JBoss EAP 6 で JBAS014134: EJB Invocation failed on component ... could not obtain lock within 5000 MILLISECONDS エラーが発生する

Issue

• web アプリケーションでステートフル EJB にアクセスすると、JBoss EAP 6.x ログに以下のエラーが出力されます。

ERROR [org.jboss.as.ejb3.invocation] (ajp-/10.96.192.74:8009-51) JBAS014134:EJB Invocation failed on component example/MyStatefulEJB for method public abstract com.jboss.example.cart.MyCart com.jboss.examples.MyJSFBackingBean.getCart(com.jboss.examples.MyContext) throws com.jboss.examples.exception.CartException,java.rmi.RemoteException: javax.ejb.ConcurrentAccessTimeoutException:JBAS014360:EJB 3.1 FR 4.3.14.1 concurrent access timeout on org.jboss.invocation.InterceptorContext@2775f9ab - could not obtain lock within 5000 MILLISECONDS
  at org.jboss.as.ejb3.component.stateful.StatefulSessionSynchronizationInterceptor.processInvocation(StatefulSessionSynchronizationInterceptor.java:117) [jboss-as-ejb3-7.2.0.Final-redhat-8.jar:7.2.0.Final-redhat-8]
  at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288) [jboss-invocation-1.1.1.Final-redhat-2.jar:1.1.1.Final-redhat-2]
  ...