Bug 49170

Created attachment 25333 [details]
patch against trunk.

Config
<Manager className="org.apache.catalina.ha.session.DeltaManager"
         sendAllSessions="false"
         sendAllSessionsSize="XXXX" />

DeltaManager#handleGET_ALL_SESSIONS is as follows.
=====
...skip...
if (isSendAllSessions()) {
    sendSessions(sender, currentSessions, findSessionTimestamp);
} else {
    // send session at blocks
    int len = currentSessions.length < getSendAllSessionsSize() ? currentSessions.length : getSendAllSessionsSize();        Session[] sendSessions = new Session[len];
    for (int i = 0; i < currentSessions.length; i += getSendAllSessionsSize()) {
        len = i + getSendAllSessionsSize() > currentSessions.length ? currentSessions.length - i : getSendAllSessionsSize();
        System.arraycopy(currentSessions, i, sendSessions, 0, len);
        sendSessions(sender, sendSessions,findSessionTimestamp);
...skip...
    }
...skip...
}

=====

sendSessions maintains previous Session. 

For instance,
currentSessions=[ssA, ssB, ssC, ssD, ssE]
sendAllSessionsSize=3

loop1 : sendSessions=[ssA, ssB, ssC]
loop2 : sendSessions=[ssD, ssE, ssC]

ssC is transmitted two times.
It should be the following. 

loop1 :  sendSessions=[ssA, ssB, ssC]
loop2 : sendSessions=[ssD, ssE]

This problem exists in TC5.5, TC6.0, and TC7.0. 

I made a patch against trunk.

Best Regards.