controller/src/main/java/org/jboss/as/controller/AbstractControllerService.java

@@ -334,7 +334,10 @@ public void start(final StartContext context) throws StartException {
                 rootResourceRegistration,
                 new ContainerStateMonitor(container, getStabilityMonitor()),
                 configurationPersister, processType, runningModeControl, prepareStep,
-                processState, executorService, expressionResolver, authorizer, securityIdentitySupplier, auditLogger, notificationSupport,
+                processState, executorService,
+                getMaxParallelBootExtensionTasks(),
+                getMaxParallelBootSubsystemTasks(),
+                expressionResolver, authorizer, securityIdentitySupplier, auditLogger, notificationSupport,
                 bootErrorCollector, createExtraValidationStepHandler(), capabilityRegistry, getPartialModelIndicator(),
                 injectedInstabilityListener.getOptionalValue());
 
@@ -395,6 +398,14 @@ public ServiceTarget getServiceTarget() {
         bootThread.start();
     }
 
+    protected int getMaxParallelBootExtensionTasks() {
+        return 1;
+    }
+
+    protected int getMaxParallelBootSubsystemTasks() {
+        return 1;
+    }
+
     /**
      * Gets whether this controller service should install a {@link ModelControllerClientFactory}
      * and a {@link org.jboss.as.controller.notification.NotificationHandlerRegistry}

controller/src/main/java/org/jboss/as/controller/ModelControllerImpl.java

@@ -125,6 +125,8 @@
     private final OperationStepHandler prepareStep;
     private final ControlledProcessState processState;
     private final ExecutorService executorService;
+    private final int maxParallelBootExtensionTasks;
+    private final int maxParallelBootSubsystemTasks;
     private final ExpressionResolver expressionResolver;
     private final Authorizer authorizer;
     private final Supplier<SecurityIdentity> securityIdentitySupplier;
@@ -153,6 +155,8 @@
                         final ContainerStateMonitor stateMonitor, final ConfigurationPersister persister,
                         final ProcessType processType, final RunningModeControl runningModeControl,
                         final OperationStepHandler prepareStep, final ControlledProcessState processState, final ExecutorService executorService,
+                        final int maxParallelBootExtensionTasks,
+                        final int maxParallelBootSubsystemTasks,
                         final ExpressionResolver expressionResolver, final Authorizer authorizer, final Supplier<SecurityIdentity> securityIdentitySupplier,
                         final ManagedAuditLogger auditLogger, NotificationSupport notificationSupport,
                         final BootErrorCollector bootErrorCollector, final OperationStepHandler extraValidationStepHandler,
@@ -186,6 +190,8 @@
         this.processState = processState;
         this.serviceTarget.addMonitor(stateMonitor.getStabilityMonitor());
         this.executorService = executorService;
+        this.maxParallelBootExtensionTasks = maxParallelBootExtensionTasks;
+        this.maxParallelBootSubsystemTasks = maxParallelBootSubsystemTasks;
         assert expressionResolver != null;
         this.expressionResolver = expressionResolver;
         assert securityIdentitySupplier != null;
@@ -600,9 +606,10 @@ private BootOperations organizeBootOperations(List<ModelNode> bootList, final in
         final ManagementResourceRegistration rootRegistration = managementModel.get().getRootResourceRegistration();
         final MutableRootResourceRegistrationProvider parallellBRRRProvider = parallelBootRootResourceRegistrationProvider != null ?
                 parallelBootRootResourceRegistrationProvider : getMutableRootResourceRegistrationProvider();
-        ParallelExtensionAddHandler parallelExtensionAddHandler = executorService == null ? null : new ParallelExtensionAddHandler(executorService, parallellBRRRProvider);
-        ParallelBootOperationStepHandler parallelSubsystemHandler = (executorService != null && processType.isServer() && runningModeControl.getRunningMode() == RunningMode.NORMAL)
-                ? new ParallelBootOperationStepHandler(executorService, rootRegistration, processState, this, lockPermit, extraValidationStepHandler) : null;
+        ParallelExtensionAddHandler parallelExtensionAddHandler = executorService == null || maxParallelBootExtensionTasks < 2 ? null : new ParallelExtensionAddHandler(executorService, maxParallelBootExtensionTasks, parallellBRRRProvider);
+        ParallelBootOperationStepHandler parallelSubsystemHandler = (executorService != null && maxParallelBootSubsystemTasks > 1 && processType.isServer() && runningModeControl.getRunningMode() == RunningMode.NORMAL)
+                ? new ParallelBootOperationStepHandler(executorService, maxParallelBootSubsystemTasks, rootRegistration, processState, this, lockPermit, extraValidationStepHandler)
+                : null;
         boolean registeredParallelSubsystemHandler = false;
         int subsystemIndex = 0;
         for (ModelNode bootOp : bootList) {