JBoss EAP start up doesn't complete with 1024 ServerService threads in use

Issue

• Our JBoss start up is timing out and failing to complete at random. Thread dumps or heap dumps in that time show 1024 ServerService threads present and in use and all stuck in wait states:

"ServerService Thread Pool -- 252" #853 prio=5 os_prio=0 tid=0x000055d2e6f95000 nid=0x13c8 in Object.wait() [0x00007f56e10f9000]
   java.lang.Thread.State: WAITING (on object monitor)
    at java.lang.Object.wait(Native Method)
    at java.lang.Object.wait(Object.java:502)
    at org.jboss.msc.service.StabilityMonitor.awaitStability(StabilityMonitor.java:313)
    - locked <0x0000000739d956d0> (a java.lang.Object)
    at org.jboss.msc.service.StabilityMonitor.awaitStability(StabilityMonitor.java:228)
    at org.jboss.as.weld.WeldStartCompletionService$1.run(WeldStartCompletionService.java:85)
    at org.jboss.threads.ContextClassLoaderSavingRunnable.run(ContextClassLoaderSavingRunnable.java:35)
    at org.jboss.threads.EnhancedQueueExecutor.safeRun(EnhancedQueueExecutor.java:1985)
    at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.doRunTask(EnhancedQueueExecutor.java:1487)
    at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1364)
    at java.lang.Thread.run(Thread.java:748)
    at org.jboss.threads.JBossThread.run(JBossThread.java:485)