, that uses one DAO class (sometime a DAOFactory to map proper DAO) to perform a DB operation. This DAO is also singleton.
My concern is in load
testing, when say a load of 50 concurrent users will be tested, would this singleton-design may slow down the application? (50 user threads are trying to use same instance of POJO class & same instance of DAO to perform one DB job)would there be any locking on POJO may happen?