HPROF analysis with MAT in the context of CONTROLLER-1756 is showing 50 MB used up in org.opendaylight.ovsdb.southbound.transactions.md.TransactionInvokerImpl, at a stage when (according to Sridhar/Sai) the system should be "at rest" - so this looks suspicious.. so I'm guessing something is probably not really done right there.

see also OVSDB-423 in related code, but that just cleaned up shutdown, not fix this.