Deadlock on Wildfly startup

SingletonA.java: @Singleton public class SingletonA { private static final Logger log = LoggerFactory.getLogger(SingletonA.class); private static final List< Integer > DATA = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9); @PostConstruct public void postConstruct() { log.info( "hello from SingletonA" ); } public List< Integer > getCachedData() { return Collections.unmodifiableList(DATA); } }   SingletonB.java: @Singleton @Startup public class SingletonB { private static final Logger log = LoggerFactory.getLogger(SingletonB.class); @Inject private SingletonA singletonA; @Inject private ServiceC serviceC; @Resource private ManagedExecutorService managedExecutorService; @PostConstruct public void postConstruct() { log.info( "hello from SingletonB" ); managedExecutorService.execute(() -> serviceC.run()); log.info( "job scheduled; continuing initialization" ); sleep(500); // some other stuff List< Integer > data = singletonA.getCachedData(); log.info( "got {} elements in cache" , data.size()); } private static void sleep( long ms) { try { Thread .sleep(ms); } catch (InterruptedException e) { throw new IllegalStateException(e); } } }     ServiceC.java: @ApplicationScoped public class ServiceC { private static final Logger log = LoggerFactory.getLogger(ServiceC.class); private static final Random RANDOM = new Random(); @Inject private SingletonA singletonA; @PostConstruct public void postConstruct() { log.info( "hello from ServiceC" ); } public void run() { List< Integer > data = singletonA.getCachedData(); int index = RANDOM.nextInt(data.size()); log.info( "next number: {}" , data.get(index)); } }    

There is no workaround for deadlock caused by too early client access. Workaround for deadlock caused by jobs from executor service: the jobs in managed executor service should be started by some other bean D that also is started on a managed executor. This way D will hold on StartupAwaitInterceptor but will not block any singleton. After all singletons are ready the StartupAwait will be released and D will start the jobs (in terms of my example D will execute managedExecutorService.execute(() -> serviceC.run()); )