In the following src portion of DGCClient.java,

---- jdk7u9/jdk/src/share/classes/sun/rmi/transport/DGCClient.java ---
...
    652 /**
    653 * Make all of the clean calls described by the clean requests in
    654 * this entry's set of "pending cleans". Clean requests for clean
    655 * calls that succeed are removed from the "pending cleans" set.
    656 *
    657 * This method must NOT be called while synchronized on this entry.
    658 */
    659 private void makeCleanCalls() {
    660 assert !Thread.holdsLock(this);
    661
    662 Iterator iter = pendingCleans.iterator();
    663 while (iter.hasNext()) {
    664 CleanRequest request = (CleanRequest) iter.next();
    665 try {
    666 dgc.clean(request.objIDs, request.sequenceNum, vmid,
    667 request.strong);
    668 iter.remove();
    669 } catch (Exception e) {
    670 /*
    671 * Many types of exceptions here could have been
    672 * caused by a transient failure, so try again a
    673 * few times, but not forever.
    674 */
    675 if (++request.failures >= cleanFailureRetries) {
    676 iter.remove();
    677 }
    678 }
    679 }
    680 }
.....

--------

when rmi connection(dgc.clean()) completes and then exceptions(other than ConnectionException) occur, the connection seem still alive in "catch" clause.

Furthermore, in "while()" loop, the above mentioned flow (dgc.clean() and exception) is iterated(re-tried),
a lot of rmi connections(resources) remain.
It seems that the rmi connections should be closed explicitly in catch(Exception) clause.
(or in a timely manner)