Singleton totally mulitread-capable ?

[nimo22]

When I use a Singleton, do I have to bother with multithreaded issues or does the container care of all that issues?

For example:

When using a Map in a Singleton. Should I delcare it this way:

private Map<AtomicInteger, Users> users = new ConcurrentHashMap<AtomicInteger, Users>();

or can I use this:

private Map<Integer, Users> users = new HashMap<Integer, Users>();

[jaikiran]

Section 4.8.5 ("Singleton Concurrency") of EJB3.1 spec has the complete details including this:

It is legal to store Java EE objects that do not support concurrent access (e.g. Entity Managers, Stateful Session Bean references) within Singleton bean instance state. However, it is the responsibility of the Bean Developer to ensure such objects are not accessed by more than one thread at a time.

[nimo22]

thanks!