Why to use it? There are many objects we only need one of: thread pools, caches, dialog boxes, objects that handle preferences and registry settings, objects used for logging, and objects that act as device drivers to devices like printers and graphic cards. For many of these types of object if we were to intantiate more than one we would run intol all sorts of problems like incorrect program behavior or overuse of resources

Regarding the usage of synchronization it is definitly expensive and the only time syncrhonization is relevant is for the first time or the unique instatiation once instantiated we have no further need to synchronize again. After the first time through, syncrhonization is totally unneeded overhead :(

When would you need to use one? There are many objects we only need one of: thread pools, caches, dialog boxes, objects that handle preferences and registry settings, objects used for logging, and objects that act as device drivers to devices like printers and graphic cards. For many of these types of object if we were to intantiate more than one we would run intol all sorts of problems like incorrect program behavior or overuse of resources

Regarding the usage of synchronization it is definitly expensive and the only time syncrhonization is relevant is for the first time or the unique instatiation once instantiated we have no further need to synchronize again. After the first time through, syncrhonization is totally unneeded overhead :(

Why to use it? There are many objects we only need one of: thread pools, caches, dialog boxes, objects that handle preferences and registry settings, objects used for logging, and objects that act as device drivers to devices like printers and graphic cards. In fact for many of these types of object if we were to intantiate more than one we would run intol all sorts of problems like incorrect program behavior or overuse of resources

Why to use it? There are many objects we only need one of: thread pools, caches, dialog boxes, objects that handle preferences and registry settings, objects used for logging, and objects that act as device drivers to devices like printers and graphic cards. For many of these types of object if we were to intantiate more than one we would run intol all sorts of problems like incorrect program behavior or overuse of resources

Regarding the usage of synchronization it is definitly expensive and the only time syncrhonization is relevant is for the first time or the unique instatiation once instantiated we have no further need to synchronize again. After the first time through, syncrhonization is totally unneeded overhead :(