Study possible ways to replicate HTTP sessions (Tomcat based)

[mshaposhnik]

Description

To enable parallel run of several master instances we need to synchonize state of the HTTP sessions to avoid unstable behavior.

Docs:
[1] https://tomcat.apache.org/tomcat-8.0-doc/cluster-howto.html

[mshaposhnik]

I have tried the following conf and everything is worked except the Subject object needs to be refactored.

Changes reqired:

• web.xml - add <distributable/> tag;
• server.sml - add cluster section:

<Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"
        channelSendOptions="6">

        <Manager className="org.apache.catalina.ha.session.BackupManager"
          expireSessionsOnShutdown="false"
          notifyListenersOnReplication="true"
          mapSendOptions="6"/>
        <Channel className="org.apache.catalina.tribes.group.GroupChannel">
          <Membership className="org.apache.catalina.tribes.membership.McastService"
            address="228.0.0.4"
            port="45564"
            frequency="500"
            dropTime="3000"/>
          <Receiver className="org.apache.catalina.tribes.transport.nio.NioReceiver"
            address="auto"
            port="5000"
            selectorTimeout="100"
            maxThreads="6"/>

          <Sender className="org.apache.catalina.tribes.transport.ReplicationTransmitter">
            <Transport className="org.apache.catalina.tribes.transport.nio.PooledParallelSender"/>
          </Sender>
          <Interceptor className="org.apache.catalina.tribes.group.interceptors.TcpFailureDetector"/>
          <Interceptor className="org.apache.catalina.tribes.group.interceptors.MessageDispatchInterceptor"/>
          <Interceptor className="org.apache.catalina.tribes.group.interceptors.ThroughputInterceptor"/>
        </Channel>

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

[mshaposhnik]

The following error appears when Tomcat tries to send session state:

2018-02-23 14:40:45,865[nio-8080-exec-4]  [ERROR] [.a.c.t.t.AbstractReplicatedMap 477]  - Unable to diff object. Will replicate the entire object instead.
--
  | java.io.NotSerializableException: org.eclipse.che.multiuser.api.permission.server.PermissionCheckerImpl
  | at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1184)
  | at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
  | at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
  | at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
  | at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
  | at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
  | at org.apache.catalina.ha.session.DeltaRequest$AttributeInfo.writeExternal(DeltaRequest.java:401)
  | at org.apache.catalina.ha.session.DeltaRequest.writeExternal(DeltaRequest.java:294)
  | at org.apache.catalina.ha.session.DeltaRequest.serialize(DeltaRequest.java:308)
  | at org.apache.catalina.ha.session.DeltaSession.getDiff(DeltaSession.java:138)
  | at org.apache.catalina.tribes.tipis.AbstractReplicatedMap.replicate(AbstractReplicatedMap.java:472)
  | at org.apache.catalina.ha.session.BackupManager.requestCompleted(BackupManager.java:98)
  | at org.apache.catalina.ha.tcp.ReplicationValve.send(ReplicationValve.java:523)
  | at org.apache.catalina.ha.tcp.ReplicationValve.sendMessage(ReplicationValve.java:511)
  | at org.apache.catalina.ha.tcp.ReplicationValve.sendSessionReplicationMessage(ReplicationValve.java:493)
  | at org.apache.catalina.ha.tcp.ReplicationValve.sendReplicationMessage(ReplicationValve.java:404)
  | at org.apache.catalina.ha.tcp.ReplicationValve.invoke(ReplicationValve.java:333)
  | at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
  | at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803)
  | at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
  | at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
  | at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459)
  | at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
  | at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
  | at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
  | at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
  | at java.lang.Thread.run(Thread.java:748)

[skabashnyuk]

we want to avoid http session replication.