JBoss slow to start with long jandex indexing times for large applications

Issue

• We have large applications deployed on EAP 7. We've seen that its start up time and heap required during start up has increased moving to EAP 7.3.1+ and again moving to 7.4.6+. When the app first begins its start up, the log stays silent for many minutes. During that time, CPU remains high on a single core from a single thread and thread dumps in that time show continual jandex indexing:

"MSC service thread 1-7" #22 prio=5 os_prio=0 cpu=1622528.18ms elapsed=1799.27s tid=0x0000000003561800 nid=0x9a0d runnable  [0x00007efda0380000]
   java.lang.Thread.State: RUNNABLE
    at org.jboss.jandex.StrongInternPool.eq(StrongInternPool.java:139)
    at org.jboss.jandex.StrongInternPool.intern(StrongInternPool.java:246)
    at org.jboss.jandex.NameTable.intern(NameTable.java:109)
    at org.jboss.jandex.ClassInfo.setMethods(ClassInfo.java:781)
    at org.jboss.jandex.Indexer.index(Indexer.java:1992)
    at org.jboss.as.server.deployment.annotation.ResourceRootIndexer.indexResourceRoot(ResourceRootIndexer.java:99)
    at org.jboss.as.server.deployment.annotation.AnnotationIndexProcessor.deploy(AnnotationIndexProcessor.java:51)
    at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:182)
    - locked <0x00000004054bcef8> (a org.jboss.as.server.deployment.DeploymentUnitPhaseService)
    at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1739)
    at org.jboss.msc.service.ServiceControllerImpl$StartTask.execute(ServiceControllerImpl.java:1701)
    at org.jboss.msc.service.ServiceControllerImpl$ControllerTask.run(ServiceControllerImpl.java:1559)
    at org.jboss.threads.ContextClassLoaderSavingRunnable.run(ContextClassLoaderSavingRunnable.java:35)
    at org.jboss.threads.EnhancedQueueExecutor.safeRun(EnhancedQueueExecutor.java:1990)
    at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.doRunTask(EnhancedQueueExecutor.java:1486)
    at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1377)
    at java.lang.Thread.run(java.base@11.0.5/Thread.java:834)