[Inquiry] java.lang.IllegalStateException: setAttribute: Session already invalidated during Cluster Replication (Tomcat 9.0.73)

[조재현]

Hello
I am seeking expert advice regarding a java.lang.IllegalStateException
occurring in our Tomcat clustering environment. We have analyzed the logs
and suspect a race condition during session replication, but we would like
to verify our proposed solutions with the community.
[Environment]
Tomcat Version: Apache Tomcat 9.0.73
JDK Version: Java 11
OS: [RHEL 9.x]
Cluster Nodes: 2 Nodes (Static Membership)
[Current Configuration (server.xml)]
<Cluster channelSendOptions="8"
         channelStartOptions="3"
         className="org.apache.catalina.ha.tcp.SimpleTcpCluster">
    <Manager
        className="org.apache.catalina.ha.session.DeltaManager"
        expireSessionsOnShutdown="false"
        notifyListenersOnReplication="true"
    />
    <Channel className="org.apache.catalina.tribes.group.GroupChannel">
        <Sender
className="org.apache.catalina.tribes.transport.ReplicationTransmitter">
            <Transport
className="org.apache.catalina.tribes.transport.nio.PooledParallelSender" />
        </Sender>
        <Receiver
            address="192.168.0.11"
            autoBind="0"
            className="org.apache.catalina.tribes.transport.nio.NioReceiver"
            maxThreads="6"
            port="3100"
            selectorTimeout="5000"/>
        <Interceptor
className="org.apache.catalina.tribes.group.interceptors.TcpPingInterceptor"
staticOnly="true"/>
        <Interceptor
className="org.apache.catalina.tribes.group.interceptors.TcpFailureDetector"
/>
        <Interceptor
className="org.apache.catalina.tribes.group.interceptors.StaticMembershipInterceptor">
            <Member
className="org.apache.catalina.tribes.membership.StaticMember"
                    port="3200"
                    host="192.168.0.12"
                    uniqueId="{0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,2}" />
        </Interceptor>
        <Interceptor
className="org.apache.catalina.tribes.group.interceptors.MessageDispatchInterceptor"
/>
    </Channel>
    <Valve className="org.apache.catalina.ha.tcp.ReplicationValve"

 filter=".*\.gif;.*\.js;.*\.jpg;.*\.png;.*\.htm;.*\.html;.*\.css;.*\.txt;"
/>
    <ClusterListener
className="org.apache.catalina.ha.session.ClusterSessionListener" />
</Cluster>

[The Issue] We are intermittently encountering the following error during
period of session sync: java.lang.IllegalStateException: setAttribute:
Session [SESSION_ID] has already been invalidated at
org.apache.catalina.session.StandardSession.setAttribute(StandardSession.java:1330)
at
org.apache.catalina.ha.session.DeltaSession.setAttribute(DeltaSession.java:769)
[Questions & Proposed Actions]
Change channelSendOptions from 8 to 6: We currently use ASYNCHRONOUS mode
(8). We suspect that updates are arriving after a session invalidation
message due to lack of order guarantee. Would changing this to SYNCHRONOUS
(6) effectively resolve this without a significant performance penalty in a
2-node setup?
DeltaManager vs BackupManager: Given our 2-node setup, would switching to
BackupManager provide better consistency for session states, or is this
error purely a timing issue inherent to how DeltaRequest is processed?
notifyListenersOnReplication="false": We are considering disabling listener
notifications during replication. Could having this true (current setting)
be a bottleneck that contributes to the IllegalStateException?
MessageDispatchInterceptor and PooledParallelSender: Does our current
combination of these two components have any known issues regarding session
attribute consistency in Tomcat 9.0.73?
Any insights or recommendations on how to fundamentally suppress these
errors would be greatly appreciated.
Best regards,