The EJB container is highly configurable by web console and XML file. For example, if we start WildFly through the command standalone.sh we will have a configuration as:

<subsystem xmlns="urn:jboss:domain:ejb3:1.2">
  <session-bean>
    <stateless>
      <bean-instance-pool-ref pool-name="slsb-strict-max-pool"/>
    </stateless>
    <stateful default-access-timeout="5000" cache-ref="simple" clustered-cache-ref="clustered"/>
    <singleton default-access-timeout="5000"/>
  </session-bean>
  <entity-bean>
    <bean-instance-pool-ref pool-name="entity-strict-max-pool"/>
  </entity-bean>
  <pools>
    <bean-instance-pools>
      <strict-max-pool name="slsb-strict-max-pool" max-pool-size="20" instance-acquisition-timeout="5" instance-acquisition-timeout-unit="MINUTES"/>
      <strict-max-pool name="entity-strict-max-pool" max-pool-size="100" instance-acquisition-timeout="5" instance-acquisition-timeout-unit="MINUTES"/>
    </bean-instance-pools>
  </pools>
  <caches>
    <cache name="simple" aliases="NoPassivationCache"/>
    <cache name="passivating" passivation-store-ref="file" aliases="SimpleStatefulCache"/>
    <cache name="clustered" passivation-store-ref="infinispan" aliases="StatefulTreeCache"/>
  </caches>
  <passivation-stores>
    <file-passivation-store name="file"/>
    <cluster-passivation-store name="infinispan" cache-container="ejb"/>
  </passivation-stores>
  <remote connector-ref="remoting-connector" thread-pool-name="default"/>  
  <thread-pools>    
    <thread-pool name="default">      
       <max-threads count="10"/>      
       <keepalive-time time="100" unit="milliseconds"/>         
    </thread-pool>
  </thread-pools>
  <iiop enable-by-default="false" use-qualified-name="false"/>
  <in-vm-remote-interface-invocation pass-by-value="false"/>
</subsystem>