Grouper Users - Open Discussion List

I've moved on to the next phase of our work with ldappc, and 
replicating group memberships from MACE Grouper into an ldap 
directory. I've encountered a problem, and I'm seeking suggestions.

I'm using an instance of MACE Grouper that uses Oracle to store group 
definitions; an ldap directory holds  the referenced user objects. 
I'm using ldappc to create and manage group objects in an ldap 
directory; I'm also asking ldappc to manage the isMemberOf values on 
the user objects in the ldap directory.

MACE Grouper currently contains several thousand groups. In my 
current tests, I'm trying to replicate all of the groups in one stem. 
I believe there's about 5-600 groups in this stem; several of them 
contain 18,000 members. (yes, a future note will ask whether having a 
group object with 18K hasMember values represents good practice  ;-) 
).

ldappc runs along, happily synch'ing group memberships, until it 
encounters a specific group. My initial assumption as that this might 
be a problem with heap size, so I tripled the the JVM size when 
invoking java + ldappc (to -Xmx768m ), but ldappc stopped at the very 
same group.... I am able to list the membership of the group when I 
use the MACE Grouper GUI..... so I'm presuming the DB is ok.....

Here's the specifics on the error messages:

Suddenly, for every member of this problem group, it seems to output 
this error message:

[edu.internet2.middleware.ldappc.synchronize.GroupEntrySynchronizer] 
SUBJECT[[ NAME = shinwon moon ][ ID = 100489850 ]] connection closed

I can see the corresponding ldap searches in the logs on the ldap 
server side, and they appear to be successful....

the last msg associated with this group is:

[edu.internet2.middleware.ldappc.synchronize.GroupEntrySynchronizer] 
GROUP[[ DISPLAY NAME = 
COMMUNITY:APPLICANT:DEGREE:COMMUNITY.APPLICANT.DEGREE.SCB ][NAME = 
COMMUNITY:APPLICANT:DEGREE:SCB][UID = 
7d745cc5-f508-4cfa-a47c-665ca5667e79]] :: 
javax.naming.CommunicationException: connection closed [Root 
exception is java.io.IOException: connection closed]; remaining name 
'brownGroupRDN=COMMUNITY:APPLICANT:DEGREE:SCB,ou=groups,dc=brown,dc=edu'

and then it moves on the next group......

For fifty or so groups, it outputs the java.io.IOException msg on the 
first member.....

and, then suddenly, for one group, reverts to the plan and simple 
"connection closed" message again.....

when done with that group, it goes back to the java.io.IOException 
msg's for the next batch of groups....

The last msg in the error log file is:

Grouper Provision Failed: null dto in class 
edu.internet2.middleware.grouper.GrouperSession

and then it stops (before completing the set of groups in that stem....)

Any and all suggestions welcome, even for next steps to try......