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magro / memcached-session-manager

A tomcat session manager that backups sessions in memcached and pulls them from there if asked for unknown sessions
Apache License 2.0
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Session data not copied to node after recovery. #300

Open JakubDziworski opened 8 years ago

JakubDziworski commented 8 years ago

I have a problem non-sticky session configuration:

 <Manager className="de.javakaffee.web.msm.MemcachedBackupSessionManager"
    memcachedNodes="n1:host1.yourdomain.com:11211,n2:host2.yourdomain.com:11211"
    sticky="false"
    sessionBackupAsync="false"
    lockingMode="auto"
    transcoderFactoryClass="de.javakaffee.web.msm.serializer.kryo.KryoTranscoderFactory"
    />

I tested the following scenario:

  1. n1 goes down
  2. there are changes to session being performed
  3. n1 recoveres
  4. n2 goes down
  5. Session does not have changes from point 2

Looks like n2 does not copy data to n1 after n1 is recovered. Is it a bug or am I missing something in configuration?

magro commented 8 years ago

As I understand the scenario then the webapp receives a request only at 2, but not between 3 and 4. In this case msm cannot do anything because session replication is passive, i.e. only performed per request. To have active session replication you'd need something like couchbase.