JSF is creating two instances of an ApplicationScoped bean

Question

I have two managed beans which both have an @ApplicationScope annotation:

Storage.java:

@ManagedBean(eager = true)
@ApplicationScoped
public class Storage {

    private static final Logger LOGGER = LoggerFactory.getLogger(Storage.class);

    private List<Sheet> sheets = new ArrayList<Sheet>();

    public List<Sheet> getSheets() {
        return sheets;
    }

    public Sheet load(String id) {
        // ...
    }

    public void storeSheet(Sheet sheet) {
        sheets.add(sheet);
        LOGGER.trace(""+this.hashCode()+" Stored sheet: "+sheet);
    }

    public void delete(Sheet s) {
        sheets.remove(s);
        LOGGER.trace(""+this.hashCode()+" Removed sheet: "+s);
    }

}

StorageInitializer.java:

@ManagedBean(eager = true)
@ApplicationScoped
public class StorageInitializer {

    @ManagedProperty(value = "#{storage}")
    private Storage storage;

    @PostConstruct
    public void init() {
        int nofSheets = 10;
        int min = 20;
        int max = 200;
        for (int i=0; i<nofSheets; i++) {
            storage.storeSheet(new Sheet(
                    "Sheet "+i,
                    ThreadLocalRandom.current().nextInt(min, max),
                    ThreadLocalRandom.current().nextInt(min, max)));
        }
    }

    public void setStorage(Storage storage) {
        this.storage = storage;
    }

}

When the application starts, StorageInitializer should write 10 instances into the storage. Other beans with @RequestScoped do access the store and make the sheets visible. They all have a

    @ManagedProperty(value = "#{storage}")
    private Storage storage;

to access the Storage bean.

By logging the hash I can see that I sometimes get two instances of the Storage bean. The first one gets initialized by StorageInitializer. The second one gets used by the @RequestScoped beans and is empty.

To mee this looks like a race condition or timinig problem. If I set a break point in StorageInitializer.ini() everything works ok.

Any ideas?

Answer 1

I had the same problem with two @ApplicationScoped beans with "eager = true". The duplicated bean was in a @ManagedProperty in the other @ApplicationScoped bean. I solved the problem by changing the eager value to false on the bean that owned the @ManagedProperty. In my case the eager value wasn't strictly necessary.